ExhausT NoTE - The Turbo Diesel Register conversation yielded the “Exhaust Note” column. Each ... The principle of the steam turbine ... The turbocharger was the result

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Thought Provoking Discussions with Automotive/Motorcycle Journalist Kevin Cameron

Excerpts from the Turbo Diesel Register

ExhausT NoTE

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I’m a magazine junkie. I subscribe to all types of enthusiast publications. I’ve noted a trend that has the final page of the magazine addressing the audience with thought provoking commentary or question. I have followed Kevin Cameron ‘s writings since the ‘70s as a columnist for Cycle magazine. As a current motorcycle columnist for Cycle World, I read his prose monthly. Kevin can make a rod bolt interesting (Yes, he recently wrote about rod bolts). His writings will make you marvel at the intricacies of the mechanical world. I contacted Kevin and sent him several TDR magazines. “Kevin, do you know anything about diesels?,” I asked. His response, “I’ll give it a try. Reciprocating mass is reciprocating mass.” Our conversation yielded the “Exhaust Note” column. Each quarter, you’ll find Kevin in the back with his comments on machinery and engineering. Thanks, Kevin.

Robert PattonTDR Editor

From the TDR Editor

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Table of Contents74 OfficialCure-Alls77 WhatisaHemi?80 StayinginOnePiece82 Issue48’STheme–Historical

Perspective:China’sDevelopment83 GastoLiquid—GTLDieselFuel84 TurbochargerHistory86 SCR,FuelEconomyandTwoStroke

Diesels88 ToolboxDiary90 UnlimitedEnergyfromCarpetFluff?92 MoreHarpingonanOldTune94 AddingUpSmallGains96 CoffeeTableEngineering–

MyToo-RealExperiences98 DieselsatSea100GettingItRight102HittingtheNewNumber105LegalForceandaCrazyQuestion108ShootingUpForDiesels?110Hoping112DiselAlternatives–MakingtheChoice114Cummins,Chrysler,Fiat116GTLRevisited118Smoke120ByGolly,YouDon’tSay!122OnHold124MoreThanOneWay126PurelyAcademic128DieselsintheUSA130ConflictingInterests133SimplicityandSomethingtoThinkAbout

4 KevinCameronBiography5 DieselsandTurbos6 WinterFuel,Power,Bearingsand

CombustionTemperature—SomethingtoThinkAbout!

8 TorqueConverters10 TorquedOff12 RingsandBreak-In14 EngineLubeOil18 TDR–80/2020 DieselCombustion22 TDR–Basics24 TheFactoryKnowsBest–24 AStockVehicle?26 DieselPoweredFuture?26 WhereTheyLeftOff28 MoreAboutOil32 Apples-to-ApplesBaselineandOverkill34 Reasons38 TiresandtheMarketingofAmerica42 DieselDevelopments46 IntheToolbox48 RacingDiesels?50 Choices52 Brakes56 BurningItAllUp58 ThroughtheCycle60 DieselPolitics62 FutureofDieselintheUS64 FlameDiffusionandYourNextDiesel67 InvisibleTechnology70 It’saDrag72 DieselReview

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Whocanaccountfortheinterestsofverysmallchildren?WhenIaskedmymotheraboutcarengines,shereadtomefroma1942Britannica—“TheAeroEngine,”“TheAutomobile,” and “Motorboats.”She toldme years later that shewassure I understood very little of theinformationatthetime,butIinsisted.Indesperationshephonedalocalgarageand a run-out, six-cylinder, flatheadStudebaker enginewaswinchedontoourgaragefloor.WithborrowedtoolsIremovedtheoilpanandthenstaredinpuzzlementatthelumpsofsludged-upmetalwithin.Nothing looked like thecleangeometriesshowninbooks.

Later,myuncleandIstoodataBriggs&Strattonpartswindowandreceivedthethingsweneededtorebuildthefamilylawnmower.Mydadwasskepticalbutmy uncle said, “If it has fuel, spark,compression,andtiming,physicsmakesit run.”And itdid.Faster thananyonecan think it, thedumbmetal repeatedits cycle, intake, compression, power,exhaust.

AttheuniversityIstrayedfromphysics,trudging up a busy avenue toRobertBentley Publishers, where for $10 IboughtRicardo’s“HighSpeedInternalCombustion Engines.” It carriedmebeyondgrinding valveswith a suctioncupontheendofastick,andcleaningringgrooveswithabrokenring.Makingthings run is good, but I alsowantedaccess to ideas, to have some ideawhere technology was going. Morebooks followed, on aircraft engines,on two-strokes—andA.W. Judge’sclassic, “HighSpeedDieselEngines,”with its descriptionsof the fascinatingNapier‘Deltic’andtheturbo-compound‘Nomad’flat-12. I had nomoney, somotorcycleswerewhat I could afford,andthenmyfriendsandIwentracing.The books helpedme navigate theprejudicesofpracticalmen.(“See,thecoolant’sgoin’thrutheenginesofast,itdon’thavetimetopickuptheheat.Yougotta slow it down…,” or “Them two-strokers is like awoman—sometimesthey rungood, an’ sometimeseven ifyou do everything the same, they goblooey.”)

Years inmotorcycle racing followed,building and tuning. I have the usualcollectionof racingstories,backedbypistonswithsaggeddomes,connectingrods broken and twisted into limbodancers, needle rollers flattened intolittlebluepancakes.In1973Ibegantooccasionallywrite for the lateCYCLE magazineaboutracingandmotorcycletechnology.Andtherewasalwaysmoretoread—forexamplePaulSchweitzer’sslim1949volume“ScavengingofTwo-StrokeCycleDiesel Engines,” whichreveals the variety of thinking thathas gone into thesemachines.AndSchlaifer andHeron’s “DevelopmentofAircraft Engines andFuels,”whichshowed how close aircraft enginemanufacturers came to adoptingthe Diesel cycle around 1930—andwhy.Themore I looked, theclearer itbecame that everything is connected.In “LiquidRockets andPropellants” Ifounda chapter byF.A.Williamswiththedauntingtitle“MonodisperseSprayDeflagration.”Williamshasdevotedhisentireworkinglifetothestudyofhowfueldropletsburninasurroundingoxidizinggas—the diffusion flame problem inDiesel design turns out to be directlyrelatedtocombustioninrocketengines.Fuelinjectorsdevelopedfortwo-strokesend up in gasoline direct injection(GDI) four-stroke engines. Conceptsdevelopedinattemptstocontrolspark-ignition knock turn out to beuseful inreducingDieselemissions.Thereisnoknowledgethatisuselessorirrelevant.Andit’sallinteresting.

My family came into being and full-schedule racing became impossible.Motor-journalismtookmoreofmytimeas racing took less—it turnsout therearen’t toomany peoplewriting aboutinternal combustion technology.Oneday Robert Patton phoned.Would IliketowriteaboutDieselengines?Yesplease.

We’ve had the great fortune of Kevin’s insight into all things mechanical since Issue 17 in the beginning of 1998 when the TDR was a healthy 108 pages.

Kevin Cameron Biography

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Diesels and TurbosI‘mnotsurewhataregularcontributortomotorcycleandsnowmobilemagazinesisdoinghereinTDR,butindefenseoftheidea,letmepleadtobeingawide-rang technology enthusiast. Once,ona trip toFrancekindlyprovidedbyMichelin,IvisitedthePantheonwhich,anadditiontobeingabouttofalldown,has amysterious subterranean cryptinwhichallsortsoffamouscharactersareburied.InoneofthemassivestoneboxesweretheremainsofSadiCarnot,whoseworkon thermodynamiccyclesinspired Rudolf Diesel’s attempts todevelopamoreefficientheatengine.NodoubtyouhavereadofDiesel’sstrangedisappearancein1913,fromthedeckofa channel steameroperatingbetweenEngland and the continent. Was thisan accident or suicide. Was he, assome alleged, eliminated by personsunknown, intent upon preventing hisspecial knowledge frombeingappliedtoanothernation’ssubmarines?* TheDieselenginedidhaveafascinationforsubmarinebuilders,foritsuseoflow-volatilityoilfuelmadeitallbutimmunefromthevaporexplosionsthatdestroyedmanyanearlysub. Most importantly,because of theDiesel’s high thermalefficiency, the total weight of engineandfuelwaslessthanthatofanequallypowerful geared steam turbine, thenthe dominantmarine power system.This made Diesels a natural whenGermany,limitedbythepostWWItreatyofVersailles to building vessels of nomorethan10,000ton,chosetwo-stroke,double-actingDiesels for its “pocketbattleships”of1931andlater. In the automotive field, the Dieselappears overweight as comparedwith equivalent gasoline enginesbecause; (a) Itmust be strongly constructed towithstandsteady,unthrottledoperationathighcompressionratio.InaDiesel,theairsupplyisunthrottled,butthefuelisthrottled. (b) It can efficiently react only about80%of theaircharge itdraws into itscylinders.

For the creativemind, a problem isjust an opportunity, and the power ofaDiesel engine is limited only by theair pressure in its intake, and its ownphysical strength; blow in twice asmuchair;mixwith additional fuel andgettwiceasmuchpower.Theprincipleof the steam turbine—a high-speedjet of gas spinning a vanedwheel todevelop power—suggested using theenergy in internal combustion engineexhaust gas to drive a supercharger.Theturbochargerwastheresult. ThefirstDieselstobeturbochargedwereslow-turning large two-strokes,whichneedlargevolumesoflow-pressureairblownthroughtheirports,toscavengeawayexhaustgasandrefillthemforthenext power stroke. Dr.AlfredBuchi’sexhaust-drivenblowerwasanaturalforthisservice. Today, themost efficient primemoverin theworld remains the largemarineturbochargedtwo-strokeDiesel,typicallyturning60-90rpm,withgiantcylindersmeasuringaslargeas36inchboreby60 inch stroke. Thesemonsters canconvert 55% of the fuel’s availableenergyintohorsepoweratthepropellershaft. Compare thatwith the20-25%efficiency of the spark-ignition autoengine, or the 30-35%of high-speedDiesels.Economiesofscale! Research begun at the end of WW I by SanfordMoss and othersled to evaluation of turbochargersasameansof improving thealtitudecapabilities of aircraft. Gear-drivensuperchargers had to spin faster athigher altitudes, requiring complexmulti-speed drives. Turbos had nosuch problem, andmany thousandswerebuiltforAmericancombataircraftinWW IImost notably for themajorbombersB17,B24,andB29,plusforhighaltitudeenginessuchasP47.Intheaircraftcase, the turbocontinuedtoevolveafterthepistonenginehad,sotospeak,driedupanddroppedoff,leavinguswiththeaircraftgasturbine,whichisjustafancyturbochargerthatgeneratesitsownhotgasandcreatesapropulsivejet.

Metals developed for these toughapplications havemade possible thepresent-day automotive turbocharger.The power-developing expansionprocess in its turbine ismirror-imagedby thepower-consuming compressionprocess in its compressor. In theturbine,exhaustgasisledintoacircularcavitythatsurroundstheturbinesteel.Thiscausesthegastowhirlasitflowsradiallyinward.Thewhirlingmotionofthe exhaust gas is transferred to thevanes of the turbine wheel, and thegasesexitfromthecenterofthewheel,essentially stripped of their energy.Typical turbine efficiencies are in therangeof80%.Onthecompressorside,airenters thecenterof thewheelandisflungoutwardthroughradialblading,exitingthewheelmovingatessentiallythewheel’sbladetipspeed,whichmaybe1500feetpersecondormore.Inacircularhousingaroundthecompressorwheel, this high velocity is sloweddown,ordiffused,beingconvertedintopressureenergythatsuperchargestheengine’s cylinder.Again, compressorefficiency is somewhere near 80%atbest. Since efficienciesmultiply, thetypicalturbocharger’soverallefficiencyis .80 x .80= .64, or 60-oddpercent.These is a lot better than just lettingtheenergydumpouttheexhaustpipewithoutdoinganyusefulwork. Turbochargers are pumps, and assucharecousinsof the rocketengineturbopumpsthatsupplyfuelandoxidizertoliquid-fueledrocketengines.EachoftheSpaceShuttle’smainoxy-hydrogenengineshasa compact high-pressurefuelturbo-pump,aboutthreefeetlong,that develops 74,000 horsepower toinject 178 pounds of hydrogen persecond at about 8000 psi. Contrastthis with a typical automotive turbo,supplying a 6 liter enginewith a 10poundboost,developinginthevicinityof 20 horsepower. Turbochargers,fascinatingdevices! Turbo Diesel RegisterIssue 17

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Winter Fuel, Power, Bearings and Combustion Temperature — something to Think about! Elsewhereinthisissue,JoeDonnellyreferstochemistryaspartofthereasonforlighterdieselfueluseinwinter.Onaper-poundbasis,Dieselfuelcontainsmoreenergythanmotorgasoline,andheavier fuels usually contain morespecific energy. Winter diesel fuelhas to be lighter to resistwaxing, soit contains less energy andmileagesuffers.Backinthelate1980’s,however,designersofFormulaOneracingcarsgotinterestedinthisrelationship.Sincetheyhadalreadypushedengine rpm,compressionratio,andbreathingability,theydecidedtopushchemistryequallyhard.If,theyreasoned,itwerepossibletogetmoreenergyfromeachcubicfootoffuel-airmixture,theirengineswouldmakemorepower. AsMr.Donnellynotes,nature’spetroleumis backward for our purposes; for thelightermolecules, volatile enough toconstitutegasoline,naturehassuppliedastructureofstraightcarbonchainsthatare susceptible to the detonation, orknock, that limits compression ratio inspark-ignitionengines.Fortheheaviermolecules found in the less-volatilecompression-ignitionengines.Fortheheaviermolecules found in the less-volatile compression-ignition fuels,nature has supplied branched chainsand ring structures that would behighly effective in fighting knock—butthis is the very opposite of what weneedforgooddieselignition.Tomakediesel fuel ignite promptly, we needsimplemolecular structures that areeasilyknockedtopiecesbytheheatofcompression—piecesthatthencombinewith atmospheric oxygen to begincombustion.Thisproperty,almostthereverseofoctanenumber,isthedieselfuel’scetanerating,ameasureofeaseofignition. WhattheFormulaOnechemistswantedwas stuff volatile enough to form amixture in theirspark-ignitionengines,with an adequate octanenumber, butwiththehigherenergyofcompressionignition fuels. This turnedout tobea

classofcompoundscalleddienes,thosecontaining two double carbon bonds.The fuelscontainingsuchcompoundsweren’t really gasoline, because theywere laboratory creations, but theydidallowausefulpowerboost.Ifyouwatched televised races in the 1991period, you’ll have seen the refuelingcrews,dressedhead-to-toeinspacemansuits to protect them fromhe slightlycarcinogenic,diene-basedracefuel,aweirdcousinofthestuffyouputinyourtruck’stank. I recently toweda heavy horse trailermanymiles behind a spark-ignition-powered pickup, and I foundmyselfwishing,inthehillsofNewHampshire,thatputtingmyfootintoitwouldproducesomethingmorereassuringthanweakaccelerationandlouderknocking.Likethethin,between-the-teethmusicofaturbo spooling-up, effectivelymakingtheenginebiggerbyblowingabiggerengine’s-worthofairintoit. An engine’s power is proportionalto its rpm, times its stroke-averagedcombustionpressure,timesitsdisplace-ment.Rpmisreallyjusthowoftenyouperform the power producing cycle,combustion pressure varieswith howmuch air you get into the cylinders,anddisplacementisthesizeofthehallwhere thisdance isheld. Backwhenthefirstcrisishit,makersofheavytruckdieselenginesdecidedtoimprovefueleconomyby reducing rpm from2200to about 1800. Since a diesel usesonly about 80%of its air charge, thatmeant engines needed either moredisplacement (undesirable increasedweight and bulk) ormore combustionpressure. The combustion pressureoption was the path taken, and theturbochargerwasthetoolthatmadeitpossible. All these engines use so-called plainbearings,consistingofthinshellsplatedwith bearingmetal, running againstsmooth cylindrical journals groundonthecrankshaft,withoilbetweentocarry

theload.Aplainbearing’sload-carryingabilitydoesnotcomefromthepressureof theoilpump,but fromtheviscosityoftheoil,combinedwiththemotionofthecrankshaft.Viscosityisliquidfriction,andasthecrankturns,viscosityallowsthecranktosweepoilfromtheunloadedsideofthebearing,aroundtotheloadedside.Theunloadedsideofthebearingisconstantlykeptfullofoilbytheoilpump.Oilisconstantlysqueezedfromthesidesof thebearingsby the load,butcrankrotation and viscosity always sweepmoreintoreplaceit.Thisactionresultsinthefortunateabilitytocarrythousandsofpoundsofloadperprojectedsquareinchofbearingarea. As a plain bearing is loadedmoreheavily,itsjournalispushedoff-centermoreandmore,andtheminimumoil-filmthicknessintheloadedzonedecreases.Friction rises—but not as fast as theload.The result is that the bearing ismostefficientat the instantbeforetheloadcrushedtheoilfilmtozeroandthebearingfails.Ontheotherhand,frictionrisesasthesquareofrpm.Thesetwofactsbeingso,itismoreefficienttobuildahigh-pressureturboengineoperatingat a lower rpm, rather than a lower-pressure, non-turbo) or ‘atmospheric’)engine,runningatahigherrpm. Dieselenginescanbemadetorunatmuchhigherrpm—off-shorepowerboatracing diesels regularly turn 6000revs—butinthisgame,fueleconomyisless important thanbrutehorsepower.Butovertheroad,fueleconomyisthedieselengine’sreasontoexist,solowrpmandhighcombustionpressurearethewinningcombination. Theexhaustpollutantscallednitrogenoxides result from high combustiontemperature,butadieselalwaysburnsits fuel in the presence of excess air(leanburn).Thisoughttoreducepeaktemperature.Whatgives?Thecauseofthenitrogenproblem is called ‘sheathburning.’ As a fuel droplet clusterevaporatesinthecombustionchamber,

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itisveryfuel-richatitscenter,veryleanatitsouteredges.Somewherebetween,there is a layer (sheath) where themixture is chemically-correct, and thecombustionflameseeksoutthisregionbecauseitburnsfastesthere.Thispeak-temperatureflameregioniswheremostofthenitrogenoxideisproduced.Theproblemisattackedbymorethoroughfuel-airmixing—developingfuelinjectorsthatcandeliverfinerspraysthatarestillcapableofdeeplypenetratingthedensecompressedairinthecylinder.Thisisthereasonforthosehighinjectionpressuresup around 20,000 psi. High-poweredrifles,whichmaybefiredatmostafewthousandtimesintheirlifetimes,developpeakpressuresonly2-3timesgreaterthanthis,whileaninjectionpumpmustlastthroughahundredmillioncycles!

Turbo Diesel RegisterIssue 18

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Torque Converters

Yourtruck’sturbochargermaynotbetheonlyturbo-machineryonboard.Ifyouarerunninganautomatic transmission, itstorqueconverterisanotherapplicationofsimilarprinciples. Atorqueconverterisaspecializedkindoffluidcouplingthatcanconvertaninputatlowertorqueandhigherspeed,intoanoutputathighertorqueandlowerspeed.It is, in effect, a kind of continuously-variable transmission using fluid flowratherthangearsandothermechanicalelements.Becausetheconverteritselfcannotchangespeedoveraverywiderange, it is coupled to an automaticgearboxwhoseseveralspeedssupplythenecessaryextra range.The resultisasystemabletokeeptheengineatanefficientrpmoverthevehicle’swholespeedrange. The converter looks like a big sheet-metaldoughnut,boltedtotheengine’sflywheel,withashaftcomingoutofitscenter. Inside are an input impeller,face-to-face with an output turbine.Thereisalsoathirdelement—thestator.Impellerandturbineareequippedwithradial vanes. The engine spins theimpeller,which centrifugally throwsoil(the entire unit is kept full ofATF, orautomatictransmissionfluid,atalltimes)outward,thenintoandagainstthevanesoftheoutputturbine.Theturbine’sshaftdrivestheload. Thereareanalogiestoaturbocharger.The converter’s impeller is like theturbo’scentrifugalcompressor.Insteadofair,oilentersitsvanesattheirsmallestdiameterandisflungoutwardbythem,gainingkineticenergy.Thisoutflowoffast-movingoildrivestheturbine. Atorqueconverter’sturbineisaradial-inflowmachine just like the exhaustsectionofaturbo.Intheturbo,exhausthasisductedtowhirlaroundtheoutsideoftheturbinewheel.Asitflowsradiallyinward, the whirling gas strikes theturbine blades. Decelerating againstthesebladesconvertsthekineticenergyofthegasintopressure.Thispressuredrives the blades around, deliveringpowertotheturbine.

In the torque converter, power comesfromthewhirlingoilbeingflungoutbytheadjacentinputimpeller.Asthisoilenters the inlet faceof the turbine, itskineticenergyisconvertedintopressureagainst the turbine’s blades. Thiscreatesthetorquethatspinstheturbine.Theoilflowsinwardthroughtheturbine’sradialbladingandemergesatasmallerdiameter,andwithlessenergy. Itisthereredirectedtoflowbacktowardtheimpelleragain.Theoilcontinuouslymakesthisloopfromimpellertoturbineandaroundagain. So far,we’re just describing a simplefluidcoupling.It’susefulbecauseitcanallowanenginetoidlewhiletheoutputturbinesitsstill,yetcanmakeastrongconnection as the engine speeds up.But there’saproblemwith thissimpledevice.Fluidcouplingsareefficientonlywhen the differencebetween impellerandturbinerpmissmall.Astheimpellerspeedsupandtherpmdifferencerises,efficiencyfalls.Thisisbecausethelow-energyoilemergingfromtheturbineisrotatingmuchmoreslowlythanarethevanesoftheimpellertheyaretryingtoenter.The result is violent fluidshear,turbulence,andreducedefficiency.Thismeansafluidcouplingispoordeviceforacceleratingavehiclefromastop. The stator of a true torque converterfixes this. It isa ringofcurvedvanes,located between the turbine’s outflowregionandtheimpeller’sinflowregion.Thesestatorvanesturntheoilemergingfromtheturbine,sothatitnowrotatesin the samedirection as the impeller.Withthissidewayskickfromthestator,theoilenterstheimpellerwithoutallthatshear and turbulence. Now couplingefficiencyishighevenwhenthereisalargedifferencebetween impeller andturbinerpm. Because of its efficiency, we canexamine the torque converter from aconservation-of-energy standpoint.Energyinmustequalenergyout.Let’ssayourengineisspinningtheimpellerat2000rpm,puttingin400pounds-feetoftorque.Let’ssaytheturbineisturning

only1000rpmbecausethevehicleisstillaccelerating.Inorderforenergytobeconserved,rpmxtorqueinmustequalrpm x torque out.This give us 400 x2000=torqueouttime1000rpm.Output torquemust therefore equal 800pounds-feet. Real torqueconvertersdohavesomelosses because theATF in them,although very light-bodied, doeshavesome viscosity (fluid friction).Also,despitethebestpossibledesignofbladeshapes,thereisstillsometurbulenceintheconverter’sinternalflows. Thisdoublingoftorqueisnotsomethingfor nothing—it is just usinghydraulicsinsteadof gears. If youmechanicallygearedtheenginedownataratioof2:1,youwouldcertainlyexpecttheoutputtobe800pounds-feet of torqueat 1000rpm(minus“nature’stoll”intheformofacoupleofpercentfrictionloss). Buthowdoestheimpeller,turning2000rpm,with 400 pounds-feet of torque,produce800pounds-feet of torque ina turbine of the very samediameter?Thistorqueistheresultofkineticenergycoming from the impeller—the high-energyoilbeingflungoutofit,againsttheturbine’sblades.Stopthinkingofitasanimpellerandthinkofitinsteadasapowerfulfirehose,producinga jetoffast-movingoil.Ifweincreasethespeedoftheliquidshootingfromthefirehose,won’tweexpecttogetincreasedtorqueon the turbine?The impeller is just apump that throws oil at the turbine.Thefastertheimpellerspins,themoreoilitthrows,atahighervelocity,attheturbine.The result is greater turbinetorque. Howmuch torquemultiplicationcanatorqueconverterproduce?Theefficientrangeof torque converters is typically2-2.5. As thevehicleacceleratesandturbine and impeller speeds cometogether, torquemultiplication dropsuntil, at cruise, there is only minorslippage and no torquemultiplication.The device ceases to be a torqueconverter andbecomesa simple fluidcouplingagain.Tomakethispossible,

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the stator vane ring ismounted on aone-way clutch. In torque-convertermode, the torque on the stator kicksit back against this one-way clutch,lockingitsoitcandoitsjobofturningtheflowemergingfromtheturbine.Butasturbinespeedcomesupnearimpellerspeed,torqueagainstthestatordropsandthenreverses,andthestatorturnswiththerestoftheassembly.Thetorqueconverter has become a simple fluidcoupling. Tosavefuel,torqueconvertersarenowmadewithalock-upclutch,hydraulicallyoperated and (usually) electronicallycontrolled. Under non-accelerationconditions, no torquemultiplication isneeded,sotheimpellerandturbinearelocked together, eliminating the smallslippageandlossthatwouldotherwiseoccur.

Big and Little Torque converters are sized to thetorquetheymusttransmit.Atanygiveninputrpm,thebiggertheconverter,thehigher the velocity of oil coming fromitsimpellerwillbe,andthegreatertheareaofengagementbetween impellerandturbinefaces.Thisgivesthebiggerconverteritsgreatertorquecapacity. Dragracersandfansknowthatpowerfuldragsters in automatic transmissionclassesmayuseverysmallconverters.To launch from the starting line, theenginemust turnata speedatwhichitmakes high torque, and in a raceengine,thiscanbe5000ormorerpm.Convertersforthisapplicationareratedin terms of “stall speed”—the rpm atwhichtheywillholdtheengine,onfullthrottle, with the brakes on. Even a“little”9-inchconvertercandothejobinsomeoftheseapplications,becauseat8-10,000 rpm this small converterwilltransmitenormoustorque.Inthiscase,torque capacity is coming from rpmratherthanfromconverterdiameter.

history Lesson At the usual rpm of Diesel engines,adequateconverteroutflowvelocityhastocomefromdiameterratherthanfromrpm. Both the fluid coupling and thetorqueconverterwereinventedbeforeWWIbyHermannFoettinger,anelectricalengineer working at Vulkanwerke, ashipyard in Hamburg,Germany. Asalways, it’s fascinating to see howofteninnovationscomefromoutsiders.Despitecreativeworkbymanypeopleinthe1920sand‘30s,successfullarge-scaleapplicationofthetorqueconvertertovehicledrivehadtowaitforWWIIandthemeninGM’sProductStudyGroupNumberThree. EarlyUS tanksweremadeespecially vulnerable by havingto pause to shift gears, and by thesmokepuffsemittedduringshifting.Theengineers inPSG#3quicklycombinedan industrial torqueconverterwith theautomatic-shiftgeartrain fromanearlyGMHydramatic transmission (whichthenusedonlyafluidcoupling),andinsixweekstheyhadmachinedcastingsandadyno-readyprototype. Many variations on the basic torqueconverterhavesincebeenbuilt.Someusemultiplestatorringsorvariable-pitchstator blades to broaden the rangeoftorquemultiplication. Today, amajorgoal of torque converter transmissiondesignistoholdenginesneartheirmostfuel=efficientrpmasroadloadchanges.Thesimple2-and3-speeddesignsofthepasthavegivenwaytothe4-and5-speedgearunitsof today,drivenbylockup-typeconverters,andcontrolledbyevermore-complex(oftenelectronic)controls. Anyonewishingtoreadmoreaboutthedevelopmentofautomotivetransmissionswillenjoy thebook “ChangingGears,”byPhilipG.Gott. It is published bythesocietyofAutomotiveEngineersinWarrendale,PA.TheSAEpublicationsorderlineis412-776-4970. Turbo Diesel RegisterIssue 19

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Torqued off

You’vefinishedassemblingyourcylinderheadandhavesetitinplaceonanewheadgasket.Anyalignmentdowelsareproperlyinplace.Yourunthefastenersdownsnug,thenlightlyseateachonewithashort-handledratchet.Youreachfor the torquewrench, ready to starttightening.Haveyoueverthoughtaboutwhatisreallygoingonhere? As you tighten the nut on a stud, thenuttriestopullthestudupthroughthecylinderhead,evenafterthegaskethasfullycompressed.Asyouturnabolt,theheadstayswhereitis,butthethreadspulldeeperintotheblock.Something’sgotta give here;what is happening isthatthestudorboltshankisstretchingaswe torque it up—stretching like aspring.And that is exactlywhat boltsand studs are—powerful springs thatare tensioned to hold parts together.Threadsare simply a convenientwaytotensionthosesprings. The rule of thumb for head gasketclamping force is that it should befour times the force of peak pressureduring combustion. If, for example,that peak pressure is 1500 psi in afour-inch cylinder, thenwehave1500pounds times the bore area of about13 square inches, for a total peakcombustion force of 18,000 pounds.Four times this—64,000 pounds—iswhat we have to get from the headbolts or studs around the cylinder, inordertoensureadurableseal.Iftherearefiveboltsaroundeachcylinder,thatis a tension of approximately 13,000pounds fromeachbolt.Therefore themainthingtorememberasyoutightenboltsornutsisthatyouareestablishingaparticular,necessarytensionineachone.Thistensioniswhatholdsmachinestogether. Thistensionisthedirectresultofhowmuch thematerial in the fastener (ourspring)isstretched.Everymaterialhasasortofspringconstant,calledYoung’smodulusofelasticity.Itrelatesstretchtotension.Forsteel, thismodulushasavalueofaboutthirtymillion,anditdoesn’tvarymuchwithalloycompositionorheattreatment.Young’smodulushasnothing

todowiththeforcerequiredtobreakorpermanentlystretchamaterial—itonlytellsushowmuchstretchproduceshowmuchtension. Asyoutightenabolt,itbecomeslonger.As you loosen it, it becomes shorteragain,resumingitsoriginallengthwhenallstresshasbeenremoved.Thiskindofstretchiscalledelasticdeformation. If you deliberately tighten a bolt untilyoufeel thatdreadful looseningof thewrenchinyourhand,youwillfindthatwhentheboltisremovedanditslengthremeasured,thatithasnowpermanentlystretched.Lookcloselyandyouwillseethatsomepartofthebolthas“necked-down”toasmallercross-section.Thisiswhythewrenchloosened—thematerialwas stretchedbeyond its elastic limit,andhasbeguntodeformelastically.Astheboltnecksdown,itlosestension. The strength of a fastener is just ameasureofhowhardwehave topullon it before it stretches permanently.Strength is therefore a measure ofhowfarupthematerial’selasticrangeextends—howmuchtensionwecangetoutof itbeforeitbeginstoneckdownor actually breaks.The rigidity of thematerialisitsspringconstantwhileitisoperating in itselasticrange.Strengthistheouterlimitofthematerial’selasticbehavior. Ifwetightenafastenerenoughtodriveitpastitselasticlimit, itstartstoyield,beginning to neck down, lose cross-sectional area, and lose tension.Thisiswhy fastener-tightening torquesareserious business, not a testosteronechallenge.Recommended installationtorquesaredetermined to letyouusemostofthefastener’sstrength,leavingsomemarginofsafetybeforepermanentstretchbegins. My favorite story concerns a hot-rodder whowas having trouble withhigh-strength studs breaking on trickSummersBrothersaxleshewasusing.Overthephone,thecompanyengineerverifiedthatthecomplainerwasusinga

torquewrench,anddidknowthecorrecttorquevalue.So far, sogood,but thebreakage continued. Eventually, thecompany sent a rep to figure out theproblem. “Letmeseeyoutorqueupthestuds—justlikeyoualwaysdo,”requestedtherep. Theracerranthenutsontothestuds,seated them, and began torqueing,usinganimpressive,name-brandclickertorquewrench.Smoothly,hesweptthewrencharounduntilitjustclicked.Thenheturnedthenutanotherquarter-turn.“Stop!” shouted the rep. “What, in thenameofheaven,areyoudoing?You’resupposed to stop when the wrenchclicks!” “Well,” replied the racer, “I don’twant‘emtocomeloose.” By over-torqueing those studs, thewell-meaning, but ignorant racer,wasdriving thematerial past its elasticrange, permanently stretching thestuds.Weakenedinthisway,theywerebreakinginservice.Assoonastheracertorquedafreshsettothecorrectvalue,hehadnomorebreakage. This story is amusing, but people stillmakethismistaketoooften—losing,notgaining, installation tensionby addingmoretorque. How dowe know howmuch tensionweareputtingonafastener?Insomeapplications,itcanbemeasureddirectly.Forthecon-rodboltsinsomeengines,the instructions call out amicrometermeasurement tensioning technique.Measure the fastener’s length beforeinstallation,thentorqueituntilitmeasuresacertainnumberofthousandthsofaninchlonger.ThisissimpleandaccuratebecauseitisbasedonYoung’smodulus,whichrelatesstress(tension) tostrain(theamounttheboltisstretched). But you can’t use this lovelymethodwhenoneendofthefasteneristhreadeddeepintoyourengineblock.Inthatcaseyoumustrelyonatorquewrench.What

11

doesitmeasure?Itmeasurestheforcerequiredtostretchtheboltorstud,plusthefrictioninthethreadsandagainstthewasher.Howmuchof the total torquevalue is fromstretch, howmuch fromfriction?Thereisnowaytoknowexactly,butindustryassumesastandardamountof friction, based upon standardizedconditionswhenthefasteneristorqued.Thismeansnew,freshparts,freefromrustandgrit,anditusuallymeanswithlightlyoiledthreads-notdry.Underthesestandardconditions,therecommendedinstallation torqueproducesadequatefastenertensiontodothedesiredjob. Butinourrealworldofprivatelyownedmachinery,nutsandboltshaveusuallybeenassembledat least oncebefore(at the factory). Thismeans that thethreads of the nuts will be slightlydeformed,because theyaredesignedto do just that on assembly.Nuts arepurposelymadesofterthanboltsinordertoevenoutstressconcentrations.Aftersuch deformation, nuts producemorefrictionthanbefore.Rust,grit,orlackoflubricationalso lead to deviation fromstandardconditions. How can you do it right and guardagainst assembly failures?The bestwayistoreturntothestandardsusedat the factory. Inheavily-loaded,high-stressapplicationslikecon-rodboltsornuts,usenewfastenerseverytimeyoubuild.Makesurethethreadsarecleanandputadropofoilorassemblylubeonthembeforeassembling.Inlesscriticalapplications,atleasthavealookateachfastenerasyoubuild,andrejectthosethat are obviously deformed, orwon’tthreadsmoothlybyhand.Cleanandoiltheparts. Use the torquewrenchwherever themanualcallsoutaninstallationtorque.Ifyouarejustbeginninginmechanics,letthetorquewrenchteachyourhandwhat reasonable torques feel like forthevarioussizesoffasteners.Tryingtoextractbrokenfastenersisnofun. Ifyouplantouprateanexistingenginewithmore turbopressure, there is thepossibility that the resulting higher

combustion pressure will pop yourheadgasket.Findoutinadvanceiftheexistingheadbolts/studswilldothejob;asksomeonewhohasdoneit.Ifbiggerorhigher-gradefastenersarerequired,they are cheap insurance against alongwalk.


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becauseofcompressionleakage,anditmayuseoilatanexcessiverate.Thisiswhymanufacturersnowadvise thatenginesbebroken-inwith fairlyheavythrottle,alternatingwithcoasting. On the oil container youwill find twobasic pieces of information. One isthe viscosity rating, such as 15W-40.The other is theAmericanPetroleumInstitute (API) category, such asCG-4.The first letter identifies theenginetype—C for compression ignition, Sfor spark ignition. The second letteridentifiesasetofstandardsthattheoilmustmeet.This, ineffect,defines theadditivepackageintheoil,whichdoesthings like provide anti-wear action,resist rusting,oxidation, sludging,andsoon.EarlyAPIcategories,suchasCA,CB,etc.,haverelativelylittleinthewayof additives.Recent categories havemuchstrongeradditivepackages. It isthe anti-wear additives, such as zincdialkyldithiophosphate(ZDDP–justtrysayingthatonerealfastfourtime),thatmakebreak-inharderthanitusedtobe.Thishasledtopracticesthatyoumayhaveheardof,suchasthe“drybreak-in,”or theuseofspecialbreak-inoils.Follow theadviceof themanufacturerorexperienceddealerhere–theyaredoing this every day and they knowwhatworks. Inadrybreak-in,theengineisassembledwithnooilonthecylinderwallsorpistons,andjustadabofoilisappliedtoeachpistonskirtasitgoesintothehole.Otherbuildersrecommendjustawipeofoiloneachcylinderfromanoilypapertowel.When the engine is started, the revsarebrought up to half of red-linewithnoload,andheldtherefor30seconds.Thentheengineisstoppedandtheoilischanged.Strangetosay,thisseeminglyweirdpracticeworkswellinsomecaseswherenothingelsedoes.Itisevidenceofhowdifficultthehighperformanceofmodernoilscanmakebreak-in.Thisisespecially trueof syntheticoils,whichoften have extra-aggressive additivepackages.Manyenginebuilderspreferthatanenginebebrokeninonmineraloil beforebeingswitched tosynthetic.[Trueof theCumminsengine.Donot

Rule (1) avoids generation of excessheat and wear particles that couldcausedamage.Rule(2)accomplishestwothings.First,shortperiodsofheavythrottle apply the pressure that isnecessarytodrivepistonringsthroughboththeoilandadditivefilmstoachievethe surface-to-surface contact that isnecessary to break-in. [Editors note,CumminsReConenginesareeachrunon the dynamometer for a 20-minutebreak-inperiod.Fiveminuteswarm-upto check for leaks then followedby aprogressivefullpowerrun.Newenginesare only tested for leaks.] Second,gettingoff-throttleterminatesthebreak-inaction,preventingexcessbuild-upofheatandwearparticles.Thecoastingtimeallowstheoilsystemtosweepthewear particles to the filter, andallowslocallygeneratedheattoflowawayintotheenginestructure. A special problem of our era is thefailed break-in.This canbe the resultof “babying” during break-in—steadydriving at very low speed and load.Thiscanbemadeworsebyhigh-techanti-wearadditivesinmodernoils.Suchadditivesformsolidmetallicsoapfilmsonenginefrictionsurfaces.Thesefilmshavemuch lower friction thanmetalonmetal, and canwithstand severalpasses at high pressures like 90,000psibeforetheyaregougedaway.Thefilmsaresacrificial–theyyieldatmuchlowerforcethandoestheunderlyingpart–andtheyre-formaslongasthereisadditiveremainingintheoil.Theycanaffectbreak-inbybeingabletocarrythelocalloadbeforethepistonringshavewornintofullcontactwiththecylinders.The ring, in effect, develops polishedareasandthenthebreak-instops.Forthisreason,someenginesaresuppliedwithspecialbreak-inoilalreadyinplace,tobechangedafteraspecifiedperiod.[Editor’s note,Cummins engines areshippedfromthefactorywithaninitialfillofCumminsPremiumBluemineralbasedmotoroil.]Suchoilcontainslessanti-wearprotection,sothatbreak-incanoccurmoreeasily. Iftheringsfailtobreakincompletely,theenginewillneverdevelopitsratedpower

Engine parts aremade as preciselyas technology and economy permit,but the finalmanufacturing operationis performed by you, the owner.That is break-in. In this process, themicroscopically imperfect surfaces ofpiston rings and cylinders, crankshaftjournals and bearing shells, tappetsand cam lobes, are given their finalsmoothingbybeingruntogetherintheassembledengine. Normally, throughmost of the enginecycle,moving parts are separated bycompleteoilfilmsorbyacombinationofanoilfilmwithprotectivesurfacelayersprovidedbyanti-wearadditiveS in theengineoil. Theminimumoil film thickness underloadinacrankshaftbearingcanbeaslittle as 1.5microns,which is .00006inch.As manufactured, neither thebearing shells nor the crank journalsare anything like that smooth.Undermagnification, their surfaces are seentoconsistofendlesspeaksandvalleys,many of which are taller than theminimumoilfilmthicknessunderload. Thereforewhenyoustartupyournewengine, the tallestmountainsoneachsideoftheoilfilmaregoingtohiteachother.When they do, the high localpressurecausesthemtoweldtogether,afterwhichthecontinuedmotionofthepartsbreaksthisbond,releasingwearparticlesintotheoilfilm.Allthiswearingandpluckinggeneratesheat,and thatcauses the local oil viscosity to drop.That,inturn,causestheminimumoilfilmthickness togetevensmaller, leadingtomorecontact,welding, tearing,andheating.Continuedwithout let-up, thiscanleadtoseizure. Crankshafts prettymuch take care ofthemselves in thisprocess,butpistonringsand cylinderwalls are critical tosealingand therefore to performance.The general rules for break-in haveremainedthesameforalongtime:(1)nosustainedfull-throttleoperation(2)alternatecyclesoffairlysubstantialthrottle with periods of coasting orreducedpower.

Rings and Break-In

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change to synthetics or a syntheticblenduntilafter theengine is“settled”atapproximately10kmiles.] The lighter the duty of the engine,themore difficult break-in becomes,because the average applied load issmall.Whenyouhearofpeoplehavingbreak-in troubles, the explanationusuallylieswiththeoilandafailuretoapplyheavyenoughload. Informertimes,break-inwasagradualprocess taking as much as 1,000miles, consistingmainly of painfullyslowdriving.Thisworkedbecauseno-additiveoils of the1940sand’50sdidnot save rough engine surfaces frommetal-to-metalcontact,andringswerefiled by the cross-hatch honing of thecylinderwallsintoagoodfit. Thecomingofmorecapableoils—bothmineralandsynthetic—hasforcedenginemakerstoprovidefinersurfacefinishesand rounder, straighter cylinders. Ineffect,moreofwhatusedtobebreak-inisnowperformedinthefactory,leavinglessmaterialtoberemovedinthefirstfewhundredmilesofuse.


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Engine Lube oilLubricationcomesinthreeflavors:

1)Full-film,orhydrodynamic.Asapistonringslidesalongthecylinderwall,orasacrankshaftjournalrevolvesinsideitsbearing shells,metal-to-metal contactiscompletelypreventedbytheabilityofoiltoformawedge-shapedfilmbetweentheparts.Full-filmlubricationdependsuponthephenomenonofviscosity—oil’sinternal friction prevents it frombeinginstantly squeezed out from betweenmovingparts. 2)Boundary Lubrication.Whenanoilfilm isnotpresent, additives in theoilformprotectivelayersontheparts.Suchprotective layers can preserve partsfrommetal-to-metalcontactuntilfull-filmlubricationisrestored. 3)Mixedlubrication.Thisisacombinationoftheabove,whichoccursduringenginestarting,whenmostoilhasdrainedawayfromparts,orwhenpartsmotionistooslow tomaintain full-film lubrication,aswhenpistonsand ringsmoveveryslowlyandunder great pressureneartopdeadcenter. Thisdescriptionmakes it clear that, tolubricate under all conditions, oilmusthaveviscosity,anditmusthavetheabilitytoformprotectivelayersonparts. Acrankshaft journal ispushedslightlyoff-center in itsbearingsby theforcesacting on it. The result is that theclearance spacebetween journal andbearingsisthickerononeside,thinnerontheother;itformsawedgethatlooksrather like an extremely thin crescentmoon.Onthethicksideofthiswedge—the unloaded side—the clearancebetween journal andbearing is about.003”. On the thin, loaded side, theclearanceismuchsmaller—onlyafewmicrons,maybe as little as .00006-.0001”.Whatdrivesoilintothewedge,towards a local pressure that can beas high as several thousand poundspersquareinch?Certainlynotoilpumppressure,whichneverexceeds100psi.Thedrivingforceisinfactthemotionofthecrankshaftitself,combinedwiththeinternal friction—the viscosity—of the

oil.Crank rotation continuously dragsoil into thewedge,with enough forceto generate extremely high pressuretherethatsupportstheload.Naturally,muchofthishigh-pressureoilescapesfromtheedgesofthebearing,butfreshoil is being supplied to the unloadedsideofthebearingclearancespacebythepump, throughdrilledoilholes.Aslongasthereisoilaheadofthewedge,with enough viscosity to carry it intotheloadedzone,thecrankjournalandbearingshellswillnevertouch. If theoil hadno viscosity, if itwereacompletely frictionless liquid, itwouldinstantlybesquirtedoutofthebearingandwould never support any load atall.Conversely,bearing friction isalsocaused by viscosity—because of oil’sinternal friction, it takespower to turntheloadedbearing. Alittle-knownandcounter-intuitivefactisthatplainbearingsandrollingbearingshaveapproximatelyequalfrictionlossesin running engines. Rolling bearingsdo have lower friction at low speeds,which iswhy automanufacturers arebeginningtouserollertappetsagaininvalvemechanisms. Al l o i ls lose v iscos i ty as the i rtemperature increases, and the slopeoftheviscosity-vs.-temperaturecurveiscalledtheviscosityindex.Twoobviousrequirementsforanyoilare(a)thatitsviscositymust be low enough at lowtemperaturetopermitcold-startingand(b)thatatthetemperatureofhotengineparts,itmuststillretainenoughviscositytoformafilmthickenoughtoseparatepiston rings from cylinder walls andcrankjournalsfrombearingshells. Intheold,pre-additivedays,thismeantsearching high and low for oil basestockswithahighviscosityindex(VI).Pennsylvania crudeoilsweregood inthis respect.Now, however, there areways to alter any oil’s viscosity indexwithadditives,tocreatewhatarecalledmulti-viscosity or multi-grade oils.Whenyouseeaviscositygivenastwonumbers, such as 10W40, the oil solabeledbehavesasa10gradeatzero

degreesF (W stands forWinter), butasa40gradeat200degreesF.Thisoffersanadvantage,asfollows.Ifyoufilled your crankcasewith a straight10 grade, at piston-ring temperatureinawarmed-upengine, thisoilwouldhave lost somuch viscosity as to beunabletosupporttheloadsrequiredofit.Pistonrings,backedbycombustionpressure,wouldsqueezethisthinoiloutfrombetweenthemselvesandcylinderwalls, resulting in unacceptably rapidwear.Butifyoufilledupwith40-gradeoil,nostarterdevisedbymancouldturnyourcoldengineinFebruary,inThreeRiverFalls,MN.Thereforemulti-gradeoilswerecalledintoexistencethroughchemicaltrickery.

Theyworkthisway.Anadditiveconsistingoflong-chainpolymersisdevised.Whencold,moleculesofthispolymerhavelittleactivity, and so theyeffectively roll upintolittleballs,havinglittleinfluenceonviscosity.Butasthetemperaturerises,allmolecules—oil and additive—havemorethermalactivity.Thelongpolymers“unroll”, and their longchainspartiallycountertheoil’slossofviscosity.Bythetime200degreesisreached,theoilisnolongeractinglikea10;it’sactinglikea 40-grade instead.Theoil still losesviscosity,butbecauseofthepresenceoftheVI-improver,itlosesless. Thepossibleflyintheointmentisthattheselongpolymerchainsarenottotallydurable.Theycanbebrokenbypassingthrough gearmeshes and cam lobe-and-tappet contacts. Some polymersare stronger than others.Thismeansthat, as time passes, the multi-VIsadditivebreaksdown.Atfirst,theDieselcommunitywasskepticalofmulti-gradeoils,but today, ithasbeendiscoveredthat a goodmulti-grade oil’s slowerloss of viscosity as temperature risescontinuestoholdgoodeveninthetoughenvironmentofthetoppistonring,whichmay operate up near 350 degreesF.Durablemulti-gradeDiesel-qualifiedoilsnowexistwhichretaintheiradvantagesthroughstandardoil-draincycles. Now amomentary digression. Oneaspect of design that is nowexerting

15

pressure on lube engineering is topringplacement.Whenanenginefires,combustion chamber pressure risesvery high, and this pressure entersthe landclearanceabove the top ringandthepistonringcrevicespaces(thesmall clearance above and behindeach ring), carryingwith it some fueland/orpartial productsof combustion.As thepistondescendson thepowerstroke, cylinder pressure falls as thecombustiongasexpands.Highpressureremainsintheringcrevicespaces,onlyemergingwithitscargoofunburnedfuellateinthepowerstroke.Thismakesameasurable contribution to unburnedhydrocarbons in the exhaust, causingred lights to come on inAnnArbor,Michigan.AnythingthatcanbedonetoreduceringlandandcrevicevolumewillthereforecutunburnedHCemissions.This, in turn, tempts engineers tolocatepistonringsclosertothetopsofpistons,and to tightenup ringcreviceclearances. Both of these changeshave a potential tomake rings stick.First,higher temperatureoxidizesandpolymerizesoilintogumfaster.Second,the smaller the ring clearances aremade,theeasiertheyaretoclog.Lubeengineerswill have to livewith thesechanges,findingwaystolubricatehotterringsandtokeepthemfree. The oil can or bottle carries anotherpiece of useful information, theAPIcategory. TheAPI is theAmericanPetroleumInstitute,andtheydivideoilsintotwobasictypes:thosecompoundedforspark-ignition(S)engines,andthosemade for compression-ignition (C)engines. Every engine oil, therefore,carrieseitheraCorSprefix,followedby another letter that designates theparticular set of standards that theoilmeets.Asconditionsinenginesbecometougher(forexample,astopringsarerequired to runhotter in turbochargedengines),oilsmustbecompoundedtohandlethoseconditions.Newtestsaredevised,bywhichoilscanbequalifiedfortheseharsherconditions.

Back in 1950, oils contained nothingmuch but oil, and you will still hearold-timerswho say, “Just givemean

oil that’s all oil—none of these fancyadditives.”Backthen,therewasagrainoftruthinwhattheysaid.Oneofthefirstwidely-usedoiladditiveswasoil-solubledetergent,addedtopreventtheformationofsludgeandvarnishonengineparts.Whena sludged-upolder enginewasswitched to thenewdetergentoil, thedetergent action released a flood ofcorruptionthatblockedfiltersandevenblocked oilways.This is the basis ofthe old-timers’ objections.This is nolongervalidbecausetoday,asallnewvehicles employ detergent oils,whichprevent sludge from accumulating inthe first place. It is removedwith theoilandfilteratthescheduledchanges.Non-detergent oils are stillmade forapplicationsinwhichtemperaturesaretoohighfortheadditivestosurvive.Thetypicalexampleislawn-careequipment,whose air-cooled cylinders, their finsusuallyblockedwithgrassclippings,runatunbelievabletemperatures. Asapistonrisesandfalls, itsvelocityvaries from zero at top and bottomcenter, to a maximum at about 78degreesaftertopdeadcenter.Althoughpiston rings are springy,most of theforce pressing them out against thecylinderwall comes from combustiongas,whichentersthepiston-ringcrevicefromabove,thenpushesouttheringsfrombehind.Thisensurestheirsealing.*But if thepressureof theringontheoil filmbeneath it is toogreat, theoilfilmwillbecometoothintocompletelyseparate the ring from the cylinder.Theoilfilmalsovarieswithvelocity;asthepistonslowsnearTDC,oiltendstobesqueezedoutfromundertherings.The tallest imperfections on the ringwill begin to occasionally touch thoseonthecylinderwall.Wheretheytouch,the pressure is tremendous, and theresult is localwelding.As the pistonmoveson,theweldsbreak,generatingwearparticles.Theheatgenerated inthisprocessheatstheoillocally,whichloses yetmore viscosity,making theoil film thinner yet, leading tomorecontactandheat.It isaviciouscycle,oftenleadingtoscuffing.Somethingisneededtoprotectsurfaceswhenpartialcontactismade.

Thatsomethingisfrictionmodifiersandanti-wear additives. Frictionmodifiersaremoleculessuchasfattyacidsthathaveanelectrical affinity for surfacesand therefore form a protective layeron them. They are oily long-chainmolecules, and the layer they formhasconsiderablestrengthandamuchlowercoefficientof frictionthanmetal-on-metal. Anti-wear additives react chemicallywithmetal surfaces to forma layerofmetallicsoap.Suchlayerscanwithstandmanyunlubricatedcyclesatpressuresofthousandsofpsi.Theyprotectpartsbybeingweakerthanthemetalunderthem,sothatscuffingoccurs,notonthepartsthemselves,butinthesacrificialadditivelayersadheringtothem.Whensuchafilmislocallygougedoff,itre-formsfromadditionaladditivecarriedintheoil. Inareasofmixedlubrication(pistonringsnearTDC,allenginepartsatcold-start,betweencamlobesandtappets,etc.),these additives achieve remarkablereductionsinwearanddamage. Really large concentrations of potentanti-wearadditivesareusedintruegearoils-thisisresponsiblefortheirspecial“stink”.With theaidofsuchadditives,manygearsactuallybecomesmootherthe longer they run. In high spots,where localpressure isveryhigh, therateoffilmformationanddestructionisalsohigh.Becausesomemetal is lostwith thescraped-awayadditivefilm,apolishingactionresults.GL-5gearoilisawonderfulthing,andIhaveseengearssurviveinitthathadpreviouslyfailedinordinaryoils.Additiveswork! Other types of additives prevent rust,allowoils to remain liquid at very lowtemperatures, and slow oil oxidationat high temperatures.Modernoilmaycontainasmuchas20%byvolumeofadditives,eachofwhichhasaspecificandessentialjobtodo. Afreshcontroversysurroundsthelatestin automotive oils (those designatedwith the S category, those labeled“Energy-Conserving”, orSJ.Becausemost auto engines are spark-ignition

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andemployexhaustcatalysts,theuseofmetallicadditivesintheiroilhassomepotential for poisoning the catalyst inthesamewaythatfuelleaddoes.Thepotent anti-wear additive ZDDP (zincdialkyl dithiophosphate) contains zinc,and for catalyst protection, engine oilzinc content forS oils has nowbeenlimited.Oils for compression-ignitionapplications (diesel those designatedwiththeC—forcompression—category)are not limited in this way, andmaycontainasmuchanti-wearasengineersfindnecessarytoensureadequatepartsprotection.Therefore, it is not true tosay“Oilisoil”andblithelypourintoyourenginewhateveryoufindonsaleatthepartsstoreorsupermarket.Dieselsworkharderthanspark-ignitionengines,andtheyareworkedharder.Theyneedalltheprotectionthatmodernoilscangive.Readyourvehicle’sowner’smanualtofindtheoiltypespecified,anduseit.Ifthereisanyconfusion,askyourdealerorcallthemanufacturer.


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Your Notes:

18

TDR – 80/20

Although you, the reader,maynot beawareofit,allofuswhowriteforTDRreceive a certain amount of directionfromour forwardair controller,RobertPatton.Thatway,we are allmore orlessshootingatthesametargetinanygivenissue.Inthisissue,thattargetisoneoftheunwrittenlawsofnature,thatof diminishing returns. Everyone hasanecdotesrelatingtothis,andI’llgettomineinamoment,butfirst,this; ThecentralfactoftheDieselengine—itshighcompressionratio—isaperfectexampleofthisrule.Internalcombustionengines make power by burning acompressedmixtureoffuelandair.Theheat addedby combustion raises thepressure of this gasmixture, and thispressure, allowed to expand againsta piston or other device, performsuseful work.Themorewe compressthe air before burning fuel in it, thehigher the combustion pressure thatresults.As a rule of thumb, this full-throttlepeakpressureisabout80timesthe compression ratio—a pretty highpressure,whichiswhyDieselengineshavetobeheavilybuilt. Themoreweexpandtheburnedgasesaftercombustion,themorecompletelywe extract their energy. These factsmakehighcompressionandexpansionratios desirable.For obvious reasons,aDiesel’scompressionandexpansionratiosareequaltoeachother.TheDieselengine’s desirable fuel efficiency is adirectresultofitshighcompressionratio.Sparkignitionenginescannotusesuchhighratiosbecause,ongasoline, theyresultindestructiveknock. Ideally, to get all theavailable energyinhigh-pressurecombustiongas,we’dexpand it all the way down to zeropressure,butthisisimpossiblebecausetheenginehastoexhaustagainst15psiofatmosphericpressure.Also,ittakesa certain amount of pressure just toovercomepistonandpiston-ringfriction.For theseandother reasons, there isno useful gain in expanding the gasindefinitely.Indeed,ifwegraphouttheenergy extracted from high-pressurecombustion gas versus compression

ratio,weseeacurvethatrisessteeplyat first. For example, you get a biggain by going from theModel-TFordcompressionratioof3to1,uptothe5to1ratioofChrysler’s“high-compression”sixesof theearly1930s.Asyoukeepraisingthecompressionratio,however,the gains get smaller, and the curveriseslessandlesssteeply.Finally,whenyougetuptonumberslike13or15,thegainfromgoingtothenextratiohighergetsprettysmall.Thisiswhatthelawofdiminishingreturnslookslike! Ofcourse,aDieselenginewon’tevenstart and run unless its compressionratioishighenoughtoheatitsairchargeabovethetemperatureof fuel ignition,so that and other characteristics ofthe engine set a desirableminimumcompressionratio.Pre-chamberDiesels,suchasthatintheVWRabbit,havealotofextrainternalcombustionchambersurfaceareathroughwhichheatislostas the piston rises on compression.Such engines therefore need highercompression ratios, above20 to one,justtostartreliably. But there’s another effect to considerhere, which redoubles the law ofdiminishing returns. That is overallheat loss during combustion.Asweraise the compression ratio, we alsoraisethepeakflametemperature,andthatpushesheatoutthroughtheheadand piston crown faster.A couple ofparagraphs agowemade a curve oftheoretical energy recovery versuscompression ratio—andnow thisheatlosseffectcausesthatcurvetoflattenoutevenfaster.Theresultis,foreitherDiesel or spark-ignition (gasoline)engines, that peak efficiency comessomewhere pretty close to 17 to onecompression.Bearinmindthat,forthespark-ignition engine, detonationmayverywellpreventyoufromreachingthathighnumber. Thereyouhaveit.Theorysuggeststhatmaximumenergyrecoveryoughttobeassociatedwithaninfinitecompression/expansion ratio, but realitymakes usstopwellshortofthatgoal.Asit turnsout,more than eighty percent of the

recoverableenergyhasbeenexpendedonthepistonbythetimeitisonlyhalf-waydownthecylinder.That’sausefulfact,becauseitallowsustheluxuryofbeginning to open theexhaust valvescomfortably before BDC—withoutsignificantlossofpower. I mentioned anecdotes. My specialinterestismotorcycleracing,andasinotherformsofmotorsport,bikeenginebuildersuseaflowbenchtodevelopandimproveflowthroughintakeandexhaustports. In general, higher flowmeanshigher power. Flow specialists spendtheir lives surroundedby the insistentwhineoftheflowblower,watchingthegages expectantly to see if that lasttweak pushed the numbers up. It’sascloseasengineeringgets toaslotmachine.Anumberofyearsago,IaskedRobMuzzy, a prominent builder, if heusedtheflowbench. “Areyoukidding?”hereplied.“Youcanloseyourmindthatway.Yeah,Iuseit,butonlytothepointofgettingabout80%oftheimprovementI thinkispossible.IfIspentmoretime,I’dbetakingitfromanotheractivitythatdeserveditmore.” Anotherracerfriendcompiledstatisticsfrom ten years of bike road racingchampionships.The peoplewhowonchampionshipswerenotthepeoplewhowonthemostraces—infact,theytendedtofinishanaverageof third—butwithzeroDNFsandzerocrashes.Assomeannoyingpersononcenoted,“theyonlyawardthepointsatthefinish.” You can see the reason for this on astopwatch at any race.Put thewatchonsomeonewhoisrunningbyhimself,withoutaclosecompetitor,andeverylapwillbeexactlythesame,oftenwithinacoupleofhundredthsofasecond.Thisutterconsistencycomesfromrunningatapacethattheraceriscomfortablewith.Nowputthewatchonthetwomengoingfor the lead and the picture changesdramatically.Because the leaders aredrivingeachotherashardastheycan,eachman has to try things he’s notentirelysureof.Theresultisthatbothmenmakesmallmistakes,whichcause

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thelap-to-lapvariationtobecometenthsofasecondinsteadofhundredths.Themancruisingback in third isdelightedwith this situation. The leaders arein danger of crashing because of themistakestheyaremaking,andbotharepushing their engines and tires veryhard.Will theycrash,blowup,or justburn up their tires?Theman in thirdgladly accepts any of the above.Hehasdoneagoodday’sworkthroughhiscraftsmanlike conservatism—and hasscoredchampionshippoints. Thereare lots ofways to throwawaytheoverallresultbytryingtoohardforthedetails.Aparticularfavoriteofmineis the “King of the late brakers.”Thisis themotorcycle racerwhodiscoversthat,bybrakinglateandveryhard,hecanoftenpassother ridersgoing intoturns.Thisbecomeshisreligion.Whenhefinallygetsintoreallyfastcompany,his systemstopsworking.By brakinglate,heentersthecornertoofast,whichforceshimtogowide,muttering“Oops,oops,oops”underhisbreath.Themanhepassedonthewayinnowre-passeshimonthewayout.Believingutterlyinhissystem,LateBrakerdoesitharderatthenextcorner,causinghimtoarriveinmid-corner even hotter andmoreout-of-shape than before. The othermanagaindivesunderhimand,whileLateBrakerisgettinghimselfcollected,motors away.Eventually he overdoesitanddisappearsintoabigdustcloud.Thereisnowaytogetdeprogrammedotherthan(a)toquitracingisdisgustor(b)seethattoomuchofonegoodthingscrewsupallothergoodthings. Nowafinalanecdote,fromacompletelydifferentfield—jetengines.BackwhenLockheedwas developing itsTri-StarL-1011 airliner, the engines werecontracted to come fromRolls-Royce.Rolls engineers worked with mightandmain tomake the RB-211 theirbestengineever,but for reasons thatescapedthem,theyjustcouldn’treachthe thrust and fuel consumption theyhad guaranteed to Lockheed. Thesituationbecamecritical,resultinginacostlycorporatereorganization.Aretiredveteranengineer,StanleyHooker,was

recalled to straighten out themess.Theoneconditionhesetwas thathisrecommendations be followed to theletter.Itwasagreed. RB-211developmenthadbeenbrokenupintosections—oneforthefan,anotherforthelow-pressurecompressor,andsoon.AsHookerwentfromdepartmenttodepartment,hefoundthatoutstandingperformance had been achievedeverywhere. He also found that theoutstandingoutputfromthefansectionwasscrewinguptheflowintothelow-pressure compressor, and that therewere similar startling mismatchesthroughoutthedesign.Accordingly,hewent fromdepartment to department,givinginstructions. “Justputthisextrabitofbladetwisthere.Ithinkwe’dlikealittlelessturningthere,”andsoon. Department chiefswereaghast. “He’sruining our stage!” they objected tohighermanagement.Hookerremindedthemoftheiragreementandhischangeswere grudgingly implemented over allobjections.Whenawholeenginewithhis changeswas assembled and putontest,itproduced6000poundsmorethrustthaniteverhadbefore. Themoralofthestory?Whatisthepointofmakingasystemofoutstandingparts,if those parts are not integrated intoanoutstandingwhole?Bymaking theoutput of each stage compatiblewiththe needs of the next stage,Hookerraised the efficiency of the engine asawhole,even though individualstageefficiencieswere thereby reduced byminoramounts. Pushing too hard in one areameansneglectoftheothers.Withonly24hoursinaday,wehavetostandback,takethelongview,andputtheenergywehavewhereitwilldothemostoverallgood.


20

Diesel Combustion

When theplunger in the fuel injectionpumpmoves,thefirstpartofthemotionpressurizestheheavy-walledlineleadingtotheinjector.Rigidasitis,thelineisn’tveryspringy,butbecauseitisamaterialobject,ithassomegive.Thenextbitofplungermotion unseats the injector’spintle,andfuelbeginstoaccelerateasa spray, into the hot compressed airswirlinginthecombustionchamber. Itwould be nice if combustion begannow, but it can’t. It can’t becauseliquid fuel—what the injecteddropletsaremade of—can’t burn. Itmust firstevaporate and its separatemoleculesmustmixwithair.Thinkoftheinjectedfuelasatorrentoflittleliquidfastballs,pitchedbythepump’s15,000psi,acrossthe injector pintle.These hot pitchesrocket into the hot air, being heatedas they go, shedding comets’ tails ofevaporatedfuel. Because these fuel droplets areevaporating, and because evaporationis a cooling process (it takes energyto boil water, right?), the result is thatthe evaporation of injected fuel coolsthe surrounding air somewhat. Thisfurther delays the process of ignition.Finally the fuel droplets slowdownandtheir temperature climbs back up fromcontinuedcontactwiththehotcompressedair.Aroundeachdroplet,acloudofvaporforms,veryrichatthecore,lessrichasyoumoveawayfromthedroplet. Becausethehotcompressedairinthecombustionchamber isabove thefirepointofthefuel,assoonasfuelvaporformsanditstemperaturerisesenough,itignites.Veryquicklynow,aflamefrontracesalongthatpartof thevaporthathappenstohavean ideal(chemically-correct)mixtureoffuelandair.Theresultisarapidpressurerise,becausebynowquiteabitoffuelhasbeeninjected,butthere has been no combustion.Thisrapidpressureriseisresponsibleforthecelebrated “DieselKnock” thatmakesfuel-miserlydirect-injection(DI)enginessonoisy.Whatyouarehearing is thesudden, rapid combustion ofmuchofthefuelthathasbeeninjectedintothecylinderuptothetimeofignition.

IDI, or indirect-injection Diesels arethose that inject their fuel,notdirectlyintothemaincombustionchamber,butinto a small pre-chamber, connectedto themain chamber througha smallhole. IDIenginesarequieterbecause(a)ignitionoccurssoonerinsidethehotpre-chamber(allorpartofitmaybeofceramic, purposely allowed to remainvery hot) and (b) the rate of pressureriseinthemainchamberisslowedbyhaving to flow through the connectingorifice,whichactsasa“shockabsorber.”Unfortunately, the extra surface areaof thepre-chamberand thehighheattransfer rateassociatedwith the rapidflow through the orifice conspire todecreaseefficiency.WhereDIDieselsoftrucksizemayuseabout.38poundof fuel per horsepower, per hour, IDIDieselsusemore,upinthemid-.40s.Gasolineengines,asacomparison,needmorelike0.5lb/hp-hr.offuel.Gasolineengines are less efficient becausedetonationlimitstheircompressionratiototherangeof8-11:1,significantlylowerthanthe17:1ofanefficientDiesel. Considerableresearchisbeingdevotedto findingways to limit the amount offuelinjectedbeforeactualignition.ThiswillnotonlyquietthenoiseofefficientDI engines, but can also cut nitrogenoxide emissions. Ideally, a Dieselengine burns its fuel in the presenceofexcessair,which isone reason foritshighefficiency.Butexcessairexistsonly on average, not everywhere inthefuelsprayregions.Asthecloudofinjected,evaporatingfuellightsup,theinitialflameseeksout thepartsof thecloudwherethemixturehappenstobechemically-correct,racingalongwhatiscalledthe“stoichiometriccontour:”—theregioninwhichflamespeedisfastest.Thisisaprimezoneforthegenerationofnitrogenoxides,for(a)formationofsuchoxidesaccelerateswithtemperatureand(b)stoichiometric,orchemically-correctcombustiongeneratesmaximumflametemperature. AnotherconcernofDieselcombustionengineers is soot formation,which isresponsiblefor,inthewordsofthesong,“exhaust…blowin’blackascoal.”Inthe

richregionsofthefuelspray,heatdoesbreak down the fuel, but combustionis incomplete because there is notsufficientoxygenpromptlyavailable.Theresultisfreecarbon,lookinginvainforoxygenpartners.Someof this carbondoesfindoxygenlaterincombustion,butascarbonisstickystuff,muchofitfindsothercarboninstead,clumpingtogethertoformsootparticles. AcharacteristicofDieselcombustionisinfraredradiation,whichplaysapartinheatingandignitinglater-burningpartsof the fuel.This infrared isemittedbytheglowing carbon, someofwhich islater emitted as particulates.Anyonewho has seen the exhaust flame ofpiston aircraft engines (gasoline fuel)during a night takeoff has seen thelong, red plume of glowing carbonparticles, resulting from the very hot,butchemicallyuncombinedcarbonfromrich combustion. These engines areenrichedfortake-offbecausetheextrafuel lowers combustion temperature,making detonation less likely. This,in turn, allows supercharger boostto be turned up to make the extrahorsepowerneeded for take-off.Oncesafelyairborne,powercanbereduced,andthemixtureisleanedout.Theredexhaust flamegrows shorter and lessbright,dwindlingtoasix-inchbluecone,surrounded by a whitish glow. Thisblue color results from radiation fromhydrogencombustionandthewhitefromtherecombinationofdissociated(brokenapartbyheat)molecules.Itcanalsobeseenintheflamesofacetylenetorchesandoxy-hydrogenrocketengines(likethoseoftheSpaceShuttle).Allthishotdrama occurs inside the combustionchambers of your truck engine everytimeyourunit,andwhatismore,yourturboeatsthisstuffforbreakfast. At one time, the Diesel engine wasthe white hope of the auto industrybecauseofitslowunburnedhydrocarbonemissions.This is part of the reasonsomanyDiesel carswerebuilt in theearly 1980s. Later, itwas discoveredthat theparticulates inDieselexhaustcontain significant amounts of certaincarcinogens,mostlybasedonbenzene

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rings of six carbonswith added side-chains.Currently,Diesel developmentcenters around achieving reductionsin particulates (and as noted above,nitrogenoxides). Onepartialremedyhasbeenimprovedsprayformation,asameansofproducingsmaller droplets, each surrounded byair adequate for combustion. Injectionrate can be varied—slow initially toshorten the ignition delay, then at afaster rate later.Another approach toquick,uniformlight-offistosupplypartofthefuel,notasaspray,butasvaporaddedduringintake.Simplerfuels,suchas alcohols, break up andburnmorequickly thantraditionalDiesel fuel,butbringwith them ignition problems.AsmallresearchoutfitcalledSonexhasaprocessofacceleratingcombustionbyseedingeach freshchargewithactiveradicals(reaction-acceleratingchemicalfragments)createdduringthepreviouscycle.This, it isclaimed,reducessootconsiderably and canallow ignitionofalcohol fuels.Thecumulative resultofresearch like this is cleaner-burning,moreefficientengines. Diesel combustionhasa bright futurebecause primemovers based on itremainthemostefficientheatengineswehave.Thismakesall the researchworthdoing.


22

TDR – Basics

One of the stand-out features of thismagazine is the inventiveness andpractical skill of its readers.Thebookisfulloflettersfromreaderswhohavemodifiedtheirtrucksorhavefiguredoutengineorchassisproblemsontheirown.Thispleasesmebecauseitfliesinthefaceofoneof themajor trendsofourtimes;thetrendtowardhelplessnessinthefaceoftechnology.Asmywifeputsit,therearemoreandmoremenwhohaveonlytwobasicskills:(a)Whateveritisthattheydoatworkand;(b)WatchingsportsonTV. Ourgreat-grandparentscoulddeliverababy,buildabarn,graftplumtrees,orrepair a side-delivery rake—but eachsucceeding generation has becomemore specialized. General skil ls,common sense, and the willingnessto try unfamiliar tasks have been lostalongtheway.Intheirplacehascomeahelplessdependenceon“experts.”Wehavecometoexpectallusefuldevicestobearthemessage,“Nouser-serviceablepartsinside—returntomanufacturerforservice.” A couple of years ago, I had dinnerwith three profs from a well-knownengineeringschool.Allofthemagreedthateveryyear,thefreshmanstudentsarrivewithhighermathandkeyboardskills—andlessandlessunderstandingof anything physical and practical.Instead of growing up with clocks,radios, lawnmower engines, andtools, these people have spent theirchildhoods studying.As adults, theywill have to buy a new refrigeratorwhenthecondensergetsblockedwithlint,havetocallanelectricianwhenabreakertrips,andhavetowalkwhenatirebecomesflatonthebottom.Noneofthisisnecessary. What is theremedy?Playwith things!Getinandmesswithstuff—yourtruck,for example. Otherwise, the steadyadvance of gadgety technologywallsusinwithunknowableblackboxes—ofwhichcomputersaretheworst.Afterabrief honeymoonof normal operation,myfirstcomputer(1986)gotflakyandquitworking,soIcalledthedealer,90

milesaway.IhadastorylostsomewhereinthatcomputerandIneededtogetittomymagazinerightaway.Another90-miletripdidn’tappealtome. “Yougotascrewdriver?”thevoiceinthephoneaskedme.WhenItoldhimyes,hecontinued,“Breakthesealwhereitsays‘breakingthissealvoidswarranty.’Take out the screws, and lift off thetop.Inside,you’llseesomeflatcableswith connectors at the ends. Thoseconnectorsarethemostunreliablepartsinyourcomputer.Unplugeachoneandcarefullyplugitbackinagain.Chancesare,thiswillfixyourmachine.” It did,proving that simple skillsandawillingness to tackle problems remainvaluableeveninthecomputerera. Sixty-odd years ago,mymotherwasdriving her father’s huge touring-carwhen it quit in traffic. Because it justquitratherthanstuttering,shenaturallysuspected an electrical problem,because engineswith a fuel problemmisfireandsputterastheyquit.Openingthehood,shelookedaroundandfoundanunconnectedwire. Looking further,shefoundaplacewhere itseemedtobelong.Sheattachedit.Thecarran.Youdon’thavetobeamotorheadtohaveusefulcommonsense! My first wife watched me and myracetrackfriendsstrugglewithamodifiedHondatwinwithtrickcarburetorsonit.Nomatterwhatwetried,onecylinderdidnotrun,andwesuspectedthosecarbs.Shecouldseeus losingourcool,andknewnoonewasleavingthetrackuntiltheproblemwasoutoftheway.Dinnerlooked pretty unlikely. So she asked,“Those carburetor thingies—do theyeachdoexactlythesamejob?” We looked up from our frustration toansweryes. “Wellthen”shecontinued,“couldn’tyoutakeofftheright-handcarburetorandputitontheleft,andvice-versa?Thatway,ifoneofthecarburetorsisatfault,theproblemwillmovetotheothercylinder.Andthenyou’llknow.”

Welookedateachother,helplessinthefaceofpurelogicatwork. Common sense plus awillingness tohaveagoarewhatyouneedtobegin.In theprocessof learningmechanicalskills,weallroundoffaboltortwo,twistoffsome taps,andbangourknuckles—thecostsaresmall.Weemergewithakindofconfidencethatyoucan’tgetanyotherway. Machines are not mysteries. Theymake sense.As one old-timer put it,“The humanmind has created thesedevices, so therefore another humanmindcancomprehendthem.”Itisonlylaziness that allowsus tobelieve thatunderstandingisbeyondus. Myuncleoncewenttoworkforanoutfitthatwantedtomakeeducationalfilms.Theyneededascreeningroombuthadditheredforweeksafterbeingquotedbigmoneyforthenecessaryremodeling.Hisanswerwastoask,“where’sthenearestlumberyard?”Afewdayslatertheyhadbuiltwhattheyneeded—forabout1/10of that quote—not becausemy unclewasagoodcarpenterorelectrician(hewasahacker,infact),butbecausehedidn’t like to be stopped bywhat arereally non-problems.Wanting a resultisthebestreasontotakeuptoolsandlearnhowtousethem. Only you knowexactlywhat it is thatyouwant.Ifyoudoajobyourself—evenif haltingly and (at first)withoutmuchcraftsmanship—you aremore likelytogetwhatyouwant than ifyouhaveto explain it to others who then dotheirversionof itforyou.Anyonewhohas dealt with home-improvementcontractorsknowsthetruthofthis.Manyproblemsinlifecannotbesolvedwithacellphoneandadeckofcreditcards. Thereisanelementofjumpingintocoldwaterhere;youwant toswim,but theonlywayistoactuallytaketheplunge.Tacklingunfamiliarmechanicalworkcanbeabitofaplungetoo.WhenIwasfirstmessingwithengines,Iavoidedignitionwork because I didn’t understand it.AlthoughIcouldteardownandrebuild

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engines, I had no idea of how to setignition timing.Thenonedaya friendarrived with his newly-completedTriumphengine,expectingmetoinstallandtimeitsrebuiltBTHmagneto.Iwasterrified. It was time for a showdownwithmy own ignorance. I got out abookandforcedmyselftoreadthroughthetimingprocedure.Ofcourse,itwasstone-simple.Ittoldmetogetawheelspokeandfilenotchesinitevery1/16ofaninch.Pokeitinthroughasparkplugholeuntilitrestsverticallyonthepistoncrown.Startingwith the piston at topcenter,rotatethecrankbackwarduntilthepistonhasdescendedfivenotches.Withthecrankinthisposition,rotatethemagneto housing until the (correctly-adjusted)pointsjustbreak.Tightenthemaghold-downbolts.Nodialgages,noohm-meters—just a simple procedurethatworked.Ihadovercomemyignition-phobia,andwehadarunningengine. Notknowinghowisneveragoodexcuseforinaction,becausethereisalwaysahow-tobook,aknowledgeablefriend,oramanualavailabletohelpyouthroughthehardbits. Thereisapleasingsenseofaccomplish-mentatgettingthrougha joblikethis,and thebestpartof it isknowing thatyouovercameyourself intheprocess.Thejoblookedscary,butwhenyougotintoit,andunderstooditsvarioustasks,youcoulddoeachinturnandmoveontosuccess.Sortoflikelifeitself.


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The Factory Knows Best – a stock Vehicle?

Anyone who works with machineryconstantly has ideas as to how thatmachinerycanbe improved.Adesignthat has or developsproblems, or anarrangement that is hard toworkwith(having to takeoff the frametoemptytheashtrays)alwaysmakesusthinkofpossibleimprovements.Forthepersonwho is handy in themachine shop,thereisagreattemptationtomaketheimprovementsandseehowtheywork.Oftentheydo,whichisagreatsourceofpersonalsatisfaction. Sowhynotgettoworkandjustdoit?Alotofusdojustthat—replacingrusted-in-placeoriginalfastenerswithstainless,forinstance,sowe’llneveragainhavetofindawaytodrilloutbrokenstudsbyfittingseveninchesofdrillmotorintofiveinchesofspace. Backinabout1964,amajorcarmakerdidastudyonwhatitwouldtaketomakeitsvehicleslasttwentyyearswithonlyminor service—not the usual flood offailedbelts,hoses,U-joints,waterpump,exhaust system, andwheel bearingsthatisnormallyunleashedatagefive.Theyconcludedthatsmallincreasesinbearingsizes,higherspecsinmaterials,and judicious use of stainlesswoulddo the job, and atmodest cost.Thatcostincrease,however,wouldputtheirproductsatsuchamarketdisadvantagethatitwouldbefoolishtoputthetwenty-yearschemeintopractice. From recent experience with a 45-year-old aircraft engine, I know thatthe twenty-year-scheme could work—if anyone were willing to pay theincreasedinitialcost.TheengineIamconcernedwithcamefromaTruman-eramilitary transportplane,andhasbeenoutdoorsforatleasttwentyyears,lyingon the ground.Yetwhen I crack theinstallation torque on its stainless orplatedfasteners,mostofthemspinfreeinmyfingers—notwist-offs,noroundedhexes.Theexhaustsystem—madefromtemperature-andtime-resistantinconel—is ready for start-up any time.The

drawbackisthatthisenginewasmadeforaviation,tothehigheststandardsoftheengineeringofitstime.Pricewasnotamajorconsideration. Now for the other side of the story.Backinthe1960s,Iwastryingtoracea Japanesemotorcycle. It was earlydaysfortheJapaneseindustry,andthismachine had lots of problems. Iwasdeterminedtofixallofthem.Icoveredthemachinewithmyowninnovations,andIwasveryproudofmywork.ThenI crashed. Instead of a simple trip tothe dealer for a few dollars’worth ofcrash parts, getting running againmeantduplicationof longhours in themachineshop,makingallmyneatstuffasecondtime.Istartedthinkingaboutthisproblemofcleverprototypes,versusmaybe lessclever,but low-pricedandeasilyavailablestockparts. I like to read history, so I knew thatin 1945,Messerschmitt’s top aircraftdesignerKurtTankhaddescribed theeasewithwhich hewas able to pullaway fromAlliedfighters inhisoh-so-superior long-nosedTA-152.Whatdidthismeanwith respect to thewar? Itmeantnothing,becausewhileGermanycould produce these highly superiormachines in prototype quantity only,onesinglefactoryintheUSwasrollingout a completed, four-engined B-24every fifty-fiveminutes. Yes, Tank’sengineeringwas superior, but couldit defeat thousandsofP-47andP-51aircraftthatwereonlyslightlyinferior? Massproductionhasitsdrawbacks,butits great strength is that it candeliverintoourhands,atlowcost,enoughtools(airplanes,trucks,ships,etc.)togetthejobdone.WhenanAmericanwartimepilotwouldcomplaintohiscrewchiefthathisenginewasrunningrough,they’djusthanganothermass-produced,available-in-quantityengineonthefrontofitandtheproblemwouldbegone. Inanotheroften-heardstory,anAmericanintelligence man was debriefing a

German artillery officer.TheGermanhadbeencapturedafterhisbatteryhadknocked outmore than a dozen tall,undergunnedUSM4tanks.TheofficerwasholdingforthonthepoorqualityandtrainingofUSforces.“Ohyeah?”saidtheAmerican,“Thenhowcomeyou’reinthiscagehereandI’mtheguyaskingthequestions?” “Because”,theGermanreplied,“Weranoutofshellsforour88mmgunbeforeyouranoutoftanks.” Usablemass-produced goods—evenif far from perfect—get the job donebecausetheyexist.Betterideasarecheap,butproductionisthekey. Ithoughtabouttheproblemofrunninganairforce,oratruckingcompany,orarailroad.Availabilityofpartsandserviceiscrucialtoalltheseundertakings.Mymodifiedmotorcyclewasasuccess intermsofideas,butinhardware,itwasafailurebecauseIcouldnotproduceallthepartsIneededasfastasIneededthem. IwasaboyoftenwhenmyfamilydroveuptheAlaskaHighwayina1951Kaiser.Kaiserwasamass-producedautomobile(Henry J. Kaiser had automated theproduction of Liberty ships during thewar)but itwasverymuchanoddball.Thehammeringofhundredsofmilesofdirtroaddrivingresultedintransmissiontailshaftleakagethatthreatenedtoleaveusstranded.ADawsonCreekmechanictold us that, although he couldn’t besurewithout prying it out and therebydestroying it, he thought the tailshaftsealwasaFordpart.ThiswastemptingbecauseweknewtherewerenoKaiserparts anywhere north of Vancouver.Fortunately,itwasaFordpart,andwewereable tocontinueour journey,butthistaughtmethevalueofstandardizedparts, available everywhere. Thinkyour LamboorAston-Martin is a finecar?Thinkagainwhenyou’restoppedin Tok Junction, with a broken half-shaft.Likewise,ifyourmass-produced

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vehicle is coveredwith clever, one-offinnovations,who’sgoingtoserviceitinthemiddleofthenight,inpouringrain,whensomethingquits?Youare. Another aviation story, this oneaboutstockprocedures.A certain shopwasdoing a nice little business regrindingsix-throwaircraftenginecrankshaftsforundersizedbearings.Theservicebook,doubtlesswrittenin1937,insistedthatthegrindingwheel bedressed freshlyforeverycrankshaft.Anyonewhousesgrindingwheels hates to dress them—anewwheel24”indiameteris$300ormore, and repeated dressing justturnsthewheeltopowdermorequickly.Thereforethisoperatorbegantodresshiswheel less often, after every fiveshafts. It wasn’t long before in-flightfailures of his reground crankshaftsbegantocropup,andsoontherewasaninquest. The problem? By not dressing hisgrindingwheelasoftenasspecifiedinthe factorymanual, the operatorwascontinuing to grind bearing journalswith abrasive grains that had losttheirsharpedges.Dressingthewheelknocks out these dulled grains andexposesa layer of fresh, sharpones.Not dressing thewheelmeantmoreheat,higherfeedpressure,andslowercutting. The increased heat in turncausedmicro-scalesurfacecracksinthecrank journals—called heat-checking—thatunderflightstressenlargedintooutrightcracks.Thiswasacaseofanoperatorsecond-guessingthereasonsfor factory-recommendedprocedures.Howdid the enginemaker know thatthewheelshouldbedressedaftereveryshaft?Becausetheyhadalreadymadethissamemistake,painfullyfiguredouttheproblem,andfoundasolution;dressthewheelforeveryshaft. This underlines another principle; thefactoryknowsitsownproductsbest. One ofmy favorites has to do withvehicleemissionsandfuelconsumption.

Anymodificationthatresultsina1/10ofampgimprovementinstandardtestingisworthmillionstoautomakers,intheirannual struggle tomake theirmodelshit the Federally required numbers.Yetmagazines remain full of ads formysteriousdevicesthatclaimtoreducefuelconsumptionbyasmuchas25%.Wouldn’t it beodd if thesedevicesorsubstancesreallyworked,andnotoneofthethousandsofpeopleintheautoindustryknewaboutthem? Another one of my favorites is theliquid,claimedtoreduceenginefrictionbyhugeamounts. In theusual demo,the salesman attaches a tachometerto your engine as it sits idling. Younoteand record the idle rpm.Nowhetriumphantly pours his additive intoyour oil filler, and points at the tach.Miraculously,youridlerpmhasrisenbyahundredormore,“proving”thatfrictionhasbeencutby themagic liquid.Andinfactfrictionhasbeencut.Themagicliquidiskeroseneordeodorizedlampoil,withperhapsafewccperquartofsomestandard-packageoiladditive.Youridlerpmhas risen, not becauseofmagic,butbecausethekerosenehasreducedtheviscosityofyouroil—especiallysoif the enginewas cold to beginwith.Then why not reduce oil viscosityall the times and reap the savings?Because the oil viscosity specified byyour enginemanufacturer is the onethatbest satisfiedall requirements forperformanceand engine componentslife,inprolongedandexpensivetestingthatgoesonallthetime.Iskeroseneabetterlubeoil? This example is a shocker; the no-oiltest.Therepresentativeoftheadditivecompany pours his product into alate-modelvehicle, itsengine running.Thenhepulls thedrainplugand thendramatically drains all the oil into apan,whichheshowstotheincredulouscrowd.Thenhehops intothenowoil-lessmachineanddrives itaround thelot. The admiringmultitude buys theproduct.

In fact, the product could be almostanything,becausemodernengineoilsareso loadedwithanti-wearadditivesthat this demo can be successfullyperformedonalmostanyvehicle(neitherInoranyothersensiblepersonwouldrecommend you try this). Just the oilfilm remaining on parts, aided by thenormaloil additivepackage,will allowtheenginetorunat lowrpmforafewminuteswithoutdamage. The factory knows a lot about itsproductsasaresultofconstanttesting.Do you think (a) that some idea-menwithachemistrysetcandobetter?And(b) that theywouldprefer to sell theirideatoyoufor$9.95ratherthantotheoilcompaniesorvehiclemanufacturersformillions? Thesimplestatement“stockisbest”isnot true in detail, because new ideasare incorporated into vehicles everyyear, frombothwithinandwithout theindustry.Anything can be improved.But that’s not the point. The point isthatstock,forthemostpart,representssomething that is known to work,backed by a lot of experience. Stockalsomeansthatserviceandpartscanbefoundanywhere.Thosearevaluableconsiderations.


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Diesel Powered Future? Where They Left off

BeforeWWI,Dieselenginedevelopmentwas of great concern to Europeangovernments, as theseengines reallymade the submarinepossible. In thatwarand theone that followed twenty-one years later, submarines nearlysucceeded in isolating England andwinningthewarforGermany. Later, as Diesel applications spreadwidely, these engines were evenconsidered for aircraft, despite theirweight. The reason is curious. UntilThomasMidgleyofDelcodiscoveredtheantiknock properties of tetraethyl lead(TEL), and until SamHeron inventedthe internally cooled exhaust valve,the gasoline-burning, spark-ignitedengine was not expected to reachreallyhighpowers.Thephenomenonofcombustionknock,ordetonation,madeitimpossibletoeitherraisecompressionratioveryhigh,ortouseausefulamountofsuperchargerboost.Inengineswhoserpmwas already limited by bearingtechnology,thatseemedtoputacaponspark-ignitionprogress. ThetripImade,towingaheavyhorsetrailer behind a spark-ignition-engine-poweredpickup,gavemeadirectfeelingforthiskindoftechnologicaldeadlock.Once the engine’s throttlewas openwithrpminthegreenzone,thatwasallshewrote.Torquewasmodestbecauseof theengine’s lowcompression ratio,andhad therebeena turbocharger, itcouldonlyhaveboostedtorqueuntiltheenginebegantoknockontoday’s1936-level gasoline.So I had to shift downto keep speed up even onmoderateInterstatehighwaygrades. Facedwiththistechnologicaldeadlock,progressive engine designers in theearly1930shadgoodreasontobelievethat the future of high powersmightliewiththeDiesel,whosecombustionprocessisimmunetodetonation.Blowas hard as you like into a Diesel’sintake-iftheinjectorscanmatchfueltoair,theenginecanburnitandmakepower.

TheGermanJunkersfirmwentaheadand designed its famous Jumo two-stroke 205 opposed-piston, twin-crankshaft Diesel aircraft engine. Itmade 700 hp at 2600 rpm from aweight of something over 1500 lb.Guiberson in theUS flight-tested anair-cooledradialDieselof1020cubicinches,making310hpfromaweightof653lb.InEngland,enginepioneerHarryRicardoprepared test enginestoevaluatesuperchargedDieselsforaircraftapplications. Meanwhile,MidgleyatDelcodiscoveredTEL,which greatly raised the knock-resistanceofgasoline fuels;andSamHeron’s cooled valve greatly reducedthe temperature of the hot exhaustvalve—a prime cause of detonation.Thesediscoveries,plusmuchcollateraldevelopment,madethegasolineengineagain the leading powerplant wheregreatpowerfromminimumweightwasthe requirement.With the exceptionof thewidely used JunkersDiesel, allcombataircraftinWWIIweregasoline-powered.Strangely,whiletheexcellentSovietT-34medium tankwasDiesel-poweredinthatwar,allGermantanksstillburnedgasoline. TheaircraftDiesel seemed to haveanichejustafterthewar,whenpayloadofpiston-enginedtransportswaslimitedbythefueltheyhadtocarryontrans-Atlantic flights.Neither turboprop norjetengineswereyetefficientenoughtoreplacethem.Napierthereforedesignedits dinosaur-like Nomad two-strokeDiesel, which recovered extra powerfromitsexhaustviaturbo-compounding.As it turned out, piston enginesweregoodenoughtofillthegapwhileturbinedevelopmentpushedefficiencyof thatengine to ocean-spanning levels.Thecomplex andwonderful Nomadwasneverproduced. In the postwar era, fuel refinerswereleft with huge excess capacity formakingaviationgasolinecomponents.The auto industry over time took up

someoftheslackbyconstantlyraisingthecompressionratiosofcarengines,as a means of increasing torque.This required fuel with higher knockresistance. One beneficiary of thiswas the light truckbusiness, inwhichinexpensivebig-blockgasolineenginescouldhaulalotoffreightthankstohighcompressionandgasolinegoodenoughtokeepknockatbay. Theeraofregulatedexhaustemissionschangedall that,making the 1970sadecadeofbigchanges.Highcompressionratioleadstohighemissionsofnitrogenoxides,whicharecreatedbyhighflametemperature.As part of emissionsabatement,compressionratiosofspark-ignition engines were forced down.Regular-gasautosof1968-70routinelyranon10:1compression,andsportiermodelswentall theway to12:1.Veryquickly,thisdroppedbackto8:1.Torquedroppedwith it. Thiswas the end ofthespark-ignitionengineasapossiblecompetitor formedium- to light-dutyDieselpower. Meanwhile, the Interstate HighwaySystemencouragedhigherspeedsforcommercialtrucking,bringingademandforhigherhorsepower-per-pound fromtruck Diesels. The succession of oilshocks, bringing higher fuel prices,underlined further theneed for lighter,moreefficientandmorepowerfultruckengines. WWIIaircraftenginescarriedthespark-ignitionconcepttoanewhigh,alongtheway developing large turbochargersthat allowed engines to maintainground-level power beyond 30,000feet. The gas turbine (jet engine)that rapidly replaced these pistonengines after 1945was conceptuallyjustthecompressorandturbineofthisturbocharger,withburnercans takingthe place of the piston engine as agas generator. In the process, high-temperature metallurgy necessaryfor successful turbine operationwasdevelopedandcommercialized.

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This, in turn,made the highly turbo-supercharged Diesel truck enginepractical. The harder you blow intoaDiesel, themore fuel the injectionsystemmustprovidetoburnwiththeairprovided.Theonlylimittothisboostingprocessisbearingdurabilityandenginestructure.Beginningwith atmosphericenginesataround160hp,truckDieselpowerhaspushedallthewayto600hpwithturbocharging. Today’s turbochargedDiesel engineshavetakenupwheretheaircraftDieselengine left off in the 1930s, after theinterludeofthehigh-powerspark-ignitionengine. Diesel engines, particularlythosedesigned formarine patrol-boatservice,arenowgeneratinghorsepowerpercubic inchsimilar to thatmadebygasoline-burningwartimepistonaircraftengines, and are only moderatelyheavier.This is a grandachievement.With the single exception of autoracing, all high-power piston enginedevelopmentnowtakingplaceemploystheDieselcycle. Foryearswe’vebeentoldthatturbineswouldsoontakeovertheseheavy-dutyapplications—marine and truck.Whyhasn’t this happened? The smallerturbines are made, the greater theproblemtheyhavewithinternalleakageand low efficiency.As light aircraftownersarediscovering,smallturbinesareextremelyexpensivebecauseofthesuperalloysandotherhigh technologyin them.Highdurability ceramics thatwereexpectedtomakecheaperturbinespossiblehavebeenslowindevelopment.Dieselenginesthereforeremainahugebargain on a dollars-per-horsepowerbasisandtheirdurabilityisexcellent. Even thedesignof future lightaircraftpowerplants seems to be turning intheDiesel direction—mainly becauseof thedecline in the knock resistanceof available aviation fuel. The highlyknock-resistantwartimegrades115/145(purple)and100/130(green)aregonenow, replaced by aviation lo-lead

(blue). Supercharged spark-ignitionpiston engines of the previous eramust be derated to run on this lessknock-resistant fuel, and it likewiseprevents future designs from beinghighly supercharged or turbocharged.The reworkedWW II fighter aircraftsthatruneveryyearintheRenoairracesburn special fuels containing triptane,custom-compoundedforthem. Ontheotherhand,everyairportofanysizestocksturbinefuelintheformofJet-A.Dieselenginesburnthisfuelreadily,motivating designers of future lightaircraftenginestoconsiderDiesel.USmilitary forcesappeardetermined thattheiroperationswill, in the future,useonlyasinglefuelforaircraft,tanks,jeeps,trucks, andevenportable generators.Thisfuelwillnotbegasoline! Therefore,asonceappearedtobethecaseinthe1930s,thefutureorheavy-dutypowerisprobablywithlightweightDieselengines. Imaybenostalgic forthesweetsmellofhigh-alkylateaviationgasoline,butIcanseethetechnologicalwriting on thewall. In the future, allhigh-torque,high-durabilityapplicationswillbefoughtoveronlybyturbinesandDiesels. It’s still no contest on the world’shighways. Whataboutautoengines?Fora timeinthe1980s,itappearedthattheEPAwas turning toward the Diesel as alow-emissionspowerplant for cars. Itsappealisthatbecauseitburnsitsfuelinthepresenceofexcessair,theDieselhas low levels of CO and unburnedhydrocarbons in itsexhaust. It isalso,becauseof itshighcompressionratio,highlyfuel-efficient. Then the carcinogenicity of thebenzene-like ring compounds inDiesel exhaust particulates wasdiscoveredanddocumented,andEPAenthusiasm abated. It is theDieselexhaust particulate problem that is

driving all the current developmentof common-rail injection, particulatefilters, and improved combustion.It is hoped that a more thoroughunderstandingof thedetailsofheavyfuel combustionmay lead toways topreventparticulateformation.Likewise,researchcontinuesonmeansofafter-treatment, such as plasma-assistedburningofparticulates. Howaboutotherareas?Therearestillasignificantnumberofsteam-turbine-poweredshipsplyingtheworld’sseas,but the highest efficiency is deliveredby large two-stroke turbochargedDiesels, coupleddirectly to propellerswithoutexpensivereductiongearboxes,and turning 60-90 rpm. These hugemarineDiesels(typicalboreandstrokemightbe36X60inches)arethemostefficientprimemoversnowinuse,withoverallthermalefficienciesabove50%.Dieselpowereliminatesexpensiveandunreliableequipmentnecessaryforthesteamcycle,suchaslargecondensersandfresh-watersources. Electrical power stations were, formany years, steam turbine powered,withDieselpowerreservedforsmallerinstallations or for topping or back-upunits.Lately,however,gasturbineshavebeen eating into this business.Whentheir reliability anddurabilitywere stillinquestion,theirusecameastoppingunitsonly,withbase-loadstillcarriedbysteam.But today,with turbinesmuchmorehighlydeveloped,evenbase-loadelectricalgenerationisbeingcarriedoutbygasturbinepower. Fromthisview,thespark-ignitionengineis a strange holdout in the light-dutypowerfield,keptaliveintheautomarketby its lightweight, low first cost, andmomentaryadvantageintheemissionsarena. Everywhere else on wheels,Dr.Diesel’sefficientengine isnumberone.


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More about oilThequestionofaftermarketoiladditiveskeepscomingup(Steed,Prolong,STP,Microlon, world without end), and italwayswill.Whenapersonhaslaidoutbigmoney for a shiny,wonderful newTurboDiesel,thatpersonintendstodomore than justdrivearound in it.Thatpersonwantstohavearelationshipwiththattruck.

In the old days, the relationshipwaseasy.Youchangedyourownoileverythousandmiles, yougroundyourownvalves,andyourotatedyourowntires.In fact, there wasmore relationshipbetweenman and vehicle thanmostpeoplewanted.That’swhytoday’scarsandtruckshavebecomesuchturnkeyoperations, with extended oil drainintervals andno tune-ups. Just get inanddrive.

Onewaytohavearelationshipwiththenewvehicleistobuyandmountacastaluminum“LoneWolf–NoClub”licenseplate frame and somewhite rubbermudflapswith jeweled reflectors.Oh,andbluedots for your taillight lenses,togivethemthatdistinctivepurplelookatnight.

Okay, all that went out with the endof the1950s.This is the21st centuryhere,atimewhenpeopleareconcernedover things like dietary fat and badcholesterol.Becausewearewhatweeat,andwewanttobegood,wehavetoeatcarefully.Thisappliesbyanalogytonewtrucksthathavecostus$32,000.Justasweareeatingvitamin-C,DHEA,andno-flavorleanbeef,sowearealsotemptedtopourexpensiveadditivesintothelubricatingoilofourtrucks,inhopesthatperformancewillimproveandthatusefullifewillbeextended.

I read a wonderful line somewhere,whichwent like this; “Vitaminswerediscovered in 1911.Before that time,peoplejustatefoodanddiedlikeflies.”Somethinglikethisideaseemstodrivepeopletodaytouseadditives—ordinarypumpDiesel fuel andmanufacturer-recommended oils can’t be enough.Aftermarket additives are, therefore,the “vitamins”weare tempted to give

ourvehicles.Nevermind the fact thatsomehighly-advertised“super”oilscostmoreperquartthanmostofuspayforacase.

The ads arewonderfully persuasive.OneIsawrecentlyfeaturesregularguysstrollinginajunkyard.Theyapproacharustyclunker,starttheengine,andlistentoitsassortmentofclatters—collapsedtappets, rod knocks, loosewristpins.“Soundsprettybad,Bob,”remarksoneofthestrollers.“That’sright,Bill,”returnsanother.“We’lltryabottleofNoo-Life,”Bill confides to the viewer.They pourit into the oil filler and instantly theclatteringgoesaway(orthetechnicianat theaudiomixercuts thetreblewaydown—it’shardtotellexactlywhichitis).“Soundsprettygoodnow,Bill,”saysthepourer,turningtotheviewerandholdingupthenow-emptyNoo-Lifebottleforourinspectionof the labelgraphics. “Whydon’tyoutryabottletoday?”

Inourminds,weknowhow it’s done,butinoursofthearts,we’revulnerable,temptedtotryabottle.Yes,weknowthatunscrupulous used car dealers have,intheunregulatedpast,usedsawdustto quiet timed-out transmissions, andwe know that thick oil or a dose ofmotor honey (viscosity-index improveradditive)will calm the high-frequencyrattlingofawarn-outengine.But,havinglaidoutthosethirty-twothousandonesend-to-endforthatbeautifulnewtruck(that’smorethanthreemilesofmoney),it justdoesn’tmakesense topassupproducts thatmightwork, right?Afterall,theywouldn’tlet‘emsayitonTVifitdidn’tworkasadvertised,wouldthey?Wouldthey?

How and why does oil work as alubricant,anyway?I’vetouchedonthistopicbeforeinthesepages,butadeeperlook always gives some fresh insight.Asnotedinapreviousarticle,therearethreeregimesoflubrication:

(1)Full-film,orhydrodynamiclubrication–mostoftheparts inyourenginearelubricated in this regimemost of thetime.Viscosityandtherapidmotionofthepartsdragsoilbetweenslidingparts,

forminga fulloilfilmthatsupports theload.Thereisnocontactatallbetweenthe moving parts, as revealed byelectricalconductionexperiments.

(2)Contact,orboundarylubrication–intheabsenceofanoilfilm,thereiseitheractualmetal-to-metalcontactbetweenparts,orthepartsareinsomedegreeprotectedbychemicalfilmsofoiladditiveused for the purpose. Such films notonly protect parts fromdamage, theyreduce contact friction to 1/10or lessofwhat itwouldbe inactualmetal-to-metalfriction.

(3)Mixed lubrication – some of theload issupportedbyanoilfilm,somebycontact.Thiskindof frictionoccursduring start-up, after oil has largelydrainedfromengineparts.Italsooccurswherever partsmotion is too slow togenerateafulllubricantfilm—atlowidlespeedbetweencamlobesandtappets,ornearTDCbetweenpistonringsandcylinderwalls,whenthepistonismovingvery slowly and combustion pressureishigh.

Inwhat follows, Iwant to describe inmore detail how full-film lubricationworks, andwhat affects it. In a laterissueI’lltalkaboutmulti-gradeoils,oiladditives, and their relation to snakeoils.

THEPRESSURE INBEARINGS:Ourintuition tells us that crank and rodjournal bearingsmust work becausetheoilpumpforcesoilintothebearings,andthatoilpressurethensupportstheload.Simple arithmetic tells us this isfalse.A four-inchpistonwith1000psiofcombustionpressureoveritpushesdown on the connecting rod and rodjournalwith a forceof roughly 12,000pounds.Ifitwasthe60psifromtheoilpump that supports this load, the rodjournalwouldneed12,000÷60=200squareinchesofbearingarea.Sincetheactualprojectedareaoftherodbearingismoreliketwoorthreesquareinches,wecanseethisideaiswayoff.Infact,this bit of figuring revealswhat actualbearingpressuresarelike—namelythe12,000 pounds divided by, say, three

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square inchesof actual bearing area,givingus4000psiasthepeakpressureexertedontheoilfilminactualcon-rodbearings.Wheredoesallthispressurecomefrom,if itdoesn’tcomefromtheoilpump?

VISCOSITY:Itcomesfromtherotationoftheparts,actingwithviscositytodragoilfromregionsoflowpressure,intothehigh-pressure region under the load.Viscosityistheinternalfrictionofafluid,suchasoil,air,water,etc.Ifonesolidsurfaceslidesoveranother,separatedbyafluid, the layersof thefluidmustslidepasteachother.Theresistancetothisslidingiscalledviscosity.Itiseasytounderstandwhythisresistanceoccurs.As themolecules in one layer collidewiththoseinthenext,kineticenergyisexchanged.Because the collisions ofthesemoleculesareanythingbutorderly,thiskineticenergyexchangeproducesrandommolecularmotion,whichisheat.Thus,theprocessofslidingonesurfaceoveranotherwithafluidbetweenthemconvertsorderlymotionintoheat.Thisproducesaviscousdragforce,tendingtoopposethemotion.

Weknowthat thefluidsknownasoilshavemore viscosity than, say, air orwater.Whyshouldthisbe?Oilsconsistofmoleculesthatarelongchains,whilethemoleculesoflow-viscosityfluidslikewateraresmallandresembleballsmorethan they do chains.As one layer offluidslidesoveranother,longmoleculestransferkineticenergytomorepotentialpartnermolecules because they areso long, surrounded bymany othermolecules.Thisproducesahigherfluidfriction,orviscosity.Thesmall,ball-likemolecules ofwater, because each ofthemcontacts fewer othermolecules,transfer kinetic energy less widely,and so display lower fluid friction, orviscosity.

THEBOUNDARYLAYER:Nearasolidsurface,thesituationisalittledifferent.Molecules—eventhosehavingtheformof longchains—areverysmall.Atanytemperatureaboveabsolutezero,theyareinconstantmotion.Themoleculesofafluidareespeciallyso,sinceinorder

forthefluidstatetoexist,theaveragemoleculemusthaveenoughenergyofmotiontoovercomeanyforcestendingto bond it permanently to another.Therefore thesemolecules vibrate,rotate, wiggle, and slither over oneanotherconstantly.Atanysolidsurface,thesemoleculescollidewithitsteadily.Because,onthemolecularscale,eventhemostfinelypolishedsurfaceisrough,thesecollisionsresultinreboundsatallangles,favoringnoparticulardirection.Forthisreason,therefore,thefluidnearasolidsurfacehasnonetmotionalongthat surface.This relatively immobilelayer near a solid surface is called,reasonably,theboundarylayer.

Thismeansthatinthesituationdiscussedabove,inwhichonesurfaceslidesoveranotherwithafluidbetween, thefluidcannotsimplyslidealong thesurface.The relativemotion has to takeplaceinthefluid,atsomedistancefromthesurfaces.Thismeans that there is noescape from the effect of the fluid’sinternalfriction,orviscosity.Nocoatingwecouldputonthesolidsurfaceswouldbesmoothonamolecularscale,andsopreventtheformationofaboundarylayerthere,permittingthefluidtosimplyslidealongthesurfaces.Therelativemotionalwaystakesplaceinthelubricantitself,sopowermustbeusedtoovercometheslightviscousdraginvolvedinslidingthelayersoflubricantpasteachother.Nosnakeoilcanchangethis!

PUTTINGTHEOILUNDERTHELOAD:Now, why does oil remain betweentheslidingsurfaces, rather thanbeingimmediatelysqueezedoutbyanappliedload? Imagine a situation in whicha loaded slidermoves over anothersurface, with a viscous fluid—oil—between.Theload,byexertingpressureon the film of oil between, tends tosqueezetheoilout.Ifmoreoildoesnotsomehowenterthespacebetweenthesurfaces,thislossofoilwillsoonresultincontactandpossiblesurfacedamage.Whatcanputoilintothespacebetweensurfaces?

FORMINGAN OILWEDGE: Thatsomething is viscosity.As themoving

sliderglidesalong,itassumesaslightlytilted position because the oil at itsrear edge has been under pressurethe longest, so the most has beensqueezed out from that region. Theoil film between, therefore, takes theformofawedge,thickerattheleadingedge, thinner at the trailing edge.Astheslideradvances,oilaheadofitdoesnotimmediatelyflowawaybecauseitsviscositypreventsitfromdoingso.Onceoilentersthewedge,theonlywayitcanescape is to be squeezed out to thesides,orfortheslidertopasscompletelyoverit.It’shardtosqueezetheoiloutbecauseforcingviscousoiloutthroughsuchanarrowspacerequiresverygreatpressure.Somedoesescape,naturally,butitescapesslowly.

Astheslideradvances,asteadystateissoonreached,inwhichtherateatwhichoilentersthewedgeatthefrontequalstherateoflossthroughbeingsqueezedoutatthesidesandatthetrailingedge.Oil enters the wedge at essentiallyzeropressure,but theadvanceof theslider,coupledwithviscosity,carries itinto regions of higher pressure—highenoughtocarrytheloadontheslider.Thesliderrisesuponthewedgeofoilthusproduce.Themoreviscoustheoil,thethickerthewedge.

Our“slider”couldbetheskirtofapiston,slidingonalubricatedcylinderwall,oritcouldbe the lobeofacam, rotatingagainsta tappet. It couldevenbe therotatingjournalofacrankshaft,turninginsideasleevebearing.Inallcases,theload is carried by the samenaturally-formingoilwedge.Oilentersthewedgeatessentiallyzeropressure,andoncetheoilisbetweenthesurfaces,viscositymakesiteasierforittocarrytheappliedloadthanfor it tobesqueezedout. Intheprocess,thefrictionaldragforceinthebearingistypicallyaboutoneortwothousandthsoftheappliedload.Thisiswhyenginefrictionisaslowasitis.

The above argument shows thatviscosity is necessary if loads are tobe carried by sliding parts—it iswhatkeeps the lubricant fromescapingoutfrom under the load so fast that the

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lubricantwedge collapses.Yet at thesametime,thefrictionlossinherentinlubrication is produced by this sameviscosity. It is thereforeobvious thatacompromiseisnecessaryhere.Wemusthaveenoughviscositytocarrytheloadson sliding parts, butmuchmore thanthatsimplyincreasesthefrictionlossinourmachine.

THE VISCOSITY COMPROMISE:WhenengineersspecifyoilsforDieseltruck engines, they are obliged tomake this compromise.They cannotallow themoving parts to touch eachother,becausethatcausesacceleratedwear and parts damage. Thereforetheymust specify enough viscosity tokeepparts separated asmuchof thetime as possible.On the other hand,theyalso know that themore viscousthe oil, the greater the force it takestomake lubricated parts slide overeach other.Too little viscositymeanswearanddamage.Toomuchviscositymeanspower lossand increased fuelconsumption. For example, a changefroma30oiltoa50oilincreasesfriction-lossapproximately20%.Becausewell-designedengines typically loseabout15%oftheirpowertofriction,thismeans20%of15%,orapowerlossof3%.

Shall we play with this compromiseourselves, inhopesofeither reducingfriction and gettingmore power, orconcentrate onextending engine life?It’s obviously true that we can cutthe friction of well-lubricated partssignificantly by reducing oil viscosity.This isaployconstantlyused inautoracing.Shallwerunoutandgetcasesofwatery0W-5oilandreapthebenefitsoflowerfriction?Wedon’tdothisbecausewe know the factory chose a heavieroil tocover the full rangeofoperatingconditionsthattheirproductwillmeetinuse.Yes,wemightbeabletogetawaywith a lighter oil ifwedidn’twork ourenginesveryhard—this isanold trickfromtheMobileconomyrunsofyearsago.Butweboughtthesetruckstodoheavywork,sowhenwe’retowingthatbigstocktraileruptheRockiesonahotday,we’regoingtoneedtheviscosityofthefactory-specifiedoil.

Okay,butwhataboutenginelife?Can’tImakemyenginelastlongerbyusingthicker oil?Won’t that keep the partsseparatedbythickeroilfilms?

Enough i s enough. I f fac to ry -recommended viscosity keeps themovingparts separated,makinggoodoilfilmsthickerwithaddedviscositygetsusnothingbutaddedfuelconsumption.Also,someofusliveinThiefRiverFalls,MN,whereengineshavetocold-startatminus forty.With that thickstuff in thecrankcase, the starterwon’t turn theengine.Even if it does, the heavy oilmovessoslowlyatthattemperaturethatitwilltakelongminutesforflowtoreachallthewaytotherockerarmsandotherpartsmostdistantfromtheoilpump.

Thefactory,baseduponitsthousandsofhoursoftesting,andontheyearsofwarrantyandserviceexperience,arrivesatanoilspecificationforitsengines.Canweget better informationbywatchingthemotorhoneyadsonlate-nightTV?


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Your Notes:

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apples-to-apples Baseline and overkillOneofmyfavoritedemonstrationsisthe“tricksparkplugplay,”anditgoeslikethis.Theaveragevehiclehashalf-wornsparkplugsinit.Thismeansthatheatandsparkerosionhaveroundedoffthesharp edges of the centerwires andground electrodes, somewhat raisingthevoltagerequiredtoproduceaspark.Therefore,suchhalf-wornplugsareabitless certain in their performance thannewplugs.Thereissomeirregularityatidle,evenafewmisfires.Thetopendisnotquiteassharp.

Now Mr. Wizard removes thesespark plugs and screws in his patentalternative. Itmay have extra groundelectrodes, like aircraft plugs do, or itmayhavespecialjaggededgesontheelectrodes. In any case, these plugslook really different.Mr.Wizard runstheengineandlo!theidleirregularityisgone,replacedbysilkysmoothness.Ifadynocomparisonismade,thelinemadewiththenoveltyplugsliesslightlyabovethatof thestockers.Pointproven,Mr.Wizardacceptsonlookerapplauseandpreparetotakeordersforhisproduct.What’swrongwiththispicture?

What’s wrong with it is that we arecomparingtheperformanceofhalf-wornplugswiththatofbrand-newones.Wedon’tneedengineeringdegreestoknowthatnewplugsperformbetterthanoldones.Acorrectprocedurewouldbetotestfirstwithabrand-newsetofstockplugstoestablishatruebaseline,thentest againwithMr.Wizard’s igniters.Chancesaretherewouldthenbelittledifferencebetween the two.Plays likethis one rely on our enthusiasm forwhatisnew,andourdesiretodiscoversomethingwonderful.That is nowaytodoengineering.Alotofbadsciencewillgetpastus ifwedon’t thinkaboutthesethings.

Aneagervehicleownerdrivesintothemodificationsshoptohaveexpensiveprocedures performedon his ride.A“baseline”isrunonthedyno,thenthemodsareinstalled.Naturally,thenewequipmentrequiressomeadjustment,so everything gets set to exact newvalues.Whenthedynoprinterbegins

toprint theresultsafterall thiswork,thenewcurvesaresensationallybetterthanthe“baseline.”What’swrongwiththispicture?Thebaselineisthevehicleasitarrivesintheshop,withthestockdaily driver’s usual suite of out-of-adjustment problems. Butwhen thenewpartsareinstalled,whatamountsto a complete tune-up is performed,so that everything is exactly up toscratch.The fact is that if themodsshop operator wanted to, he couldleavethecustomer’senginestockandstill showaperformancegainon thedyno,justfromthetune-upworkalone.Thereforetheruleisthatifyouwanttoknowwhatyouaregetting,youhaveto design your testing to show onlythat.Atruebaselinetestshouldrevealthebestthatyourstocksetupcando,becausetheafter-modificationstestwillcertainlytrytoshowthebestthatitcando.Compareappleswithapples.

Indynotesting,itisnormalto“correct”horsepower figures towhat is calleda standard atmosphere.This is doneto remove the effects of changes inthe weather.When the barometergoes up or the temperature goesdown, air density rises, and sowillhorsepower—andviceversa.Likewise,ifyoucomparedynoworkperformedinShreveport(sealevel)withworkdoneinDenver(5,000footaltitude),youmustcompensateforthealtitude’seffectonairdensity.Abiggainorlossinpowerwillalwaysbeevidentondynoprintouts,butifyouareworkingwithsmallgainsandlosses,theycaneasilybemaskedorevenreversedbyahighbarometerduringTuesday’s dyno session anda low pressure storm center glidingover duringWednesday’s session.That’swhy raw dyno horsepower iscorrected to standard atmosphere.Becausemanypeopledon’tunderstandthepurposeofdynocorrections, theysuspect some kind of jiggery-pokery.They may demand “raw figures,”believingthesetobetrueandcorrect.They are, but because theweatheraffects them, theycan’tbecomparedwith other figures, taken under otheratmosphericconditionsonotherdays.The dyno correction takes out the

effectofcurrentweather,andtellsuswhat horsepower would have beenon a so-called “standard day,” withatmosphericpressureof29.92inchesandtemperatureof65degreesF.Thishorsepower correction is, like otherhuman achievements, imperfect, butwhat it strives to do is to allowus tocompareappleswithapples.

My all-time favorite is the “parts-listbuilder.”This optimist sendsaway forall the speedparts catalogs and thendesigns his ultimatemachine on thekitchen table.Thesepistonswith thathead,theotherpipes,somebodyelse’sturbo, and a trick injection pump.Allthesepartsareultimates in theirfiled,right?Put‘emalltogetherandyougottahavedyno-mite combo, right?Wrong.Anengineisasystem,notapartslist.Betterbyfartogotoapersonwhobuildsmodifiedenginesallthetime,andwhohasseenwhatworksandwhatdoesn’t,what parts functionwell together andwhichdonot.It’syourchoice—youcaneither get the experience by trial anderror,oryoucanbuyit fromsomeonewhoalreadyknows.

BecauseI’vebeenthroughthekitchen-table processmyself, I understandthe tremendous enthusiasma personfeelswhenhedecides to takecontrolof the variables and build somethingreally radical andwonderful. It’s hardtothenbeconfrontedbytheresult—avehiclewhose drivability is poor andwhoseperformance isspottybecausethevariouscomponentschosenonthekitchen table don’tworkwell togetherunder thehood.Thebasic fact is thatparts don’t make engines perform.Performance requires both parts andinformation.Again and again, I haveseen enthusiasts break the bank ontrick parts, then refuse to spenda bitmoremoney on the dyno time andprofessional advice necessary to getthosepartsworkingtogethercorrectly.Isa cake just flour, sugar,milk, eggs,baking powder, and flavoring? No,that’sjustastickymess.Togetacakefromtheseingredientsyouneedcorrectinformationonhowtocombinethemandbakethem.

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Inmotorcycleracing(whichismyfield)Ihaveoftenseenpeopledisappointedbyenginestheyhavebuilt.Iasktheowner,“How did you phase the cams?” andtheanswercomesback,“Ilinedupthemarkslikeitsaysintheservicemanual.”Inotherwords,sametimingasthestockcams.Isthatthebestsettingwiththispipe, these carbs, this compressionratio?Theonlywaytofindoutisto“rollthe cams” on thedyno—try variationsoncamphaseuntilyoufindwherethegoodtoppoweris,thebestdrivability,orthebestacceleration.Onceyouhaveafeelingforcamphase,youcanchoosethekindofperformanceyouwant.

Sometimes lackof knowledgebreaksthings.Ahomebuilder“throwsin”anewcamand bends all his valves.Why?Valve-to-piston clearance should bemeasuredany timenon-stockcamortiming is used. Lining up themarksisn’t enough.Another hot bike ownerbolts on big carbs, but doesn’t knowthedifferencebetweenanidlejetandanF-14.What chance does he haveof gettingwhat hepaid for?As oftenas not, the engine doesn’t idle on itsgleamingnewmixers,ithesitateswhenthe throttle is snapped, andwhen itfinallycomeson,thepowerislikethefabled light switch—either all thewayonornothing.Carefultuningworkwitha personwho understand carburetorsystemscouldtransformthisengineintoarunnerthatwill idle,accelerate,andtop-endnicely,but theowner“doesn’twantanyhelp.”

WhenChuckYeager flew faster thanthe speedof sound in summer 1947,theflightwaspromotedasall-Americanheroism.ThepublicviewwasthatYeagerhadswitchedonallfourrocketenginesandthenmasterfullytamedtheX-1byrawcourage.Thefactsweredifferent.Inscoresofcarefullyinstrumentedtestflights, Yeager hadmapped out thehandling characteristics of the planeas it approached the speedof sound.Speedwasincreasedinincrementsof0.05Mach,orabout35mph,andcontrolresponses were evaluated at eachstep, in complete detail.Yeagerwaschosen for thiswork, not becausehe

wasa swashbucklingadventure-lover,but because his flyingwas accurate,reproducible,andreliable.Intheprocess,Yeager discovered a need for greatlyincreased elevator control authority,and testingwas halted until thiswasprovided.Ontheotherhand,GeoffreyDeHavilandwas killedwhen his jetaircraft entered the transonic region,backedbyalesserdegreeofresearch.It developed oscillations fromwhichit could not be recovered. It tumbledand broke up in flight.We can callYeager’swork“exploringthetrendsofperformance.”Byestablishingthetrendsofcontrolresponseathigherandhigherspeeds,heandtheengineerswereableto uncover a possible loss-of-controlsituationanddesignaroundit.Afterallthis carefulwork,Yeager’ssupersonicflightwasroutineanduneventful.

Whenanengine’sperformanceisbeingraised in novel ways, it is valuableto similarly explore the trends in itsperformance.Manyahastilybuiltenginehasrewardeditsownerwithmechanicalproblemsthatcouldhavebeendetectedby a step-by-step approach.Whenyou pay an establishedmodificationshouseforahigh-pressureturbosetup,onlypartofwhatyouarepayingforisaturbocharger,controls,andassociatedplumbing.The rest ofwhat youget iscarefullyresearchedfreedomfromtheunexpected.Insomecases,reliabilityofamodificationismoreamatterofcommonsensethanofdynodevelopment.Wireswillchafethroughandshortoutiftheyare not supported by tie-wraps andprotected by rubber grommetswherethey pass through sharp-edgedholesin sheetmetal. Steel pressure linesvibrate, fatigue, and break off if theyarenotsupportedinsuchawayastopreventthis.Thinkabouteverypartofanewinstallationandtrytoimaginethefailuremodesbeforetheyhappen.OneF-14prototypesuffereda totalcontrolhydraulics failure thathad theexpertsstumped.Howcould three completelyseparatehydraulicsystems—theservicesystemplustwoback-ups—failatexactlythesametime?Itdidn’ttaketoomuchdifferential calculus to discover how.Linesforallthreesystemswererouted

andsupportedidentically.Atonepoint,allthreelinesmadealong,unsupportedspan that could vibrate strongly.Withthe same vibratory history, all threelinesreachedthepointoffatiguefailureat essentially the same time.Whenthefirst linefailed,theloadtransfertothe second and third systems failedthemtoo.Commonsensewouldhaveprevented this. (TheEditor, andothercolumnist,couldwritemanyastoryonthe “unreliability factor”ofaccessorieswe’ve installed.My experience fixingtheseself-imposedaccessoryproblemsmakesmemarvelattheengineeringofthevehicleasbuiltbyDodge.)

AnothereffectiscausedbyourgoodoldAmericanloveofgadgets.Amangoesintoacamerastoretogetsomethingtotakesnapshotsofhiskids,butcomesoutanhour laterwith$1,500worthofprofessional photo equipment that henever quite learns how to use. Theparallel is the operator whose routeand load take him over hills that aretoo steep for fourth gear and too fastforthird.Whathe’dreallylikeisalittlemore torque—something he can getvery easily froma variety of sources.Butifthegadgetbugbiteshim,histruckwillcomeoutoftheshopgleamingwithintercoolers and amaze of delightfulplumbing and gadgets. Keeping thisleading-edgesystemrunningrightmaybemorethantheownerbargainedfor.Therefore,anotherruleofperformancemodificationwouldbereasonable.Iftheexistingmachine isn’t strong enough,howmuchstrongergoesitneedtobetodothejob?Howoftendoyouencounterthose types of operating conditions?Overkillmaybefun,butthemore“over”itismade,themoreproblemsitislikelyto have. Running something radicalhas its ownappeal.Big numbersandsmokingtiresarethrilling.Buttheharderyoupushagivenpieceofhardware,thecloseritmustlivetofailure,andwhenitfails,thetallerthecolumnofsmokethatresults.Enoughisenough.Ifyoureallyhavetohave1,000horsepower, therearebiggerengines.


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ReasonsTheusualreasongivenforthesuperiorfuel economy of theDiesel engineis its high compression ratio. Ingeneral,thecompressionratioisalsothe expansion ratio. By raising thecompressionratio,youraisethepeakcombustion pressure. Because thisisalsotheexpansionratio, itmeansthatthegasisallowedtoexpandveryfully.Thetwoeffectsworktogethertoresultinwhatiscalledahighaircycleefficiency.

Aircycleefficiencyisanabstraction,anidealpictureofrealitythatisusefulforcomparingoneenginewithanother,butis far from thewhole truth.Twomoreeffects intrude here tomodify the aircycle—theincreaseofthespecificheatsof gases anda chemical temperatureeffect call dissociation. In comparisonwithspark-ignitionengines,botheffectsworktotheadvantageoftheDiesel’sfuelconsumption.

Increase of Specific Heats with TemperatureThespecificheatofagasisthemeasureof howmuch heatmust be suppliedto heat a given amount of it by onedegreeC. It isnormallyassumed thatthis specific heat is a constant. Thesimplemodelofagas isofhard, tinyspheres in constantmotion, collidingwith each other andwith thewalls oftheir container.As the temperature ofthegasisraised,theaveragevelocityof these spheres is increased. Thepressureof thegas is the sumof theimpacts of these tiny spheres againstthecontainerwalls.

Ifthismodelweretrue,thespecificheatsofgaseswouldremainconstantastheirtemperatures rose—each increasein energy suppliedwould produce aproportional increase in themolecularactivityinthegas.Infact,themoleculesof the gases in air are not hard littlespheres, but consist of two ormoreatoms,joinedtoeachotherbyelectricalbonds thatareelastic.Themoleculesof the combustion products carbondioxideandwater vaporeachconsist

of three atoms, further complicatingthepicture.

At moderate temperatures, thesegasesdobehaveprettymuch like theaforementionedhardlittlespheres,andtheir specific heats therefore changelittle.Butathighertemperatures—suchas those found in combustion gas inengine cylinders—additional modesof energy storage appear.Moleculescanrotatelikelittledumbbells.Thetwoatomsofoxygen(O2)andnitrogen(N2) molecules can vibrate rapidly towardsand away from each other like twomassesonaspring.Gas temperatureismanifestbytheaveragevelocitiesofthemolecules,butthesenewmodesofmotionmake little contribution to this.Thereforeas thegasbecomeshotter,moreandmoreheatenergyislostintothese rotational and vibratorymodes,andisnotavailabletogeneratepressurethereforemoreheatisrequiredtoobtainagivenincreaseingaspressure—morethanpredictedby the simpleair cyclemodel.Theresultisthatthehotterthesegasesaremade,thelessefficienttheybecomeatconvertingtheheatsuppliedintopressure.

For this reason, engines are moreefficient the lower the temperature oftheircombustioncanbemade.Dieselengines have no air throttle, so theytake in a full charge of air on everyintakestroke.Atpartialload,onlyasmallamountoffuelisinjectedintothislargemassofair,sotheresultingtemperaturerise of the air during combustion ismoderate. Even at full load, Dieselengines operate with about 15-20%excessairtopreventsmokeformation.Becauseofthisexcessairdilution,theconversionofheatintopressureismoreefficient,solessfuelisused.

In a gasoline engine, throttling has tocontrolbothfuelandair,assparkignitionwillworkonlywithinanarrowrangeofmixture strengths.Therefore at partialthrottle,agasolineengineadmitsasmallamountofpremixedcharge.Whenthischargeburns,itisnotdilutedwithagreatmassof extraair as inaDiesel, so itburnsatahightemperature.Conversion

of heat into pressure is less efficientbecause of increase in gas specificheats,somorefuelmustbeused.

Thisisnotasubtle,single-numberseffect.Itis,infact,solargethatitispresentlydrivingmuch of the development ofnew gasoline engines. These are ofthe so-called lean-burn type.Toallowconventional ignitionsystems to igniteleanmixtures of around 25-to-one,the charge is supplied to the engineinstratifiedform—witharich,ignitablezonearound thesparkplug,andverylittle fuel elsewhere.As in theDiesel,the presence of extra air limits thetemperatureriseoftheburningcharge,makingconversionofheatintopressuremoreefficient.

DissociationInorderforfuelstoburn,whethertheybefireplacelogs,naturalgas,orDiesel,theirmoleculesmust first be knockedapart by heat. Then the fragments,whicharehighlyreactive,cancombinewith oxygen and release energy inactualburning.Inasimilarfashion,ifthetemperature is highenough, even theproducts of combustion themselves—carbondioxideandwatervapor—canbeknockedapartbytheviolenceofthermalmolecularmotion.Thisprocessiscalleddissociation.Even thenormally highlystablenitrogenmolecule—N2—canbedissociated.

Whencombustionproductsdissociate,theyabsorbenergyfromthecombustiongas.This lowers its temperature andpressure.Asthepistondescendsonthepowerstroke,thecombustiongascools,and thedissociated fragmentsCO1O2,andH2cannowrecombine.Astheydoso,theyreleasetheenergytheyearlierabsorbed, but by now the piston hasalreadymoved a significant distance,sotheresultingbitofextrapressurehaslessdistanceinwhichtodowork.Asaresult, there is a small loss of power.Again, the lower the temperature ofcombustion, the lessdissociation losstherewillbe—anotheradvantagefortheDieselenginewithitsexcessair.

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Nitrogen oxide FormationWhennitrogendissociates,itmaylaterrecombinewithitselftoformN2again,oritmaycombinewithoxygentoformthatmostdifficultofexhaustemissions,the nitrogen oxides,which are potentsmog-formers.

In gasoline engines, fresh charge isoften diluted with inert exhaust gasin the process called Exhaust GasRecirculation (EGR).Thepresenceofthisextragas,whichcannot takepartin combustion, acts to reduce flametemperature, and thereby cuts theproductionofnitrogenoxides.

Particulates and PahsThese excellent advantages of theDieselcombustionprocesssocharmedtheEPAinthe1980sthatforatimeitappearedtheDieselwouldbethechoiceas the future auto engine.Then theydiscoveredthechemistrycarriedalongonDieselparticulates,andtheloveaffairwas over—back to the spark ignitionengine.Whatwasfoundonparticulateswas calledPAHs—polycyclic aromatichydrocarbons. These aremulti-ringstructures basedon thebenzene ringofsixcarbons.Somealsocarrynitrogenoroxygensidegroups.Someofthesecompounds are highly carcinogenic,probablybecauseoftheirabilitytomimicbiologicalsubstances.TheyarecreatedwhenDieselfuelburnsincompletely,andtheyadheretoparticulates.

Particulates means smoke—we allknowthewordstothesongthatgoes,“Myexhaust is blowin’ black as coal.”ModernDiesels ingoodconditionandadjustmentdon’tsmokemuchexceptatstartupandslightlyonfullload.Itdoesn’ttakemuchfuelburningincompletelytomakevisiblesmoke—evenconversionofaslittleashalfapercentofthefuelintosmokeresultsinunacceptablydarkexhaust.AnyDieselenginewillsmoke:(a) If its injectors aredeteriorated so

theirsprayhasbecomecoarse,(b)Ifmorefuelisinjectedthancanbe

completelyburned.

Sparkignitionenginescanusealltheirair,butifaDieselismadetousemorethan about 85% of its air charge, itwillsmoke.Sometimes, in the interestof increasing torque without regardfor smoke, an operatormayhavehisinjectorracktravelextendedtosupplymore fuel than this, and the result isheavy smoke. In the songmentionedabove, the owner-operator remarks,“Myrigmaybeold,butthatdon’tmeanshe’sslow.”

Particulatesare thesubjectofa lotofresearch.Somedevelopments centeronnotcreatingparticulates in thefirstplace.Among these are the Sonexcombustionprocessandcertainspark-assistedcombustionschemes.Neitherconcept requires the desulfurized fuelnowbeingdiscussedtobecompatiblewithfutureDieselcatalyticconverterstoeliminatenitrogenoxides.Anywayyoulookatit,desulfurizingwillcostmoney,butcatalyticconvertersmaywinintheend.

On the post-treatment side, the basicscheme is to catch particulates on ahigh-temperature ceramic filter, fromwhichtheycanbeburnedoffperiodically.Inarecentpublicdemonstrationofsucha system, a clean handkerchief wasplacedover theexhaustpipewith theenginerunning,thenshowntobefreeofcarbonandodor.

The Nitrogen oxides ProblemWhy shouldDiesel engines produceanynitrogenoxides,whenatlessthanfullthrottletheircombustiontakesplacein the presence of somuch excesscoolair?Theanswertothis iscalled“sheath burning,” and takes placeearlyincombustion.Asfuelbeginstobe injected into the hot compressedair in the cylinder, the fuel is heatedby the air but its evaporation alsocoolstheair.Theresultisthatthefueldoesnot instantlyheatup to ignitiontemperature.Thisperiodoftime—afterthebeginningof injection,butbeforeignition has occurred—is called thedelayperiod.

Meanwhile,moreandmorefuelisbeinginjected, providing yetmore coolingthroughevaporation.Finallythehotairwinsandtheevaporated,mixed-with-airpartofthefuelignitessomewhere.Howdoestheburningproceed?Becauseachemicallycorrectmixtureburnsfastest,theearlyflameracesalongthatcontoursurroundingthefueldropletcloudwherethemixturehappens to be chemicallycorrect.Thisfastflameishot,becauseit is burningwithout excess air (therecan’t verywell be excess air ifwe’vealready defined the localmixture aschemicallycorrect).Hotflamesgeneratenitrogenoxides.Afterthisinitialperiodofburningthepremixedpartofthecharge,combustionsettlesdowntothenormalDieseldiffusionflameburning,inwhichfuelvapordiffusesintotheairaroundit,burningassoonasconditionspermit.

OnewayaroundthisNOxproblemistorunalltheexhaustthroughareducingcatalyst.Anotherway is to somehowlimit the amount of fuel that is in thecylinder at themoment combustionactually begins—by shortening thedelayperiod.

OneofthestrengthsoftheDieselengineis that it can bemade to operate onalmost any kind of combustible liquid(peanut oil, canola, filtered crankcasedrainings, etc.) but this doesn’tmeanit does so happily. The fuel’s cetanenumber is themeasure of howeasilyit ignites,andthisvariesamongfuels.Fuels of differing cetane numberwillhaveignitiondelayperiodsofdifferentlengths, requiring (for best economy)different injection timings. In concept,cetane number is the reverse of theoctane number used tomeasure theself-ignitionresistanceofspark-ignitionfuels.

One way to reduce the amount offuel burned at high temperature asdescribed above is to initially injectfuelatalowrate,asystemcalledpilotinjection.Thesmallmassoffuelinitiallyinjectedquicklyheatstoignition.Onceignition is achieved, fuel injectionrate can be increased to deliver thefull amount quickly. New electronic

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injectors operating from common-railfuel supply can do this because theyarejustsolenoid-controlledvalvesthatdowhat they are told—including pilotinjection.Anotherreasonforinterestincommon-rail systems is that injectionpressure remains constant at all rpm.Thisensuresgoodfuelspraybreak-upandrapidignition,evenatpart-throttle.

Spark-assistschemesworkby forcingearlyignitionoftheinjectedfuel,avoidingmuchoftheignitiondelaycausedbytheusualprocessesofevaporativecooling,fuelbuild-up,thenfinallyignition.

TheSonex system operates in quitea different way. Small cavities areprovided in the piston, each reachedthrough a small orifice.During actualcombustion, hot gas containing fuelmolecule fragments and hydroxylradicals is driven into these cavities.The small size of the cavity orificescausestheleak-downtimeofthisgastobecomparablewiththeengine’scycletime.Thismeans that during thenextintake stroke, gas from the cavities isstill emerging, andmixeswith the aircharge.ThepresenceoftheseradicalsleadstoearlierignitionwithreducedsootandNOx,itisclaimed.

Engine speed and Ignition DelayIgnitiondelay periodaffects allDieselengines. In largemarine units, tencrank degrees of delay, at 90 rpm,allows plenty of time for the injectedfuel to penetrate the air charge, heatup,evaporate,mixwithair,andfinallyignite.Butinyourtruck’sengine,turning2200rpm,thislengthoftime—say.02second—would be almost a wholecrankrevolution.Therefore,asenginesaremade smaller and faster turning,the process of mixing injected fuelwith theairchargemustsomehowbeappropriatelyspeededup.

In large truck engineswith full borediameter combust ion chambers,high pressure injectorswith six radialinjector orificesare used to push fuelrapidlyoutwardthroughtheverydense

compressedcharge.Injectionpressuresof15-22,000psiarenecessarytogivethefuelthevelocitynecessarytobreakitupintofinedropletsthatwillevaporatewith the necessary speed. Injectionvelocitycanbehigher than1,000 feetpersecond.

Insmallerheavy-dutyengines,thepistonmayhaveacentralhockey-puck-shapedcavity of smaller-than-bore diameter,and employ intake swirl. During theintakestroke,theintakeflowisgivenatangentialdirectionbyvariousmeans,causingtheairchargetorotatearoundthecylinderaxis.WhenthepistonnearsTDC,mostofthischargeisforcedintothepistoncavitywhereitsrateofrotationspeedsup.Fuelinjectedintothisrotationmassofairismixedmorequicklyyet.

To reach even higher crank speeds,pre-chambersmaybeused,connectedto the space above the piston by asmall orifice.As the piston rises oncompression, air is driven into theprechamberwhereitformsaveryrapidlyrotating,smallsingleordoublevortex.Fuel injected into this environment(IDI, or Indirect Injection) is mixedmostquicklyofall—appropriateforthehigherrpmlevelsofsuchsmallengines.Thedrawbackoftheprechamberisitsincreasedsurfacearea,whichincreasesheatlossandthereforefuelconsumption.WherelargeDieselsmayuselessthan.35poundof fuelperhorsepower,perhour,prechamberenginesconsume.42poundormore.Comparethesenumberswith.5poundforwell-designedspark-ignitionengines.

Wehumansnever let anything alone,orallowanythingtoremainsimple.TheDiesel engine is an excellent primemover,buttocoexistwithcurrenthumanneeds, its combustion process andexhaust emissions are being broughtsteadilyclosertoperfection.Wakemewhenit’sover.


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Your Notes:

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Tires and the Marketing of americaTire ConstructionAll the recent talk aboutmysterioustiredefectssuggestsit’stimeforsomebackgroundonhowtireshavedevelopedtotheirpresenttechnologicallevel,howtiresaremade,andhowtheyrespondtotheirconditionsofuse.

Progress in tires has always dealtwiththetwinproblemsofstrengthandtemperaturemanagement.

A tire is basically a flexible rubber-impregnated fabric structure, givenrigiditybythetensioningofitscarcassofcordfabricbyinflationpressure.Appliedoverthiscarcassisthepartthatrollsontheroad—therubbertread.Theflexibilityof the tire allows it to lay downa flatfootprint on the road, largeenough togenerateusefultraction.

Theearliesttirecarcassesweremadeof cotton fabric verymuch like heavycanvas,withinterwovenfibers.Rubberdidn’tsticktothisfabricverywell,andtheweaknessofcottonrequiredmanyplies of fabric tomakeanadequatelystrongtire.

Rubber iselastic,butnotperfectlyso.Whenyoustretchorotherwisedeformapieceofrubberwith100unitsofenergy,thenreleaseit, it returnsto itsoriginalshape, giving back not 100 units ofenergy,butsomelesseramount–say70units.Therest—thatother30%ofthedeformationenergy—appearsasheatintherubber.Flexingrubbergeneratesheat.

Becausethisisso,asatirerollsandthetreadandcarcassrubberflexestolayaflatcontactpatchon the road,heat isgenerated.Themorerubberthereisinthetireandtread,andthefasteritrolls,themoreheat itgenerates.The lowertheinflationpressure,thebiggertheflatfootprintlaiddownontheroad,andthemore sharply the rubbermust flex asit enters and leaves that flat footprint.The lower the inflation pressure, themoreheatisgeneratedasthetirerolls.Because applied load also increasesfootprint size and rubber flexure, the

moreloadthetirecarries,themoreheatitgenerates.

Back in 1920, pneumatic truck tireswereimpracticalbecausetheheattheygenerated in the necessary 15 or 20pliessoondestroyedthetire’sstrength.This,andtheabsenceofgoodhighways,werethereasonswhytherewasnolong-distance trucking before about 1927.In-citytrucksusedsolidrubbertiresinthatperiod,and thesewere limitedbyflex-driven heating to low speeds like20mph.Racing cars at Indianapolisactuallyhadtheirpneumatictirescatchonfirefromhigh-speedheating.

Interwoven t ire fabric had to beabandonedveryearlyonbecause,asthe tire flexed, the interwoven fibersof thefabricsawedateachotheruntiltheybroke.Thiscausedtheadoptionofso-calledcord fabric,whichhasall itsfibersgoinginonlyonedirection—therearenointerwovenfiberscrossingthem.Togetstrength inalldirections, thesecordplieswereappliedatanangle tothe tire centerline—oneply angled totherightat45degrees,thenexttotheleft,andsoon.Eachplywasembeddedin a thin skim layer of rubber, so thatwhen the plies becamepart of a tire,theywereseparatedfromeachotherbythisrubber,andsowereunabletosawagainsteachother.

Therubberintheseplieswas“green”,thatis,uncured,andinaslightlystickycondition.Thisstickiness,calledtack,iswhatholdsthepartsofthetiretogetherduringthebuildingprocess.Earlytireswerebuiltonatire-shapedmetalform,onwhich theywere cured by heat inwrapped stacks, inside steam-heatedautoclaves.Later,tireswerebuiltasflatbandsonabuildingdrum, thengivenshape by being driven into a heatedfemaletiremoldbytheinflationofaring-shapedbag.Aftertherequirednumberof fabricplieswerebuilt up, the treadwasappliedasalong,extrudedbeltofrubber, carefully applied soas to trapnoairbetweencarcassandtread,rolledinto placewith rollers as the buildingdrumrotated.Therightandleftedgesofthecordplieswererolledovertwohoops

of high-strength steelwire called thebeads, inalternatingdirections. In thefinished tire, these beadwires providethetensilestrengthtopreventinflationpressurefromforcingthetire’sedgesupandovertherimflanges.

The green rubber contains curingagents,accelerators,andcuremodifiers,sothatwhenthegreenrubberentersthehotmoldat315degreesF, itcures toproducerubberofthedesiredproperties,inareasonablelengthoftime.Curingisaprocessbywhich thesoft,putty-likegreenrubberistransformedintoatough,elasticsolid.Thelongrubbermoleculesare cross-linked to each other duringcuringbysulfurbonds—aprocessdrivenbyheat.Oncethetireiscured—afewminutes—themoldopens inclamshellfashionandthefinishedtireispulledout.Itisthenplacedonadummywheelandinflatedtotensionitscordfibersinthepositionstheywilloccupyinuse.

Tomakerubberstickbettertothecottonfabric, itwasfirstrunthroughbathsofrubberthinnedwithsolvents,todrivetherubberdeepintothefibers.Thisbroughtagreatimprovementinthestrengthofthe tread-to-carcass bond, and in tireintegrityasawhole.

Since tires generate heat as they roll(andmoreastheyrollfaster),atsomehighspeedatiremaygenerateenoughtemperature to threaten its structuralintegrity. Such failures are familiar toanyonewho has an interest inmotorracing.The twomajor typesof failureareblisteringandchunking.

In blistering, oily orwaxyelements ofthetreadrubber,addedtoenhancethesoftnessandgripofthetire,begintoboilandgenerategaswithintherubber.Asaresult,theaffectedpartofthetreadturnstofoamandswellsup,causingthumpingandvibration.

Inchunking,heatdeterioratesthebondbetween tread and carcass, allowingpiecesoftreadtoseparateandflyoff.I have seen pieces of thrown treadpenetrate heavy fiberglass seats onracingmotorcycles,andweknowfrom

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the recentConcorde aircraft disasterthatthrowntread(inthatcasemovingatbetween200and300feetpersecond)can penetrate fuel tanks and destroyhydraulicandelectricalconnections.

Anyonewhohasdrivenacarhasseenplentyofseparatedtrucktiretreadsbythe roadside.Checking tire pressuresonan18-wheeler takestime,which iswhyit’susuallydonebybonkingeachtire with a tire iron. If it sounds likethe others, it’s assumed to be okay.Sometimesthechecksaren’tdone,andtirescomeapart.

Tiresforthefastestofallapplications—racingatBonneville—havethethinnestpossible tread.This reduces heatingfromrubberflexure,anditrelievestherubber-to-carcass adhesive bond ofmostofthecentrifugalloadcreatedbythemassof the tread. In trackracing,whenever a tire shows excessiveoperating temperature (as read by athermocoupleneedle,carefullypusheddowntothetread/carcassinterface),tworemediesmaybe tried. First, inflationpressureisincreasedtoreduceflexure.Second, some of the tread thicknessmaybepared,or “skived”off the tire,to remove someof the source of theheating.

Something needs to be said abouthow rubber creates traction.Bybeingelastic,itisabletotakeaprintofalltheasperitiesontheroadsurface,creatingakindof “key”between tireandroad.Other,more complicated, phenomenaalsocontribute.Gripincreaseswiththetotal surface area of rubber in actualcontactwiththeroad,whichiswhytiresthatrequirethehighestpossiblegripindryconditionshavenotreadpatternatall.Theyareslicks.Thewholepurposeof tire tread patterns is to providedrainagepathwaysforwaterinwet-roadoperation.Racetiresformoistconditionshave just a very fewwavy lines cutintothem.So-calledfullraintireshaveextensive drainage, and resembleordinary auto tire tread patterns.Themorecutsandchannelsinatread,thelessstiffitbecomes,themoreitflexesinuse,andthehotteritruns.Whenrain

tires are used in a race, and the rainstops, the tirespromptlyoverheatandmust be exchanged for intermediateorslicktires.ThereasonFormulaOneracingcartiresnowhavefivegroovesisadecisionbytheF1governingbodyto reduce tire grip for racemarketingreasons.Theedgesoftiretreadpatternsdonotgeneratetractionbycuttingintotheroad–theroadismuch,muchharderthanthetire.

Attheendofthe1920s,tiretechnologyhadadvancedenough that truck tirescould be built with some chance ofsurvivalon theroadsof the time. Inawell-publicizedPRstunt,GoodyearfilledaconvoyoftruckswithtiresanddrovethemacrossthewholeUS,incidentallyusingupallthetiresintheprocess.Thepointwasmade; tireswere ready forlong-distancetruckservice.

During and afterWW II, cotton as acarcassmaterial was abandoned forthemuchstrongernylon,pioneered inaircraft tires.Therewere problems inmakingrubbersticktothenewmaterial,but thesewereovercome.Becauseofthestrengthofnylon,fewerplieswereneededtoachieveagivenstrength,sotirecasingsbecamethinner.Lessrubberflexingmeant lessheatgenerated, sotreadworemore slowly.That, in turn,alloweduseof thinner tread for equalmileage, leading to less heating, andsoon, in a cycle of improvement thatcontinues to this day.Other types oftirecarcassfiberhavereplacednylon–rayon,polyester,steel,andaramid.Theconstantimprovementinthestrengthoftirefibershasallowedasteadydecreasein the number of plies necessary toachieve mechanical strength. This,in turn, has reduced heat generation,makingtiresingeneralmuchsaferandlonger-lasting.

The crowning achievement of tiretechnology is the radial-ply tire,whichrequires only one carcass ply, andthereforeoperateswith the least heatgeneration.Radialtiresforheavytruckswereviewedwithsuspicionbyoperatorswhentheywereintroducedintheearly1970s, but the outstanding durability

andlonglifeof thesetiressoonmadebelieversofthem.

Bias-ply tires are built as I describedabove—by laying on plies with theirfibersatanangletothetirecenterline,thefirstangledoneway, thenextonetheotherway,andsoon.Inaradial-plytire, the single carcass ply is appliedwithitsfibersatrightanglestothetirecenterline, so that in the finished tire,these fibers runup the sidewalls in aradial direction, then straight acrossthe tread region at right angles tocenterline.TheradialtirewasinventedbyMichelin in about 1948, and hassincebeenimprovedbymanykindsofmodificationssuchasvarioustypesofunder-treadstiffeningbeltsandsidewallstiffnessmodifiers.The radial tirewasmadepossible by thedevelopment ofcordfabricsstrongenoughtomaketheconceptworkable.

In a sense, the development of theradial tirewas nearly suicide for thetire industry.Wherebias-ply tires hadlasted 15,000-20,000miles, radialsimmediatelymore than doubled this.ThismadeAkron,Ohio,formerlythetirecapitaloftheworld,intoaghosttownofemptybrickmanufacturingbuildings.

Marketing Versus PhysicsWe live in the commercialworld thatsomecall“TheMegastore.”Marketing,image, and brand recognition areeverything, and quality is, at best, asecondary issue.We no longer buycars and trucks for value.We buyadventure,aruggedimage,anAmericanicon.Vehiclesmarketedaspartof therugged, manly off-road experiencetherefore must have tread patternsthat suggest all thosepioneer virtues.These are invariably described in themarketing blurb as “aggressive treaddesign.”What thismeans is that theyarerough,knobby-lookingaffairs,withdeepcanyonscutbetweenranksoftall,sculptured,Gibraltar-like treadblocks.You canbe sure that plenty of focus-grouptimeisconsumedindeterminingjustwhatkindoftreadpatternwilllightthe

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public’sfirethisyear.Nevermindthefactthattheonlyoff-roadmudlikelyevertospattertheseSUVscomesfromaspraycanbearingthevehiclemanufacturer’saccessorypartnumber.

Now here’s the problem. By jackingthe tire up on all these hundreds oflittlerubberfeet,byapplyingthisthick,sculptured layerof tractor-styled treadrubber, the tire designer is building astoveintohistire.Remember,themorerubber there is in the tire, themoreheat itwillgenerate.ThetireengineerknowsallthesethingsbetterthanIdo,butasnotedabove,marketingisprettyimportantintheMegastore.

The vehiclemanual tells us to checktirepressuremonthly,and to increasetire pressure when carrying heavyloads.Italsoprovidesspeedwarningsorevenlimits.ButinonereviewIknowof, forty-percentofenthusiastvehiclescheckedatatouringrallywerefoundtohaveoneormoretiresunderinflatedby5psiormore.Thecombinationoftiresburdenedwithexcessheatgeneratedbyflexing,thick“aggressive”treadpatterns,pluspossibleextraheatresultingfromunderinflation,plusheatfromoperationin theAmericanwest and southwest,appears toresult in instancesof treadseparation. Tractor tires were neverintended for high-speed operation,butmarketing founda special use forthem.

In the press, these tread separationsare spokenof as if theywere causedbysomemysteriousagency,a“sinisterforce” yet to be discovered. Nothingwhateverissaidofthepossiblephysicalcircumstances of underinf lat ion,operation in hot climates or at highspeedsand loads,or the fact that thethicker tread ismade, the hotter thetiremustoperate.To thepress, it’sallamystery.

Couldthevehiclesthemselvessomehowincrease theprobabilityof tire failure?Thisquestionhastobeaskedbecause,inthegameofcorporateresponsibility,everyone sues everyone e lse .Remember the big rollover scandals

thatpanickedSUVownerssorecently?On the basis of what she’d read inConsumerReports,mysisterwentoutandboughttheRangeRover,becauseitpassedwhateverrollovertestCRused.MybetwasthatRoverwiselyfittedtireswith harder, less grippy tread rubber,or deliberately underinflated the tires,therebyreducingtheircorneringstiffnessenoughtomakethevehiclesskidbeforetheywouldrollover.Problemsolved.

Many people are confused about theeffectoftirepressureontiregrip.Whenstuck in sand ormud, it is useful toreducetirepressure,therebyincreasingtheareaofthetirefootprintandmakingthe tire less likely to dig itself in.Thismakes it easy to assume that lowerpressurealwaysequalsmore traction.On pavement, the reverse is true. Inthis case, reduced inflation makesthe tire casing less stiff, allowing thefootprint to distort and lift up from thepavement.Thiscausesreducedtiregrip.ThoseofyouoldenoughtoremembertheCorvair handling controversymayalso recall what was done to “fix” it.Theswingaxlerearsuspensioncould,under certain circumstances, jack upanddestroy rear tiregrip,causing thecartooversteerviolentlyandspinoutofcontrol.Theanswer?Chevyreducedthegripatthefrontbythesimpleexpedientof placarding front tire inflation at anamazinglylow12psi.

It’salawofphysics,notamystery,thatifyoubuildavehiclewithagiventrack(lateraldistancebetweenwheels),butwith its center of mass raised highenough off the ground, itwill tip overbefore it begins to slide. The focusgroups tell the manufacturers howhigh the vehicles have to be to look“Baja-rugged” and adequatelymanly,and that’s how tall theymake them.Therearenotwowaysaboutit—ifyoumakevehiclestaller,theytipovermoreeasily.

Perhaps, as someare saying, oneoranother of theSUVmakers didwritereduced inflation pressures into theirowner’s manuals, in the interest ofavoiding the already prickly rollover

problem.Then the questionwas,willthetiresgiveadequatereliabilityatthatpressure?The tiremaker’s statisticsprobablylookedprettygood.Nothing’sperfect—there are bound to be a fewdefects becauseeven fully-automatedmanufacturing cannot produce zerodefects.Becausetireshavetobeheat-cured from their surfaces inward, thedegree of cure decreaseswith depth,and surely some zones in some tireswillbetoadegreeundercured,othersslightlyovercured.Whenplies,breakers,and treadareappliedduring thebuildprocess,someairorevenmoisturemaypossibly be trappedbetween, formingnuclei aroundwhich trouble becomesa bit more likely. Thismeans therewill be some statistical scatter in thetoleranceofapopulationoftiresforload,speed, temperature, and accidentalunderinflation. It is the job of qualitycontrol to squeeze that scatter to anacceptablewidth.

Themostvulnerabletiresattheedgeof that scatter will not all belong topeoplewhotravel loaded,at90mph,throughDeathValley in summertime,underinflatedforconditions—butsomewill.Andwhenthosegreatthicktreadsgetcookedoffof the tiresandthrasharound inside the wheel wells at ahundred feet per second, somemaydamage steering linkage, and thesudden thumping and banging aregoing to badly spook their drivers.Somewillcoast,shaken,toasafestop.Otherswillapplytheuniversalremedyandjamonthebrakes,compoundingtheir problemsby locking thewheelsandsolosingcontrol.Somewillactuallybeinjuredorkilled,andwe’reallsorryaboutit.

Itmaybethattherearemoredefectsinapopulationofthesubjecttiresthaninsomeothertirepopulation,butthepublicdebate on this business is not likelytogiveus that information.Therefore,wewon’treallylearnanythinguseful.Isuspectthatalltiremakerstrytoachievesimilar, industry-widestandardsof tirequalityscatter,butnowit’sthejobofthecourtsandtheteamsoflawyerstofindoutifthisisindeedsointhiscase.

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WhentheConcordesupersonictransporthaditsWashington/Dullestireincidentin1979,fragmentsofaseparatingtiretreadpenetratedtheaircraft’sfueltanksinmorethantenplacesduringtake-off,butfortunatelytherewasnofirethattime.Onceaperceptivepassengeralertedtheflightcrewtotheexistenceofa3X4footholeinthetopofthewing,themachinewas turnedaroundand landedsafely.Theimportantthingaboutthisincidentwaswhatwaschangedbecauseof it,someofwhichisasfollows;

(1)AirFranceswitchedtoanothermakeroftires

(2) Inflationpressurewas raised from187to220psi,intheinterestofreducedflexandheating(eachtirecarries50,000poundsofloadattake-off)

(3) Much more frequent checks oftire pressure before takeoff weremandated

(4) Strain gaugeswere added to themainwheeltruckstodetectandprovidecockpit warning of asymmetric strainresultingfromadeflatingtire

(5) In any case inwhichwheel braketemperaturehadrisenaboveasetlevel,theentireassemblywastobestrippedandinspected

(6)Pilotswereordered to limit taxiingpriortotakeoff(evenrollingatlowspeedatfulltake-offweightgeneratesalotofheat,andconstantuseofthebrakestocontrol taxiing speed generates evenmore)

Most ofwhatwe can learn from thisis obvious—treads separate becauseheat destroys their bond to the tirecasing. The lower the tire pressure,and themore weight being carried,themoreheat is generated.Frequenttirepressurechecksarenecessary topreventaccidentalunderinflation.Otherpossiblesourcesoftireheatingmustbecontrolled.

On a commercial aircraft, all thesesafe ty mat ters are handled by

those professionals who carry thatresponsibility.Evenwiththeexerciseofgreatcare,accidentsarestillpossible.

In the case of pr ivate ly-ownedautomobiles,matters like tire inflation,vehicle loadand speed, highwayandambienttemperature,andthepossibilityofoneormoredraggingbrakesaretheresponsibilityoftheoperator.WhatevertheoutcomeoftheFirestoneaffair,anyoperatorcangreatlydecreasehisorherchancesof ever suffering a tire treadseparationbydoingthefollowing;

(1) Choosing tires appropriate to thespeedsandloadscontemplated

(2)Beingawareofconditions—i.e.notdrivingatexcessivespeedsinveryhotweatherorwhencarryingheavyloads

(3)Settingandfrequentlymaintainingtirepressuresatthevaluesrecommendedforcurrentloadsandspeeds.

(4)Sensingtheabnormal.Experiencedracers running at high speed on theDaytona banking slowdown instantlywhen they feel the sudden build-upof vibration that signals blistering orchunking.


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Diesel DevelopmentsA lot is happening in Diesel enginedevelopment and I expect the pace ofchangetoaccelerate.We’renotdoneyet.

Theobviousdrivingforceisemissionsregulation by governments.This pastDecember,EPAreleasedmuchtighterstandards that Diesels must soonmeet.There is also serious pressurefrom trucking companies. Truckinghas become so competitive duringthese past years of economic boomthatminor differences in specificationcandetermine theequipment choicesmadebymajorfleetswhenreplacementtime comes. The automotive trendtowardheavySUVsmakes ithard forautomakerstomeetmandatedfleetfueleconomylevels.ExpecttoseenewlightDiesel engines replace gasoline-firedpowerplants in theseapplications.Yetanotherreason(notyetacceptedintheUS,whereglobalwarmingisperceivedas a sinister plot by theDemocraticParty) for increased interest inDieselpoweristhatcarbondioxideemissionsper horsepower-hour are lower withDiesel power thanwith gasoline.Theresult is thatDiesel development hasneverbeensorapidasitistoday.

Turbocharging was a revolution forhighwayDieselsbecauseitcutengineweight-per-horsepower.This, ineffect,madefrictionlossessmallerinrelationtohorsepower.

Whenanengine idles,100percentofitspowerisbeingconsumedinfriction.Astheloadisincreased,friction’ssharefallsprogressivelyuntil,atfullloadanddesign rpm, frictionmay only be 15percent of output horsepower.Whatthismeansisthatthelowertheloadonanengine, thegreater thepercentagefrictionloss.Asitturnsout,thefrictioncoefficientofaplainsleevebearinglikethoseusedoncranksandrodsdropsasloadisincreased,becomingaminimumat a load just short of that requiredto cause bearing failure. Thereforeturbocharging,byincreasingtheloadonbearingsbeyondnon-superchargedfullload,hastheeffectoffurtherreducingthefrictionlossasapercentageofthepower delivered.The effect becomes

stronger as engine rpm is reduced.Thoseof youwho flew recip-poweredpropeller aircraft inWW II, Korea, orVietnamwill recall thatmaximum fuelendurance comesatminimumenginerpmandhighboosttopullasteepproppitch.Thecauseisthesame.

Thereareproblemswithturbocharging.Amajoroneisthatasmoreandmoreair is delivered to a cylinder for eachpower stroke, somore andmore fuelmust be injected in proportion. Thattakes time.While the fuel is beinginjected, the crankshaft is turningandthepiston ismoving.Anyfuel injectedafterthepistonhasmovedasignificantdistancealongitspowerstrokeisburnedat less thanmaximumefficiency. Forexample, if the engine’s compressionratiois17:1andthepistonhasalreadymoved through1/16 of its stroke, theeffective compression ratio applied tofuelburnedthatlateisonly9:1.Forcingmore air into the engine and burningmorefuelcertainlymakesmorepower,but because of this late-burn effect,it doesn’tmakeasmuchmorepoweras it should because less of the fuelisburnedatorverynearTDCandfullcompressionratio.

Togetmorefuelintothecylinderbeforethe piston has moved significantlytakesmorepressure,which is part ofthe reason why such high injectionpressures (like 20,000 psi) are beingused.

Common Rail InjectionClassicDieselfuelinjectionusesajerkpump containing tiny pump plungersdrivenbyacamgearedtotheengine.Fuelquantityiscontrolledbyvaryingtheeffective stroke of these plungers—aportinthewalloftheplungercylinderisopenedoncethedesiredfuelhasbeeninjected,thereby“spilling”theremainderof the fuel back to the low-pressureline.Thisworkswellattheenginerpmforwhich it is designed. In this case,the injection pressure drives the fuelspraydeepintothedense,compressedcylinder air charge, therebyachieving

good fuel dispersion and an efficientburn.At lowerengine rpm,pump rpmand pressure are also less, so theslower-movingpumpplungerdrivesfuelfromthe injectionnozzlewith reducedvelocity. The result can be less fuelspray penetration and/or incompletefueldropletbreakup,leadingtoexhaustsmokeandreducedefficiency.

Inbigtruckengines,jerkpumpoperationwas optimized for themost frequentload condition,whichwas full power.Engines for smaller trucks or for carsmust operate efficiently over awiderload rangebecause the open road isnottheironlygig.Onewayofobtainingconstantinjectionpressureatallenginerpmistodeliverthefuelfromaso-calledcommon rail,which is a fuelmanifoldwhosepressure iskeptat thedesiredlevelbyapump.Fuelfromthiscommonrailisdeliveredtotheindividualcylindersby injection valves thatmaybeeithermechanicallyorelectricallyoperated.

soup-ups and smokeWhenastockengine’spowerisboostedbyequippingitwitheitherabiggerturboor with two-stage turbocharging, theextra air deliveredmust bematchedby extra fuel. In jerk pump engines,thismeantreplacingthestockinjectionpump with one of greater capacity.Fuel injection is normally a carefullydeveloped system that ensures goodfuelpenetrationintotheaircharge,withrapid evaporation and light-up. Justinstallingabiggerpumpgetsmorefuelinto the engine, so power increases.But simply pushingmore fuel into thecylinders does not guarantee that itwill penetrate, break up properly, orburnquickly.Highway-certifiedenginesnormally“burn”onlyabout80%oftheiraircharge.Supplyingmorefuelthanthisresultsinlesscompletecombustion.Theresultisthedenseexhaustsmokeyouseeattruckdragracingevents.

Nox and ParticulatesBecauseDieselenginesburntheirfuelinthepresenceofabout20percentexcess

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air,thereislittleCOorunburnedHCintheir exhaust—these are products ofincomplete combustion.What theydoproduce is nitrogenoxides (a productof high-temperature combustion)and particulates—both troublesometo eliminate. Particulates are sootparticles—clustered carbon atoms—withhighmolecularweightunburnedhydrocarbonmolecules stuck to theirsurfaces.Unfortunately,theseadheringhydrocarbonsturnouttoincludesomespeciesthatarepowerfulcarcinogens.Inlayout,thesemoleculesresembletinysix-sidedbathroomtilesingroups.Themostcarcinogenicofthesearetheoneswhosearrangementofsix-sidedcarbonringshas“bays”—regionsopenononesidebutsurroundedeverywhereelsebyothercarbonrings.

As is often thewaywith such things,measuresthatsuppressnitrogenoxideproductionmayincreasesoot,andviceversa.Nitrogencompoundsformathighcombustion temperature, but coolingcombustion by recirculating cooledexhaust gas (cooled EGR) tends toincreaseparticulate formation.A lotofhigh-tempcombustionresultswhenfueltakestimetoigniteafterbeinginjectedintothecylinder.Thistimeiscalledthedelayperiod,and it is just the intervalrequired for the hot, compressed aircharge to evaporate and heat up theinjectedfueldropletsuntiltheyignite.Ifdelayislong,alotoffuelgetsinjectedbeforeignitionoccurs,andmuchofitthenburnshot,creatingNOxcompounds.Toavoidthis,so-calledpilotinjectioncanbeused.Asmallamountoffuelisinjectedbefore themain fuel charge, so thatwhenitignites,thereisnotenoughfuelpresenttocreatethehightemperaturethatmakesNOx.But there is, by thesameprinciple, also not enough heattoavoidcreatingparticulates.Insomecases,theseparticulatesmaybepartlyburnedupbypost injection—squirtingin a small amount of extra fuel afterthemain combustion phase.Gettingeverythingtotherightbalanceisnotaneasyproblemtosolve.

Currently,onetechniqueforsolvingthisdualproblemusesoneaspecttofixthe

other.Itturnsoutthatnitrogendioxideisbetteratburningupparticulatesthanoxygenbyitself.Thissuggestsusingthenitrogenoxideemissionsasanoxidizerto burn up the particulate emissions.Whiletheengineruns,nitrogendioxideis adsorbedonto a special surface intheexhaustcatalyzersoitcan’tstreamoutinthetailpipegas.Thisisthenusedtoburnuptheparticulates,whichhavebeentrappedinthetiny,complexporesinaceramicexhaustfilter.Whenthetwocombine,theyreacttoformordinary(andharmless)diatomicnitrogen,pluscarbondioxide.Makingthishappenincorrectproportionsandwithoutplugginguptheparticulatefilterrequiressometrickery.Thismaytaketheformofreversingtheflowdirectionofexhaustgasthroughtheceramicparticulatefilterperiodically,orof addingextra reactivenitrogen fromanexternaltankofurea.

Theeffectofpilotinjectioninreductionofnitrogenemissionshasbeenknownforsometime.Ithasnowbecomemucheasiertoimplementwiththecomingofhigh-pressure(20,000-psi)common-railinjection through solenoid-controllednozzles.A computer can send lots ofpulses to a solenoid valve in a shorttime,butit’shardtoimagineduplicatingtheeffectwiththetraditionaljerkpumpand its tiny cam-driven plungers.Pilotinjection also cuts noise, becausethe less fuel there is in thecylinderatlight-up, the lessnoisy the thump thatis delivered toengine structureby theresulting pressure rise.As I left myfavoritelocaldinerrecently,therestoodalate-modelhighwaytractor,idlingquietlyin theparking lot.Quietly?ADiesel? Iconcludedthismustbeoneofthenewengines in which this improved pilotinjectioncombustionprocessisused.

Diesel ResearchA group of researchers at UniversityofWisconsin has recently done somehigh-level playingwitha sophisticatedcomputermodel ofDiesel intake, airmotion,fuelinjection,andcombustion.Rather than just try whatever ideastheymight havehad, they decided to

basicallyletthecomputertryeverything.Theygave theirprogramcertain rulesby which to evaluate the results ofeachsimulationrun,andbytryingoneset of combinations of variables afteranother, steering toward improvedresults, theywere able to learn somenovel things. For example, instead ofinjectingthewholefuelchargeatonce,muchbetter resultswere obtainedbyinjectingitinaseriesofcloselyspacedmicro-injections.Whyshouldthiswork?All-at-once fuel injection creates bigfuel-richzones(typicallysixoreightofthem—oneforeachorificeinthecentralinjectortip)surroundedbyleanerzones.Combustiontakesplacefastestwherethemixture is chemically correct, andmore slowly where richer or leanerthan that.Combustion is “completed”byaprocessofrandommixingofrichand lean zones such thatmost fuelmolecules eventually combine withoxygentoliberateheat.

Thistakestime.Itwouldbeamuchbetterprocess if the fuelwere bettermixedlocally, resulting in overall lean-burncombustionwhose lower temperatureproduceslittlenitrogenoxide.Injectingthe fuel in sequential micro-dosescreatesmore numerous and smallerrich zones, surrounded on all sidesby much leaner zones. Mixing andcompletecombustioncanthereforetakeplacefaster.Thisisacloserapproachtotruelean-burn.Sootformsfastestinacoolflame,butbydistributingthefuelbetter,sequentialinjectionmayverywellpreventlocalveryrichcoolspotsfromforming—richsourcesofsoot.Whenthecomputerresultswerereplicatedinrealengines, satisfying gains in efficiencyanddropsinpollutantswereachieved.

Anything that speeds up combustionhas some chance of increasing fuelefficiency.Asnotedabove,ifcombustiontakes so long that it’s still in progressasthepistonmovesdownonitspowerstroke, the laterpartsof the fuelburnexert their effect at lower pressure,and through a reduced expansionstroke.That’salossthatresultsinhighexhaust temperature and increasedfuel consumption.The new breed of

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common-railsolenoid-controlledinjectorcandoabetterjobofgettingthefuelintothecylinder inashort time.Efficiency—especially at part-load—is therebyincreased.

Thisallsoundslikealotofwork,anditis.Butwhen lotsof good researchersconcentrate on a problem, sooner orlaterthebestandsimplestmethodsofsolvingitarediscovered.Thatwillmeanmoreefficient, quieter, andmuch lesspollutingDieselenginesinallsizes.

a Note about TurbochargingTheusualwaytoturbochargeenginesistohookupaturbocharger’sairoutlettotheengine’sintakeplumbing.Where’stheproblem?Theproblemisinthewordplumbing—that’sjustwhatitlookslike.Pipe, elbows, joints. This is thewaysupercharged gasoline engineswereplumbed years ago. Intake plumbingdidn’thavetobesmoothandfreeofflowrestrictions, they reasoned, becauseyouhadall that pressure to cram theairinwhetheritwantedtogoornot.Ifyouneededmoreair, youcrankeduptheboost.

ThenCosworthEngineering began toturbochargeraceenginesforIndianapolis.They discovered that concepts thatworkedwell inunsupercharged racingengines—smooth,straightintakeportswithminimum flow restriction, havingtunedlengthtotakeadvantageoforgan-pipeeffects—worked just aswell in aturbocharged engine.Therefore theydesignedtheirturboenginesasiftheywereunsuperchargedengines,runninginanartificiallydenseatmosphere.Theywererewardedwith “free”horsepowerbecause now that lots of turbo boostwasn’tbeingwastedinforcingairaroundsharpcornerswhereitdidn’twanttogo,moreof itwasgetting to thecylinderswhereitcouldmakepower.

ThereforeIexpecttoseeDieselintake“plumbing” evolve to look a lotmoreliketheslick,high-flowintakesystemswenow see on unsupercharged highperformancegasolineengines.Airfrom

theturbowillgointoalongplenum,fromwhichindividualintakepipeswillgotoeachcylinder.

other Fuels?Diesel fuels consist of longer-chainormulti-ring hydrocarbon structuresthat have to be broken apart duringcombustionsotheycanrecombinewithoxygen to releaseheat.Unfortunately,many of the hydrocarbon varieties inthisfuelstronglyresistbeingbrokenupunlessthetemperatureisprettyhigh.Bythetimethermalcollisionshavebrokenup themost shock-resistant carbonchains,mostoftheoxygenalreadyhaspartners.Thatleavesalotoffreecarbonchainsfloatingaround.Carbonstickstoeverything—that’swhyit’ssooftenusedforpurifyingwaterorwhiskey,andwhyitmakesgood,high-frictionbrakedisks.Italsostickstoitself,sofreecarboninthe combustion chamber can clumptogetherfasterthanitcanfindoxygenpartnerswithwhichtoburn.Theresultissootparticles.

Simpler fuelmolecules break up andburnfaster,andcouldleadtoreducedsootemission.ThisiswhytherearecallstorunDieselengineson“reformulatedfuels.”Thedaymaycomewhencitiesorregionsinwhichairpollutionremainsadifficultproblemwillrequiretheuseofsuchfuelswithintheirborders.

Onethingiscertain.IfcatalyticexhausttreatmentsystemsbecomethedominantDiesel clean-up technology, low-sulfurfuelsmust be provided for their use.Sulfur deactivates catalysts.Refineryprocesses for desulfurization are nowindevelopment.

Variable Valve TimingAnyonewho’sbuiltafewcircle-trackV8sknowsthatcamtimingisjob-specific.Ifyouwantbottomacceleration,yourunshort duration and long lobe centers.If you want top end, the recipe isdifferent.Noonesettingisanythingbutacompromise.

Thisgetsworsewithsuperchargingorturbocharging.Often, to keep pistonsandvalvescool,longtimingsareusedin turbo engines.Air blowing throughthecylinderonvalveoverlapperformsausefulcoolingofpistonsandexhaustvalves. But if this same engine isoperatedatlowerloads,thelongvalvetimingreducestheairchargebecauselate intake closure allows the risingpistontopumpoutwhatwasjustsuckedinonthepreviousintakestroke.

Theupshotisthatengineershavelongwished for variable cam timing.Manypatentdevicesforachievingthisexist,but no systemcombinedall desirableattributes—variable lift and timing,reliability, simplicity, and acceptablecost.

Nowthe increasedvalueofasolutionmay have brought one into being.Navistar(International)hasintroducedahydraulicsystemofvalveoperationthathasnocamshaft.Instead,eachvalveisopenedandclosedbyhydraulicpressure,delivered through an electromagneticcontrol valve directed by a computer.Valvespoolmotionisverysmall—onlya few thousandths of an inch—but itcancontrolamuchlargerflowofhigh-pressurehydraulicfluid.ThistechnologyhasbeendevelopedasanoffshootofmilitarysystemsbytheSturmanCo.Inessence,enginevalvescanbeoperatedthrough any lift and timing desired,simply by changing the programmingofthecontrolsignals.Thiswouldallowanenginetohaveshortvalvetimingatlower rpm,with the timing extendingas rpm built up during acceleration.This ensures amore nearly constantair charge regardless of rpm. Longeroverlapcouldbeprovidedduringhighboost operation of turbo engines, asameansof internal cooling.Likewise,engine braking would become asoftwareitem—aspecialsetofcomputercommandsthatturnstheengineintoanaircompressorbyopeningtheexhaustvalves at the top of the compressionstroke.Variablevalvetimingallowstheenginetobecontinuouslyre-optimizedfor changing conditions—no morecompromise.

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Don’t expect to see this valve drivesystem on FormulaOne racing carssoon—itsoperatingspeedispresentlyappropriateonly forslowerRPMtruckcrankshaftspeeds.

JustwhenwethinkoftheDieselengineas a highly developed and efficientpower system, along come significantnew refinements that push it to newheights.There’smoretocome.


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In the ToolboxEvery person’s toolbox contains a lotmore than tools.With the possibleexception of those who cl imbedimpulsively into the Snap-On truckand cried out “One of each, please!”everyone’stoolshavestories,andeventheuseof tools canarouseparticularmemories.

For example, allmy life I have heardfrommechanics that even ownershipofanadjustablewrench(muchlessitsuse)labelsmeasahacker.Thereisareason for both sidesof thisquestion.Yes, if I put a pipeonmy twelve-inchCrescent wrench and try to tightencritical fastenerswith it, I run the riskof rounding-off their hexeswhenmyimproperchoiceoftoolopensupunderabusivepressureandslips.Thisdoesnothappen,however,because Iamahumanbeingwithbothexperienceandjudgment.Iknowthattherangeoflargebox-orcombinationwrenchesthat theCrescent’srangerepresentswouldaddfiftypoundstomytoolboxandsubtractathousanddollarsfrommybankaccount.Ineedthosebigsizesonlyafewtimesayear,andwhenreasonablepressureontheadjustablewrenchdoesn’tmovethepart,IbuywhatIneed.Meanwhile,thosethreeadjustable life-savers stay inmytoolcollection,andIamstronglyresistanttohootsandcatcallsfrompurists.

Therearethree#2Phillipsscrewdrivers.The little stubbyone goeswhere theotherswon’t,butyoucan’tspinit.ThebiglongonedatestowhenIwasjettingKawasakitriplesandhadtoreachcarbclampscrewsclearacrosstheengine.Picking up that tool remindsme ofdesperatedaysinthehotsun,workingovertheheatofapistonseizure.

Yes, Iadmit toadmiring thebeautyofSnap-Oncombinationwrenches.Theirsmooth shape is as right as that of acatorahorse—apleasure tohave inhandor to lookat.Purists, avert youreyes!Mixedinwiththesebeautiesareothermakes.Irememberahot-headedfriendoncesayingtoaSearssalesman,“Thereareonlytwokindsoftoolsinthisworld—Snap-On and snap-off––and Ionlyhave time for the former.” While

extremesarefun,IenjoythevarietyofhandwrenchesIhave.

Canascrewdriverbebeautiful?WhenIwasalittleboy,Ilovedtheemerald,ruby,topaz,andcrystalclearplastichandlesoncheapscrewdrivers.WhenIgrewup,Ilearnedthatsuchhandlescould,undergreatpressure,slipontheshafts.Well,nevermind,forthirtyyearsIhada#3Phillipswithaclearyellowhandlethatdideveryjob.EverytimeIreachedforit,hopingthatthisparticularPhillipsheadwouldnotbetheonetoslipandbecomesomangleditwouldhavetobedrilledout,therewasatinysparkofthatlong-agolittleboypleasureinthattool.FinallyI broke it doing something I knew atthetimewasimproper.Mypunishmentis its replacement—a practicalNAPAspecialinadrearymilitarygray.It’sasunattractive in its way as thematte-black-handledSnap-Onsnexttoit.

In the top center drawer, next to agrizzled pair of Vise-Grips are myRobinson wire twisters. Fastenerson racing equipment and aircraft aresecuredagainstunscrewingbystainless,brass,orcoppersafety-wire,twistedintoplaceaccordingtoprescribedrules.AtonetimeIwasdoingalotofthis,andincompanywithothers.Iorderedleft-handtwistersinthehopethatinthiswayI’dbeable to knowwhohaddonewhat.Recently, indisassemblingabigPrattandWhitneyaircraftengine,Ifoundthatleft-handtwistersgetaround;whilemostof the safetywire on this 28-cylinderenginewastwistedtotheright,Ididfindsomeleft-twistaswell.

Pleasureintherighttool?Forme,thisismosttrueofsnap-ringpliers.YearsagoItriedtomakedowithauniversalsnap-ring“system.”NowIknowthattheword“universal”asappliedtotheusesofatool,oftenmeans“doesnotwork.”Afterspendingfiveminutescarefullyinsertingand tightening thecorrectsetof jaws,onejawwouldsproingacrosstheroomfromtheforceappliedinunseatingthesnap-ringIwantedtoextract.Aftermuchsearching, Imightfindthe jawandtryagain.Afterthreetries,Ihadauseless,incompletetool.Forget it—nowIhave

every kind of snap-ring plier, inside,outside,straight,45,andright-angle.InthedrawerIwillfindtheanswer.Evenmore satisfying in their way are thetransmissionpliersIbought,whicharelikenormalbroad-billpliersinreverse,with the serrationson the outsidesofthethinjaws.Thesearedefinitelystrongenoughtoreliablyextractandcontrolthethickest, stiffest eyeless transmissionsnaprings.Standingthereatthebenchthefirsttime,withthefirstextractedringstillonthetool,Ismiled.NowIwasthemasterofthesituation.Nomoresproing,nomorehands-and-kneessearchingforringsthathadshotoffofmakeshifttools,bouncedoffawall,anddisappeared.

TheSnap-OnorMatco truck used tocometoshopswhereI’veworked.ThiswasaweeklyEaster for usall.Therewaspleasureinlayingoutquitealotofmoneytohavethosegleamingobjectsthatworkedsowell.OccasionallytodayIseeatooltruckinthepitsataracingevent and I have to climb up, beholdperfection,andwalkaway$100lighterwith just a few items I’vewanted fora long time. The beautymost oftenperceivedisthatwhichisclosesttous—thestuffweuseeveryday.

Oppositemyhydraulicpressisabadly-mushroomedpieceofthickcopperbarstock.Thisismysofthammer.Whynoofficial copper or brass hammerwithproper handle? The impromptu fist-hammerhadbecomeashopfriendbythetimeIcouldcountenancespendingallthemoneytheywantfora“real”softhammer.Besides, holding this tool asour long-agoNeanderthal ancestorsheldtheirfist-axeshasitsownhistoricalcharm.Thepieceofcopperhasitsstory,too.ThisisOFHCcopper,forOxygen-Free, High Conductivity. In general,everytimeyouaddanalloyingelementtoametal,youreduceitsmeltingpointanditselectricalandheatconductivity.Thisbitwasoriginallyboughtformakingsomekindofdetectorinapreviousjob.Now it straightens pressed-togethercrankshafts.

Where’s the torquewrench?They’rehere somewhere, and they are not of

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the kind that have to be recalibratedin a lab every sixmonths. They aresprings—bendingbarswithpointerstoshowtheamountofbendinfoot-poundsorinch-ounces.Theaccuracyofthesesimpletoolsdependsontwothings—myabilitytoreadthescale,andtheYoung’smodulus of steel. Neither of theserequiresperiodic recalibration (okay, ifthepointerdoesn’tzero,Ibendituntilitdoes).Ifthewrenchfallsonthefloor,Idon’thavetocallanambulanceforit.SummersBrothersspeedpartswerehotinthe1970sandtherewasasalesmanwhoseproblemcustomerkeptbreakingthe special super-strength fastenersused with these classy axles. Howcould this happen?At the customer’sshop,thesalesmanaskedhimtoshowhimhowhetorquedhisbolts.Themanobliged, pulling out one of the veryfanciestof“clicker”torquewrenchesandcarefullypulling the fastenerup to therecommendedvalue,“click!”Thenwithequalcarehegavethefasteneranotherquarter-turn...

Evenmytoolboxmayattracttheirscorn—a1963Craftsmanwithunfashionablyfewdrawers(madeinthelastcentury,forcryingoutloud).MaybeI’llgetmyselfanewonesometime,butfornow,thelabor of cutting the rubbermatting tofit thedrawers,andof screwingdownthe socket-retaining clips is alreadycomplete.Itworks.Anewtoolboxwouldneed to have all thiswork repeated.Also,Icancarrythisboxouttothetruck—barely.SometoolboxesI’vehelpedtoliftfeellikethey’vebeenpouredhalf-fullofsteel.That’snotpracticalforme.

For a long time I carried a large andbeautifulmetric combination wrenchthat fit only one thing—the rear axlenutsonKawasakiracingtriples.Ithadnootherapplication.Ididn’twanttousetheCrescentbecauseaxlenutsareoneof those critical items.Doing the axlenut became a ceremonial affair. Thewrenchstayedintheboxuntilthebikesforwhichithadbeenboughtreturned,twentyyearslater,asclassiccollector’sitems.

Forallthesereasons,thereisapleasureformeintheuseofeachofmytools.Idon’treviewtheirstorieseachtimeIusethem,butonsome level I’mawareofthemallthesame.Theyarehighabovethestatusofmereobjects.

Irememberlooking,asaboyorayoungman, into the toolboxes ofmy eldersandbeingamazedattheunimpressivenondescriptnessofwhatwasthere.Thisisjusthowmytoolswilllookifandwhengrandchildrenarrivewhocaretolookatthem.“Howcanheworkwithallthatoldjunk?Whydoesn’thegetridofhalfofthisstuffandgetsomeREALtools?”


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Racing Diesels?An early example ofDiesel enginesin racingwas the attempts byWW IGerman submarines, operating onthe surface, to catch up tomerchantshipping. The German “pocket”battleshipsofthelate1930s,builttothetermsofthepost-WWIsettlement,fullyexploited the compactness ofDieselengines and their fuel, as comparedwith the larger volume occupied bysteam boilers and engineswith thelargeramountofoilfueltheyrequired.This,intermsofdesign,wasaformofracing– trying to extract speed frompowerplantadvantages.

AtIndianapolisin1952,theCumminsDiesel racing car was fast enoughto set a new lap record and qualifyon the pole for the 500-mile race.Adecision had beenmade in 1950 toallowDiesel-poweredcarsof402cubicinchesdisplacement,superchargedornot, competingwith unsuperchargedgasoline-powered engines at 270cubic inches.After beginningwith aroots-blown and overbored versionof their six-cylinder truck engine,Cummins decided to try that new-fangled device, the turbocharger.Thisnewcar,althoughheavyat2500pounds,showedthatDieselpowerwasnot just for slogging up hills, pullingheavyloads.Withtheengineturning4000 rpmand the tuboassisting theintake process to the tune of 15-20psi, theCumminsmade about 400hp.Becauseofitsengine’sefficiency,the car was able to carry enoughfuel to run the racewithout refuelingstops. Unfortunately the turbo inletwaspositionedsuchthatinthe1952500race,itbecamepluggedwithtrackdebrisandtheCumminsroadsterwasoutatlessthanhalfdistance.

Diesel engines are not throttled—their cylinders always take in a fullcharge of air. This is valuable forefficiency because lean combustiontakesadvantageofbetterconversionofcombustionheatintocylinderpressureat lower temperatures.This specific-heat-of-gaseseffectisalsothebasisforallthecurrentlean-burndevelopmentingasolineengines.

Atfullpower,itisnormalforDieselstodeliver only enough fuel to useabout80%ofthecylinderaircharge.Thislimitis observedbecause it has proven toburnalmostall the fuel,andwithverylittlesmoke.Theconversionofaslittleas5%ofthefuelsuppliedintocarbonresults in heavy black smoke.Power,however,continuestoriseaspeakfueldelivery is raised, offensive smoke isproduced,andconcernedcitizenspointandsictheauthoritiesonyou.

Combustionpressureistheresultof(a)thetemperatureoftheburnedgasesand(b) thenumberofmolecules resultingfrom combustion.Themore zoomingmoleculestherearetocollidewiththepistoncrownsthegreatertheresultingpower.As it happens, enriching thefuel-airmixturepastthepointatwhicheveryhydrogenandcarbonatomfromthe fuel finds its oxygenpartner doesincrease the number ofmolecules inthecombustiongas,andthisincreasespower.

ThiseffecthasbeenusedforyearsbyDieselmechanicstocoaxabitofextrapower fromhard-worked units—but itdoescausesmoke.

IsawthiseffectatworkthispastmonthatBonnevilleSalt Flats,whena truckcalled “Phoenix,” powered by a two-strokeDetroitV-16engineof1472cubicinches, set an unlimitedDiesel truckrecordatjustover250mph.Itleftatrailofblacksmokefivemileslong.

A crewmember toldme that they had“runintoawallofair”at190mphandhadtoimprovetheirtruck’sshapetogofaster.Thefrontofthismonstervehicle(weight is 18,000 pounds) ismostlydefinedbya1943InternationalK-7cab,withpermittedroundingandsmoothingperformedinaflawlessmanner.Behindthiscab,theshapetapersgraduallylikeanaircraftfuselage,endinginthefourupturnedturboexhaustpipesanddrag-chutehousings.

TheV-16 engine is aDetroit 16V92,an industrial engine normally used intugboats,topoweroffshoreoilplatforms,

and to driveUSNavy river craft likethoseonceusedinVietnam.Itismoreorlesssixfeetlong.Thecrankismadein two sections, bolted together at itscenter,sotheengineisineffectapairofV-8scoupledend-to-end.EachV-8sectionhas itsown largerootsblowerin theVeeof the cylinders, andeachblowerisequippedwithbypassvanes.These,whenusedwithturbocharging,allowtherootsblowertostarttheengine,but then open to allow flow from theturbo(s)tobypasstherootsonceturbopressureexceedsrootspressure.

Detroit two-strokeDiesels are uniflowengines,withfourexhaustvalvesineachcylinderhead,andringsoffresh-airportsat the bottomof each cylinder. Freshair under pressurewaits to enter thecylindersfromanairgallerysurroundingthebottomsofthecylinders.Whenthedescendingpistonuncoversthechargeairports,thisairrushesintothecylinder,pushingexhaustgasupwardtowardtheopenexhaustvalves.

Four large turbochargers (eachwithacompressorwheeljustundersixinchesindiameter)areusedonthistruck,alongwithacoupleof turbinesdisintegratedearlyinBonnevilleSpeedWeek.Turboproblemsarecommononthesaltflats.Theapparentcausewasdebrispassingthrough the engine.Two replacementturboswereflownin.

Because of the increased charge airfrom the turbo system, fuel deliveryhad tobe increasedaswell, but I didnot get a crewmember to revealwhatkind of injection changesweremadetoaccomplishthis.Theseenginesusecam-drivenunitinjectors.

Whatkindoftirescanpossiblysurvivetheweight and speedof this giant? Iwondered; but the answer is simple—tiresfromheavyjetaircraft.Thedrivewheelsofthistruckarebias-plyBoeing747main-bogietires,eachratedtocarry40,000poundsandtosurviveoperationat225mph.Onthistrucktheywouldbeloafingwithrespecttoload,andthereforelikelyabletotoleratesomeoverspeedwithoutdamage.ThefrontsareBoeing

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707nosewheeltires,mountedonwheelsfromaFokkerF-28.

Thecrew“don’tliketoturntheengineover3000rpm,”butfigurehorsepowerat about 4000, which would be 2.7horsepower per cubic inch.At 250mph,thepressureofairresultingfromfull conversion of kinetic energy intopressure is 167 pounds per squarefoot.Ifthefrontofthetruckwerejustaflatplateandtherewasnotaperingtailbehindtoreducewaketurbulence,dragwouldbeapproximatelythis167poundfigure,multipliedtimesthefrontalarea.Since frontal area is about 55 squarefeet,thiscomestoabout9000poundsofdrag.At250mphthiswouldrequireabout6000hp. Ahighwaysemidoesbetterthanthis—itsdragisonlyabouthalfthatofaflatplateofequivalentarea.This reduction comes about becauseinstead of stopping the oncoming aircoldagainstthefrontofthetruck.Muchoftheflowisdivertedaroundtheshape,retainingmuch of its original speed.Even if the actual drag of the VastDieselRacerishalfthatofaflatplate,we are still leftwith a need for 3000hp, plus several hundred horsepowermoretoovercomerollingresistanceandtransmissionlosses.Maybethat4000hpisarealisticfigure!

Iwatchedatthestartasthebiggreentruckmadeoneofitsrunsdownthesalt.Someminutes before time to go, theenginewasstartedby its twinelectricstarters and on-board complement ofheavybatteries. Itstarted immediatelyandwaswarmedupbythrottlecycling,soundinglikeadistantrailwaylocomotiveidling.Itcontinuedthisidlingasitspush-truck (powered itself by a twin-turbo16V92engine)accelerateditofftheline.ApushtruckisnecessaryforveryfastBonneville vehicles because their tallgearingmakesstartingfromrestallbutimpossible. Incidentally,TurboDieselpickupsarethestandardtow,push,andsupportvehicleofchoiceatBonneville.Altitudeis4000feetandSpeedWeekweatherisusuallyhot,resultinginamid-dayairdensityonly80%ofthatatsealevel.Thismakeseveryoneappreciateturbocharging!

A fewhundred feetout from thestart,driverCarlHeapappliedpower.Instantlythe push truckwasmade invisible bythe thick streamof black smoke fromthe four six-inch chrome stacks. Likeawind-tunnel flowdemonstration, thesmokeflowedupoverthepushtruckanddownitsbacktothesalt.Thepushtruckpulledoff the laneand thegiant racerquicklydisappeareddown-course.Whatdid not disappearwas its long heavysmoke cloud,which continued to driftnorthward,risingfromitsownheat,fortwentyminutes.Rich-mixturepower!

Withtwofastpasses,madewithintherequired time, their averagewasover250mph, raising their own record byalmost 20mph. It was fascinating towatch two of the crewmen loadingdrag chutes for thismachine (just tryto imagine stopping from250mphbyusingonlytheservicebrakes).Firstoneman coats all internal surfacesof theparachutecontainerwithtalcumpowder.Thenwithanothermanfeedinghimthenylonharness,hefoldsitinaprescribedway, back and forth, and places it inthecavity, followedbythechute itself,suitablyfolded.

Another16V92-poweredtruckraninastock-bodiedclassona224-mphrecord(itsown).Thisonewasbasedonthecabshape of a 1997Freightliner,with notapered tailbehind it.Theenginewasmounted behind the cab in the open—animpressiveassemblyofmachinery,driving through anAllison automatictransmission.

Wretchedexcessisfun!Intheworldofhot-rodding, toomuch is just enough.Whatnext?Iwonderwhatadeterminedcrew of big spenderswith 3/4” drivetoolscouldgetfromanEMDlocomotiveengine?


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ChoicesTheDiesel engine is themost efficientprimemover currently available.Sparkignition engines lose out because thedetonation-prone-nessoftheirfuellimitscompressionratioandsolimitsaircycleefficiency.Gasturbinescoupledtohigh-speedalternatorsmightbeattractivebutarelimitedinsmallsizesbyleakagepastthetipsoftheirfast-movingblades.Fuelcellssoundgreatbutwherewillwegetalltheplatinumthattheywillrequire?Wherewill we get and howwill we store thehydrogenthatreallymakesthemshine?

Thisbeingso,thequestionis,howcanweusetheDieselenginetobestservehuman purposes? In theUS, fuel isstillcheap,sothat’snottheissue.Theissueisthatterrible1980sdiscoverythatDiesel particulate emissions carry ontheirsurfacessomeprettycarcinogeniccompoundscalledPAHs,orPolycyclicAromatic Hydrocarbons. It is for thisreasonthatsomuchemphasisisbeingplaced upon reduction of particulatesby suchmeans as exhaust filtration.Accumulatedparticleson thefilterareburnedoffperiodically,usingpartlythenitrogenoxidesnormallypresentintheexhaust, and partly nitrogen suppliedexternally.

Europehasdifferentprioritiesbecauseoil has to come a long way, frompartsof theworldEuropeancountrieswould prefer not to be dependentupon.Europeangovernmentsalsotakegreenhousewarming ofworld climatemore seriously than is general in theUS.Cuttingtheoverallfuelburnisthekeytoreducedcarbondioxideemission,and the excellent economy ofDieselengines is the key to this. ChoosingDiesel power ismade easier by taxbreaksthatreducethepriceofDieselascomparedwithgasoline.EmissionsarecertainlyanissueinEurope,butcuttingoilimportsandcarbondioxideemissionsareequallysought.Europeanstrategyistoencouragetherapiddevelopmentofhighlyefficient,reasonablycleanDieselenginesforpassengercars.Tothisend,Euro-regulatorsarewillingtorelaxautoDieselemissionsstandardssomewhattomakedevelopmentofsuchenginesmoreattractive.

HereintheUS,smallerDieselswillhavetomeet the same standards as largetruckengines,andthehighcostofthisinsmallerenginesisexpectedtokeepUSdriversincleanbutlessfuelefficientgasoline-burners for the foreseeablefuture.

On another subject entirely, back intheperiodbetweenWorldWars I andII,theUSNavywasearnestlyseekingimprovedDiesel submarine engines.Dieselswerepreferredbecauseoftheirfueleconomyandbecauseheavyfuelsarelesspronetoformexplosivevaporthanisgasoline.

Thesubmarinewasadifficultproblembecause thenecessarysurfacespeedrequiredalotofpower,whiletheenginespaces were small.When compactlightweightDiesel engineswere built,engine frames, cylinder heads, andpipingcracked,andcrankshaftsbroke.Afterthenotoriousmilitaryprocurementscandals ofWW I, a new strictnessmade the sale of engines to theUSgovernmentmuch less attractive.Nocompany wanted to undertake thenecessary engine developmentwhenonly small numbers of engineswouldbebought.

Thespecialproblemwasthecrankshaft.Bigpowermeant lotsofcylindersandfairly high rpm, but the resulting longand complicated shaftswere subjectto thebuild-upof torsionalvibration inparticular rpm bands. This constanttwisting back and forth soon fatiguedandbroketheshafts.Makingthepartsheftiermade theengineunacceptablyheavy.Simply forbidding operation atcertainspeedswasaboutaseffectiveastheAirCorp’sperpetualcampaigntostoppeoplefromwalkingintospinningairplane propellers.Words don’t stophabits.

The solutionswere a clever piece ofwork.SomeoneintheNavydepartmentrealized that the needs of submarineengines—high power and high speedwith lightweight—were close towhatwould be required if Diesel railwaylocomotiveswere built. It’s not clear

tomewhether the Navy helped therailroads develop their engines, orwhethertherailroadshelpedtoamortizethe cost of developing submarineengines.Eitherway,adealresulted,andtwotypesofdurableengines—theGM-WintonandFairbanks-Morse—resulted.ThesewerethebasisoftheUSNavy’shighly successful, but largely unsung,suboperationsinthePacificinWWII.

The crankshaft torsional vibrationproblem was solved in an equallyneat way. Instead of coupling theDiesel engines directly to the sub’spropellers for surface operation, or tomotor-generators for battery charging,a railway-likeDiesel-electricdrivewaschosen. In this system, theDieselsdrive only the generators, and arenevercoupledtotheprops,whichweredrivenbyelectricmotors.ThisallowedtheDieselstorunatagoverned,saferpmwhile propeller rpmwas variedelectrically.Inlocomotives,thissystemeliminated theproblemofdesigningaclutchstrongenoughtostartatrain.

Automot ive Diesel engines arealso subject to crankshaft torsionaloscillations,buttheircranksarerelativelyshort. This shortness canmake thecrank’s oscillation frequency enoughhigherthanitsfiringfrequencytoavoidtrouble.Automotive cranks can alsobemade robustenough to liveoraregiven torsionaldampers toabsorb theoscillationenergyfastenoughtopreventitsbuildinguptodangerouslevels.

TodayitappearsthatautomotiveDieselenginedesignhasconvergeduponanopen combustion chamber four-strokedesignwithfourvalvesandacentrallymountedinjector.However,thehistoryof the Diesel engine reveals a richvariety of alternatives.TheFairbanks-Morse engine referred to above is aprime example.A two-stroke, it hadtwoopposedpistons in each cylinder,connectedtotwocrankshafts. Ineachcylinderonepistoncontrolledexhaustports through the cylinderwall, whiletheothercontrolledtheinlets.Exhaustportsweremade to open before theinletsbyphasingtheexhaustcrankto

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runabout15degreesaheadoftheinletcrank.Manysuchopposed-pistonDieselengines havepowered trucks, buses,railcars, andevenaircraft. In some,asinglecrankshaftoperatesbothsetsofpistons bymeansofmassive rockinglevers.Amoreusualarrangementwastocoupletwocrankshaftsbybevelgearsandashaft.TheclassicengineofthistypewastheJunkersJumo205Diesel,whichpoweredsomanyGermanJu-52transportaircraftjustbeforeandduringWWII.

Theaimof theopposed-pistonDieselwas to achieve uniflow two-strokescavenging.Asexhaustleftthecylindervia cylinderwall ports exposedwhentheexhaust pistonwasnear itsBDC,fresh air would enter through inletports uncovered by the inlet piston atthe opposite endof the cylinder.Thissimplified end-to-end flowminimizedthemixing of exhaust gas and freshair.Anotheradvantageoftheopposed-pistonengineisthatithasnocylinderheadsthroughwhichtolosecombustionheattocoolant.

Currentlycommercialsoftwarepackagesexist bywhich tomodel in detail theformationofspraysbyDieselinjectors.The penetration of the fast-movingdropletsintothedense,compressedairnearTDCcanbestudied,anddetailsof how evaporating vapor, trailingbehindthem,mixeswiththeaircanbeconsidered.Othercomputermodelsdealwiththeactualignitionandcombustionof this vapor. Ideally fuel vaporwouldmix intimatelywith air beforeburning,butmuchofcombustionisatfirstveryincompletebecauseoxygentakestimetomixwithfuelvapor.Heatfromnearbycombustionknockshydrogenatomsoffof fuelmolecules to leave connectedringsofcarbonatoms.Ifthesecarbonstructures clump together before theyfindoxygenwithwhichtocompletetheircombustion,theymaybecomeexhaustparticulates.Otherformsofincompletelyburned fuel form the carcinogens thatadhere to particulate surfaces. Thisclumping and sticking is a naturalattributeofcarbon,whichiswhyitcanbeusedingasmasksandotherpurifying

apparatus—carbonattracts andholdsimpurities.Anearly applicationof thisnatural stickiness of carbon is in the“smoothing”ofexpensivewhiskeysbystoring them in barrelswhose insideshavebeencharredtocarbon.

Combustionresearcherswouldlovetofinda“silverbullet”thatwouldpreventformation of carbon particulates, butfor the moment the available pathto reduced particulate emissions isexhaust filtration.Cross your fingers.Back in the 1920s,when itwas clearthat detonation—combustion knock—wasabarriertofurtherdevelopmentof spark ignition engines, systematicresearch atGM-Delco labs revealedjustsuchasilverbullet. In thiscase itwastetraethyllead,ahighlypoisonousorgano-metalliccompoundwhich,addedto fuel in gram-per-gallon quantities,couldreversepre-combustionchemicalreactionsthatledtodetonation.ThusfarnosuchmiraculousfixhasbeenfoundforDieselparticulateformation.

Oneway or another, the particulateproblemwill be solved, because theDieselengine is toousefulamachinetodowithout.


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BrakesBrakesusedtobesopoor,withsolittleability toabsorbenergy, thatevencardriverswere advised to “use a lowergear”whendescendingsteephills.Thereason for this was that the brakes,unassisted, did not have the capacityto continuously dissipate the requiredenergy. If you reliedon thebrakesbythemselves, the temperatureofdrumsand linings would rise high enoughto deform the drums, causing themto expand and cone away from theshoes.Thelining,optimizedfor lower-temperature use, would lose part ofitsfrictioncoefficientandbraketorquewouldfall.Thepedalwouldfeelspongybecause of the bending thatwent onas shoes were forced against nowconeddrums,andbrakingeffectwoulddiminish.

Hence,itwasnecessarytosupplementthe energy-conversion and heatdissipationabilityoftheservicebrakesby shifting to a lower gear and usingenginecompressionandinternalfrictionaswell.

Diskbrakesweresupposedtofixallthat.BackwhenDunlopdiskbrakeswereforthefirsttimefittedtotheJaguarfactoryracecarsat theLeMans24-hourracein France, it was like amiracle.TheJaguarswouldstayonfullthrottlelongafterothermakeswereonthebrakes,thenbrakeviolentlyatheseeminglastinstant and dart around the corners.Mercedes had resorted to equippingtheirendurancecardswithan“airrake,”aflapnormallylyingflatagainsttherearbodywork, whichwas erected like asailbyhydrauliccylindersasthedriverapplied the brakes. Jaguar’sDunlopdiskbrakeswerecompactandsimple,acontrasttothelastofthedrumbrakeswerehugefinnedaluminumaffairsthatfilledtheentirespacewithinthewheels,andhadseveralshoes.

Theadvantagesofdiskbrakesarereal.Asadiskexpands,itstillliesflatandsodoesnot curve away from the frictionmaterialbeingpressedagainstitbythecaliper.Thereisnobellmouthingaswithadrum,thereforenospongypedal.

However, disk brakes have their ownspecialproblems,andthesehavecometo light as engineers have becomemoreskilled ingivingvehicles just theamount of brake capacity they need,andnomore.Oneoftheworstproblemshas been created unintentionally bygovernment fuel-economy regulations.Alightcarortruckgenerallygetsbettermileagethanaheavierone,andallpartsofthevehiclearefairgameforweightreduction—includingthebrakedisks.

Apanicstopformthevehicle’smaximumspeedtakesonlyafewseconds,duringwhichthereisalmostnotimeforbrakedisks to transfer any heat to the airaroundthem.Thus,essentiallytheentirekineticenergyofthevehicleanditsloadisputintothedisksasheat.Theheavieror faster the vehicle, the greater thekineticenergyandthehigherthefinal,end-of-brakingdisktemperaturewillbe.Thesame is trueofdiskmass—if thetotalweightofbrakedisksonthevehicleis reduced, brake temperaturemustincrease.This iswhat has happenedonproductioncarsandlighttrucks.Theweighttakenoutofdisksintheinterestof improving fuel economy becomesa liability when you see brake lightsright ahead and have to use all therakeyouhavetoavoidbeingpartofachain-reaction rear-ender.As you arebraking,youcanfeelthebrakingforcefading as disk temperature drives thepads to a temperature atwhich theirfrictioncoefficientfallsrapidly.Youhopeyou’ll get stopped in time. (Hope is awonderful emotion, but notmushuseagainst physics.)After a fewof theseexperiences, peoplewant somethingstronger.

Invehiclesofthe1980sitwasn’ttoobad—you could still get back themissingbrake torque by installing aftermarketpadssuchasmetal-ceramicorsinteredmetal.Butwhatevertheconsumercando,thefactoriescandobetter.Knowingthat smallish disks and better padsequalbetterbrakes,theyreducedbrakediskmass again, restoringmarginalbrakingpowerbyuseofthelatest,mostaggressivepads.

Thisiswhythereisabriskaftermarketbusiness in improved brakes. Mostproductionbrakesusedisksofmarginalsize. This reduces brake torque bysimple leverage—the bigger the discyourcalipergrabs,thelargertheleverarmonwhichcalipergripacts—andviceversa.Owners of sporty autos like toincreasewheelsize,thenfitlowprofile,race-style tires that give the samerollingdiameterasoriginal.Thismakesa lot of extra room inside the biggerwheel. Into this room, theaftermarketputsbiggerdiameterdisks,grippedbycalipersthatoffersomethingmorethanmarginal function. I am talking hereaboutsystemsthatcost$1,500-4,000.OEMcalipers tend tobesinglepistondesigns that accommodate wear byslidingonapairofrails.Theaftermarketcalipershavepistonsonbothsidesofthe disk, so the caliper body can besolidlymounted.Multiplepistoncalipershaveelongatedpadsthat“wrap”alargersectorofthedisk.Theirincreasedareatranslatestolowerpadtemperatureandso less fade inhardbraking. In somecasesthecalipersarealuminum,whichcompensatesforsomeoftheincreaseddiskweight.Whenvehiclesequippedinthiswayhavetostoprightnow,thepedalstays upandbrakingpower doesnotdiminish—althewaytoadeadstop.

Whenavehicleahsamarginalamountof diskmass, causing its brakes tooperate at high temperature, severalthingscanhappen—allrelatedtoheat.Oneis“hard-spotting”ofdisks,resultingina rhythmic thumpat thepedal (thiscouldalsooccurwithdrums).Whenadisk is repeatedly driven to very hightemperature, the structure of the ironcrystals in it can change to anotherform that occupies a slightly greatervolume.Youwillthenseedark,slightlyraised regionsonyourdisks,possiblywithstreaking.Youcanhavethedisksturned to expose a new, flat surface,buttheprocessdoesn’tstop.Itcomesbacktomakemorehardspotsandmorethumping.Thecureforthisproblemiseither to switch to disks of a superiormaterial, or to increase disk massto bring peak operating temperaturedown.

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Loss-of-pedalAnotherproblemisdiskconing. Ifyouapply theedgeofa12”metal ruler tothesurfaceofanewdisk, itwill toucheverywhere—the disk is flat. But ifthe disk has been used hard, as inmaking repeatedmountain descents,thediskmaybeslightlyconed,asthestraightedgewill show.The pads canwear at an angle to accommodatesomediskconing,butbeyondacertainamount—andespecially if you fit newpads—itwillcauselossofpedalheight.Asyouapplythebrakes,thepadswilltouch the disk, and then have to bepressedenough further tomake themflattenagainst the slightly angleddisksurface.Thiscausesthecaliperpistonto tilt in itsboreaswell—something itcan,withinlimits,do.Thisloss-of-pedalcanbeaproblemifreallyhardbrakingisneeded,butlittlepedalheightremains.

Whydodiskscone?Heatisgeneratedinsomeproportiontothespeedofthediskpastthefrictionpad.AstheODofthediskhasalargercircumferencethandoesacircledrawnaroundthediskattheinneredgeofthepadtracks,theODpart of the diskmoves past the padsfasterthandoestheIDpart.Thereforethereismoreheatgeneratedthefurtheroutyougoonthedisk.Attheextremecase—inwhichthedisksbecomereallyhot—thisgreatertemperatureathediskODcausesthatregionofthedisktotrytoexpandmorethanthe innerregion.Atlowertemperatures,thediskisstrongenoughtoresistthis,butwhenveryhot,evenironlosesstrength.Theexpandedouter regionof the disk pulls so hardon thecooler, inner regionof thediskthatitcausesittoyield.Inotherwords,theexpansionof thehotterODregionstretchesthecoolerIDregion.Whenthediskcoolsandeverythingtriestoreturnto itsoriginal size, thestretched innerregionisstinybittoobig.Thiscausesthedisktoassumeaslightconeshape.Becausethediskmaterialisnowatthisslight angle between the two pads, ittakesmorepedalstroketogetthepadsflatagainstthediskwhenyoubrake.

Thetrendinbrakedesignistomakethepadtrackonthediskradiallynarrower,therebyreducingthedifferenceindiskvelocity(andheatingrate)betweenouterandinneredgesofthepadtrack.Thislossofpadwidthismadeupbymakingthe pad longer circumferentially.Youcanseethisbestinmulti-pistoncalipersmadewith either four or six pistons.Anotheradvantageofthisnarrow-pad-trackdiskdesignisthatitplacesmoreof the pads’ action at a larger radiusfrom the center of the disk, therebyincreasing the leverageand thereforethebraketorque.

Anothercauseoflossofpedalisfrictionpaddeformation.Mostfrictionpadsaremoldedontoametal backing, but thetwomaterialshavedifferentexpansioncoefficients. The hot, expanding padmaterialthereforearchesupthecoolermetalbacking.Onceyourfootisoffthebrake, this archingof thepadpushesthecaliperpistonsbackintotheirbores.Whenyounextgoforthebrakes,yougetabigadrenaline rushasyour footnearlygoestothefloor.Aquicksecondstabasthepedalbringsthebrakesback,butdoeslittleforyourconfidenceinyourstoppingpower.

Another cause of low pedal is loosewheel bearings or flexibility in thestructuresupportingthewheelbearings.Asyoudrivethroughacorneratsomespeed, the side-load of corneringcausesthewheelstococktothesideabit,carryingtheirdiskswiththem.Thiscockingpushesthecaliperpistonsbackinto their bores slightly in a processcalled “pad knock-off”.The next timeyou go for the brakes, the pedal hastomoveanextradistancetopumpthepadsbacktothedisk,soagain,youhavemomentarylowpedal.

Brake FluidMuch is made of the problems ofbrake fluid boiling.Everyone’s vehiclemanualprovidesaschedule forbrakefluid replacement but hardly anyone

everpaysanyattentiontothis.Littlebylittle, thehighboilingpointclaimedbythe fluidmanufacturer becomes lowerand lower because the fluid absorbsmoisturefromtheair.Inveryharduse,heatcanpenetratethebrakefrictionpadandheatthecaliperpistonenoughthat,whenyoutakeyourfootoffthepedal,theoverheatedfluidbehind thepistonboilswithenoughpressuretopushthefluidbackuptheline,throughthemastercylinderreliefport,andintothemastercylinder reservoir. Now you have areallyseriousproblemwhenyougoforthebrakesnext time.Enough volumeofgasmayhavebeengeneratedinthehotcaliperthatafullstrokeofthepedal—right to the floor—fails to bring thepadsbacktothedisk.

Hey, this expensive bottle of siliconebrake fluid has amuchhigher boilingpoint than that nasty old DOT3 orDOT4 fluid.That’s gotta be better. I’llswitch…

Tryit—itmayworkforyou.MyexperiencewithsiliconeDOT5wasn’tgood,however,becauseDOT5isalousylubricant—insomecasesbadenough tocause themaster cylinder piston to fail to returnall theway.Therefore I just follow therecommendationinthevehicleOwner’sManual, rather than trying to second-guessthemanufacturer.

Brake Pads

Asdisk brake performance has risenwithsuchthingsassinteredmetalpasor carbon pads, used inmulti-pistoncalipers,strongermeasureshavebeentaken to keepheat from reaching thebrakefluidbehindthecaliperpiston(s).Sometimesinsulatingmaterialisplacedbetweenthefrictionpadandthecaliperpiston.The (open) end of the caliperpiston, facing the pad, is sometimesslottedtoresembleacastlenut,therebyreducingthecontactareabetweenpadandpiston,andalsoallowingairtoflowthrough the piston cavity.A variety ofcooing baffles is sometimes used todirectairthroughthecaliper.

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Ventilateddisks—thosewithradialslotsthroughwhich cooling air canmove—neatlydouble thesurfacearea fromwhich brake heat can be transferredtotheair.Inracingorotherheavy-dutyapplications,airductsmaybeusedtobringcoolingair tocalipersanddisks.Openings in thewheels can assist inmovingairacrossthehotparts.

Frictionmaterial is another subject.Originally, friction padswere organic,made of a reinforcing fiber (todaythis isKevlar,but inolderpads itwasasbestos) impregnated with organicresin. Such pads give good frictionwithout heavy pedal pressure, buthave limited temperature tolerance.Fade beginswhen the resin contentvolatilizes,forminglow-frictionlayersofglazeorevengasbetweenthepadanddisk.Sometimesbrasswirecanbeseen,molded intoorganicpads. Itspurposeis to conduct heat away from the hotfriction surface.Diskwear is lowwithorganicpads,but inwetweather theiractioncanbeerratic.

Metal-ceramicandsinteredmetalpadsretaintheirfrictioncoefficientstohighertemperaturesandtheyworkwellevenin wet conditions. Because of theirhardness theywear disksmuchmorerapidly.

Thebrakematerialofthefuture—usedwidely on high performance aircraft,racing cars, and motorcycles—iscarbon-carbon.Thismaterialisamatrixof amorphous carbon, reinforced bysuper-strengthcarbonfibers,allbakedtogetherintoasolid.Boththedisksandpads aremadeof the samematerial,anditsfrictionpropertiescanbetailoredbychangingtheorientationofthefibersduringmanufacture.

Aircraftbrakesaremadejustlikeaclutchstack, with half of the disks rotatingwiththewheel,andtheotherhalfheldstationary. The stack is compressedby a ring of hydraulic cylinders.Theadvantage of carbon brakes is thattheyareverylightandcancontinuetooperatenormally at temperatures thatwouldmeltironbrakerotors.Thisisvery

importantinaircraft,whoselandinggearmust be light yetwhose brakesmustabsorbhugeenergiesfromheavyweightandhighspeed.

Carbon is slowly moving into thecommercial field as a componentof friction pads. True carbon-carbonremains too expensive for such use,theproblembeing that thismaterial ismade in high-temperatureovensbyaprocess that can take as long as sixmonths.Carbonitselfisagoodfrictionmaterialbecauseitissticky(that’swhyit’s used inmakingwhiskey, inwaterfilters,i.e.impuritiessticktoit).Bearinmindthatcarbonexistsinseveralforms.Diamondsareforever,graphiteisadrylubricant,andplainoldcarbonmakesagoodfrictionmaterial.

Brakesbeingasimportantastheyare,it’s a shame they are so often poorlymaintained.But it’s understandable—brakeslacktheglamourandexcitementof engines and turbochargers—andthey’re coveredwith roaddirt, hiddenbehindthewheels,invisible.Theproblemisthatwhenbrakesfail toworkaswerequire,theexcitementisimmediateandunbearable.


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Your Notes:

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Burning It all upTheturbochargerwhistlesthinlythroughits teethasyouopenupthethrottlealittle toclimb the longhill that lies justahead, hardly seeming to notice thebigstocktrailerhookedupbehind.Youtakeanothersipofcoffee.Attimeslikethis,lifeisgoodandit’shadtothinkofDieselpowerasanythingbutamatureessential ofmodern life.Meanwhile,back inAnnArbor, Michigan, newhoopsarebeingdreamedupforDieselcombustiontechnologytoleapthrough.TheEPAisatworkonstifferemissionsstandards.

WhenIvisitedMIT’sSloanAutomotiveLabinthe1960sandearly‘70s,ithadalmost become amuseum, so littleresearchwas conducted there. In thefoyerwasaLibertyV-12aircraftengine,alegacyofWorldWarOne.Somewhere,youcouldfindProfessorTaylor’sfamed“rapid compression machine,” withwhichsomuchvaluableflamechemistryresearchwas once performed. In thetest cells stood research engines,bothDiesel and spark-ignition,mostlycold and unused.When I asked thedirectoraboutthis,Iwastoldthatenginetechnologywasno longerauniversityresearch subject. It had all becomeproprietary—corporateproperty.

Allthatchangedwhenengineemissionsbecamebigbusiness.TodaytheSloanLab, andmany others like it, is backin full operation.Engineeringstudentsknowtherearewell-paidjobsinindustryfor peoplewho have spent their fouryearsstudyingcombustion.

Currently, X-ray imaging has beenused to studyDiesel fuel sprays, andnew insights have been gained.Oneof themost interesting is that fuelcancavitate as it emerges from the spraynozzle—that is, the fuel is somehowpulledaparttoforminteriorcavities,filledonlywithfuelvapor.

Cavitationisafamiliaranddestructivephenomenon for those who designmarinepropellers.Onthelow-pressureside of such propellers, pressure candroplowenoughthatcavitationbubblesare produced, which stream across

thebladesurface.Whensuchbubblescollapse,fluidrushesfromalldirectionstoward a single point. When theycollidethere,extremelyhighpressuresand temperaturesareproduced.Asaresult,cavitationbubblesthatcollapseagainst the prop blade surfaces canactuallyremovemetal,causingerosionthatlookslikesand-blasting,orliketheeffectsofheavydetonationonaluminumpistons.

Why would fuel oil cavitate duringDiesel injection? Isn’t the pressurevery high during injection—like 1300atmospheres,or20,000-psi?Yes,andthatmaybejustthepoint.Althoughwelearn in school that liquids likewaterandDiesel fuelare incompressible,atveryhighpressures this isnot trueatall. In fact the venerableDowty, Ltd.,makersofaircraftlandinggearintheUK,substitutesthecompressibilityofoilforheavysteelspringsintheirsuspensions.Quitelikely,therefore,fueloilcavitatesduringDieselsprayformationbecausethecompressedfuelisexpandingsofastasitleavesthenozzle.

It has been remarked that this fuelcavitationmaybeusefulincausingthefuelspraytobreakup.Previously,ithasbeenassumedthatfuelspraysdevelopinstabilities as they rush through thedense, hot air near top dead centeron a Diesel engine’s compressionstroke. These instabilities cause thefuel stream to break up into twistedsausage-likedroplets.These,stillrichinkineticenergy,havinginitiallyemergedfrom the fuel nozzle above the localspeed of sound, break apart by thefamiliarmechanismof being flattenedbythepressureoftheirencounterwiththeair, and thenbreak into circletsofsub-droplets.Eachfast-movingdropletleavesafuel-richvaporbehindit.

In the intentionally turbulent air, thesemillionsoffuel-richtailsarewhippedandfoldedandcombinedwithmoreair.Atsomepointintheprocess,airandfuelsomewherebecomeheatedenoughtoignite, and the charge so far injectedbegins to burn. It does so fastest inthosezoneswherethefuel-airmixture

happens to be near to chemicallycorrect,becausesuchamixtureburnsfastest.Richerorleanerzonesarehot,but delayed in catching fire by theirslowerchemistry.Inthesezones,heatbreaks fuel and airmolecules apart.Hydrogen atoms are stripped off ofcarbonchainsand,becauseofcarbon-to-carbon attraction, these fragmentsclump together.When the flamedoesfinally sweep through these slower-burning regions, the carbon clumpsmayalreadyhavegrownlargeenoughthatoxygenfromsurroundingaircannotreachmostofthem.Insteadofburning,thesecarbonlumpsbecomesoot.

Asinjectioncontinues,theprocessesofdroplet breakup, evaporation,mixtureformation,andignitionalsocontinue—and in the zones almost too rich toburn,carbonclumpscontinuetoform.The amount of fuel energywasted insoot formation is insignificantly small.What is large is human concern overthe effects of the soot.Diesel enginemakers don’t like soot because it issomethingobviousthatcriticscanpointat.TheEPAdoesn’t likesootbecausecarbon is attractive—things stick toit.The stickinessof carbon is a basictechnology in thecompoundingof tiretreads—bymixing carbon into rubber,theattractionofcarbonparticleshelpstielongrubbermoleculestoeachotherinusefulways.Similarly,carbonisusedinsmoothingwhiskey—bystoring it inwoodbarrelswhoseinsideshavebeencharred. Bad-tasting “impurities” areabsorbed onto the carbon. InDieselcombustion,carbonattractsotherbadcompany. These are the polycyclicaromatichydrocarbons(PAHs)thatwereadabout—multiplecarbonringswitha variety of geometries and attachedside groups. Some of these mimicmolecules necessary formetabolism,andcan leadtoconcerns.Until itwasdiscovered that soot particles carrythese carcinogenic passengers, theDiesel engine was looked upon asatworst ill-smelling and occasionallysmoky,butessentiallyblameless.Sincethatdiscovery,eliminationof soothasbecomeamajoraspectofDieselenginedevelopment.

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Two basic approaches exist to thisproblem. One is to improve thecombustionprocesssothatsoot isnolongerproduced.Theotheristoacceptthat Diesel combustion is inherentlysooty,andconcentrateontrappingthesoot inafilterofsomekind,and theneliminatingit.

Thefirstapproachhasproducedclassichigh-pressure injection into a swirlingair charge. It is also driving suchdevelopmentsasmulti-burst injection,in which fuel is no longer injectedsteadilyuntilthewholequantityentersthe cylinder. Instead, a small pilotinjectionismade,andthereisapauseto allow it to ignite. Then themainfuel charge is sprayedas a series ofbursts, with time intervals betweento allow better fuel-air mixing. Onetechnologydiscussedinthisconnectionispiezoelectricdrivers.Solidsareheldtogetherbyelectricalforces,soitmakessense that their dimensions are alsodetermined by these forces. Certaincrystals have the curious property ofchanging their dimensions when avoltage is applied across particularplanes.Suchpiezoelectricdeviceshavelongbeenusedastransducersinphonocartridges,orassend-receiveelementsin SONAR. Because they can actquickly,theysuggestanewgenerationofmulti-burstDieselinjector.

Anotherpossibilityissuggestedbythediscovery of cavitation inDiesel fuelsprays.Or, if a gasweredissolved inthefuelathighpressure,itsexpansionas the fuel emerged from the nozzlemightbreakupfuelspraysevenmoreeffectively than the newly-understoodcavitationeffect.InDr.Diesel’soriginalengine,andforsomeyearsthereafter,fuel was blown into the cylinder andfinelybrokenupbyanassociatedveryhighpressureairblast.Intheautomotivefield, thishas itsparallel in theOrbitalEngineCompany’s gasoline injector.Thisinjectsameasuredfuelquantityintoapre-chamber,thenbyairblastforcesthat through an orifice at supersonicspeed into the main chamber. Anextremelysmall10-micronfuelparticlesizeisachievedinthisprocess.

Another concept is suggested by thefuelairbleedthathasbeenstandardformanyyearsonautomotivecarburetors.The first purposeof feedingbleedairinto the fuel flowing in a carb’smaincircuitistocorrectthemixture.Thisdoesnotconcernushere.Thesecondistocreatewithinthefuelalargeamountoffreesurface(theinterioroftheresultingairbubbles)whichassiststhebreak-upofthefuelstreamasitemergesintothelowpressure intake air flowing to theengine.Allliquidshavesurfacetension,which results from weakmolecule-to-molecule forces within the liquid.Becauseof this,energy is required tocreate fresh liquid surfaces, and sodropletsresistbeingbrokenintosmallersizes. If those surfaces already exist(fuelairbleed)orifthereissomesourceofpotentialenergywithin the fuel thatcancreatesuchsurfacearea(suddenexpansion/cavitation of compressedfuel,orexpansionofdissolvedgasintobubbles) thesewould provide usefultoolswithwhich to reduce fuel sprayparticlesize.

It would also be very agreeable ifa chemical “fix” for soot formationwerepossible. In thecaseofgasolinecombustion,theorgano-metallicadditivetetraethyllead(nolongerlegalforuseinpumpfuels)actsasa ratecatalyst,countering the conversion of heat-producedmolecular fragments into aformthatleadstoknockingcombustion,or detonation. One could imagine achemicalprocessthatwoulddiscouragethe clumpingof free carbon into soot.Sofar,nosuchmagicbullethasbeenfound.

It is now being suggested that themethodologiesofsparkignition(gasolineengines) and compression ignition(Diesel)willconvergeastimepasses.Tomeetfuelconsumptionstandards,sparkignitionenginesmust seek to operateeither at higher compression ratios orwithleanermixtures.Tocutparticulateemissions, Dieselsmust re-engineertheircombustionprocess.

Some years ago, Honda showed atwo-strokemotorcycleenginethatran

onCAI, orControlledAuto Ignition.In this process, a premixed charge,somewhatdilutedwithhotexhaustgas,is compresseduntil it spontaneouslyignites inmanyplaces.Althoughyouwouldexpect suchcombustion toberoughand rapid, it canbecontrolledto produce a rate of pressure risemuch like that of current engines.Of particular interest is the ability ofthis system to operate on very leanmixtures.This gets the attention ofDieselengineersbecauseitsuggestsawaytoavoidamajorcurrentproblem;aDieselcombustionchambercontainsacontinuousrangeofmixturestrengthfrom 100% fuel (injection spraydroplets) to100%air regionsnotyetreached by fuel. Somewhere in thisrangeliesideal,completecombustion,butelsewhereliessootformation.Ifthemixturestrengthcouldbecontrolledinadvance,andthechargethenignitedinmany places byCAI, the volumepercentage of charge inwhich sootformation could take place could begreatlyreduced.

Operating an engine in this modecalls for charge volume control andvariable exhaust gas recirculation toholdthechargeatthetemperaturelevelneededforControlledAutoIgnition.Toavoidpumpingloss,thiswouldrequireanother technology, nowappearing—that of variable valve timing. Suchengineswouldalsohavetobecapableof multi-mode combustion, for theCAI phenomenon cannot cover thenecessaryloadrange.

Muchissaidinthepressofthecomingfuelcellvehiclepowerrevolution,butevenwithamaturetechnologyinhand,alongtimewillberequiredinwhichtoconstructtheproductionfacilitiesandfuels infrastructure required. In themeantime,pistoninternalcombustionengineswill soldier on in evermorerefined form, burning less fuel andmore cleanly, to provide the powerwe require.There is no shortage ofideas.


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Through the CycleAs thepistonofaDieselengine risesoncompression,thereisnothingaboveitbutair,pluswhateverfractionofinertexhausthaseitherbeenleftinthecylinderfrom the previous cycle, or has beenintentionallyadmittedtothecylinderasexhaustgasrecirculation(EGR)alongwithfreshairasanemissions-reductionmeasure.Eitherway,thegasabovetherisingpistonisbeingrapidlyheatedbycompression, bringing its temperatureuptomanyhundredsofdegrees.

Fuelissprayedintothishotairfromaninjectornozzle.At first,evaporationofthefuelcoolstheairimmediatelyaroundit, but turbulent airmotion brings theresultingfuelvaporintorenewedcontactwith heated air.This little interlude ofevaporation, cooling, and re-heatedis lumped together under the term“ignition delay.” Chemical reactionsbegin, increasinginintensityuntil theyhave to be lumped into the complexmesswecallcombustion.Itlookssimpleon the white page in the chemistrybook—the carbons and hydrogens ofthe hydrocarbon fuel combine neatlywith oxygen atoms from the air—asif theywere all polite dance partnersatacotillion—but in fact thousandsofdifferent reaction steps are involved.Theprocessisviolentandchaotic,withmolecular fragments speeding in alldirections, colliding, combining, flyingapart,andre-combiningagain.

One thing is sure: heat is released,increasing the velocities of all themoleculesthatemergefromcombustion.Previously, pressure in the cylinderwashighfrompistoncompression,butnow,astheaveragevelocitiesofallthemoleculesbeatingagainstthewallsofthiscontainerhavesorisen,theybeatmuchharder.Meanwhilethepistonhasreachedtopdeadcenter(TDC)andtherodhasbeguntoswingpasttheverticalposition.The tangentof the rodangle(TDCiszero),multipliedtimeshalfthestroke,nowgivestheeffectiveleverarmofthecrankshaft.AtTDCthereiszeroleverage, but as the rod swingsover,leveragegrows, reachingamaximumwhen rod and crank arm are at rightangles—somewhere near 76 degrees

after TDC. Meanwhile, combustionpressurecontinuestoriseastheinjectorspraysmorefuelandthatfuelisbrokenupbythermalcollisions.Itspiecesfindoxygenmates, releasing heat, addingandaddingtothecylinderpressure.

Butnowthepistonbeginstofall,sothevolumeaboveitbeginstoincrease.Thesameamountofhotgas,occupyinganexpandingcontainerlikethis,meansthepressuremustfall.Aspeakcombustionpressurebeginstofade,effectivecrankleverage increases.The net result isthat torque on the crank continues toriseuntilsomethinglike30degreesaftertopcenter.Thentorquebeginstofadeto lowervalues. Itmayseemstrange,but80%ofacylinder’spowerstrokeisgeneratedinthefirst70-80degreesofrotationafterTDC.

As the piston descends on the powerstroke, under ever-dwindling pressure,thegasaboveitfallsintemperatureaswellaspressure.Becauseadieselengineneedsahighcompressionratiotoheatairhotenoughtoignitetheinjectedfuel,italsohasahighexpansion ratio.Themorethecombustiongasisexpanded,theloweritstemperaturefalls.

Whenexhaustvalvesopen,somewherenearbottomcenter,gastemperatureinthecylinderismuchlowerthanitwouldhave been in a comparable gasolinespark-ignitionengine.Thistemperaturedifferencearisesfromthedifferenceincompression(andthereforeexpansion)ratio.Compressionhastobeonthelowsideinagasolineengine(between8and11toone)becauseotherwisethetouchy,heat-sensitivefuelwilldetonateatsometime late in combustion, generatingsonicpressurewavesthatmaketrouble.In a diesel engine, despite its highercompression ratio (between 15 and23toone),therecanbenodetonationbecausefuelburnsalmostimmediatelyupon being injected into the cylinder—ithasnotimeinwhichtobealteredby heat into a sensitive explosive, asin gasoline engines.Detonation takestimetodevelop,butdieselcombustionconsumesthefuelbeforethattimecanelapse.

When theexhaustvalveopens,spentgas, still at several hundred degrees,acceleratesthroughtheportandrushesout.This situation is an ideal one forrapidheattransfer.First,thegasishot.Second,itsvelocityishigh.Highvelocitycausesviolentturbulence,whichinturnkeepsfreshhotgasswirlingagainstthemetalinterioroftheexhaustport–thereisnorelativecalminwhichaninsulatinglayerof stagnantgascanbuildupontheportwallstoinsulatethem.Thefast-movinghotgas scours theportwalls,constantlydrivingheat into them.Thehigherthetemperatureandvelocity,thefastertheheatflowsfromthegasintotheportwalls.

Inagasolineengine,abouthalfofthetotalheatrejectedtothecoolingsystemispickeduphere in theexhaustport,becausevelocityand temperatureareso very high. It is for this reason thatexhaust ports aremade as short aspracticable—to limit the heat pickedupbytheengine,whichmust thenbecollectedby thecoolingsystem in theformof heatedwater, and thenpipedaway toa liquid-to-airheatexchanger(radiator)tobedisposedof.

But in a diesel, because of its highcompression/expansion ratio, exhaustgas is much cooler, and thereforemuch less heat is rejected to coolantfrom the exhaust port region.This iswhygasoline-powered truckshavenotroublemustering up heat from theirbusycoolingsystems,withwhichtoheatthecabinwinter.Inthecaseofdieselengines, it can bemore complicatedbecausealesserreleaseofheatmeansslower enginewarm-upand lessheatavailablefortheside-jobslikekeepingushumanswarm.Dieselenginesalsoneed coolant radiatorsmuch smallerfor their horsepower thandogasolineengines.

The other side of this coin is thatif less heat is being rejected to thecooling system, that heat must begoingsomewhereelse. It is—muchofitisgoingintodrivingthepistons,doingusefulworkintwistingthetransmissioninput shaft. This is why we bought

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diesels in the first place.With someof themoneywe saved on fuel, wecanbuywoolenshirtsthatwillkeepuswarmwhilethelesserflowofwasteheatfromtheenginetakesitstimewarmingeverythingup.Efficiency!


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Diesel PoliticsRudolph Diesel invented his enginequite deliberately, acting from hisunderstanding of thermodynamics.The resultsweren’texactlyashehadplanned,buttheefficiencyofhisenginewashigh,basedasitisuponthedualprinciplesofhighcompression/expansionratioandlackofintakethrottling.Ithadanother importantmerit: because itsfuelwasvaporizedby themechanicalaction of the fuel injector, assistedbythehightemperatureofcompressedairin theenginecylinder, the fueldidnothave tobenaturallyvolatile.Theveryfirst internal combustion engines hadsolvedthemixturepreparationproblembyrunningoncityilluminatinggas,andlater types by adopting that volatile,unwanted,anddangerousby-productoflampoilmanufacture:gasoline.

UnlikeDiesel fuel, these fuels couldeasilyformcombustiblemixturesoutside theenginestheyserved.Weknowthatwiseownersofgasoline-poweredinboardboats take elaborate precautions toforce-ventilatetheenginespacebeforestarting,lesttheybeblowntoKingdomComeby a gasoline vapor explosion.TheDiesel’srelativeimmunityfromfuelexplosions,combinedwithefficiency,gotitsteadyemploymentaspowerfirstforships, and then for submarines.Earlyenginesranbestonfullthrottle,asittooktimetolearnhowtocontrolinjectedfuelspraysoverarangeofloads.

The next natural application was inrail locomotives,where fuel efficiency,reliability, andmodular constructionwere seen as powerful advantagesover the traditionsof steam.With thedevelopment of easier starting andwider load range,Dieselenginesnextappearedintrucks.Itwasprobablythemarine and heavy truck applicationsthatgavethepublicthelastingideathatDieselpowermeantmassiveweightanddreary (ifefficient)performance. IwellrecallearlyDieseltransporttrucksracingdown rollingPennsylvania hills, thengrindingarduouslyupthenextslopeinlowergears,followedbyalonglineoffumingautodrivers.

Help arr ived in the form of theturbocharger. This device had longexisted—Dr.SanfordMossatGEhadexperimentedwith turbochargers justafterWW I—but what was requiredwas the urgency of WWII to forcethese previously exotic devices intolarge-scaleproduction, and to compeldevelopmentofthemetalalloysrequiredfor turbine blades, stators, and disks.Turbos enabled aircraft tomaintainconstant horsepower from take-off allthe way tomaximum altitudes over30,000feet.Furtherhelpcamefromtheextremely rapid postwar developmentof jet engines, whose large scaleproductiondrovedownthepriceofthematerialstechnology.

The turbocharger turned the Dieselengine into the ideal truck engine.The power to keep upwith traffic onthenew interstatehighways—uphillordown—no longer required a giganticengine,asthepowerofaturbochargedDiesel is proportional not to its pistondisplacement,buttoitsairflow.Andthatairflow, delivered by the turbocharger,wasreallylimitedonlybythemechanicalstrength of the engine and by theinjectionsystem’sability todeliver therequiredfuel.Thedensercompressedcharge of turbo-Diesels required yethigher injection pressures to achievethenecessaryspraypenetration,buttheresultswerewellworththedevelopmenteffort.

Europe has always been fuel-starvedbecause taxes are high and oil fieldseither distant or well protected bypolitical barriers. The automobile gotitsstartinEurope,butitwasintheUSwherefuelhasalwaysbeencheapthattheautofirstreachedmassproductiontobecomeanecessityoflife.PostwarEuropeancarsweresmall,poweredbytinyengines.TheDieselengine,bynowdeveloped into a flexible, convenientpower source, offered away to buildevenmoreeconomicalautos.Europeannationsofferedspecialtaxincentivestoencourage theproductionand sale ofDieselvehicles,withtheoverallgoaloflimitingtheoutflowofcurrenciestooil-producingstates.

The visible result in theUSwas thatDieselEuropeanprestigeautosenjoyedabriefvogueinthe1980s,stimulatingdomestic automakers to “convert”gasoline-fueled designs to Dieseloperation.The resulting failures gaveDieselautosablackeye.Inthissametime period the EPA decided thatDiesel particulates were a greaterthreat tohumanhealth thanhadbeenappreciated. This triggered a questfor anti-particulate technologies thatcontinuestothepresent.

VeryhighlyturbochargedmarineDieselsweremeanwhiledevelopedformilitaryand sportingmotorboats.The specificpowerof theseengines is impressive,equaling the levels set by someWWIIgasolineaircraftengines.Suchhighpower density requires the best inbearings, piston sealing and cooling,andfuelcontrols.

ThemilitaryforcesoftheUSnowbegantodevelopwhattheycalled“thesingle-fueledbattlefield,”inwhichallvehiclesandotherpower-conversionapparatusto be procured for anymilitary usein futuremust run on jet engine fuel.FromtheturbineenginesintanksandhelicopterstotheDieselenginesinArmytrucksandothervehicles,thesinglefuelgreatly simplifies logistics. Comparethiswithapastinwhichthreeormoreaviationgasolines,avehiculargasoline,andturbinefuelallhadtobeseparatelyprovided.Could thisbeamodel foracivilianfuture?

During the 1990s the trend-settingCaliforniaAirResourcesBoard calledinsistentlyforthedevelopmentofzero-emissionsvehicles,whichcametomeanelectric cars. Political power provednomore able to prevail over realityin this case thanwhenKingCanutecommanded the flooding tide to gobackouttosea.Efficientelectriccarsatattractivepricesfailedtomaterialize.Asaquestionof further interest,considerhowmuchmore severe California’spowerblackoutscouldhavebeenhadhundredsofthousandsofelectriccarshadbeenforcedtotaketheirpowerfromthesamegrid.

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All thewhile, technologiesofgasolinespark-ignition and Diesel enginesmovedahead,andevenshowedsometendency to converge.A stratified-charge, lean-burn gasoline enginebeginstolookalotlikeaDiesel.Dieselenginesgainedeconomyandflexibilityfromelectronically-controlledcommon-railfuelsystems.Eithertechnologycannowreachefficiencylevelscomparablewithorsuperiortothemuch-ballyhooedfuelreformerfuelcellcycles(fuelcellswhich get their hydrogen by breakingdown a liquid fuel such as alcohol inan on-board reformer). Even higherefficiencycanbereachedbyfuelcellsoperating on pure hydrogen fuel, butthere isnocheapsource for this fuel,noconvenientmeansofstoringit,andthereexists nodistribution system forprovidingittomotorists.Thisbeingthecase,itlookslikewe’llgoaheadprettymuch as before, using piston internalcombustionenginespoweredby fuelsthat actually exist, are easy to store,andarewidelyavailable.Whileitcouldbe that revolution will in future beatevolution, for themoment the steadyevolutionofthepistonengineisdoingthetransportation jobandpromisestodoitbettereveryyear.Dieselpowerisnotgoingawayanytimesoon.


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Future of Diesel in the usRightnow,40%ofnewcarsdeliveredinWesternEuropeareDiesel-powered,while inFrance, that number rises to60%. In theUS, hardly anyDiesel-poweredcarsaresold,andDieselandspark-ignition power share the lighttruckmarket. Is this as far asDieselpower will penetrate into the non-industrialtransportationsectorhereintheUS?

ManyyearsagoEuropeangovernmentsgavemaximumprioritytofuelconservationbecausealmostallpetroleumtheremustbeimported.Nogovernmentrelishesanunfavorablebalanceoftrade.BecauseDieselenginestypicallyburnonly75%asmuchfuelperhorsepower-hourasdogasoline engines, those governmentscreatedfueltaxincentivestowidenuseofDieselpower.

Here in theUS, fuel has historicallybeenmuch cheaper than in Europe.Whensmog inUScitieswasofficiallyattributed in large part to vehicleexhaust,thenaturalprioritywastocutsmog-formingemissionsanddonothingaboutfuelconsumption.Earlyemissionslegislation concentrated on reducingemissions from private cars,most ofwhichwere gasoline powered.Dieselengines, because they burn their fuelinthepresenceofexcessair,emitlessunburnedHCandCOthandogasolineengines.Theywere therefore, at first,lessregulated.

In the 1980s, it was discovered thatparticulates (soot) in Diesel exhaustwas a carrier for complex polycyclichydrocarbons, at least someofwhichare highly carcinogenic.Emissions ofoxidesofnitrogen(NOx)wereofgreatconcernbecauseof their role insmogchemistry. They are particularly hardto eliminate, and they are present inDieselengineexhaust.Foratime,USautomakers seeking lower-emittingengineshad consideredDiesel powerasapossiblesolution.NewemissionsregulationsforDieselenginesincreasedthecostofsuchdevelopments,makingitcheapertocontinuerefiningthespark-ignitiongasolineengineinstead.Costsrule!

By contrast, European nations placehighervalueonreducingtotalfleetfuelburnthanonreachingthelowestpossibleemissions.EuropeanregulationsacceptsomewhathigherDieselemissions(theNOx componentwhich contributes tosmog) in return for their considerablefuel savings. Here in the US, useof Diesel power in automobiles isdiscouragedbytighter(moreexpensivetomeet) emissions standards. (If youneedall thedetailsof the tighterNOxlegislation in theUS, check out Issue38,page28,“DieselPowerintheUSA.”)Thebasic differencebetween theUSandEuropeanoutlookarises from thedifferent value placed upon the fuelsavedbytheDieselengine.Thisvalueis bothmonetary (a gallon saved intheUSis$1.65,butagallonsavedinEuropeis$5.00)andpolitical.InEurope,allpetroleumisimported,butintheUS,only about 25%of the oil is importedfromArabcountries.

In addition, USmotorists like theirsmooth, fast-accelerating, relativelyodorless gasoline-powered autos.SalesresistancetoDieselpowercomesfrom (1) its association with heavytruckingandthereforeunexcitingengineperformanceand(2)theextranoiseandexhaustodorofDiesels.

Whatcanchangetheseperceptions?

In response to tightening emissionsstandardsworldwide,Dieseltechnologyhasadvancedvery rapidly in thepastfiveyears.Developmentsnowenteringserviceorabouttodosohavethepowerto change the public’s perception ofDieselpower.

(1)Diesel noise—the clatter ofDieselcombustion is caused by the rapidignitionofalargeamountofinjectedfuel,resultinginasteeppressurerisethatislikeahammerblow.Thehighpressure,common rail injection systems nowcoming intouseonadvancedenginesovercomethisbypilotinjection.Insteadofinjectingthewholefuelchargeinonecontinuousspray,asmallpulseoffuelis injected first, after which injectionpauses. Because the pilot injection

contains only a tiny amount of fuel,its ignition is accompanied by only amodestpressurerise—andlittlenoise.Only then is themain charge of fuelinjected.Becauseitignitesimmediately,itspressurerisedependsontherateofinjection—whichcanbecontrolled.

(2)AssociationofDieselpowerwithlowperformance.Older drivers rememberbeing trapped behind Diesel truckslaboriouslyclimbinglonghills.Atypicalheavy-duty truckengineof thatperioddeveloped 165 horsepower. Today,almostthreetimesthatpoweristypicalinhighwaytractors.ThedevelopmentofturbocharginghasmadepossibleDieselengines that deliver asmuch powerper cubic inchasany sporty gasolineenginemade.Anyonewhohasdriventhecurrentgenerationofsportyturbo-Diesel European cars is familiarwiththistruth.FormulaOneengineerJohnBarnardhassuggesteditistimethatF1adoptedaturbo-Dieselengineformulatospeedthedevelopmentofsuchenginesfor autos.ModernDiesel engines candeliver all the performanceanydrivercouldwant.

(3) Emissions problems—CurrentlyDiesel engines can deliver either lowparticulates and high NOx, or lowNOx and high particulates (We’vecovered these basics!See page__.),butdevelopmentssuchaspiezo-electric-actuated injector valves, cooledEGR,andexhaustpost-treatmentarewhittlingawayattheedgesofthiscompromise.Meanwhile, amore profound changein the form of Homogeneous-ChargeCompression Ignition (HCCI) is in theresearchstage.Ifthedifficultload-controlproblemsinherentinthistechnologycanbesolved,itmayinthefuturedeliververylow levels ofNOxemissions, allowingexhaust HC andCO (inherently lesswithDiesels)tobedealtwithbyasimpleoxidationcatalystprocess.

Meanwhile,theGasolineDirectInjection(GDI) engine has been touted as theengineofthefuture—abletoclosethefuelconsumptiongapbetweengasolineandDiesel, butwithout currentDieselproblems.Thisenginetypeoperatesat

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low-andmid-loadsinastratified-chargecombustionmode,achievingitseconomyand low NOx emissions through areducedcombustiontemperature.GDIisthefavoredtechnologyintheJapaneseauto industry. In Japan, urbanizationand crowding limit vehicle speeds.Therefore Japanese emissions-testdrivingcyclesfavor lowloads.Insuchtest condition,GDI engines look verygood—approaching Diesel levels offueleconomy.WhoneedsDiesels,saytheproponentsofGDI,whenyoucanachievethesameresultswithimprovedgasolineengines?

ThesurprisehasbeenthatGDIhasfailedtodeliverintheUS.Here,wherehigherloads are common,GDI’s advantageshrinks because the engine spendsless time in its efficient, low-throttlestratified-chargecombustionmode.ThisleavestheDieselengineverymuchintherunningasa futurepowerplant forUSautosand light trucks. Its positioncan only grow stronger as currentrapid development brings it closer tocompliancewithUSEPAautoemissionsstandards.

OtherproblemsofwiderconversionofautoproductiontoDieselpowerincludetheneed for expansionof componentmanufacture (turbochargers, EGRcoolers,exhaustcatalystsystems,etc.)andforhigherproductionof low-sulfurDieselfuel(requiredifcatalystsaretobeusedonDieselexhaust).

Fuelconsumptionasideforthemoment,thefactisthatmanyAmericansstilllikebigcars.Abigcarcancarrythewholefamily, while towing a boat or horsetrailer.Auto emissions standards hadnearly killed off the big family sedan,butthentheSUVarrived,madepossibleby anemissions loophole intended toprotect certain commercial vehiclesfrom regulation. Despite attack fromenvironmentalistsandothers,theSUVthrivesandearnsrecordper-unitprofitsforitsproducers.Thisvehicleisanidealapplicationforturbo-Dieselpower.

Wider conversion to Diesel cannothappenwhileenginesnowinproduction

donotmeet the 2004and tighter still2007EPAemission standards.Whichwillchangefirst—thestandardsor theengines?Compliancewith each newlevel of emissions reduction costsmotorists the hundreds of millionsof dollars required to develop andmanufacturethenecessarytechnology.This cost is hidden in the purchaseprice of new vehicles (someestimatethat compliance and “contingencyengineering”—planning for possiblefuture regulations—add 40% to thepriceofnewvehicles)andinthevariousinspections and repairs required tomaintain compliance.Will this remainacceptable to mostAmericans if inadditionthepriceofpetroleumcontinuestoriserapidly?Ourlivesareconstructedaround cheap transportation.At somelevel of fuel price, advancedDieselengines will become the best andcheapestall-aroundsolution.


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Flame Diffusion and Your Next DieselDieselandsparkignitioncombustionarequitedifferent. In thegasolineengine,a pre-mixed fuel-air charge is ignitedatoneormorepointsbyspark.Asthismixture is nearly uniform throughoutthe combustion chamber, turbulentflamepropagatesthroughit,ignitingthemixtureaheadofitasittravels.

Thedieselprocessbeginswithpureairthathasbeenheatedbycompressiontoseveral hundreddegrees—well abovetheignitiontemperatureofthefuel.Intothisdense,hotairissprayedliquidfuelas a very high speed spray—movingatclose to1000 feetpersecond.Thetiny fuel streams collidewith the air,become unstable, and break up intopieces whose fluid surface tensiontendstodrawthemintosphericalformasdroplets.Largedroplets,stillmovingfast, break into smaller ones, rapidlyincreasingthetotalsurfaceareaoftheinjectedfuel.Evaporationintofuelvaportakesaboutonemillisecond.

Ignition can’t take place instantlybecause evaporation is a coolingprocess—energy is taken from thesurroundinghotairtogivefuelmoleculesthevelocitytheyneedtobreakfreefromtheliquidstate.Bymomentarilycoolingthesurroundingair,evaporationdelaysignitionforseveralcrankshaftdegrees.But rapid localmixing is being drivenbytheturbulenceoftheaircharge—inmanyDiesel engines there are swirl-inducingfencescastintotheintakeportsforthepurposeofforcingchargeairtoenterthecylindertangentially,creatingrapidswirl.Thisturbulentmixingbringsfuelvaporintocontactwithhotterair.

Igniting combustion is like starting asmall business—you don’t succeedunlessconditionsareright.Manysuchbusinesses fail because their incometake too long to build up, and theythereforecannotafford the interestontheir starting capital. So it is inside adiesel combustion chamber.Wherethe localmixtureof fuel vaporandairistoorich, theextrafuel takesenergyfromanysmallflamekernelthatspringsintobeing,slowingitspreadorputtingit out of business entirely.Where the

localmixtureistoolean,itisanexcessof air that robs energy from incipientflame kernels. But where fuel andoxygen happen to exist in chemicallycorrect proportion,maximum heat isgeneratedinflamekernels,andthereareminimumlossestotheirsurroundings.Itisthereforeherethatignitiontakesplacemost decisively, and here that flamespreadsfastest.

Think of the fuel spray region as an“onion” of layers, each of a particularfuel-air ratio—beginning with 100%air, zero% fuel at the outside, andbecomingricheraswepenetrateinwardto increasingly fuel-rich inner layers.One of these layers is, as LittleRedRiding Hood said, “Just right.” It ishere in this just-right layer,where fuelandairhappentobemixed inexactlyright proportion, that ignition has thebest chance of establishing itself andprogressingrapidly.

Now it getsmore interesting. If thiswere a spark-ignition engine, thefuel-airmixturewould be the sameeverywhere,andtheflamefrontcouldrace through it easily. But it’s notthe same everywhere.Aswe traveloutwardfromthisjust-right,chemically-correct mixture layer, the mixturebecomesleaner.Aswetravelinward,toward the fuel-dense core of thespray, themixture becomes richer.In both directions, the conditions forcombustion become less favorable.Therefore the flame spreads fastestalongthejust-rightlayeroftheonion,but cannotmove very fast inwardoroutward.Theflamethereforespreadslaterally through the onion shell ofcorrectmixture, enveloping the fuelspraywithacombustionlayer.Becauseof the ideal combustionconditions inthis layer, its burning temperature isvery high, so this iswhere nitrogenoxidesaremostlikelytobeproduced.

Oncethislayerhasignitedandspread,it is fedby fueldiffusingoutward fromthe fuel-rich zoneat the center of thespray,andbyairdiffusinginwardfromthe leaner zones farther out.Wherefuel and air meet in nearly correct

proportions,theyburnwell.Elsewhere,burningoccursbut,becauseitiseitherleanerorricherthanideal,combustionis slow and/or incomplete, andmustwait forfurtherturbulentmixingtofindtheadditionalfuelorairrequired.Thissituation is the “diffusion flame” thathas been and is being so intensivelystudied.

Now think of what happens as fueldiffuses toward this flame zone.Themorecloselyitapproaches,thehotteritgets.Whatis“hot”?Highertemperatureinagasmeansthateachmoleculeis,ontheaverage,movingfaster.Asthefuelmolecule—forexampleachainorringstructureoftenorsocarbonatomswithattachedhydrogenatoms—approachesthe combustion zone, it encountersfasterandfastermovinggasmolecules,beating against it.At somepoint, themostenergeticofthesecollisionscarriesenoughenergy toovercome thebondenergy of the least-strongly-bondedhydrogen atom. It flies off rapidly toits fate—combiningwith one ormoreoxygen atoms to form either activefragments likeOH-, or “going all theway”toburncompletelytowater—H2O.Thecloserthiscarbonstructurecomesto theflamezone, themorehydrogenatomsitloses.

Ideally,ourcarbonchainorringshoulditself break apart, finally reaching theflamezoneasindividualcarbonatoms,able to enter intomature consensualunionswithoxygenatomstoformeitherCO(carbonmonoxide,itselfanexcellentfuelwhichwillburnfurtherwheninhotcontactwithoxygen)orcarbondioxide.Butinfactthecarbonstructurestronglyresists being broken apart, and therearemanyoftheminthefuel-richzoneapproaching the flame. Carbon isvery sticky stuff—it likes to adhere toitselfandtootheratoms,whichiswhycarbon is used to absorb bad tastesfromwhisky and cigarettes (whiskybarrelsarecharredon the inside,andfiltertipscontaincarbon).Itisalsowhythemost powerful breaks—those onlargeaircraftandGrandPrixcarsandmotorcycles—havepadsanddisksbothmadeofcarbon.Thereforemanyofthe

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carbon structures clump together astheycollideinthemolecularfree-for-all.Thisrendersthembetterabletoresistthestormofmolecularcollisionsthatthenearbyflamezoneisproducing.SomeoftheclumpsarebrokenupandburntoCOorcarbondioxide,butthecomplexstatistics of thismolecular dodge-‘emgame guarantee that some carbonclumpssurviveandevengrowsteadilylarger.Thesewecalldieselparticulates,orsoot.

The diffusion flame is often studiedbymaking high-speedmovies of theignition and combustion of single fueldroplets.Inordertoremovetheeffectsofgravity(thehotgasesfromtheflameare lighter than the surrounding airbecauseoftheirthermalexpansion,soinagravityfieldtheyrise),suchsingledroplet combustion experiments havebeenflownontheSpaceShuttleinanapparatuscalledthe“glovebox.”

Onearth,thesingledropletissuspendedattheendofanultra-thinquartzfiberandis ignited electrically. In the absenceof gravity, and inperfectly still air, thediffusionandcombustionprocessescanbestudiedintheirmostelementalandundisturbed form. Light emitted fromthe various diffusion zones containsspecificfrequencieswhichrevealusefulinformationaboutthestagesofchemicalreaction.Oneof thefascinatingthingsseenindropletmoviesis“sunspots”—blackobjectsswimmingaroundonthedropletsurface.Thesearetinycrustsofpyrolyzed fuel—carbon particulates—whichresultfromthelossofhydrogenfrom fuelmoleculesas theyapproachtheflamezone.Carbonclumpsformasdescribed above, and some fall backonto the fueldroplet tobecome thesesunspots.Asthefueldropletevaporatesto nothing, some of these carbonparticlesremain,whilesomeareburnedorpartiallyburned.

It has been proposed that water beemulsified into Diesel fuel—that is,brokenupintodropletssosmallthattheydonotjoinintolargerdropletsorsettletoformaheavylayeronthebottomsoffueltanks.

When a fuel droplet containing sub-droplets ofwater is ignited in dropletcombustionstudies,itnaturallyisheatedby the combustion layer surroundingit. When the droplet’s temperaturesignificantly exceeds that of boilingwater, the water droplets flash intosteam, blowing the burning dropletapart. This achieves freshmixing offuelandair,andtherebymayimprovecombustion.

Thismodelalsorevealshowaseriesoftinyfuelinjectionpulses,asopposedto the traditional single injection,mygenerate fewer particulates. Eachpulseoffuelinjectedproducesitsowncloudof fueldroplets—anonionwithits own layer of chemically-correctmixturethatcanigniteandburnrapidly.Agreater totalareaofsuch layers isgenerated in several smaller onionsthan in one large one, providing agreatertotalflamesurfaceintowhichfuel andairmaydiffuse to completecombustion.

Unfortunately, rapid, high-temperaturecombustion in the chemically-correctmixture layer is responsible for theproductionofnitrogenoxides—themostdifficultofthesmog-formingchemistriestoeliminate.Nitrogenexistsinair(airis78%nitrogen) as diatomicmoleculesoftwotightly-bondednitrogenatoms.Itrequiresaviolentmolecularcollisiontobreak this nitrogen-nitrogen bondandsetsinglenitrogenatoms freeso theycan combinewith oxygen—that is, itrequireshightemperature.

Atpresent,techniqueswhichreducesootformationtendtoincreaseproductionofnitrogenoxides,andmethodsofcuttingnitrogen oxide production generallyleadtohighersootproduction.Likethecondemnedprisoner asked to choosebetween being hanged or shot, thedieselengineeryearnstosay“Noneoftheabove.”

If combustion ismademorecompletethrough improved mixing, higherinjectionpressure,smaller fueldropletsize,multi-pulseinjection,etc.,thiswillreduceproductionofparticulatesbutwill

tendtoincreaseproductionofnitrogenoxides.

Themain technique for reduction ofnitrogenoxidegeneration is to reduceflame temperature. Intercoolerswereadded to your TurboDiesel truck in1991tocooltheintakeairandreducein-cylindertemperatures.Thecurrentlyfavoredmethod is to dilute the intakeflowwith some cooled inert exhaustgas.Sadly,reducingflametemperaturesubjects the inevitable carbon clumpsto less high-speedmolecular bangingandhammering, somoreof themwillsurviverightthroughcombustiontobeblownoutintheexhausttothewaitingsootdetectorsoftheEPA.

Let’s say we choose reduced flametemperature, becausenitrogenoxidesaresohardtogetridof.Let’sstartbydilutingtheintakeair10%withoxygen-depleted,inertexhaustgasrecirculationas our means of reducing flametemperature. That 10% recirculatedexhaust gas is equivalent to throttlingourengine’sintakeflowby10%,therebyreducingitspowerbythesameamount.Thisislikepayingfora300-hpengineandreceivingonly270-hp.Howpopularisthat?

If we decide against reduced flametemperature,wehavetogetridoftheadded nitrogen oxides that result byemploying a reducing catalyst in theexhaust. Sadly, the catalyst doesn’tworksowellindieselexhaustbecauseits temperature is lower than thetemperature atwhich the cat likes tooperate.Sowetweakoneofthenewmulti-pulsefuelinjectorstoinjectsome“re-heat”fuellateinthecycle,toheattheexhaustbackupagain.Youcouldn’tdo this in a spark-ignition enginebecause it burns up all the oxygenin its charge, butDiesels, in order toavoidproducingexhaustsmoke,burnonlyabout80%oftheiroxygenonfullthrottle.This leavesenough tomakere-heatpractical.Burningfuellateinthecyclewastes thepower itmighthaveproduced,so this isnoteconomicallyattractiveeither.Butmaybewedecidetolivewithit.

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Ormaybewe decide to gowith thereducedflametemperature,whichcutsnitrogenoxidesbutboostsproductionofparticulates.Wecoulduseaparticulatefilter instead of an exhaust catalyst.Doesitgetpluggedafterawhile?Canwe periodically burn the particulatesoff of it without burning the filter aswell?Filtersandcatsaren’tfree,soweconverttheirpricetoaper-mileexpenseand make the usual comparisons.Headachetime!

Well, folks, if we reconsider the low-soot, high nitrogen oxides approach,there’salsoatechnologythatadsorbsthe nitrogen oxides onto an activesubstrate and holds them there for awhile.Periodicallywereactthembackto ordinary nitrogenwith a chemicalreaction,perhaps involvinganoutsidesourceofnitrogen.Moretechnologytobuyandmaybeeventrickfluidstocarryalongwithusaswedrive?Whatnext?AfinefromtheEPAfordrivingwithanempty urea tank?Ormaybewe’ll beratted out by our new engine-controlcomputers,whichwillsurelykeeptrackof such thingsand report them to thedealer.

Atthispointinabaddream,Iusuallytrytowakeup,realizethatit’sallimaginary,and go downstairs tomakemyself agood breakfast.Diesel engineers arenotallowedtowakeupbecausealloftheaboveisreal.


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Invisible TechnologyAturbochargerusestheexhaustenergyof a piston engine to drive a fast-spinningturbinecoupledtoacentrifugalsupercharger.Thepressureoutputofthesuperchargerinturnraisesthepoweroftheattachedpistonengine.

The idea of a turbine—a device forturningfluidflowintorotarymotion—isasold as thehumaneye,watchingawingedseedspindown fromamapletree.Avarietyofwaterturbinedesignsimprovedupontheefficiencyofsimplewaterwheels, and the steam turbinetook over the generation of electricpowerafter1900.

Working at theGermandiesel enginebuilder Sulzer in 1911,Alfred Buchiused an exhaust-driven turbine tosuperchargeadieselengine.TheFrenchturbineengineerAugusteRateau,wasaskedby the Lorraine-Dietrich firm todevelopagear-drivensuperchargerforanaircraftenginein1915.Herejectedthe idea, reasonably pointing out thattodealwiththefallofairpressurewithincreasingaltitude,suchadevicewouldrequire a variable drive ratio. In 1916he considered the alternative idea ofaturbocharger,whoserpmandoutputwould not be tied to engine rpm.Thefollowing year hemade testswith anexperimentalturbocharger.

Meanwhileattemptsweremadetobuildaself-driving turbineengine—ineffecta turbocharger whose compressorsuppliesair,nottoapistonengine,buttoaburnerwhosehot,expandingoutputofgasisfedbacktodrivetheturbine.Ifmechanicalpower is taken from theturbine,theresultisashaftturbine.Iftheengineisinsteaddesignedtoproducejetthrust,theresultisaturbojet.Ashaftgasturbine,builtinFrancejustaftertheturnofthecentury,producedlittlepoweratanefficiencyofabout3%.

IntheUS,agraduatestudentatCornell,SanfordMoss, beganwork with theturbine concept in 1901, arousinginterest atGE (bear inmind that thesteamturbinerevolutionwasatthistimeinitsfirstgreatrushofsuccess).By1907MosshadaturbinerunningforGE,but

it revealed the following discouragingtruths:

(1) The low strength of availablematerials at turbine temperatureslimitedcycleefficiency.

(2) Theefficiencyofcompressorswaslow.

(3) Turbine efficiencywas also verylow.

ThiscausedGEtogiveupgasturbinesin1907.TheFrencheffort closed twoyearslater.

TheBrown-Boverifirmnowmadeaturbo-blowersystemtoincreasetheoutputofboilers,sellingthefirstexamplesaround1910.Thiswas a simple kind of gasturbinecyclewhoseproductwashotgasratherthanmechanicalpower.

KnowingofRateau’saircraftturbochargerwork,Cornell ProfessorW.F.Durandasked SanfordMoss to consider itsproblems.Moss,who is said to havedisliked airplanes, ran the first GEturbocharger in 1918. To evaluateits performance at high altitude, adynamometerwasbuiltontothebedofatruck,whichwasdriventothesummitofPike’sPeak.ALibertyV-12aircraftengine,normallygiving400-hpat sealevel,gaveonly221-hpinthethinnerairatopthemountain.Whentheturbowasfitted, the increase in intakemanifoldpressurepushedpowerbackupto356-hp.Theideawasproven.

The critical problemmotivating thisworkwasthelossofpowerbyaircraftengines as they climbed to higheraltitudes. In the then just-endedFirstWorldWar,thealtitudeperformanceofaircrafthadbecomeamatterofstrategicimportance.

TheBritish, too, hadmade testswithsimple turbochargersbuthaddecidedthe fire risk from potential failures ofhotplumbingwastoohigh.(Manysuchfailureswould later plague theUSB-29,eachofwhoseengineswasservedby twoB-11GE turbos.)They insteadadopted the gear-driven centrifugalsupercharger previously rejected by

Rateau, andwould develop it to highefficiencyby1940.

Duringthe1930smuchworkwasdoneinEuropetoachievecoolingofturbinebladesbymeansofairorwater.Littleofpracticaluseresulted.

OncemadeawareofthevalueoftheGEturbocharger,theUSArmypaidallthedevelopmentcostsofturbochargerworkatGEfrom1919throughWWII.

TheGEturboemployedaturbinethatlookedjustlikeonestageofamodernjet engine turbine.The rim of a diskseveralinchesindiameterwasfittedwithmanyshort,wing-likevanes,andengineexhaustwasdirectedagainstthesebyacircularnozzle-box.Thespinningoftheturbineplacedgreat centrifugal stresson theveryhotblades,which throughaprocessknownas “creep”graduallygrew longer until they stretchedapartand flew off. From 1918-1922, thebladesweremadeofanordinaryspringsteelandfailedquickly.Thevanesinthenozzle box suffered “scaling”—a kindofacceleratedrustinginwhichaniron-based alloy combineswith oxygen toformlayersofscalewhicharesloughedoffuntilthepartistoothintosurvive.

In 1922 a newmaterial, Silchrome I,was adopted.This addednearly 10%chromiumandasmallamountofsilicon,therebyachievingusefuleffects:

(1)Chromiumcombineswithoxygentoformatoughprotectivelayerofchromicoxide, keeping oxygen from reachingironatomstogeneratescale.

(2)Chromiumalsoformshardcarbideswith the carbon in steel. These tinycarbideparticlesactlike“pins,”topreventtheslidingoflayersofatomsacrosseachother.Theresultisincreasedresistancetocreepathightemperature.

(3) Silicon combines with iron andoxygentoformasilicateglassthatactsasafurtherbarrieragainstoxidation.

In the early 1920s the US Armybecameawareofanewstainlessalloy,

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KE965,thenbeingusedtomakehigh-performanceexhaustvalvesinBritain.ItsuseinGEturbosallowedsafebladetemperaturetorisefromaround1100-degF toalmost1400. In thismaterialbothchromiumandnickel,witha littletungsten, are combinedwith iron andcarbon to form an austenitic crystalstructure. Tungsten’s value at hightemperaturehadalreadybeenproveninso-called“high-speedsteels”foruseinmetalcutting.Tungstencombineswithcarbontoformextremelyhardcarbidestopinatomiclayers,preventingglidingmovement.Thenickel and chromium,becausetheydissolveinironbuthavedifferent atomic sizes, further impededeformationbyactingas localregionsofstress.

KE965 was theArmy’s turbo bladematerial from 1928-33, when animproved but similarmaterial, 17W,wasadopted.

Meanwhile another set of conditionsmadereadytodriveanewprogramofmaterials improvement. BritishRoyalAirForceofficerFrankWhittlehadbeentoldby“experts”thathisgasturbine(jet)enginewould be too heavy to fly (byignorantanalogywithmassivemarinesteamturbines)andwouldruntoohottosurvivemorethanafewminutes.Hestuck by his own calculations and in1936foundprivatedevelopmentmoney.Shortlyhehadamachinerunningwellenoughtoimpressthosewhosawit.By1939 theBritishAirMinistry reverseditself,takingtheprojectfromWhittleandassigningittoprivateindustry.WorldWarTwobeganinSeptember1939,greatlyincreasingtheurgencyofdevelopment.The original turbine bladematerial“Stayblade”(asteamturbinealloy)wassovulnerable tocreep thataftershortrunningtimebladelengthhadincreasedsignificantly.When the engine wasshutdown,theloosebladingcouldbeheardtomakeaclinkingnoisewhiletheturbinewheelcoastedtoastop.Abettermaterial—Rex-78—wassubstitutedforthemoment,andtheWigginLaboratoryoftheMondNickelCo.wassetthetaskofquicklydevelopingimprovedturbinebladeandnozzlematerials.

ByJulyof1942theyhadproducedthefirst blades in theNickel-based alloyNimonic80,whichenabled,forthefirsttime, reliable jet engine turbine diskoperationfor25hours.

Earlier,theUSHaynesStelliteCorp.hadproducedsomecorrosion-resistantalloysthatlaterturnedouttohaveoutstandingpropertiesathightemperatures.Thesewerethefirstthree“Hastelloy”materials,A,B,andC.WhentestedbyGEinthesummerof1941,HastelloyBwas themostpromising.

At its plants in Lynn,Massachusetts,GE tested aircraft turbochargers byoperating them as low-grade gasturbines—connectingcompressoroutputtoasimpleburnercan,injectingfuel,androuting the resulting hot gas back todrivetheturbinewheel.

In 1937, a Swiss engineer, RudolphB i rmann, had organ ized TurboEngineeringCorp. here in theUnitedStates.His1922university thesishaddescribedagasturbine.NowheofferedtheUSNavyanew,morecompactkindofturbocharger,drivenbyaradialinflowturbine,justlikethetypeusedintoday’sautomotiveturbos.Asinthecaseofthe19th-centuryFranciswaterturbine,thisdeviceledtheflowintoasnail-shapedhousingsurroundingtheturbinewheel.Thissettheflowintowhirlingmotionsothatasitflowedradiallyinward,itgaveup its rotational energy to thewheel,emergingalongitsaxisatthecenter.

TurboEngineeringequippedtheR-2600radialengineofaTBFaircraftwithsuchaturboblowerinlate1941.Thissystemwasabletomaintainsealevelpowerallthewayto40,000feet.Birmann’sturbinewheelswereforgedofaheatresistantsteelcontainingnickel,chromium,andtungsten. Itsbladeswere internallyaircooled.

Hearguedthathisdesigncouldoperateatahigherspeedforagivenflowthancouldthelargewheelturbinesofaircraftturbos. It also exposed less bladesurfacetohotgas.Beingmadeinonepiece, Birmann’s radial-inflow turbine

solvedtheoldproblemofhowtoattachtheturbineblades.Theadvantagesofpresent-day turboswere all listed byBirmannmorethan60yearsago.

Unfortunatelywhen one ofBirmann’snovelturboswasfittedtoaNavyHellcatXF6-F2,itprovedunreliable.

Since thewar, the diesel engine hasbecometheworkhorseofthetransportindustry.Theturbocharger,onceitwasmade reliable, transformed the dieselfromaneconomicalbutheavymonsterinto a system capable of producingessentiallyasmuchpowerasanyonecould wish. There are turbochargeddiesels today capable of producingalmost one horsepower per pound ofweight—the equivalent of themuch-admiredandverypowerfulpistonaircraftengines used inWW II and throughthe1950s.Asalways,thediesel’shighcompressionratioandleancombustionmake it themost efficient of internalcombustion engines—diesels givemaximum“bangforthebuck.”

At present the industry standardturbocharger turbinewheelmaterial isInconel713C,or713LC.Thismaterialoffers high creep resistance at hightemperatureand is easily cast.Creepresistanceallowsthehotturbinewheeltowithstand the strain of spinning at100,000 rpmormore for hundredsofhours.Theabilitytobecastisimportant,for itwould beprohibitively expensiveand difficult tomachine these partsfromsolid—bothbecausethematerialisextremelyhardandbecausethedesiredshapeiscomplex.

Inconel713isnickel-based(73%)andcontains chromium for both oxidationresistance and for solid-solutionstrengtheningalongwithmolybdenum.Thisishardeningbroughtaboutbythelocalstrain—thinkofthisas“bumps”—withinthecrystal,causedbythepresenceofthedifferent-sizedatomsofchromiumandmolybdenum.

Some aluminum and titanium arepresent(6%)tobringaboutprecipitationhardening.As thematerial cools from

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melt temperature, the aluminum andtitaniumcannolongerremaindissolved.Theexcessprecipitatesoutofsolutionto form regions of hard intermetalliccompounds such as nickel aluminide.Foramodel, thinkofhow rockcandyforms as a hot, saturated solution ofsugarinwatercoolers.Theprecipitatedintermetallic forms tinyparticleswhichremain present even at high servicetemperatures.Theyactassuper-strongpinstopreventslippingoflayersofmetalatomspasteachother(creep).

Notice that there isasmallamountofcarbon in 713C (0.2%). This can beuseful in forming very hard chromiumcarbides. Because such carbidesform preferentially in the “interstitialzones” between crystals, the processsomewhatdepletesnearbycrystalsoftheir chromium, leaving themopen tooxidationattack.Topreventthis,smallamounts of niobiumand tantalumareadded. Thesemetals glom onto thecarbonfirst,allowingchromiumtostayputanddoitsanti-oxidationjob.Thisisprobably important in turbos used onDiesels,whichhavesignificantamountsoffreeoxygenintheirexhaust.

Inthe713LC,theletters‘LC’standfor‘LowCarbon,’ in this case less than0.05%

Everyonehasheardof“turbolag,”whichisthetimetakenfortheturbinewheeltoaccelerate toa speedhighenoughtodeliverratedboostwhenthethrottleis opened.Metal turbinewheels areheavy—theirdensitymakesthemabouteighttimesheavierthanthesamevolumeofwater—solighterturbineswouldcutturbolag.Oneapproachistomakethewheel out of a heat-tolerant ceramicsuchassiliconnitrideorsiliconcarbide.Such wheels have beenmade, butbrittlenessremainsaproblembecauseceramicsareextremelydefect-sensitive.Thefreeelectronspresentinmetalsactasakindofmoleculargluethatallowsmetalstotoleratetheexistenceofsmallcracks.Inceramics,alltheelectronsaretightlybound,makingthematerialslessfault-tolerant.

You can feel the effects of electronsinmaterials directly every time youdrinkhotcoffeeortea.Thecup,beingceramic,conductsheatslowlybecauseitsboundelectronscannotmovearoundto transmit heat rapidly.The spoon—especiallyifitissolidsilver—conductsheatmuchmore rapidly because theelectronsinitarefree,almostlikeagas.Theirmobility allows them to transmitheatrapidly.

Itmaybepossible tomake improvedceramicsbyeitherreducingdefectsizeorbycompressingthepartswhenhotby“HIPping”(comparabletoforgingofmetals).

Another possibility now receivingattentionisthatofmakinghotpartsoutofsolidintermetallicslikenickelaluminide,which isalso lighter thanconventionalheat-resistant metals. Intermetallicengine valves and turbo rotors havebeenmadeandarepossiblecommercialmaterialsforthefuture.

Turbochargers are small machinesthat look as simple as the basic ideabehindthem.Thehightechnology—ofturbineandcompressoraerodynamics,andofhigh-temperaturemetallurgy—isinvisible.


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It’s a DragOnce when I was droning acrossour great nation in a dinky Class-Cmotorhome, I foundmyself trying tofigure outwhat its aerodynamic dragmightbe.Imeasureditsfrontalareaatthenext fuelstop—93 incheswideby108incheshigh,orabout70squarefeet.Tofigurethedrag,Iwouldhavetoknowwhataerodynamicistscallthe“dynamicpressure,”orjust“Q.”Dynamicpressureis the pressure that resultswhen theenergy ofmoving air is transformedinto pressure by stopping it. Puttingtheflatofyourhandoutthewindowathighwayspeed isacrudemeasureofthispressure.Itincreasesasthesquareofspeed.At65mphitisabout11poundsper square foot, and at 100mph it isabout25poundspersquarefoot.

Now it gets a littlemore complicated,because themotor home (or TurboDiesel pickup, or whatever you aredriving) is not a flat platemovingwithits plane perpendicular to its directionofmotion.Insteadithasroundededgesor other attempts at “streamlining,” sothefullQisnotdevelopedeverywhereon its frontalarea.Foragivenshape,therefore, its degreeof streamlining isstatedasamultiplier,acoefficient.Thisisanumber, lessthanone,whichtellsushowgoodorbadourshapeis.Verypoorstreamlining,suchastheproverbialsideofabarn,hasadragcoefficientof1becauseitisjustaflatplate.Asanobjectisbetterstreamlined,itactsasifitweresmaller,sothecoefficientissmaller.Forahighwaytruckorotherbreadboxlikemymotorhome,orforanunstreamlinedmotorcycleanduprightrider,thisnumberisoftenabout0.6.Forveryslinkylate-modelcar,thereareclaimsallthewaydownto0.32.Forreallysmallnumbers,youhavetolookatfish-likeshapessuchasthatofthegreatairshipsoftheearly1930s, whose drag coefficients wereaslowas0.07.Thekeytolowdragisthat,afterpushingtheairasidetomakeroomforyourvehicle,youtakecaretosmoothlyputtheairbacktogetheragainafter it passes.Otherwise you leavebehindyouaturbulentwake,boilingwithenergythatyourenginehastosupply.Making the frontofyourvehiclenicelyrounded helps a bit, but not asmuch

asdoesmakingitgraduallynarrowerorlowertowardtherear.Theaimofsuchnarrowing or tapering is to keep theairflowattachedtotheshape,ratherthanlettingitseparatetoformturbulence.

Now let’s estimate somedrag. In themotor home example there are 70squarefeetoffrontalarea,theestimateddragcoefficientis0.6,andthedynamicpressureis,say,11poundspersquarefoot.Multiply themall together togivean estimated force required to pushthe vehicle through the air; 70X 0.6X11=462pounds.Ifwemultiplythisforce,timesthevehicle’sspeedinfeetpersecond,wegetthenumberoffoot-pounds ofworkwemust do to pushtheshapethroughtheair,persecond.Ifourspeed is65mph, this is95 feetpersecond,so95X462=44,000ft-lbper second.One horsepower is 550ft-lb/sec,sowedivide44,000by550togetthepowerourshapeneedstodriveit,or80horsepower.

Toestimatewhetherthisisreasonable,we can figure backwards from fuelconsumption.Themotorhomeisanastygas-burner, and four-stroke gasolineenginesneedabout0.5poundoffuel,per horsepower, per hour. I knowmyswaying road-palacegets 8milespergallon nomatter what speed I driveit,andat65mph that is65/8=8.125gallonsperhour.At6poundspergallonthat is 8.125X6=49poundsof fuelper hour.At half a pound of fuel perhorsepowerhour,thisshouldbegivingme something like 98 hp (49 poundsdividedby .5=98) IfmymotorhomehadaDieselengine,itwouldneedjustasmuchpowerbutuseonlyabout2/3-3/4asmuchfuel.

Assuming these rough figures arecorrect, howdoweexplain the80hpand 98 hp calculations?Where doesthe difference go? Tires get hotterthe fasteryoudrive,asaresultof therollingresistancethatcomesfromtheirconstantflexure.Thiseasilyeatsupthe18hpdifference.

Now let’s assume we’re driving apickup-sizedvehiclewithmore like45

squarefeetoffrontalarea.Atthesame65mph (or 95 ft/sec)we’ll have thesamedynamicpressureof11poundsper square foot,multiplied times our“breadbox”dragcoefficientof0.6,soourdragforcewillbe45X0.6X11=297pounds.At95ft/secthisrequiresustodo95X297=28,500ft-lb/secofwork.Togetpowerrequirementwedivideby550toget52hp.Let’saddin15hpforrollingfriction,giving67hp.Toconvertthis into estimated fuelmileage, wemultiply67timesagoodDieselenginespecificfuelconsumptionof.38poundperhp-hr,so67X.38=about25poundsoffuelperhour.Dieselisalittleheavierthangasolinesothisis3.8gallonsperhour,or65mphdividedby3.8gallons=17milespergallon.

What if we want to go lots faster?Dynamic pressure increases as thesquare of the speed, but to get draghorsepower,wehavetomultiplytimesspeedathirdtime(feetpersecondtimesthedragforce),sothebadnewsisthathorsepower requirement increases astheCUBEofspeed.Thatis,ifwenowwanttogotwiceasfast—130mph—ouroriginal52draghorsepowerwillincreaseninetimes—to468hp.Ourrollingfrictionwill increase too, bringing our powerrequirement, in round figures, up toabout500hp.

This is why Bonneville racers whowanted to set a truck record usinga highway tractor found themselvesmakingatonofhorsepowerfromtheirquad-turbo, two-stroke, 16V92DetroitDieselmarine engines; but theywerequiteunabletocrackthe200mphmark.Theirmonstercreationwasmakingbigwheelspinrutsinthesaltandleavingatrailofblacksmokethatacoal-burningtramp steamer could envy—but notgoinganyfaster.

Then they started trying to close uptheirwake by turning that boxy 1943tractor intoafish.A longhousingwasbuiltaroundthe16V92engine,taperingelegantly almost to nothing at thetail. (The rear sectionmainly held theparachutes for stopping.)Why shouldthiswork?Thinkofthetaperingtailas

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beingataperedwetbarofsoap,grippedby the “hand” of the surrounding airpressure.Squeezeawet,slippery,andtaperedobjectanditshootsoutofyourhand. That same air pressure couldnotactontheflatbackofthetractor’soriginalcabbecausetheflowseparatedfrom its too-suddencurvature, leavingthewakea random,whirling tangleofvortexflows—allofthemcarryingawayenergy.Buttapertherearofthevehiclesothat theflowremainsattachedto itanditspressurecanbeputtoworktoovercomedrag.Fishdon’tknowit,buttheirshapesareaboutasstreamlinedasanythingcanbe.Withtheslinkytail,thatgiantDieselachievedaspeedofaround260mph.Thatwould otherwise haverequiredtwicethehugepowertheywerealreadymaking (whichwouldn’t havehelpedanywaybecausethetireswerealready spinning at “only” 200mph!).SeeIssue34,page152,forthewrite-uponthePhoenixdieseltruck.

You’venoticed thatstylistshavebeenroundingthecornersofeventhemostutilitarianvehicleslately.Atleastsomeof the time, this has the purpose ofreducingthedragcoefficientbyteasingtheairintofollowingtheshapeatleasta little bit before separating into thenormal turbulentwake.Thishelps themanufacturerkeephisfleetaveragefuelconsumption frombeing too terrible—and itmay save a few dollars’worthoffueloverthevehicle’slifetime.Backwhen the Volkswagen van was inprototype, the planwas tomake itsbodypanelsasflataspossible to cutmanufacturingcost(themorecomplexthe die, themore it costs).With theresulting sharp-edged body, the besttheclatteringair-cooledflat-fourenginecouldcoaxwasabout45mph.Andsoback itwent for reconsideration;withthe corners rounded (as canbe seenonthemanyantiqueVWvansparkedatGratefulDeadrevivals)themachinewasabletogofastenoughtokeepupwithslowinterstatetraffic.

EverthinkaboutFormulaOnecarsandtheir reputed 800 horsepower?Withallthatpowertheyoughttobeabletogoalotfasterthantheydo—ameasly

200mph.What’shappeningisthattheymust usea lot of their power to drivetheir downforce system.This consistsof front and rear wings of specifieddimensions, plus a complex under-car venturi flow.About half the car’spowergoesintodrivingallthistrickery,generatingenoughdownforce that thecars could raceon the ceiling if needbe.Thisdownforcetranslatesintoextragripfromthetires,enablingthecarstocorneratabout3Glateralaccelerationandtobrakeat3-4G.Theirtopspeedisn’tmuchgreater, if any, than it waswhenF1carsmadeonlyhalfasmuchpower, but their lap timesare quickerbecausetheydon’thavetoslowdownsomuchforthecorners.

Drag is a drag. Even a super-slippery Zeppelin needed a thousandhorsepowerorso topush through theloweratmosphereat40-60mph.Upat30,000+feetinthemuchthinnerair,a747atsubsoniccruisestillneedsabout50,000poundsofthrusttoshoulderitsway through the stubbornly resistingmolecules.Butairhasitspleasures,soweacceptthecompromise.


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Diesel ReviewPeriodicallyIliketomentallyreviewtheseveralreasonswhyDieselenginesaresomuchmore economical than theircompetitors.

Thefirstoftheseistheiruseofahighcompressionratio.Thefirstandobviousreasonthatthisisabenefitisthatonlyby highly compressing its air chargecan a Diesel engine ignite its fuel.Compressionraisesthetemperatureoftheairchargehighenoughthatthefuel,whensprayedintoit,ispromptlyheatedenough to ignite, requiring no ignitionsparks.WhenaDiesel iscold-started,themassofcoldmetalsurroundingtheairasthepistoncompressesitcantakeenoughheat fromit topreventnormalauto-ignition,soacoldenginecanbedifficulttostart.Toenablecold-starting,electrically-heatedglowplugsorotherstarting assist is therefore temporarilyrequired.Once the engine starts, thisauxiliaryignitionsourceisswitchedoffandtheenginecontinuestorunontheheatofitsowncompressionprocess.

Highcompressionincreasesefficiency.It does so by greatly increasing thetemperatureandpressureofcombustion,and then by highly expanding theresulting high-pressure combustiongas. Ifacylinderofuncompressedairweremixedwithahydrocarbonfuelandignited,itspressurewouldrisebyaboutseventimes.Asatmosphericpressureis about 15 psi; thiswould result in apeakpressureofabout7X15=105psi—not a pressure thatwouldmakedriving a Cummins-powered vehicleveryexciting.Theruleofthumbisthatpeak combustion pressure is roughlyequal to 100 times the compressionratio. In the above example the non-existent“compressionratio”is1:1,whichmultipliedtimes100givesusasimilarpeakpressure—about100psi.

Innormalenginesthecompressionratiois also the expansion ratio. Imagineour hypotheticalDiesel engine has a17:1compressionratioandthat ithasjust burned its injected fuel to a peakpressure of 1700 psi. Ifwe open theexhaustvalvewhenthepistonhashalf-expandedthishigh-pressuregas,weare

throwingawayuseful energybecausethehot gas is still at several hundredpsi.Itcontainsvaluablepressureenergywhich can still do usefulwork on thepiston.Sowewaittoopentheexhaustvalveuntilthepistonhasexpandedthegastoapressurelowenoughthatwhatremainscannotefficientlydousefulworkonthepiston—apressureontheorderof100psi.Fortunatelyforus,thisisplentyofpressuretooperateaverylow-friction,high-speeddevice—aturbocharger.

Why not just keep increasing thecompressionratioandgettingmoreandmore temperature and pressure fromtheburningfuelandair?Thereisonlysomuchenergyinthechemicalbondsofthefuel,sothatsetsanupperlimit.Thebigquestion is,howmuchof thisfixedamountofenergycanbemadetodoworkonthepiston,andhowmuchwillgoouttheexhaustaswasteheat?Anenginewithnocompressionwastesmostofthisenergyasexhaustheat(likeacampfire),butascompressionratioisraised,moreof this limitedamount ofenergyisdirectedtothepistonandlessis lost out the exhaust.Therefore thepowerincreasetobehadfromincreasingcompressionisaneffectofdiminishingreturns;increasingcompressionratioawholenumberbeginningat1:1gainsusmuchmorethandoesraisingitawholenumberbeginningat16:1.

There is another effect that preventscompressionfromyieldingfurtherbenefitat very high numbers; heat loss.Thehigherthecombustiontemperature,thefasterheat ispushedout fromthehotgas into the necessarilymuch coolerpistonandcylinderhead.Atsomeveryhigh compression ratio, the dwindlinggain from the increase iscanceledbytherisingheatloss.

There is yet another reasonwedon’tjust keep on increasing compression.Thatreasonisthatathightemperatures,gases begin to lose their ability totranslateheatintopressure.Atnormalcombustion temperatures,mostof theenergyinthegasexistsintheformofrapidmolecularmotion—the classicexamplebeinga roomfullofperfectly

elasticbilliardballs,zooming,colliding,and bouncing off the walls of theircontainer.Theuseful pressureon thetopofthepistonarisesfromthezillionsoftinycollisionsasfast-movingnitrogen,carbondioxide,andwatermoleculesinthecombustiongasbounceoffthepistoncrown.Butaswepushgastemperatureeven higher, the energy in the gasbegins to take on other formswhichcontribute less to pushing the piston.The violently agitated gasmoleculesnow contain significant energy in theformof rotationandvariousmodesofmolecularvibration—energythatdoesn’tpushthepiston.Thislossissaidtoarisefrom an increase in specific heat of the gas—thatis,athighertemperatures,ittakesmoreenergyaddedbycombustiontoraisethetemperatureof thegasbyonedegree.

If a given molecule vibrates hardenough—itstwoormoreatomsbouncingback and forth against the chemicalbondenergyholdingthemtogether,likemassesjoinedbyaspring—canactuallycomeapart.Thisiscalleddissociation,anditisanenergylossbecauseithastakenenergyfromthegastoovercomeits ownbondenergy—breakingapart.This energymay be recovered if thedissociatedatomsrecombinepromptly,butthelikelyoutcomeisthatthiswon’thappenuntilthepistonhasmoveddownsomewhatonitspowerstroke,reducingthetemperatureofthecombustiongasenough that recombination becomesmorelikely.Butnowthemomentofpeakpressurehaspassed, and theenergy“repayment” of recombination comestoolatetohelpmovethepistonmuch.Or recombinationmaynot take placeuntilthehotgashasexpandedintotheexhaustpipe.Eitherway,ourenginehaslostatinybitofitspeakpressure,andthereforemakeslesspower.

Okay, those depressing losses exist,but it remains that Diesels benefitfromthe fact that theycan,andmust,use a high compression ratio. Sparkignitionengines coulddo this too, butforone fact—detonation.Because thefuelinaspark-ignitionengineismixedwithairforalongtimebeforeitburns,

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chemical changes that are driven byheathavetimetochangesomeofthefuel into a sensitive explosive.As thechargeofmixedgasolineandairburnsafter the spark, the hot, expandingcombustion gas compresses the yetunburnedmixture, thereby heating it.If this heating goes far enough (andhigher compressionmakes it hotter),someheat-alteredbitsofmixturegooffbythemselvesintheprocessknownasdetonation or combustion knock, andthenburnatthespeedofsound.Whenthissonicwavehitstheinsidesurfacesof the engine, it produces the ‘ping’or ‘knock’ associatedwith detonation.Normalpumpgasolinecandetonateinspark-ignitionenginesat compressionratios as low as 8.5:1, or about halfthecompression ratioofaheavy-dutyDiesel.This is amajor reason for thespark-ignition engine’s higher fuelconsumption—it cannot safely use ahighcompressionratio.Dieselscannotdetonate because their fuel is in thecombustionchamberfortooshortatimebeforeitignites;thereistoolittletimeforthechemicalchangesthatmustprecededetonation

A second reason forDiesel efficiencyhas todowith thespecificheateffectmentioned above. Because aDieselinjects its fuel only an instant beforecombustionbegins,thereislimitedtimeavailableforfuel-airmixing.Toassistthisprocess,itisnormalforDieselenginesto inject at full throttle only enoughfuel toreactwithabout80%of theaircharge.Theextraairispresentjusttoincreasethechancesthatagivenfuelmolecule’shydrogenandcarbonatomswillallfindpartnersinthemaddanceofcombustion.

That extra air also has the effect ofreducingpeakcombustiontemperature,therebyavoidingsomeof thespecific-heatanddissociation loss (mentionedabove) normally associatedwith hightemperaturecombustion.

Addtothisthefactthatmostenginesarenotonfullthrottleallthetime,butDiesel engines are not air-throttled. Becauseof this, a Diesel’s cylinders always

take in a full charge of air.At lowerload, only the fuel is throttled—nevertheair.Thus, at part-throttle, aDieselis burning its fuel in the presence ofvery large amount of extra air. Thislowers the bulk temperature of thecombustiongas,therebyderivingevenmorebenefitbyavoidingspecific-heatanddissociation loss. In the jargonofmodernengineering,aDieselengineisanaturallylean-burndevice.

Lean-burn can be achieved in spark-ignition engines, but it is neither asnaturalnoraseasyas it is inDiesels.Mixtures of gasoline and air can beignited by spark only over a rangeoffrom 10:1 (rich) to 18:1 (lean), so inorder to achieve extreme lean-burn(like24:1)aspark-ignitionenginehastocreateamixingzonenear itssparkplug rich enough to be ignited. Thisstratified-chargeoperation isachievedby spraying the gasoline toward thespark plug froma special injector—aprocessthathassomesimilaritytowhathappensnormallyinDiesels.

Back in the late1980stheautomotiveworld had a brief romancewith two-strokeengines.Amajorreasonforthisisanotherpieceofjargoncalledpumping loss.Inanormal,air-throttledautomotivegasolineengine,theusualloadconditionis10%orless,withmorepowerbeingusedonlyforon-rampaccelerationandthe like.With the engine throttled inthisway,everytimeapistonfallsonitsintakestroke,itispullingafairlystrongvacuumaboveitself,andittakesworktodothisbecausethepistonis,ineffect,compressingtheatmosphere.Insimpletwo-stroke engines, the crankcase isusedas a charge air pump, sowhenthe engine is throttled, crankcasepressurefallsjustaslowasthepressureabovethepistons.Asaresultofhavingnearly thesamepressuresaboveandbelow the piston during the intakeprocess, such two-strokes have verylittlepumpingloss.

HowisthisdifferentfromaDiesel,whichisneverair-throttled?Itisnotdifferent.Therefore,atpart-throttleaDieselenginealso benefits from reduced pumping

loss, as comparedwith conventionalspark-ignitionengines.

Forallthesereasons,therefore,Dieselengines aremore fuel-efficient thantheir competition. Intensive work ongasoline-fueled,spark-ignitionenginesis closing the gap somewhat, but thecompressionratioeffectisabiggieanddetonationwill keepgasoline enginesrelativelyinefficientaslongaspumpgasisasnastyasitis(theoldUSArmyAirCorps,circa1936,hadbettergasolinethanthestuffnowatthepump).

Another small effect also contributestoapparentDieselfueleconomy.Isay“apparent”becauseiffuelweresoldbythepoundinsteadofbythegallonthiseffectwouldnotexist.That is the factthatDiesel fuel has a higher densitythanmost gasolines.A usual densityforDiesel fuel is .85 gram per cubiccentimeter (water weighs 1.0 gram),while thatofgasolines iscloser to .75gram.This gives theDiesel operator14%morefuelmasspergallon.

The debate rages on as to whetherthe automotive future belongs togasoline orDiesel.Gasoline enginesusemorefuelbutare—atleastforthemoment—easier to clean up. Dieselengines use significantly less fuelbut remain—again, at least for themoment—controversial sources ofnitrogenoxidesandparticulates.A lotdepends on how government policy-makersevaluatetherelativeimportanceof(a)limitingpetroleumimportsand(b)limitingemissions.That’spolitics!


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Official Cure-AllsThis issue’s theme is”‘placebos,”so I thought I’d review some officialcure-alls that have come and gone.Scienceandengineeringpeopleknowthatweapproach truth by successiveapproximat ions—our knowledgeincreases, but it is never complete.We hope to learn enough about theproblemswe face to be able to dealwiththem.

Inpolitics,answersmustbepresentedas total solutions.Thismakes it veryhardforregulatorssuchastheEPAtoserveboththephysicalfactsandtheirpoliticalmasters.

Fora timeduring the ‘80s, theDieselenginewas hailed as the powerplantof the future because it was highlyfuel efficient and emitted little carbonmonoxide.Automakers hastened tocobbleupDieselheadstoputontheirexistinggasolineengineblocks.A fewretiredfolksheadedforFloridainsuchautos,gettingarefreshing30mpg.SadlythegasengineblocksprovedtoolightforDieseloperation,andtheemissionsresearchersdecidedthatDieselengineswereatleastas“atmosphericallynasty”as the gasoline variety. Carcinogenshitch rides into our lungs aboard thetinycarbonparticulatesfoundinDieselexhaust,andtheNOxproducedwheninjectedfuelsprayslightupwasdeemeda serious source of photochemicalsmog.Learnanewthingeveryday.

Intheaftermathofthe‘73oilshockwewere told that biomass-derived fuelswouldsetusfreefrompoliticallyshakydependence on imported petroleum.Midwestern farmers loved this, withitspromiseofmillionsofacresofcorntransformedintoethylalcohol.

Uh,well, there is the problemof fuelsystempartscorrosion—easilyfixedbybuyinganewvehicleequippedwithanalcohol-tolerant fuel system.Anotherbother—storage of alcohol-bearingfuels leads to formation of “waterbottoms”—layersofalcoholcontainingdissolvedwater,whichhaveseparatedfromthelighterfuelabove.Thisisacaseofnotbeinggoodtothelastdrop.Those

lastfewgallonscouldbesomethingofa public relations problem, seeing ashowwaterdoesn’tburn,andevenpurealcoholrequiresamuchrichermixturethangasolineinordertoigniteandburnproperly.

Suddenly everything was solved byMTBE, orMethylTertiaryButylEther!Whathappenedtoenvironmentallyandpolitically-correct biomass fuel fromcorn?Whenpolicychanges,sodotheexplanations.Insteadofputtinganendto dependence on imported oil andrevitalizing those vacant towns in theCornBelt,theideasortofmorphedintousingsmallamountsoflow-energyfuelssuchasalcoholsandetherstoleanoutthefuelmixtureofolder,high-pollutingcars.ThiswouldslightlycuttheamountsofCOandUHCspewingintotheurbanatmosphereandthusbenefitusall.

And soour newgasolinesall tookonthe sharp, pungent smell of MTBE.Unlikealcohol,MTBEdoesn’tdissolvelimitlessamountsofwater,anditdoesn’teatupfuelsystemparts,either.Phew!SavedbyScience!The stuff alsohasa pretty high octane number too, sogasoline-burningcarsandtrucksdidn’tknockandpingthewaytheydidbackin‘77whengasolinesfirstbegantogodownhillfast.

Andsomattershurtled into the futureforafewyears.Gaspumpslookedthesame except for the little sticker thatproclaimed“containsMTBE.”

Meanwhile, although MTBE is notlimitlesslysolubleinwater,itisalittlebitsoluble.AndsogroundwatercontainingdissolvedMTBEfromspillsandleakingunderground tanks trickled here andtrickledthere.AfterafewyearsitreachedthewellsofquiteafewCaliforniatownsandcities.Ohdear,whathavewehere?Thiswatersmellsandtastesbad!Watertests confirmed the presence of not-good-for-youMTBE.SuddenlyMTBE,theformerdarlingandsaviorofurbanair quality, becamean evilwitch, andwasbanned.TheplantsthathadbeenrushedintoMTBEproductionwereshutdown.Newplannecessary.

On another stage, the drama of fuelleadwasbeingpresented.Tetra-ethyllead (TEL) is a deadly poisonousorgano-metalliccompoundthathasanabsolutelymiraculous ability to stopcombustion knock in spark-ignitedgasoline engines.Somego so far asto say thatTELmay havemade thecrucialdifferenceintheBattleofBritain,increasingthepowerofBritain’sSpitfireandHurricanefighterstoclearEnglishskiesofGermanbombers.Adropofthepurestuffonyourskinwillkillyou,butfromthe1930sthroughthe1970s,motorgasolinescontainedupto4.3gramsofTELpergallon.Ourparentsusedtoaskfor“ethyl”atthegaspump—acommonnameforoctane-boostedpumpgas.

TheEPAchosethecatalyticconverterasitsmajoranti-emissionstechnology.The converter, by reacting exhaustpollutantsbacktoharmlessoratleastlegal forms,was nevertheless easilyputoutofactionby leaded fuel.Now,anythingthatcoulddamageconverterswas politically excommunicated.Ascheduleforleadreductioncutfuelleadtozeroby themid-‘80s.Tohelpus tohateleadmoreeasily,studiesofurbanairqualitywerequicklyrunuptorevealthatthepresenceofairborneleadwassignificantlydepressingtheintelligenceof children of lower-income families.Leadmust go!Meanwhile, the sharpsmellthatcomesfromnewcarcatalyticconverterissulfuricacid.

Topreventknockwiththeloweroctaneof reduced-lead fuels, compressionratiosweredroppedfromthepreviouslyusual10:1tomorelike8.5:1.Thisalsohadtheeffectofsignificantlyincreasingfuelconsumption,butitisourcleardutytosavethechildren.Leadwent.

Asthesecondphaseofcompensatingfor the lost octane number, the fuelcompanies began to add higherpercentagesofknock-resistantaromaticcompoundstotheirbrews.Inmycorneroftheworld,thisnewsarrivedintheformoftheplasticfloatinmyvan’scarburetorsoaking up the new aromatics andsinkingtothebottomofthefloatbowl.Myexhaustbecameblack;myengine’s

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idlebecametheclassicsputter-and-stall.Iboughtanewfloatfor$7butyoucanbetthousandsofnewcarburetorsweresold tomotoristswho needed only afloat.

Fromanoctanestandpoint,theloveliestofthearomatichydrocarbonsisbenzene,aringofsixcarbonatoms,eachcarryingone hydrogen atom.Alas, a famousstudyof the Istanbul shoe industrybythededicatedphysicianMuzzaferAksoyidentifiedbenzeneasthecauseofmanyexcessleukemiasamongthepopulationofIstanbulshoeworkers.Benzeneisapowerfulsolventforrubber(andplasticcarburetorfloats,fuellines,etc.).Mixedwith rubber it becomes an adhesivestrongenoughtoholdshoestogether.Working inshopswhoseatmosphereswereheavywithbenzenevapormadethe shoeworkers sick. Benzenewastagged as a carcinogen and its usesurroundedbyathicketofregulations.

But there are lots of other aromaticcompounds—toluene,xylidene,cumene,etc.Allarebasedonthebenzeneringstructure, butwith one ormore side-groups inplaceofahydrogenor two.Aretheycarcinogenic?Somesayyes,somesayno, andothers saymaybe.Besides,EPAcouldn’t verywellmakeallhydrocarbonchemistryillegal,couldthey?Andsoalthoughyoucan’tlegallyput much benzene in gasoline anymore(someoccursnaturallyincasing-head petroleum) you arewelcome todoublethepercentageofotheraromaticcompounds–nowoftenashighas40%.Aswithcatalyticconverters,theno-leaderaexchangesoneproblemforpossiblyanother. DDT was once advertisedas “harmless to human beings andpets,” and to this day it has its loyaldefenders.

Andwhat about other opinions?Oneof theseholds that urban incineratorsgeneratedmuch of the airborne leadas a result of disposal of old buildingmaterials, someofwhich bear layersof lead-based paint. Science? Orpolitics?When the experts get up togivetheirtestimony,wenoticethattheyallwenttogoodschoolsandgotgood

marks.But theopinions theygivearequitedifferent.Doesscienceselflesslyadvancehumanknowledge,orisitjustopinions-for-hire?

The next panacea scheduled to savetheworldwas the electric car.Whata beautiful prospect—instead of longwaits in thegasoline lines, andsittingforhoursonjammedfreewaysbreathinghotengineexhaust,wecanjusthumourwayhome,pluginthechargingcabletotheconvenientwallsocketinthegarage,andliveperfectlyeverafter.Insteadofpaying$15-20tofillthetankwithsmellygasolineeveryweek,why,it’llhardlycostanythingtodrive—pennies!Thepoliticosloved it too—thegeneratingplants foralltheextraelectricitythosecarswouldusecouldbelocatedsomewhere else.Shallwe call it “pollution relocation?”A future of zero-emissions electricvehicleswouldleavethecitiesasfreshas amountainmeadow.Meanwhile,theelectricplantscouldbelocated... Well,wherewouldwelocatethem?Howabout theFourCorners?Nobody thatvoteslivesthere—it’llbeideal!

While all this excellent planningwasgoing on, California’s electric powercrisis was brewing. Howwould thatcrisis have looked if, say, 25%of theauto transportation’s horsepower-hourrequirementwas added to electricitydemand?

Now the sums. Electricity-generatingplantsareabout30-35%efficient,andlong-distance powerline transmissionefficiencyvariesfromalowof85%toahighinthe90s.Neglectinganylossesinvolved instepping linevoltagedownto battery voltage,we know that thebatterycharge/dischargecycleisdoingwelltoachieveanoverall70%efficiency.Electricmotorsget hot,which tells usthat less than 100%of the power inbecomes power out. Let’s give theman80%efficiency.Therewillprobablybea15%mechanicallossinpoweringthevehicle’swheels,so let’sgive thatstage a generous 90% efficiency.Togetoverallefficiency,wemultiplyalltheabovetogether;.33x.88x.70x.80x.90=15%totalsystemefficiency.

Why,mygoodnessme!Thatnumberislessthantheefficiencyofordinarycarandtruckengines,whethergasolineorDiesel!Thatmeansit’smorefuelefficienttoburnthefuelinthevehiclethanitistoburnthefueltomakeheat,usetheheattoraisesteam,usethesteamtoturnagenerator,usetheelectricitytochargeabattery,dischargethebatterytoturnanelectricmotor,andfinally(gettingtirednow)usetheelectricmotor’spowertodriveacar.

The above ignores other difficultieswhicharenotinsignificant.Electriccarsneedheaters inwintertime.Ever paidforelectrichomeheating?Yougettheidea.Andairconditioning—theyusedtotellusthatautoairconditionerstook15horsepowertorun.

Twelve hundred pounds of lead-acidbatteriesbuilt intoamolded-fiberglasschassisthatdoublesasabatterycasegivearangeaboutthesameasthatofelectriccarsof1910—60miles.Betterbatteries?Yes,theyexist,butareeitherexpensiveorcontaindisagreeablestufflikemolten sulfur at 900 degrees, orboth.Unfortunately,nobatterycanstorearespectableamountofenergywhencomparedwithanequalweightofliquidhydrocarbonfuel.

Thenwhyarehybridgasoline-electricssucceeding?Theyderivealltheirpowerfromasmall,efficientcombustionenginewhich is too feeble to provide rapidaccelerationofthekindUSdriversareaccustomedto.Whenthemainenginecan spare some power (in town, intraffic,etc.)itchargesthebattery.Whenefficient cruising is required, themainengine provides it (small cars requireonly15-30-hpatsteadyhighwayspeed).Whenmore acceleration is neededthanthemainenginecanprovide,bothcombustionandelectricpowerareused.Theelectricpartofthepowerunitisineffectarubberbandwhichis“cocked”when themain engine can spare thepower, and its “snap” is added to thefeeble push of the small, economicalmain engine to result in respectableacceleration.Hybridvehiclescan,andprobablywill,bebuiltusingotherforms

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of temporary energy storage such asflywheelorcompressedair.Rightnow,the word “electric” has beenmadeiconicbyyearsofpoliticaladvertising.Tomorrow’spolicymaydiffer.

Ifyouthinkthatdoingthemathfortheelectriccar’stotalsystemefficiencywasenlightening, let’s not even talk aboutfuelcells.

It is tobeexpected that in the future,technology will continue to provideimprovedresponsestoourneeds.Thenatureofpoliticswillrequireourleaderstoseizeuponeachnewtechnologyasacompletesolution.Becausecompletesolutionsare not attainable, therewillbevariousdisappointments.Placebos,cure-alls,perhapsitalldependsonhowthepolitico’sspintheinformation.Giventhechoicebetweenlaughingandcrying,Ichoosetochuckle.


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What is a hemi?What is a “hemi”?We all know thathemi is short for hemispherical, orhalf a sphere.Noengine todayhasacompletely hemispherical combustionchamber,becausesodeepachamberwouldprovideaverylowcompressionratio. Therefore it is correct to usethe description coined by Chryslerengineers duringWW II, and call themodern hemi chamber a sphericalsegment chamber—shallower than afullhemisphere.

Thetwovalvesinahemi,orsphericalsegment combustion chamber, aredisposed with a fairly large anglebetweentheirstems.Duringthe1920sand‘30s,whendeep,fullhemichambershad their heyday, this “valve includedangle” was often asmuch as 90 oreven100degrees.Itwasexplainedatthetimethatanglingthevalvesinthiswayprovidedmuchmoreroom“onthediagonal” for large valves than wasavailableifthetwostemswereparallel,withtheirvalveheadscontainedinsidethe cylinder’s bore circle. This wasimportantatatimewhenvalveareahadtomakeup fora lackofsophisticatedportshapes.

At the time,when full anddeephemichamberswereadoptedintheenginesof racing cars andmotorcycles, poorfuelqualitylimitedcompressionratiotothe vicinity of five- or six-to-one.Thissuitedthelargevolumeofsuchadeepchamber.Around1930,whenair-cooledaircraftenginesbegan tobeseriouslysupercharged,theircompressionratiosstabilizedaround6.5:1because,evenwith100-octanefuelthatcameintouseafter1936,thatwasaboutalltheycouldstandwithoutdetonating.

Asmotor gasoline octane rose, thecombustionchambersofunsuperchargedengineshadtobecomesmallertotakeadvantageof thehigher compression.Theeasiestway to raisecompressionwas the use of high-domed pistons.Perceptivedesignersrealizedthattheirusewasadeadend—fortworeasons.First, a deep chamber and tall pistondome increased chamber and pistonsurfacearea,makingenginesrunhot.

Second,thechamberthatresultedfromahighdomebecamemoreandmoreliketheskinofhalfanorangeafterit’stakenfromthe juicer—thinandveryspread-out.Suchachambertooklongertoburnthandidamorecompactchamber.

Thereforeprogressivedesignersofthelater 1930s to 1950s began to swingvalveincludedanglestosmallervaluesandtomaketheclassichemichambershallower.Thisallowedthepistontobeflattenedout,reducingitssurfaceareaand thereby solving its heat problem,whiletheshallowerchamberreduceditssurfaceareaaswell,makingtheheadruncooler.

Meanwhile, thenewscienceofairflowmeasurement revealed that therewassomething special about the hemichamber shape.Airflow is comparedbetween ports of differing styles andsizes by expressing it in terms ofcubicfeetperminute,persquareinchof port throat diameter.When this isdone,hemichambersareseentoflowmore air for their port size than doparallel-valve chambers or pent-rooffour-valve chambers (four valves areused inmanyengines todaybecausethey overpower their flow deficiencywithsheervalvearea).Thereasonwhyhemichambersflowsowellisthatthecurvinginnerheadsurfacesurroundingthe intakevalveperformssomeof thefunction of a diffuser, slowing the airas it comesout fromunder the valveand efficiently converting its velocityenergyintocylinder-fillingpressure.Thisphenomenon is an interesting subjectinitself.

The idea of angled valves in a part-spherical combustion chamber is atleast 100 years old.GeorgeWeidelyof thePremierMotorCo.designedanenginewithinclinedoverheadvalvesin1905,andsurelytherewereothers.ThehemiideareceivednewemphasisduringWorldWarOnewhen aDr. Gibson,working at Britain’s RoyalAircraftFactory,enunciatedbasicprinciplesforasuccessfulair-cooledenginecylinder.Oneofthesewasthatthefewerholesyoumake in a hot cylinder head, the

lessitwarps.Thismeantthattheidealnumberofvalveswastwo.Hestatedthatfurther, thestemsof these twovalvesshould beangled apart far enough topermit the placement of cooling finsbetweenthemtocoolthehotcenterofthe combustion chamber.The truth inthese rules reverberated through the1920sand‘30s,causinganincreasingnumberof racingandsportsautoandmotorcycleenginestousethischambertype.By1924 thehemi chamberwasadoptedas ideal forair-cooledaircraftengines. In 1927,Charles Lindberghwouldflysolo,west-to-eastacrosstheAtlantic to Paris, behind aWright J-5Cengine featuring hemi combustionchambers.

Even with its advantages, the hemichamber took time to assert itself onthe ground.An early problem wascombustionitself.JustafterWWI,enginepioneerHarryRicardobegantolicensehis concept of “squish” combustion,as applied to side-valve engines.Theside-valveplacesitstwovalves,stemspointingdownward,beside thepiston.Thecombustionchamber includestheborecircleandtheextraareaabovethetwo valves.Ricardo’s squish conceptconsistedofshaping theheadso thatthepistonnearlytoucheditattopcenter.Asthepistonapproachedthehead,themixturebetweenheadandpistonwouldbe squished-out rapidly into themainchamberattheside,locatedabovetheside valves.This rapid jet ofmixtureprovided turbulence that acceleratedcombustion, allowing suchengines tosafely run on low-octane fuels. Thesquish effect worked at all enginespeeds, giving such engines greatflexibilityandpullingpower.

Overhead valves were at first usedmainly in racing, because the extracomplexityoftheirmechanismandthedifficulty of lubricating themadded toanengine’scost.Also,inracing,powerathigherrpmwasmoreimportantthanmiddle-rpm pulling power.Therewasnoeasyway to implement the squishconcept in a hemi-chambered OHVengine,soside-valveenginescontinuedtobeproducedfornon-sportingvehicles

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formanyyears.Ford’sfamousflatheadV8 and BSA’sM20 are outstandingexamples.

When water-cooling was adoptedon racing engines, the tilted valvechamber—whether with two or fourvalves—was retained because thisarrangement allowedall intake valvesto be operated by one cam and allexhaustsbytheother.

The lackof squish inOHVchambers,like the hemi, for a time limited theircompression ratio, andmade themliabletoknockatlowerrpm.Theythusacquiredthereputationofbeing“rough.”Gradually through the 1930s it wasdiscovered that turbulence could begeneratedbyothermeansthansquish—anglingtheintakeportimpartedarotaryswirltotheincomingcharge,speedingupcombustionandallowingsafeuseofhighercompressionratios.

Something newwas added just afterWWII.APolishengineer,LeoKuzmicki,working atNorton inEngland, addedsquish toahemichamberbybuildingupthoseareasofthepistonnotdirectlyunder the valves or spark plugs.Asthese areas approached the headoncompression,theygeneratedsquishjets.This speeded combustionevenmore,allowinganotherroundofcompressionandpower increase.When theBritishauto industry sought to assert itselfin Grand Prix racing, the 4-cylinderVanwall racing enginewas based onNorton’ssquishhemicylinderhead.TheVanwall’s successmadeBritain againa center of F1 development,which itremainstothisday.

TraditionalUSautoengineswithOHVhaveusually,forcostreasons,placedalltheirvalvesinarowwithstemsparallel,so that both valves must be smallenough tofit into theborecircle.Thissimplifiesmachiningandallowsasinglerocker-armshaftoraxis toservebothintakeandexhaustvalves.Over time,this evolved into a “bathtub chamber”ofroughlyovalshape,containingbothvalvesandaside-mountedsparkplug,andsurroundedbyflatsquisharea.This

wasthecombustionchamberofchoicethroughmostofthe“V8era”oftheUSautoindustry.

Aspistonspeedsrose,threeschemespresented themselves asmeans ofprovidingthenecessaryincreaseinvalvearea.Thesimplestwastoincreasetheboreandreducethestroke,providingawidercircleinwhichtoplacethevalves.Slightlymorecomplicatedwasthe“cant-valve” scheme,whichby tiltingvalvesslightlyandadjustingrocker-armanglestosuit,couldfitinslightlylargervalvesand improved port shapes. Finally,adoption of a “spherical segment”chamberallowedmuchlargervalvesbutrequiredacomplextwo-shaftrocker-armassembly—oroverheadcams.

Chrysler had systematically pursuedhigherengineefficiencythroughhighercompression ratio beginning in theearly 1920s, and the advent of theeffectiveanti-knock fueladditive tetra-ethyl lead reinforced this trend bymakingbetterfuelsavailable.Ultimatelysuch work reached a dead end.Aside-valve combustion chamber isinherentlyinefficientbecauseofitsextrasurfacearea,andcannotreachahighcompression ratiowithout limiting theflowareabetweenvalvesandcylinder.The best compromise between thecompetingclaimsof compressionandairflowwas reached at about 6:1.Atthe same time,GeneralMotors wasknown to be conducting its own highcompression studies with overheadvalve test engines that could easilyreach ratios of ten or even twelve-to-one.Highercompressionmeant lowerfuelconsumptionaswellasincreasedenginetorque.

Inthelater1930s,despitethedampeningeffectoftheGreatDepression,Chryslerengineering pursued similar studies,seeking also to improve high-speedengine breathing and combustion bystudying the hemi chamber that hadlong been the norm in radial aircraftengines. Atthistimemostautomakersbuiltin-lineengines,butthelongeracrankshaftis

made,themorevulnerableitbecomestotorsionaloscillations.Solongasautoengineswerelimitedtorpmbarelyabove3000,in-linesixesandeightswereokay;butitwasclearthatmorepowerwouldrequireeitherlarger,heavierengines,ornewdesignscapableofsafeoperationathigherrpm.FordhadalreadyproducedaV8withashortandstiffcrankwithonlyfourcrankpins.EventhoughtheFordV8was still a side-valve, its rpm-capablecrankshaftpointedtothefuture.

Chrysler engineers had been toldthat the spherical segment chamberwas rough-runningand suited only tohighspeeds.This informationwasnotwrong—justoutofdate.Withwhathadbeen learned in the later 1920s and‘30s,Chrysler engineerswereable tomake their hemi test engines operatesmoothlywhileusinglessfuelthananyside-valve.

Whenwar began in Europe, theUSgovernment accelerated mil i tarypreparation. In 1940Chrysler begandesignofaliquid-cooledaircraftengineinaccordancewithguidelinesoftheUSArmyAirCorps.TheArmybelievedatthetimethatfuturefighteraircraft(theywerethencalled“pursuits”)wouldneedliquid-cooledenginesofminimumfrontalarea, operating at high combustionpressureachievedbysupercharging.

Chrysler’splancalledforplacingevenmore than 12 cylinders behind a tinyfrontalareacircleofonly33½inches.Their IV-2220designconsistedof two60-degreeV8splacedend-to-end inacommoncrankcase.Thiswouldneatlysolve the problem of crank torsionalvibrationbytakingpowerfromasinglecentral gear towhich bothV8 crankswouldbolt.Toprovide theenginewiththe stiffness its length required, theymade the crankcase very deep, suchthat almost the entire length of eachcylinderwas submerged in it, leavingonlythecylinderheadprojecting.Evenso,the2220’scrankcasewaslongandvulnerabletoflexure,beinglessthan12inchesdeepatthesidesand16inchesin itscenter.Alongeachrowofheadswouldbebolteda cambox-and-rocker

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assembly to operate the two largesodium-cooledvalvesineachcylinder.Valveincludedanglewasathoroughlymodern45-degrees.

Early development of this unusualenginedidnotmovequickly, as therewerechronicproblemswithcrankcaseandcamboxcracking.Althoughby1944theenginedidreachthedesignpowerof2500-horsepower,andflewatnearly500-mph in a specialP-47-based testaircraft,itwasclearbythenthatexistingenginetypeswereenoughtowinthewarandthatpostwardevelopmentwouldshifttojetengines.Inanycase,onMarch20,1942,Chrysler contracted tobuildthousandsofair-cooledradialenginesfortheB-29inahugenewfacilitynearChicago—work that absorbed largeresources.TherewaslittleleftfortheIV-2220,whichwasthereforecancelled.

Once the war ended, auto enginedevelopment resumed. Oldsmobilereleasedits“Kettering”Rocket88OHVV8 in 1949, andChrysler was closebehindwithits331cubicinch“Firedome”V8in1951—butwiththehemisphericalsegmentchamberthathadcomefromwartime 2220work. In place of thatengine’s side-mounted spark plugs,singleoverheadcamsandrollerrockers,theFiredomehadpushrods,twinrockershafts,andsinglecentralsparkplugs.Coveringall thismechanismwere thedistinctive wide, slope-sided valvecovers,eachpiercedbyfoursparkplugtubes.Today,suchvalvecoversshoutHemi.

Wereverethename“Hemi”becauseofitsuse inChrysler’s famousFiredomeand laterV8s,which turnedout to beuniquelysuited tooval trackanddragracing.Tothisveryday,specialracinghemi engines (containing noChryslerparts)continuetobeproducedforTopFuel drag racing. Supercharged andfueledwithnitromethane,suchspecialhemi engines are claimed to produce6000-horsepower during their sub-5-secondrunsdownthe1320.

Auto marketing people know thatdistinctionishardtoachieveinaworldof

identical-lookingsmalllozenge-shapedcars (re-read page 6). Establishing abrand identity is almost impossible insuchaseaofsameness,somotivationalresearchers have turned to classicidentities such as the VW Beetle,the BMC “Mini,” and Ford’s originalThunderbird. If a great namealreadylivesinthemindsofmillions,that’sfreebaconforwhoeverchoosestouseit.ThisliesbehindChrysler’sre-introductionoftheirpremium300Cautomobileandits“Hemi”powerplant.

The newly-designedHemi nowbeingmarketed by Chrysler employs aconsiderably modified combustionchamber. This design continues thepairofangledvalves,twinrockershafts,and central sparkplugof theoriginal,but fills in thosepartsof thechambernot occupied by valves to reach highcompressionwithoutatallpistondome.This is anotherway of accomplishingwhatNortondidwith itssquishpiston,buttheextramaterialbecomespartoftheheadratherthanofthepiston.

Thebasicideasbehindthehemichamberareveryold,andhavemadeitusefulinmany quite different applications. Itsusefulnesscontinues.


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staying in one Pieceto keep thematerial solid. But eachmoleculemust also resist the forceof gravity, adding a small bias to theforcesactingonit.Ontheaverage,thevibrationalenergyofagivenmoleculeismuch less thanwhat itwould taketo dislodge it from its position. But,when through the statistics of energydistribution,agivenwatermoleculedoesgetenoughenergytochangeposition,itusuallychanges in thedirectionthatrelaxestheforcesactingonit.It“makesitselfmorecomfortable.”Summedoverthemillionsoftonsoficeintheglacier,theresultisaslownetmotion—creep.The higher the temperature of thematerial,themorerapidisthecreepinresponsetostrain.

Inearlyjetengines,creepwassorapidthatnewturbinebladeswererequiredafteraslittleas25-100operatinghours.Bladesgrew in lengthuntil theyeitherscrapedon thehousing inwhich theyspun, or necked-down somuch thattheyfailedintension.Thebladesweren’tmelting, for they were operating farbelow theactualmeltingpointof theirmaterials.Theywerecreeping.

Metallurgists soon discoveredmeansofmakingmaterialsresistcreep.Theycould, for example, include in thematerialenoughcarbontoformzillionsof tiny, dispersed particles ofmetalcarbides.Because theseparticlesareextremelyhard(youmayhaveheardofTiC,titaniumcarbide,usedasawear-resistanthardcoatingonmetal-cuttingtools), theyactasphysicalbarriers tothemotion of crystal defects throughmaterial.They can alsomake it verybrittle—averyun-usefulquality.Amajorreason for theusefulnessofmetals isthattheycanyieldunderstress,ratherthanjustsnapoff.Thisallowsmetalstosurvivesuddenloadswell,andmakesitpossibletobend,forge,andotherwiseformthemintodesiredshapes.Losingthis quality is usually a disaster for ametalalloy.

Another method of providing creepresistancewastocauseasecondphaseto formwithin thematrix of themetalas a whole. So-called “intermetallic”

Asyouputyourfootdownandhearthethinrisingwhistleofyourturbochargerspoolingup, do you everwonder how the rotor,incandescent from its high temperature,canstandthecentrifugalstressofspinningover100,000-rpm?Thesimpleansweris“nickel-basedjetenginesuperalloys,”butthat doesn’t tell us anything about howsuchmaterialswork.

Just having a highmelting point—assuchmaterialsdo—isnotenough.Thereareotherproblemstobesolved.Oneissimplystrength.Metalsarecomposedofajumbleoftinycrystals,usuallyorientedeverywhich-way.Metalatomsbondtoeachotherbysharingtheirmoreorlessplentiful bonding electrons. Becausethese electrons forma kind of gas inmetalcrystals,theforcesthatholdatomstogether are delocalized—that is, thematerialholdsitselftogetherevenifitsshapechanges.Inacrystal,theatomsassumeorderedpositions,butyieldingtakes place as sheets of atoms slideacrosseachother,orasdefectsinthecrystal’s order propagate through it.Onewaytostrengthenmetalsistomixinatomsofoneormoreothermetals,havingadifferentsizefromthoseofthebasicmaterial.Thelocalstraincreatedbytheirpresencemakesitmoredifficulttomake sheets of atoms glide pasteachother, or to push crystal defectsfromplacetoplace.Addingothermetalatoms in this way is called solutionstrengthening.

Unfortunately,alloyingusuallyreducesthemelting point. This brings us toanother problem of high-temperaturematerials subject to stress—creep.Creepistheslowyieldingofamaterialunderstress,at temperatures thataremore than halfway to thatmaterial’smelting-point.The classic example ofcreepistheslowmovementofglaciers.Snowsfallontheglacier,increasingitsthickness,beingcompactedovertimebyitsownweightintoice.Gravityactsonthisthicknessofice,causingittoslowlyspread likesillyputty.Howcan itflowwithoutmelting?

Inthelatticeofeachicecrystal,watermoleculescling toeachother, tending

compoundssuchasnickelor titaniumaluminide form small islands withinthemetal, acting like extremely hardbricksinamatrixofsofter,moreductile“mortar”—the original alloy.This kindofmaterialactedveryrigidandstronguptoaveryhighlevel,thenveryslowlyyieldedasthe“mortar”permittedsomemotion—without allowing cracks tosuddenlyshootthroughthematerial.

Promising though thiswas, it too hadproblems. In service, the materialwould at first display all the strengthand creep resistancedesigned into it,but after some hundreds of hours atoperatingtemperature,failuresoccurredthatshouldnothavetakenplace.Thematerial had lost strength. Samplesof the failed bladeswere cut throughand thecutsurfaceswere thenhighlypolished.Special reagentswere usedtoetchthepolishedsurfaces,revealingthemicrostructureof themetal to themetallographicmicroscope.Itwasfoundthatduring longoperation, the islandsof hard intermetallicsweregrowing insize and becoming fewer in number.Thisisafamiliarthingforanyonewhokeepsicecreamintherefrigeratortoolong. Ice cream is cold-workedduringfreezing to prevent the formation oflarge ice crystals that would give ita coarse, granular texture. Kept toolonginthefridge,andfairlyclosetoitsmelting point, the larger of these tinycrystalsgrowattheexpenseoftheevensmallerones.BythetimeIthink“Hey,Icouldhavesomeicecream!”thelargecrystalsmay have grown so big thattheformerlycreamystuffhasacquiredagrittytexture.

Something similar happened to theislandsofhardintermetallicsinturbinebladematerials.Since the strength ofthematerialdependedonhavingagreatmany tiny “bricks” togive ithardness,when those bricks became largerand fewer from prolonged exposureto high temperature, thematerial loststrength.Atone time,andbecauseofthis,theturbinebladesofsomeBritishjet engines had to be removed andre-heat-treated every 900 hours.Thisheatingcausedtheintermetallicstogo

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back into solution, and the followingcooling schedulewould cause the re-formationofthedesiredsizeandnumberofprecipitatedintermetallics.

Later,meanswere foundbywhich togreatly slowsuch changes, giving theresulting alloysmuch longer servicelives.

Anotherproblemwasthatwhileagivenalloymightperformverywellwhenveryhot—asinaturbineblade—whenusedinacoolerpartoftheengine,suchasinaturbinerotordisk,thatsamematerialwould be unacceptably brittle. Thisis one reasonwhy, in aircraft turbineengines,thebladesandtheirrotordisksareseldomcastinonepiece.Instead,thediskismadefromamaterialwhosepropertiesareoptimumforitsoperatingtemperature,while thebladesthatarefittedintothefir-treeslotsinitsrimaremade from something quite different,whoseproperties becomeuseful onlyathighertemperatures.Forcommercialpower-generation turbines, specialmaterialshadtobedevelopedtoallowbladesanddiskstobecastinonepiece.Itissuchmaterialsthathavebeenusedtomaketurbochargerturbinewheels.

Anyonewhohasbeenaroundautomotiveengines has heard the term “nodulariron.”Crankshafts for low-to-moderatedutyareplainoldcastiron,buttoresisthigherstress levelsnodular,orductileironwill be specified. For the highestduty crankshafts, forgings are almostalways employed. We all know thatordinary cast iron doesn’t bendmuchbeforeitbreaks—itisbrittle.Nodularironhasmoreductility—theabilitytochangeshapeunderstressratherthansimplytofracture.Thedifferenceinthebehaviorsofthesetwomaterialsarisesfromhowtheydealwith small cracks.Cast ironcontainsalotofcarbon.Inthemoltenstate, this carbon is dissolved in theiron,butasthemeltcoolsaftercasting,theironbecomeslessabletoholdthismuchcarboninsolution.Thecarbonistherefore precipitated out of themelt,forming long, needle-like crystals thatbranch inalldirections.This“acicular”carbon is likea superhighway for any

crackthatformsunderstress,givingitaneasypathofleastresistance.

Thisiswhy,aswesatinstudyhall,ourdesklidsproppedopenagainstthetopsofourheads,perusingaconcealedHotRodmagazine,we learned that ifwewantedtohopupcertainengines,wehadtolookfortheparticularmanufacturer’ssymbolonthecrankthatwouldindicatethatitwasofthemoredurablenodulariron.Innodulariron,changesaremadetothechemistryofthemeltandtotheheattreatment,whichcausethecarbontoassumetheformofball-likenodulesratherthanlongneedles.Thiseliminatedmostoftheeasypathwaysforcracks,causing them to remain dormant formuchlongerperiodsoftime.

Similarundesirableneedle-likephasescan also form in high temperaturesuperalloys, rendering thembrittle.Aswas done for acicular carbon,meanswere found by which to convert thecrack-inviting needle form into a lessharmful blocky form. In suchways itwas found possible to create alloyswhich could be cast tomake turbinewheelswithintegralratherthanseparateblades. It is from suchmaterials thatturbochargerturbinerotorsarecast.

The design of metal alloys is verymuch like tire engineering. Becauseeverything affects everything else,it is seldom possible to go after anincrease inasingleproperty (suchasductility,orcreepresistance,oroxidationresistance)withouthavingapotentiallyharmful effect on one ormore other,equallyessentialproperties.Therefore,once a useful alloy is developed andengineers become skilled in usingit successfully, it tends to remain inproductionformanyyears.

Material propert ies also dependon processing during manufacture.Making a flaky pastry requires thattheshorteningbeaddedcold,soafterblendingitremainsintheformofsmallfragmentsratherthanmeltinguniformlythroughout the dough.When baked,thefragmentsseparatethepastryintolayers,causingyourbakingskill tobe

admired.Somesuperalloysaremeltedjustas in thecaseofgeneral-purposesteel alloys.The right amounts of thevariouselementsareput into thepot,the induction heating is switched on,andpresentlythematerialmeltsandcanbebrought tothedesiredtemperaturefor pouring.After cooling, it can thenbe heat-treated as desired. Otheradvancedmaterials contain elementsthatwould, ifmelted in thisway, notdissolve into the others.Theywouldeither remain separate, orwould tendto form undesirable phases. In thesecases,thematerialmaybepreparedasanextremelyfinepowdermixtureofitselements,thenpressedintofinalshape,followed by heating (“sintering”) tocauseittofuseintoasolidpart.This,byeliminatingoutrightmelting,avoidsthesegregationof the insolubleelements.Aslongasthiskindofmaterialisusedattemperaturestoolowtobringaboutsegregationoftheinsolubleelements,itcanretainremarkableproperties.Thisispowdermetallurgy.

Alloying and heat-treating can createwithinametalthedesiredphasesandcanprecipitateoutusefulsmallparticlesthatactaspinstopreventmovement.Ifthatworks,thenwhynotjustmakethekindofparticlesyouwant,andthenaddthem to thematerial?This is done—veryhard, temperature-resistantoxideparticles are prepared in the desiredformandcanbeaddedto“powderparts”duringmanufacture.Thisusefullywidenstherangeofstrengtheningmechanismsavailabletothemetallurgist.

Thespinning,glowinglittlewheelinsideyour turbo is the result of decadesof research and service experiencewith many families of superalloys.In jet engines, higher fuel efficiencyhas requireda steady increase in hotgas temperature, and this has drivena continuous process of materialsdevelopment.Thishasprovidedamenuofprovenmaterialsoptionsfromwhichto make cost-effective and durableturbochargerturbinewheels.


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Issue 48’s Theme – historical Perspective: China’s DevelopmentIn themodern world of e-mail andimmediateresponses,KevinCameronresponded to the Issue 48 themeideawiththefollowing:“Thehistoricalperspectivetopicmakesmethinkofthetruculent (best puns come naturally)Harleyownerswhotelltheworldhowmuch they hate rice-burners, thenswitch on theirHitachi ignitions andride off on their Showa-suspendedMilwaukee vibrators, their cylindersinductingairthroughPorsche-designedports as fuel is injected by ItalianmadeMarelli injectors.GlobalizationismorethanjustThird-worldcountriesbeing creatively kept down by theWorldBankandIMF—it’sallbrandsofmanufacturedgoodsturningintoeachotheraseveryonetriestogetthebestperformance/price ratio and ends upidentical.AndwhydoF-15s andSu-27s looksomuchalike?Theydothesamejob.

“Inthebackgroundistherumbleofforktrucksastheverylatestinresearchanddevelopmentandautomatedproductionequipment isdelivered to fast-growingChinese firms with world ambitions.Soundsa lot likeJapan in1954.And,son-of-a-gun, China is the world’ssecond-largestoiluser.

“I’m going to have another look atrapidly-developingDiesel technologiesand seewhat is out there that yourreadersmight like to hear about.Anysuggestions?”

Yours truly responded: “On behalfof the TDR audience, we’re alwaysinterested in diesel development.AndI’mthankfulthatwe’vegotyourindustryexpertise to sharewith the readers.Also,asapartofIssue48,Iwillhaveanarticleontheupcoming2007dieselexhaust emissions legislation andall of the industry buzzwords: EGR,SCR,Caterpillar’sACERT, and otheremissions-type abbreviations.So,mylook at the industry, as gleaned fromtradepublications,shouldnicelydovetailintointerestingindustrytrends.

“Speaking of industry trends anddevelopments—how about China?Developedcountriesshouldlearnfromthepast,butIoftenwonderifourelectedofficialshaveaccesstoahistorybook.Perhapswecanallflipburgers,manageretail outlets or entertain oneanotherwithourrealityshowstokeepAmericastrongandprosperous.Geez....”

Kevin shied away frommy cynicalcomments about America. He is asmart gentleman.He stayed on-topicand provided a bit of global historicalperspective. Thus he completed the“Themefor Issue48”assignmentwiththislookbackintime.

China’s Industrial RevolutionEngland had the original IndustrialRevolution,andthatfirsttimeithappenedalmost by accident. Other countriessaw England’s experience and triedto do better—most notablyGermany,whereBismarckestablisheda systemof free public education, workmen’scompensation, and technical andscientifictrainingtobuildupGermany’sindustry.TheFrenchdidmuchthesame,butbeganwithtechnicalschoolsunderNapoleon.

WhenJapanemergedfromWWIIwithits66largestcitiesburnedoutbyB-29incendiary attack, they weremostlystartingfromzero;sotheycouldbeginwith the very latest in production andR&Dequipment.Atfirst,people in theWestsneeredthat“LifeischeapintheEast—theyworktheirpeople14hoursadayforpracticallynopay—that’swhytheirstuffissocheap.”Butyearslaterit was clear that Japanese cameras,measuring instruments, andmachinetoolswere theequalofanyyoucouldbuy, and then after that came thecars and the electronics. Today thelabor content of a Japanese car isdown to 18-20man-hours—the restis performed by automated systems.Meanwhile,Japaneseindustrypurposely

concentratedonhighvalue-addedworksuchasdevelopmentandbegantoleaveactualproductiontotheSouthKoreansor whoever would have it. CurrentlyJapanesecompaniesaremovingpartsproduction toChina,whose industrialrevolutionisinitsearly-middlestages,asfastastheycan.

Thefirststeponthewaytoinnovationistomasterexistingtechnologies.That’swhereChina is right now.Once theyhave done so, their cleverest peoplewill,assomanydidbeforethem,lookatthosemethodsandsay,“Whydidn’ttheydo it thisway?Itwouldbebetterandalsocheaper.”

HereintheUS,steelproductionstayedwithprocessesandequipmentthathadbeen paid for back in the 1930s and‘40s, but in Japan continuous castingwasdevelopedwhichallowedimprovedprocesscontrol,lowercosts,andabettermatchtodownstreamprocesses.

All this is bound to affect theDieselenginesomewheredownthe line, justastheJapanesehave.


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Gas to Liquid—GTL Diesel FuelGTLDiesel costs 10%more tomakethan conventionalDiesel fuel, but it isahighlysuperiorproduct.ConventionalDieselfuelcontainsahighpercentageofaromatic compounds—those basedonringsofsixcarbonatomswithattachedhydrogens.These ring structures areextremelystable—whichalsomeanstheyarenotsoeasytoignite.Itisanironyofnature that natural gasoline,whichwedesiretobehighlystablefordetonationresistance,ismainlymadeupofknock-pronestraighthydrocarbonchains,whileDiesel, which wewant to auto-igniteeasily,mainly consists of very stable,auto-ignition-resistant ring compounds.GTLDiesel,ontheotherhand,consistsof straightandbranchedchainswithaveryhighcetaneratingover70.

DuringDieselcombustion,fueldropletsevaporate,heatedby thecompressedhotairaroundthemandbyinfraredfromnearbycombustionflame.Eachdropletradiatesacloudofvaporwhichdiffusesinto the surrounding compressed air,burningonlyasthelocalratiooffueltoairreachesanearlychemicallycorrectvalue.Inthisdiffusionflame,thedropletactsasadistillationapparatus,boilingoffitslighterfractionsfirst,followedbythe heavier components. The lighterfractionsnaturallydiffusemorerapidly,andthereforereachtheflamezonefirst.Theheavy,stay-at-homefractionsarrivelater.As a result, some of the heavystuffmaynotactuallyhavetimetoburnthoroughly,butinsteadreleasescarbonatoms that clump together to form—youguessed it—thedreadedexhaustparticulates.Carbonisattractive,stickystuff—that’s why it’s used tomellowwhiskeyand to filter cigarette smoke.Therefore onto the surfaces of thesecarbon particles are attracted anyunburned carbon-ring fuel fragmentsthat happen by. It is these “PAHs”—PolycyclicAromaticHydrocarbons—thatare implicated in the carcinogenicityofDiesel particulates.This is one ofthebigbarrierstowideracceptanceofotherwisesuper-efficientDieselpowerintheUS.

WhenGTL fuel burns, its less stablechainmoleculeslightuppromptly,then

Muchofthehydrocarbonenergytrappedin subterranean petroleum depositsis gas, either by itself or dissolved inliquids.Thisisconvenientwhenthegasfieldisneargasconsumersasitcanbepipeddirectlytothemandusednearlyasitcomesfromtheearth.Otherwise,gas isan inconveniencebecause it isbulky;hardtotransportexceptasLNGcompressedliquid,heldat250°belowzero.Shipsforsuchtransportexist,butconstruction of liquefaction and portfacilitiestoservethemmeetswithlocalresistance.(Whatifthatstuffleaksoutand explodes?Willmy neighborhoodbecome “HindenburgAcres”?) Thishas stimulated research intomethodsof chemically converting natural gasintoasubstance that is liquidat roomtemperature.Muchresearchhasalreadybeenperformed—theFischer-Tropschprocess for coal liquefaction wasdeveloped in the1920satGermany’sKaiserWilhelmInstitute.Asynthesisgasisprepared from the rawhydrocarbon(natural gas in this case, but it canalsobecoalorbiomass),consistingofhydrogenand carbonmonoxide.Thisisadjustedtoa2:1ratiobyremovalofsomehydrogen, and this gasmixtureisbubbledup throughaslurry reactorconsistingofamixtureofpetroleumwaxandan ironorcobaltcatalyst.Electricfields on the surface of the catalystacceleratethecombinationofhydrogenwithcarbonatomstoformhydrocarbonchainsofvariouslengths.

Whenthisprocessisoperatedat630°,theoutput consistsof light fractions—gasoline and olefins—and this wasessentially howGermany producedsynthetic fuel frombrown coal duringWorldWarII.Operatedatacooler360°-480°theoutputassumesthemolecularweightandboilingtemperaturerangeofDieselfuel,withsomewaxes.Thewaxcan later be “cracked” (itsmoleculesbroken down by heat or catalysis toreducedmolecularweights)toyieldmoreDiesel.ThepresentcommercialprocesswasdevelopedbySasolinSouthAfricaduringthatcountry’s isolationovertheissue of its apartheid racial policies.SouthAfricahadnopetroleumofitsown,butplentifulcoal.

burn quickly—andmore completely.Compared on a combustion pressureversustimegraph,thepressurebeginstorisesoonerinaGTL-firedengine(asmuchas4degreesearlier,accordingtoDaimler-Chryslerresearch).ThereisalsoareductionofHCandNOxemissionsontheorderof1/3.HCemissionsarereduced by themore complete burn,owingtothecompleteabsenceofstablercarbon-ringcompounds.NOxemissionsdropbecause,withGTL’shighercetanerating,thefuelcanbeignitedeveninthepresenceofhigherratesofinertEGR.The key here is that NOx formationis linked to high temperature.Use ofincreased EGR at part load reducesflametemperature.

Betteryet,nearlythesameperformanceand emissions reductions result fromcuttingtheGTLwithnormalDieselfuel50/50 (in this case, aEuro referencefuel).Finally,GTLcontainszerosulfur(sulfur gets in theway of projects toclean upDiesel emissions by use ofexhaust catalysts) and zero heavymetals(sameobjection).

GTL Diesel has been described ascrystal-clearandodorless—anotherbigdifference.

Alloftheaboverevealswhyalargeplantisnowunderconstruction inQatar forthesynthesisofGTLfromnaturalgas,rampingupover thenextsixyears to600,000barrelsperday.Justwhenyougetthattingling-under-the-collaranxietythatworld events are coming to takeawayyourgloriousmobility(feebleso-calledelectriccars,“voluntary”shiftstopublictransportation,etc.),alongcomesa bit of encouraging news likeGTL.There isa lotof life left in the internalcombustionengine,andyoucanbetoilcompanieswouldn’tbebuildingbigGTLplantsiftheydidn’tagree.


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The turbocharger’s longhistory partlyconceals a very important fact—thatrapid progress depended upon howmuch money was being spent onmaterialsresearch.Earlyturbochargers,suchasthoseofSanfordMoss,duringandafterWWI,hadshort lives.Earlyaltituderecordsresultedfromthemostcareful use of such fragilemachines,astheprimitivematerialsofwhichtheirbladesweremadequicklystretchedandbroke.CaptainR.W.“Shorty”Schroeder,usingsuchaGEturbocharger,flewto33,000feetonFebruary27,1920.

ThoseofyoufamiliarwiththeBoeingB-17bomberofWWIIknowthattheturbinewheelsofitsturbochargerswerevisiblefrom below, as theywere essentiallymountedflushwiththenacellesurface,in full view.At night, their glowwasclearlyvisiblefrombelow.Thismodeofmounting cameabout througha snapdecisiontakenbyengineersseekinganymeansofprovidingextracoolingforthehard-pressedturbineblades.

TurbochargershadaneasiertimeofitonDieselenginesbecauseoftheirlowerexhaust temperature, and this iswhyturbos becamea commercial productinthisapplicationfirst.

A brief look at the performance ofexhaust valves in aircraft and otherheavy duty engines revealswhy theturbocharger problemwas so difficultin the early years. Because aircraftengine developmentwas the leadingtechnology,hightemperaturematerialswere developed primarily for exhaustvalves. An exhaust valve spendsless than40%of its timeopen,beingintenselyheatedonbothfacesbysonic-speedhotexhaustgas.Therestof itstime it spendson its seat, towhich itrapidlytransmitstheheatithascollectedfrom the previous exhaust event. Itthus “rests” between exposures toheat.Yetfromthebeginningofinternalcombustion through themid-1930s,exhaustvalvecupping,stretching,andcrackingremainedseriousproblems.

If the best heat resisting materialsperformed this poorly on a 40%duty

cycle,thinkhowrapidlytheydeterioratedwhensubjecttothecontinuousseverestretchresultingfromthe100%heatingdutycycleandcentrifugal forceactingonaturbochargerblade!

Theturbochargerhadtomakedowithwhateverthecurrentbestexhaustvalvematerialhappenedtobe.Forexample,for a period in the 1930s it was theexhaust valve stainless steel KE965thatwas chosen forUS turbochargerblademanufacture.Onlywhen itwaslaterdiscovered ina routinematerialssearch that certain alloys, originallydeveloped for corrosion resistance inchemicalengineering,werealsohighlytemperaturetolerantdidanewavenueofbladematerialdevelopmentappear.

Very soon after this the developmentof gas turbineswas taken up by thegovernments ofBritain andGermany,andlaterbytheUS.SanfordMosshadbeenadvisedearly togiveuphisgasturbine research in favor of themorepractical turbocharger. In England,RAF officer FrankWhittle had beendismissed for years by supposed“authorities” intheenginefield,onthegroundsthatnomaterialscouldsurvivethenecessarystressandtemperaturetomakeaworkablegasturbine.Althoughscientists and engineers claim to beopen to innovation, new ideas aretoooften rejectedby themwhen theyconflictwith long-held attitudes.Suchattitudesthentakeontheappearanceofnaturallaw,wheninfacttheyarejustuninformed opinions. Such attitudescan hold back progress for years.A respected researcher writes thedefinitivetextinacertainarea,becomingits leading authority and becoming afullprofessor.Whenotherresearcherspresentconflictingviewsforpublicationby technical journals, peer reviewboardsrejectthoseviewsastooradicalfor publication.The leading authority,havingmadehiscontributionatanearlyage,spends the restofhis lifestiflingdissentasanobscurantistoldfossil.

FrankWhittle,whohadmostcarefullymade the calculations and knew thetemperatures and stresses his gas

Turbocharger historyturbinewouldproduce,wasthusunabletopersuadeotherseventolookathisreasoning. Therefore he had to findprivatemoney to finance constructionof a prototype. When it operatedsuccessfully, it was obvious at oncethatthiswasthewaytomovepastthe“propeller barrier” (around 500-mph),andmoveontowardsupersonicflight,Whittlewas summarily pushed asideby theBritishgovernment,which thenfocused powerful resources on jetengine development. Decades later,Parliament votedWhittle a $160,000“tip,” and arranged for him to have ajoyride onConcorde.He lived out hislifeinFlorida.

When USAAF GeneralArnold wasmadeawareofBritishjetenginework,heorderedcrashprogramsinstitutedatGE andWestinghouse.USmaterialsresearchwent into high gear aswell.With thebestmindsatworkon theseproblems,progresswassteep.Thenewenginesmovedoutofprototypestage,needingoverhaul at 15-25hours, intosquadronmilitaryserviceneartheendofWW IIwith predictable lifetimes ofhundredsofhours.Materials researchwasthemajorbasisofthissuccess.

Materials technology does not resultfrommadscientistshavingbrainstorms.It requiresmillions of dollars to payfor the construction and around-the-clockoperationof hundredsof “creepcabinets,”apparatus inwhichmaterialsamples are electrically heated andheldatconstanthightemperatureundersteadystress,whiletheirslowstretchisopticallymonitoredtohighaccuracy.

In thespringof1944 thevastgamblethat was the Boeing B-29 bomberdevelopmentwasteeteringonthepointoffailureasaresultofthedelaysanddefectsinitsWrightR-3350engines.Justatthistimearevolutionaryrefrigeratedhighaltitudewindtunnelwascompletednear Cleveland, cooled by 100,000horsepowerofCarrier air conditioninglocated in vast machinery spacesbeneath the tunnel. Despite the top-priority needs of theB-29 program, itwasnot theailing3350pistonengine

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thatwasfirst tobe tested in thatnewtunnel. It was the GE I-16 turbojetengine.GeneralArnoldwasmakingsuretheUSnevergotleftbehindinaircraftpropulsionagain.

Onlygovernmentshavethemoneyandthe do-it-today power tomake thingshappeninmonths,ratherthanyearsordecades.Oneresultofthisworkwasthedevelopmentofheat-resistantmaterialsthat wouldmake turbocharging fullypracticalforcommercialapplications.

Despite this, the cloud of ignorancethathadalmostdefeatedFrankWhittlewas still affecting decision-making intheengineworld.Thenewofficialbeliefwas that jet engines,while powerful,weresofuel-hungrythattheywouldbesuitableonlyfordefensivefighteraircraftformany years to come.Makers oftraditionalpistonenginesassumedtheirproductswouldbecarrying the freightin themeantime,so they laidplans tophase-in the new turbine technologyas a part of what theywere alreadymaking.

Thiswasalmosta repeatofwhathadnearly stoppedWhittle.No one couldbelievethatmaterialsanddesignwouldadvance as rapidly as they did andtherefore it would be necessary toadvancebybaby steps.The first stepwas to integrate the turbocharger intoaircraftpistonenginesinnewways.Intextbookswrittenatthattime,thepistonenginewaspicturedasbecomingsmallerandsmallerasitsturbochargerbecamelargerand larger—until in theend, theturbinewouldbeallthatwasleft.

Previously, theturbochargerhadbeenanadd-onunit,supplyingcompressedairtoanengine’snormalmechanicallydrivensuperchargerasafirststageofcompression.Butnowtheplanwastouse the turbine to recoverpower fromthe cylinder exhausts and send thatpowerbacktothecrankshaft.Thiswasaprocessknownasturbo-compounding,and itwasconsidered theappropriatefirst step because existing turbinematerials could handle piston engineexhaustgas.

WrightAeronautical Corp. (WAC)developed a compact system usingthree turbines, each served by sixof their radial engine’s eighteen 186cubic inch cylinders. Each turbineextracted 120 horsepower from theexhaustflowforatotalpowerrecoveryto the crankshaft of 360horsepower.ThisTC-18 engine, at powers up to3700horsepower,setrecordsforlongrange and, in the lovely LockheedConstellationandDouglasDC-7,madetrans-oceaniccommercialflightsroutineinthemidtolate1950s.

Pratt &Whitney envisioned muchmore elaborate schemes in whichtheir 28-cylinder radial 4360 enginewouldsupplyexhaustgas tomultipleturbines, insomecasesoperatingasturbochargers and in others beingturbo-compounded. In the vast arrayof insulated stainless steel ducting,turbines, valves, compressors, andnozzles, the actual power sectionwithits28cylindersseemedtoshrinkinto insignificance. Such complexpowerplants—part piston and partturbine, containing an unbelievablenumbers of parts—were expected topowerupdatedversionsoftheB-50andB-36bombers.FortunatelyforPratt&Whitney,theseversionswerecanceled,forcing the company tomake a newplan—to begin licensed productionof the BritishNene turbojet. P &Wtodayremainsoneoftheworld’smajorproducersofturbineengines.

InEngland,Napierdesignedaflat-12,two-stroke, Diesel turbo-compoundpiston engine. It looked like a pistonenginegivingbirthtoajetengine,andwasnamedtheNomad.

Whyallthiscomplexity?Nooneatthetime believed thatmaterials sciencewouldmake possible fuel-efficient jetenginesasrapidlyas itdid.Thereforethecorrectandprudentpathtoprogresswastouseapistonengineasahigh-temperature gas generator and firststageofexpansion,andtocompletethatexpansion—orpowerrecoveryforrangeorspeed—byuseofalesstemperature-tolerantturbine.

Napier expected Nomad-poweredpropelleraircraft tocruisemoreslowlythan the then-new,all-jetDeHavillandComet. But it would reachNewYorkfrom London sooner than theCometbecause its greater fuel efficiency letit fly non-stop.Meanwhile the turbojetComet, devouring fuel like amilitaryfighter,wouldneedtorefuelinGander,Newfoundland,andprobablyinIrelandaswell.

Wright, makers of the radial turbo-compound engine, had a run ofcommercialandmilitarysalessuccesseswithitandpersuadedthemselvestheycould go on selling such engines foryears. But when 1957 came, all theairlinesplacedordersfortheradicalnewBoeing707with its improved turbojetengines—and sales of piston andturbo-compoundenginesdroppeddead.Suddenly aviation was jet-powered.The driving force had been theColdWar, which persuaded Congress tofloodaviationdevelopmentwithmoney.Boeing had produced the all-jet B-47swept-wing bomber, then the eight-engined B-52 and the air refuelingKC-135.Havinglearnedfromallthosesuccessfuldesigns,thelogicalnextstepforBoeingwasthecommercial707.JustbeforeChristmas in 1959,my collegeroommate,who had arrived byDC-7with piston turbo-compound power,decided to fly home for the holidaysby jet. But the revolutionwasn’t overyet—newgenerationsofcastablehightemperaturealloyswereindevelopmentinthelate1950sthroughearly1960s.On the news onemorning in 1964 IheardthataDC-8hadsufferedaturbinebreak-up on take-off from Boston’sLoganAirport. In the parking lot atworkIwouldfindasmallpieceofthatturbine.Today,failuresofthatkindareextremelyrare.

Almost as a footnote to all this, theresulting fall in the price of highperformance refractorymetalsmadereliable truck engine turbochargingcommonatlast.


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selective Catalytic ReductionTheUSEPAseemsdeterminedtostickto its policyofmaximumprotectionofthe atmosphere rather than shift to amore European agenda of trying tominimizetheamountoffuelburnedbyencouraging the useofDiesel. It hadbeenwidelyhopedthatsomerelaxationofDiesel emissions standardswouldaid theUSauto industry, somuch ofwhose profitability has recently comefrom sales of heavy SUVs and lighttrucks. Powering such vehicles withfuel-efficientDieselenginesmighthavepreserved their popularitywith buyersduringtherecentupsurgeinfuelprices.Itwasnottobe.

Instead, ifwider use ofDiesel poweris to take place in theUS, advancedemissions technologywill have to beadopted.

At present it is possible to fi l terparticulatesoutofDieselexhaustandtoperiodicallyburnthemoffthefilter.ThiseliminatesmuchofthesmokeandsmellofDieselexhaust,andthenewsworthycarcinogenic particles that notoriouslyabsorbontosuchparticles.

BecauseDieselenginesburntheirfuelinthepresenceofexcessair,theyemitverylittleinthewayofcarbonmonoxide(incompletelyburnedcarbon)andUHC(unburned hydrocarbons). The reallydifficult problem for theDiesel is howtoachievehighpowerdensity—alotofpower froma small package—andatthesametimecontroloxidesofnitrogen(NOx).Thisisdifficultbecause,ingeneral,thehigher thepower density—usuallyfromhighpressureturbocharging—thehigher the combustion temperature.Nitrogen, making up 79% of theatmosphere,isnormallyverystablebuthightemperaturescaninduceittoformnitrogenoxides.ThereforetheharderwetrytogetpowerfromaDieselengine,themoreNOxittendstomake.

A standard measure against NOxformation is to reduce combustiontemperaturebydiluting theair chargewith inert exhaust gas—exhaust gas

recirculation, or EGR. But for everypercentofsuchEGRdilution,weloseapercentofpower.

Oneanswertothistangleistoacceptthat a powerful Diesel will produceNOx—andthendealwith it inexhaustaftertreatment. This can be done byselective catalytic reduction, or SCR.Because similar problemsexist in theelectric power generation industry,methodshavealreadybeendevelopedtotransformNOxinfluegasbackintoharmless chemistry.A catalyst is anagentthatpromotesandparticipatesinachemicalreactionwithoutitselfbeingalteredintheprocess.Theprincipalideaistoprovideasourceofextranitrogenso that thestrongaffinitybetween thesupplied nitrogen and the nitrogen inNOxbreaksup theoxide, formingN2(ordinaryatmosphericnitrogen).Usuallysomehydrogen issuppliedalongwithnitrogen(combinedwiththenitrogenasammoniaorurea)sothattheoxygenintheNOxcombineswith this hydrogento formwater.The overall effect is totransformthepotentsmogformer,NOx,backintoharmlessnitrogenandwater.

In theabsenceofhigh temperature todrive this reaction (Diesel exhaust ismuchcoolerthansparkignitionengineexhaust because of theDiesel’s highcompression/expansionratio),acatalystmustbeused.This isusuallyametalwhosestrongelectricfielddistorts thetargetmolecule in away thatmakesits combinationwith specific reactantsmuchmorelikely.Thinkofthecatalystasa “mugger”whopins the victim sohis pockets can be ransacked.Oncethetargetmoleculehasreacted,itisnolongerasattractedtothecatalystatomand so goes on its way, leaving thecatalyst atom ready for businesswiththenextNOxmolecule.

WhatthismaymeaninthefutureisthatDieseluserswillsimultaneouslytankuponDieselfuelandurea—possiblybyuseofaco-fuelingnozzlethatsimplifiesandspeeds fuelingwhilekeeping fuelandurea separate.Urea consumptionwillbe about 4%of the volumeofDieselfuelburned.

sCR, Fuel Economy and Two stroke Diesels Diesel Fuel EconomyOne pr inc ipa l under ly ing manyapproachestoimprovingfueleconomyisthefactthatoilfilmsaremostefficientwhen they are loaded almost to thepoint of breakdown.Oneway to seethis is that it ismoreefficient touseasmallengine,operatingonfullthrottle,tomakethe50horsepowernecessarytokeepatruckrollingathighwayspeed(asanexample,50horsepower),thanitistooperateamuchlargerengineonpart-throttletomakethatsamepower.The small enginehas small bearings,and they are loaded heavily, so theygeneratelessfrictionthandothelarger,morelightlyloadedbearingsofabiggerengineonpartthrottle.

InWW II pilots discovered they couldextend the rangeof theirairplanesbyreducing RPM, increasing propellerpitch(sameasfittingatallerreargearina truck),andmaking thenecessaryhorsepowerbyincreasingsuperchargerorturboboost.Thisworkedbecauseitreducedthespeedsofallmovingparts,therebysavingconsiderablepowerthatwouldotherwisehavebeenconsumedshearingoilfilmsat thehigherspeed.Manyapilot, lowon fuel, growledhiswaybacktohiscarrieronlowrevsandhighboost,crossinghisfingersthatthistechniquewouldactuallywork.

This same principlewas applied afterthe 1973-74 oil “shortage”, when thepeakpowerrpmofhighwaytruckDieselengineswasreducedfrom2250to1800-rpm.Itwaspossibletodothisbecauseatthetime,theuseofturbocharginghadbecomecommon.Thus, engines couldmakethesamepowerat1800-rpmthattheyhadformerlymadeat2250simplybyturninguptheboost.ThelargemarineDieselsdescribedabovecarrythistoanextreme,rotatingatheartbeatspeed.

oPoC Two stroke DieselWhenthepriceoffuelgoesup,wedreamofsuper-efficientengines.Whenitgoesback down, we prefer what we have,becauseit’satleastpartlypaidfor.The

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naturalfearisthat,soonerorlater,fuelwillgowayupandstaythere.Whatthen?

Engineers dream about this evenwhen fuel is cheap, because (a) newfeatures give a competitive edge and(b)engineers retainachild-likedesiretomakenewthingshappen.

FEV Engine Technology, a GermantechnologydeveloperwithUSofficesinAuburnHills,Michigan,hasshownanewtwo-strokeDiesel engine of unusuallyhighefficiency.Whileanormalefficiencyrange(workoutputasapercentageoffuel energy supplied) is around 33%,FEV’snewOPOCenginepushes thatnumber above 40%. This is highlysignificant because themost efficientprimemoversnowinexistence—largemarinetwo-strokeDiesels—recoverjustover50%oftheirfuel’senergyaswork.Thoseverylargeenginesareespeciallyefficient because (a) they have littleheat loss surface area in relation totheir hugedisplacement, and (b) theirfrictionlossislowbecausetheyhardlymove—operatingat60-90-rpm.

OPOC stands for Opposed Piston,OpposedCylinder,anditseekstoraiseefficiency in an ingenious variety ofways.Ofspecial interest is thatmanyoftheideasimplementedinOPOCareveryold.

OpposedPistonmeansthattwopistonsoperate ineachcylinder,compressingair between them. Many types ofopposed piston engines have beenbuilt in thepast, suchas theGermanJunkersaircraftDieselsofWWII,andUS-made,Fairbanks-Morselocomotiveand submarineDiesels.Adopting thisconstruction does away entirelywithcylinder heads and all their heat lossandattendant valvesandother parts.Thus,opposedpistonsdoawaywithamajorsourceofheat loss,andreducecomplexity.

Without mechanical valves, suchenginesoperateonthetwo-strokecycle.Ofthetwopistonsineachcylinder,onecontrolsaringofexhaustportsandtheother, a ring of fresh air ports.Thus,

cylinderscavengingisfromoneendtotheother,whichengineerstermuniflow.Freshairissuppliedtothecylindersbyablower.

Inmostengines,forcefromthepistonsis delivered to the crankshaft fromoneor two rowsof cylinders above it(in-lineorV construction).This forcesthe crankshaft down forcibly againstitsmainbearingcaps,generatingfluidfrictioninthemainbearingoilfilms.IntheOPOCengine, theOCstands forOpposedCylinder—meaning that thisisaflatenginewithitscrankdownthemiddleandacylinder to the rightandonetotheleftofit.Incurrentparlance,it is a “180-degree V-engine”. Themakers cite FerdinandPorsche’s flat,opposed-cylinder “boxer” engines asinspiration for this,but the ideaof theflat engine goes all theway back totheBenz“Kontra,”designedbyAugustHorchin1897.

Howcantherebetwopistons ineachcylinder, if there are cylinders to theright and left of the crank?The twopistonsnearestthecrankareoperatedconventionally,byconnecting-rods.Thepistonsat thefarendofeachcylinderarejoinedtothecrankbylongoperatingrods passing to either side of eachcylinder.Asthecrankturns,pistonsonrightandleftapproachandrecedefromeachotherintheirrespectivecylinders,phased and counterweighted to giveexcellentbalance.

There is another advantage:with oneofeachpairofpistonspushingonthecrankandtheotherpulling(bymeansofitsoperatingrods),thereisalmostnonetforceonthecrankshaftmainbearings.The bestway to free an engine fromfrictionlossisnottogeneratethelossinthefirstplace,whichthisenginecleverlyachievesbyitsbalancingofright-andleft-bankforcesagainsteachother.

Aprototype turbochargedFEVOPOCDieselwas shown at theSAEWorldCongress inApril, 2005. It is said togenerate325horsepowerand590lb-ftof torqueat2000-rpm,whileweighing270 pounds. This is more than 1.1

horsepower per pound—anextremelyimpressive result for aDiesel. Its twocylindersandfourpistonsgivetwofiringeventspercrankrevolution—thesamedegreeofpropulsivesmoothnessasanin-linefour.


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Everyone’s toolbox tendsover time tobecomeadiaryofpastlife—everytoolhasitsstory.ForthirtyyearsIcarriedano-brand,#3PhillipsscrewdriverthatIliked.Ithadaflutedamberplastichandlewithablackstripe.Ithadbeenwithmelongerthanmostmarriageslast.Thenonedayitsaccumulatedstresshistorymaxedoutandachippoppedoutofit.NowIhaveanewNAPAreplacementbuthaven’treallygottoknowityet.

IloveSnap-Onwrenches—smoothandorganic-looking,theyfillmewithdesirewhen I step up into the salesman’struck, and I can feel themoney pouroutfrommywallet.ButIstillhaveafewCraftsmanitems—perhapsjustbecauseI perversely don’twantmy toolbox tobecomeaone-brand,add-a-pearlaffair.Somewhere inmyshop isa short,S-shapeddoubleopen-endthatbearstheclassic“Winchester”name.Itsoriginisunknowntomebuthereitis.

Because for years I was involved inbuilding racingmotorcycles, I have apairofRobinsonsafety-wiretwisterstowhichI treatedmyself in1971.Beforethat I hadeither twistedwire byhand(time-honored but a seriouswaste oftime)orhadhobbledalongwithclapped-out twisters I’d bought at a junk sale.Robinson foryearsserved theaircraftindustry—aircraft used to be coveredwith fasteners secured with twistedstainlesswire. But gradually aviationshiftedovertodeformed-thread,elasticstop,orotherformsofsecurity.WhenIboughtthosetwistersIfeltequipped—Ilovedhavingthematlast,havingtheminmyhand,beingabletoexpertlywirefivesprocketboltsinseriessotheylookedastheyshould.

Foratime,Iearnedmostofmyincomewithdiegrindersandagaswelder.Theonewasforcylinderandheadporting,andtheotherformakingexhaustpipes.Ican’tsayIhadaspecialaffectionforeither tool, but they did become veryfamiliar.

AparticularpairofdiagonalcuttingpliersisdeartomebecauseIpickedthemfromamongmany.Theirjawsmeetperfectly.

Click, thewire is cut through, and it’snotnecessarytomashagainandagainbecausethefirstandsecondbitesdidn’tquitedothejob.Ihavealittletwo-ounceball-peen hammer that has been justrightforsettingdowelpins.Icoulduseabiggerhammer,butthisonehasalwaysbeenasmallpleasure.

Becausemytoolshadtogowithmetoraces,IboughtonlywhatfitthefastenersontheequipmentIwasservicing—theodd sizes could stay in theSnap-Ontruck,andthecashtheywouldhavecoststayedinmywallet.

AtthispointIwanttointerjectaremarkIheardwhenIwasacallowbeginner.IwasinthequeueatthepartscounterofBoston’s long-agoTriumphmotorcycledealerwhen I heard loud talk comingfrom the shop.One voicewas that ofsweet reason and adult compromise,sayingthatSearstoolswereguaranteedand a good value for the money. Iagreed—myboxwasfullofthem.Theother voice wasmore strident, lessreasonable—and doctrinaire to boot.“Inmybookthereareonlytwokindsoftools—Snap-Onandsnap-off!”

Even today, I can hold both opinionssimultaneously. I have a cracked“Wizard”brandsparkplugsocket thatbelonged tomymaternal grandfather.Hewasanaturalmechanicandsowasmymother,soIthinkofthembothwhenIreachforthat13/16”tool.IhaveSnap-OnwrenchestofitthethingsIworkedoninthe1970s,andotherstufftofillin.TwoofmyoldCraftsmanopen-ends haveelectric pencil initials on them—eachbelonged to a friend Iworkedwith atonetime,andeachsomehowbecameincorporatedintomybox.Iknowitemsofminehavediffusedawayinlikemanner.Therearea coupleofhand tools thatcame tome in the frame rails of cars—setthereforamomentbysomebusylinemechanicwhohadtotakeaphonecall and forgot the tool he could nolongersee.

At one time I worked in a shop thatbuilt experimental equipment. Beingassociated with universit ies, the

Toolbox Diarymanagementtriedto instituteanopentoolboard,withapaintedblacksilhouetteofeachtooltoshowitsplace.Goodluck.Itdidn’ttakelonguntiltheonlyremainingtoolwasthe11/16open-end.Oneofthetechniciansmade an experiment. Hewenttotheindustrialhardwarestoreandboughtagrossofcheap#2slottedscrewdrivers.Thenheputsixofthemonthetoolboard.Aweeklatertheyweregone,andheputoutanothersix.

Whywashedoingthis?Hewantedtoderive from it aLawofToolDiffusion.Accordingtoonehypothesis,assoonaseveryoneoftheexecsinthisoutfithadtakenascrewdriverforhome,anotherforhisboat,onemoreforeachcar,andsoon,thedemandforscrewdriverswouldtaperoff—andsomewould remainonthetoolboard.ThismightbecalledtheLaw of Tool Saturation—stating thatpeople stop stealing available toolswhen they have enough. The othertheorywas a LawofToolAvailability,whichstatesthattoolswillbetakenaslongasthereareanyremaining.

Naturally, and as youwould expect,screwdrivers disappeared from theboarduntilall144hadbeenconsumed.This iswhy toolboxeshave locksandidealistically motivated tool boardsare empty. It’s not that people arevenal natural thieves, but that noonecan resist available tools. Tools areattractive.Andit’seasierto“borrow”atool,fullyintendingtobringitback,thanitistoactuallyrememberwhoseitisandwhereitbelongs.

I am promising myself a cordlessscrewdriver but haven’t gotten oneyet. I hatemy pile of decrepit powerhandtools,eachwithitslongcordthatinevitablytangleswiththeothers.YetIrefusetowrapcordsaroundtools—thiscreatesaspringthatconstantlyfightstheuserjustastoo-stiffgasweldinghosesdo.MaybeI’lltreatmyself.

Some ofmy favorite tools are thosefor special purposes. These are thecharacters of the toolbox.One is anoffsetboxwrenchthatfitsthe16basenutsoneachcylinderofaircraftengines

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that have come to live inmy shop.Anotherwasaproductofdesperation.OnedayasIclosedthetrunkonmy‘70Oldswith10:1,350,V8, the link fromlocktolatchfelloff.Nowthekeywent‘roundand‘roundwithouteffectandthetrunkwaslockedforever.Ifoundthatbypryingupthecardboardshelfundertherearwindow,Icouldshineaflashlightonthesituationbackthereandseethatafive-foot½”socketextensionwoulddothejob.AnelCheaposocketfromthenot-so-hot-but-too-good-to-throw-awaytoolbin,someelectricalconduit,andalittle brazing soonproduceda specialT-handle.Itworkedatreat.Idrovethatcaruntil itschassisrusted intwo.ThespecialT-handlestandsinabackcornerjustincasethatcarisreincarnated.

My great-grandfather Fred farmed inIndianauntilhediedin1946atage92.Mydadbroughtmeaball-peenhammerfrom Fred’s farm and a new handlerestoredittofullusefulness.Idon’tuseitoften,butit’sgoodtohaveit.

From the other side of the familycomes an old 19th-century brass-tubemicroscope. When connecting-rodrollers inmyKawasaki 500 racebikebegan to fail in1971, thatmicroscoperevealedtinysurfacepitsontherollersas a result of an hour’s use.After alittlestudy,Iwasabletomakeachartof surface damage versus hours ofuse.That,plussomestudyatanearbyengineeringlibrary,allowedtheproblemtobehandled.Opticsareatooltoo.

WhenallIdidwasmotorbikes,nothingwasheavy.Later,whenIwasattackedbybig-blockdreams, I bought a shopcrane.Ilikemylittleorangecraneverymuchbecauseitturnscertainbackinjurymaterialintoeasyjobs.Afterafewyearsthatchangedwhenlargepistonaircraftengines began to collect atmy shopdoor, looking in atme reproachfully.Thosemachineshaveaspecialbeauty,insideandout,thatIcan’tresist,andtheyweighonlyonepoundperhorsepower.That’saheavyproblemwhen take-offpower is 3500 horsepower at 2700rpm.Isawthesolutiononaroadtriptomy40th high school reunion, standing

out in front of a diesel shop. Itwasa12’tall,steelI-beamgantrycranewith6000poundcapacity,standingonfourgiantcasters.Lowerthetackle,sliptheliftchainsontothehook,andPRESTO,notonlycanIliftjustaboutanythingthatwill fit inmyshop, I can roll it aroundto wherever I want to put it. In themodernpsychobabble,thisispersonalempowerment.The truth is, tools arepower. Theymultiply comparativelyweakfleshintoirresistibleforce.


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I’dlovetobeabletotellyouthatalltherecenttalkaboutachievingUSenergyindependenceviabiomassfuelsisnotonlytruebutabouttohappen.However,baseduponavailablefiguresIcan’tdothat.

Let’sjustconsiderUScropland,variouslyestimatedtobe375-450millionacres.If currentUSpopulation is about 295million, using the higher croplandacreagewe get roughly 1.5 acres ofcroplandperperson.

Total US land area is just under sixmillion squaremiles, or 3840millionacres,so theabovecroplandacreagemeans that about 12% of theUS isundercultivation.Everyyearthatfiguredecreasesbecause land that is primeforagricultureisalsoprimeforhousingandbusinessconstruction.

Everyday,theUSconsumesabout19million barrels of petroleum, ofwhichabout10millionmustbeimported.

Let’ssaythattheaverageUSmotoristuses750gallonsofgasolineperyearinhis/herauto(that’sdriving15,000milesayear,getting20milespergallon).Ifweplantamixofrapeseedandsoybeansandharvest75gallonsofoilperacre,thistellsusthateachcarwillrequiretheuseof10acresofcropland(assumingonecropperyear).Howmanycarsarethere intheUS,wewonder?Ah,hereisa1995figureof136million,soattenacrespercar,thatwouldrequire1360millionacrestoproducethenecessaryfuel—anamountthatisthreetimesthetotal ofUS cropland.And, of course,usingallUScroplandforfuelproductionwouldrequireusalltogoonzero-caloriediets.Okay,I’dguesswearen’tgoingtofuelourautofleet(tosaynothingofthe65milliontrucks)onourhypotheticalmixofrapeseedandsoyoils.

Let’s look at ethanol produced fromcorn.A quick scan suggests yieldsof 160 bushels of corn per acre areachievable,with2.8gallonsofethanolbeingrecoveredfromeachbushel.Thisisencouraging—448gallonsperacre!

Nowrealitygivesustheeye—agallonofethanolcontainsonly2/3asmuchenergyasagallonofpetroleum-originatedfueldoes,sothat448gallonsperacre,times.66=296gallons.Buteventhis lookspretty good.With this figurewe couldpower our national auto fleet of 136millioncarsbyplantingonly345millionacres,or77%ofUScropland. I don’tthinkthisisgoingtohappen,butitwouldatleastallowustoeatsomething.

Ordoesit?Asitturnsout,someenergyhas to be used to raise and processall this corn, andoneestimate is thatfor each gallon of ethanol produced,the energy equivalent of half a gallonofpetroleummustbeconsumed.Thisputsadentinourplans,foritmeansthatinsteadofeachacreyieldingtheenergyequivalentof296gallonsofpetroleum,wehavetosubtracthalfof448,or224gallons, from that toget thenetyield.296takeaway224givesusanewnetper-acreyield, inpetroleum-equivalentgallons, of 72 per acre.Nowwe areback to needing roughly ten acres incultivation to fueleachautomobile.Aswesawaboveinthesectiononoilcropbiomass fuel, thisagainwouldrequirethree times the total ofUS cropland.Maybewe canmake corn cultivationand processing into ethanol twice asefficient?Okay,nowweneedonly1½timesthetotalofUScroplandtopowerour autos (again,we are leaving outtrucksandbuses,aircraft,homeheating,andsoon).

Newspapers and magazines havepresentedupbeatstoriesaboutpoweringDiesel vehicleswithwaste oils. Let’shavea look.USannual productionofvegetableoilsissaidtobeontheorderofthreebilliongallons.TotalannualUStransportandheatingfueluseismorelike300billiongallons,sopresentvegetableoil production is about onepercent ofwhatweneedannually.Goforit—howmuch do you suppose is recoverablefromthattotal?Half?Aquarter?Less?Iknowtwofamiliesinmyareathatdrivealloverthecounty,beggingusedfryoilfromrestaurants.(“Hey,yashouldabinhereanhourago—thePetersenswere

unlimited Energy from Carpet Fluff?justhereandIgave‘emfivegallons.ButI’malloutnow—sorry.”)Howmuchfuelmustbeburnedinthisway,pergallonoffryoilscored?

Icouldtakeapersonalapproach.Atmyhousewebuyaboutfivegallonsofoliveoilperyear,andabout1/10ofthisisnotconsumedbythefiveofusonsalads,sautéedvegetables,andthelike.Thatleavesuswithhalfagallonofwasteoilperourfivepeople,peryear,ormultipliedouttoanationalbasis,29milliongallons.Comparedwiththeannuallyconsumed300billion gallons of petroleum fuels,that is a fraction of 1/1000.This tellsmethatusedfryoilisunlikelytofuelUSenergyindependence.

Shallwegoontoconsiderthepossibilitiesofcompostingdryerandvacuumcleanerfluff?

No,I’llstopthere,andIwilladmitthat“everylittlebithelps.”But,Idoinsistthatalittlebithelpsonlyalittle.Anythingthatisgoingtoreplaceasignificantfractionoftheenergywenowgetfrompetroleumisgoingtohavetobeverylargescale.Therefore letusconsider some large-scalepossibilities.

Buried in the western US are thickdeposits of oil shale, in which therearemany times theprovenpetroleumreserves of SaudiArabia. In the tarsands ofAlberta are similarly largeamounts of petroleum. UnderlyingVenezuela’sOrinoco basin are vastreserves of heavy—perhaps hard topump—crude.Likewiseletusconsidercoal, of which we havemuch. Coalcanbetransformedintopetroleum-likeliquidsbyheatingitinthepresenceofsteamandacatalyst,usingtheFischer-Tropschprocess.

The key to exploitation of any of theabove is continuedhighoil prices.Toget oil fromoil shale, either the shalemust be brought to the surface, thencrushed,and thepetroleumvaporizedout of it; or some kind of clever andefficientsubterraneanprocessmustbedevised todosowithoutmining.Ditto

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theCanadian oil sands.All this costsmoney,andnosanepersonwouldhaveinvestedadimeinanyofitbackinthedays when petroleumwas at $10 abarrel.Butat$70…

Somepeoplearescrapingupall theirassetstoinvestinsuchthings,reasoningthat theWesternUSandCanadawillbecomeenergy boomareas vibratingwith economic power and radiatingpipelines full of black gold. It maybe—justhopontheInternetandreadallaboutit.Itwillbeinterestingtoseejustwhattheoutcomewillbe.Itgivesusallanincentivetolivelong.

Meanwhile, ardent word-duelists arethrustingandparryingover the issuessurroundingglobalwarming.Onelargegroupofscientistssaysit’srealandit’salreadykillingus.Another,smallergroupaskshowmuchweknowif(a)wedon’tknowwhatcausesIceAges,norareweabletopredictthemand(b)ifIceAgesareindeedcausedbysomekindofsolarcycleassociatedwithsunspots,doweknowwhatcausessuchcyclesandcanwepredictthem?

Ifwe are already killing ourselves bysomuch combustion of fossil fuels,howmuchmustwecutbacktopreventglacialmelting,coastalflooding,tempeststorms of wind, drought with killerfamine,andwhoknowswhat-allelse?Big discussion—nobodywants to putanumbertothisone.Shallwetellthebillionsof IndianandChinesepeople,nowindustriouslyraisingtheirstandardsoflivingbyscouringtheglobeforenergysupplies, “Sorry guys, your better lifeis cancelled—forever”?And ifwe didsay that,whatwould theyreply?(Andwithwhat?Both nations are nuclear-armed—operators are standing by,warheadsareinstockandavailableforimmediatedeliveryanywhereonearthin20minutes.)

Orshouldwenoblyandvoluntarilycutourownpetroleumuseinhalf?Wouldthatdo?Afterall,theUSusessome25%oftheworld’senergy.I’llwalktoworkhalfthe time—hell, it’s only 12mileseach

way.I’llkeepmyhouseat48degreesinsteadof68inthewinter.Whoneedshotwater?I’lleatriceandbeansinsteadofmeat, and all our factories (what’sleftofthem)willcuttheirproductionofeverythingexactlyinhalf.Notpractical,yousay?Youbetit’snot—withoutDieselfuelandplentyofit,wecan’tevengetfood to all the peoplewho live in ourcities.This is not a choice—weneedenergytolive.

Hmm,lookslikewe’dhavesometroubleputtingoverthe“cuteverythinginhalf”plan.EspeciallyattheKiwanis.Maybethethingtodoisforgetit—andthenthinkup some catchy hydrogen slogans orproposeritualisticthingspeoplecandotomakethemselvesfeelbetteraboutallthis.I’vegotit—we’llstopusingcertainpaperproductsathome.Yes,andthenwe’llput twobricks in the toilet tanks.Andwe’llpark theHummerexceptonweekends,anddrivetheCivictowork(better put a bicycle on the car-topcarrier,too—looks“green”).Let’sallgoonvacationstoputourmindsatrest.Aswearewaftedonourway,ourBoeing747 burns 50,000 pounds of fuel perhour.Attake-offforatrans-pacificflight,awide-bodyaircraftiscarryingenoughfueltoheatmyhousefor50years.

Ican’tthinkaboutallthis.Let’shopewehumansmuddlethroughsomehow.


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organic compounds.Youmight alsoexpect, reading the above, that thereshouldbelegallimitsontheamountofincomingsunlight,buttheyhaven’tyetfiguredouthowtoregulatethatstepinthesmog-makingchemistry.

Jokingaside,thisisseriousbusiness.MyfirsttriptoCaliforniawasin1971andasIstoodnexttopitwallattheoncegrandOntario InternationalRaceway (nowahousingdevelopment),lookingstraightup, Icouldsee longsinisterfingersofgreensmogdriftingoverhead—gaseoussewagethatputacatchineveryone’sthroatandastingintheeyes.Lookingtotheeastonemorning,Iwasastonishedtoseesnow-cappedmountains—whichhadbeeninvisiblepreviously,obscuredbytheair.

TwobasicapproachestoNOxreductionexist—to improve the combustionprocesssothatlessNOxisproduced,andhavingtakenthatasfaraspossible,to employ aftertreatment—to removeNOxfromtheexhaustgasproduced.

We’veallreadaboutthebenefitsofhighpressure, common-rail fuel injection,usingultra-fast injectors.Thefiner thedropletsproducedbyinjection,andthefurther they penetrate into the densecompressedairinthecylinder,themorefuelwill evaporate before combustionbegins.Evenonfullload,Dieselenginesinclude about 20%excess air, so ona bulk basis, Diesel combustion islean.If,asisthecaseinspark-ignitionengines, themixturewere fullymixedbeforeignition,theNOxproblemwouldbegreatly reducedby the simple factthat lean combustion is cooler thanchemically-correctcombustion.Itisthecombination of a fullymixed (and insome cases, lean)mixture plusEGRthat gives spark-ignition engines theirlowerNOxemissions.

Alas, every fuel droplet evaporatinginsideaDieselenginepushesoutrichfuel vapor that gradually diffuses intothesurroundingair,feedstheflame,andwherevertheresultingmixturehappenstobeclosetochemically-correct,itburnshotandgeneratesNOx.

EPA’sNOxlimitfor2007Dieselenginesis 0.5 grams per horsepower-hour,dropping three years later to 0.2-gm.Therearewaystomeetthesestandardsbut none of them is easy.Oxides ofnitrogen are created in the hottestregionsofcombustion,wherefuelandair happen to be ideally proportioned.There are always such regions inDiesel combustion because,with fueldroplets being injected at over 1000feet per second into hot compressedair,allproportionsoffuelandairmustexist, from 100% fuel in the dropletsthemselves, to 100%air at the outeredges of the combustion chamber.Wherever the proportions are right,combustion may be hot enough tocompelnitrogenandoxygentocombineasNOx.

Isay“maybe”becauseevenchemically-correct combustion can be cooled,simplybydiluting itwith inert exhaustgasfrompreviouscycles.Thisexhaustgasrecirculation,orEGR,isananti-NOxtechniqueusedinbothDieselandspark-ignitionengines.EGReffectivenesscanbe increased by cooling the exhaustgasthroughaheatexchanger—buttoomuchEGRflow candelay or preventignition.

Eight hours of operation at 200horsepower under the2007NOx limitproduces just under two pounds ofthe stuff.Why is it so important?Goto http://chem-faculty.ucsd.edu/trogler/CurrentNitroWeb/Section4/Section5.shtmandreadaboutitindetail.Acriticalstepintheproductionofphotochemicalsmog is the conversion of nitrogendioxidebysunlight intohighlyreactiveozone,withvolatileorganiccompoundsand carbonmonoxide involved.This(sort of!) explainswhygasoline tankshave pressure caps and activatedcarbon absorbers—so that volatileorganiccompounds(gasolineisalargecollectionofthem)donotriseinagreatcloud from all the gasoline-poweredvehicles in the nation. It also tells uswhytherearelimitsontheamountsofunburned hydrocarbons our vehiclesmay emit—because this categoryincludescarbonmonoxideandvolatile

More harping on an old TuneAnothermoderntechniqueforimprovingcombustionistoinjectthefuelnotallinonesquirt,asithadtobewiththeold,mechanical-type, piston injectors, butinaseriesofultra-short, timedbursts.This is what the new piezo-electricinjectorsmakepossiblebytheirspeedofoperation.Iftheabilitytodeliverfromfivetonineburstspercombustioneventseemsimpossible,justwatchthesheetspouroutofyourink-jetprinter,coveredwith text and color pictures.Humansaregoodatdreamingthisstuffupandmakingitwork.Bybreakingupthefueldeliveryintopulses,thissystemmakesit possible to distribute the fuelmoreequallythroughouttheaircharge.Thefaster the fuel evaporates andmixeswith air, and themore uniformly thedropletsareplacedthoughthecharge,the larger the volumeof fuel thatwillburnonthelean,coolsideofchemically-correct—andthelesstroublesomeNOxtherewillbecreated.

NOxaftertreatmentnowcentersontwomethodologies.Around2003, theEPAfavored trapping the nitrogen oxides(which are acidic) on an adsorber—abasic surface forwhich they have anelectrical affinity.When the adsorberwas close to being fully loadedwithNOx, a hydrogen-rich gas (preparedfromDiesel fuel by variousmethods)wouldbeinjected,reactingwiththeNOxtoformharmlessN2andH2O.

The EPA were suspicious of thealternative technologywhich is calledselective catalytic reduction (SCR).SCRhadbeen inuse formanyyearsonstationaryenginesandwasaproventechnology, butwhatEPAdid not likewas its need for a continuous supplyof nitrogenandhydrogen, in the formof ammonia, NH3. To employ SCR,Diesel vehicleswouldneed tocarryasmalltankofurea(whichbreaksdownto ammonia and carbon dioxide attemperature,whichwould be injectedintotheexhaust.TheresultingreactionwithNOxwouldyieldharmlessnitrogengasandwater.

EPAfearedthat,withno infrastructureinplacetosupplyureatousers,Diesel

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engine manufacturers would shrugtheircollectiveshouldersandsay,“Ourengines are certified under your newlaw. No skin off our noses if there’sas little urea on sale for Diesels asthereishydrogenforfuelcells.”Offthetruckswouldgowith theiremptyureatanks.HencetheEPAfavoredthetraptechnology,whichusesonlyDieselfuelandrequiresnosecondfueltank.

TheSCRmethodraisesquestions:(1) If the urea tank runs dry, what

motivatestheoperatortorefillit?(a)Awarninglightilluminates(b)Theenginecontinuestorun,but

atlimitedpower(c)Theenginestopsautomatically

andcannotberestarteduntiltheureatankisrefilled

(2)Where will the national fleet ofmillions ofDiesel-powered trucksfind theurea in the first place?Arunon thechemistry labsat localhighschools?

Nowtherearesuggestionsthatallmaybewell,asonetruckmanufactureralsoownsachainoftruckstopswhichplantostockthevitalfluid.

At its present level there remainproblemswiththeNOxtraptechnology.HondahasrevealedthattheywillbringaDiesel automobile to theUS soon,withanNOxsystembasedontrapping.Intheirremarkstheyrevealedthattheadsorbers used in traps prefer lowertemperatures in the range of 200°.Above some critical temperature anytrapadsorberwillspontaneouslydesorbitsNOx, causing the exhaust streamtoviolatethenewemissionslaw.Thismakesthemcurrentlysuitableonlyforanautomobile’sverylightdutycycle,butnotsogoodforheavydutyapplications.Over time,more temperature-toleranttrap materials may be developed,enablingthistechnologytobeappliedtomediumandheavy-dutyengines.

Allofthissoundstomelikeanapplicationofsophisticatedgametheory.EPAcallsforNOxemissions to drop in stages.Theenginemakersconsiderestimates

of what thiswill cost them and theircustomers,somaybetheyaremotivatedtoover-emphasizethecostsanddifficultyofcompliance,inhopesofgettingmoretime from theEPA.TheEPA, havingplayedthegamealongtimetoo,decideshow tough or otherwise to sound inpublic announcements and privatenegotiations.Whomshouldwebelieve?Meanwhileexecutivegovernmentofficeshavephonestoo.Whoknowswhosayswhat,andtowhom?Afterall,wasn’titapastpresidentwhosaid,“Gentlemen,thebusinessofthisnationisbusiness.”Just try to imagine businesswithoutDieselpower—it’sanoxymoron.

LastIknew,MercedeswerewaitingforEPAtodecideonwhatbasis—ifany—theywould allow the newMercedesBluetec,3-liter,DieselautotobecomeeligibleforsaleintheUS—withitsSCR-basedNOxsystem.WillwesoonseelegionsofMercedes-drivingdoctorsandlawyers,disguisingthemselvesinRedRoseAnimal Feeds caps, flocking totruckstopstobuytheirurea?

The technology to meet 2007 andlikely 2010Diesel NOx levels existsand is being refined.We’ll be able todrive.We justdon’tquiteknowall thedetails of the systems that the abovecomplex negotiationswill require onourengines.


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Iwasjustanrpm-worshippingmotorcycleguy in 1973-74, when the first “oiru-shokku”hit,soIdidnotatfirstunderstandthe response of theDieselworld to afutureofpotentialoilshortages.Formerly,heavy,over-the-roadDieselsoperatedat2250-rpm,butinnewdesignsthiswasreducedto1850.

Thereareatleasttwogoodreasonsforthis.First,frictionlossasapercentageof horsepoweroutput dropswith rpm.Themostefficientoperation,therefore,takes place at the lowest rpm andhighest cylinder pressure compatiblewithsmoothrunning.

DuringWW II Japanese naval pilotslearned to employ thismethod as ameansofextending theirflying range.When ace Saburo Sakai was badlywoundedinaircombat,andwasfadingin and out of consciousness, hewasable to use the low-rpm, high boostmethod to coaxhisZero fightermorethan 600miles over water, back tohisbase.AmericanfliersinthePacificwere trained in this samemethod bynone other thanCharles Lindbergh.Dick Veach’s B-29 lost oil pressureon one engine over Japan. BecausehewasawareofLindbergh’s low-rpm,highboostmethodofrangeextension,hedecidedtotryit,cuttingrpmontheremaining three engines and keepingaloftbyrunningupthemanifoldpressureand prop pitch to compensate.Theyflewslowly,butwhentheyarrivedbackovertheirbasetheyhadmorefuelstillinthetanksthanaircraftwithfourgoodenginesturning.

Had it not been for the growing useof turbocharging, a reduction of truckDiesel rpm from 2250 to 1850 rpmwouldhaverequireda20%increaseincylinderdisplacement,withacomparableincreaseinweight—notacceptable.Butwith turbocharging, the airflow of the2250rpmenginecouldeasilybeblownintothesame-sized1850rpmversion,makingevenmorepower thanbeforebecauseofthereductioninfriction.

The driver of suchmeasures is theextremecompetitivenessofthetrucking

business, whichmust keep track ofevery cent to stay in business. Thesamehas been true at sea,where in1950 the standard formof large shippowerplantwasthesteamturbinewithgear reductiondrive to thepropellers.WhenDiesel power showed it couldcompete,earlyinstallationsalsoturnedtheenginesfaster thanthepropellers,still requiring expensive, accuratelymanufactured reduction gears.TodaythetypicalmarineDieselinstallationisdirectdrive,withenginerpmreducedtopropellerrpmsothattheselargeenginesturn only 60-90 rpm.These are two-strokeengineswithmechanicalvalves,heavily turbocharged, recycling everypossiblescrapofwasteheattoachieveoverall cycle efficiencies significantlyabove50%.Thismakesthemthemostefficientprimemoversontheplanet.

Makersoftruckandautoengineshavelongbeeneyeingthepowerconsumedbyaccessoriessuchaswaterpump,oilpump,airconditioningcompressor,etc.The opportunity here arises from thefact that traditionalwaterpumpsmustbegearedtoflowcomfortablymorethanthe engine needsmost of the time tomakesureitnevergetstoolittleatanyoperatingpoint.Amorerationalschemewould use variable-speed electricmotorstopumpcoolingwateronlyfastenough to dealwith the heat actuallybeinggeneratedatthemoment.

Likewise oil pumps are sized andgeared such thatmost of the time alargefractionoftheoildeliveredcannotbeused,andisshort-circuitedbacktothesumpthroughtheoilpressurereliefvalve.Asafebutrationalschemewouldprovide a smallermechanical pump,supplemented by a variable-speedelectricpump.Asideadvantageofthisschemewouldbe theability topre-oiltheenginebeforestarting.Theelectricpumpwouldpressurize theoilsystembefore the starter turned the engine,thereby greatly shortening the timeenginesrunbeforeoilpressurereachesvitalparts.

Engineers envision future vehicleshavingall-electricaccessories,powered

adding up small Gainsby large direct-coupled alternators,operatingonahigher42-volts.Howdoyoudecideatwhatpulleyratiotodriveair conditioning compressors? If theyspin fast enough to provide adequatecabin cooling in stop-and-go traffic,surely they are turningmuch too fastat highway speeds. This is normallyhandledbyclutchingthecompressorinandout,approximatingtheneededdutycycle.Thereforeinthefuturetheymustbedrivenelectrically, andat themostefficient speed for the actual existingcooling load. Electric power steeringis already a part of many vehicles,eliminating theconstantwindmillingofahydraulicsystemasthevehiclegoesstraightdowntheroad.

Aproblemtobefacedbysuper-efficientfuturevehiclesistheneedforcabinheat;forthemoreefficientthepowerplant,thelessusablewasteheat is available inthesystem.Thishaslongbeenathorninthesidesoftruckingoperators,whotry in unsubtleways to prevent theirdrivers from idling themainengine toprovideheat as they sleep in parkingareas.WhenIaskedagroupofelectric-car experimenters what they weredoing about cabin heat, they replied“Nothing.” It is claimed that inwintercommuteroperation,25%ofauto fuelconsumptionmaybechargedtocabinheat.AutomotiveDiesels can face arelatedproblem, for the heat rejectedtocoolantbyasmallenginecanbeonthefeebleside.Asimpleapproachisastoveor“heatbattery.”Amorecomplexfixmight be a smaller version of thenewcogenerationunitsbeingproposedfor home power and heat.A smallcombustionengineturnsageneratortoproduceelectric power, and itswasteheat(exhaustheatpluscoolingsystemheat)heatsthehouse.

Efficiency concerns are driving thedesignof transmissions.My little 2.2-liter gasoline-poweredChevyCobaltautomaticdrops to1500 rpmassoonas 40mph is reached.At lower roadspeed, the transmission keeps theengine spinning faster because it is“betting”thatIneedtoaccelerate,andfor that the enginemust be turning a

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muchlessfuelefficient2000-3000rpm.Therefore, even though it takes lesspowertopushavehicleatlowerspeeds,itsfuelconsumptionneverthelesstendstorise.Onlyhybridsactuallyrealizethelowfuelconsumptionthatoughttoexistatlowroadspeed—inpartbecausetheygeneratetheirpoweratanefficientmain-engine rpm and deliver it electricallyat lowspeeds.Theother part of theiradvantageisintheirabilitytoregenerateenergyindeceleration.Therearenowproposals that suggest even heavytrucks,usedonlyincitydelivery,couldrecover asmuch as 60% of brakingenergy by use of a compressed airbraking/energystoragesystem.

Automatic transmissions experiencelossesbecausetheirtorquemultiplicationarises from the pumping of fluid. Toeliminate this torque converter loss,at least at highway speeds, lock-upfunctions are programmed in. TheCobalt performs a third-gear lock-upat 32-35mphaswell as the top-gearlock-up at 40, thereby extending itsrange of efficient operation a bit overolder transmissions that lock-up onlyintopgear.

Despite this, the four-speedautomaticin my little car returns significantlypoorer fuel economy than themanualfive-speed.Withagnashofmyteeth,Imustacknowledgethatmylateparentsweredoingitrightwhentheyshiftedtheir1951 three-speedKaiser sedan (withitssavage115hpContinentalflatheadsixengine) into topgearat the lowestrpm, commensuratewith reasonablesmoothness.Besteconomy!

Dur ing WW I I torque-conver tertransmissionsweredevelopedfortanks(Whohasthecooldetachmenttofiddlewithclutchingandshiftingwhen theremightbeaGermanPanthertankabouttoopenupwithits88outofthosewoodsover there?) and itwas assumed, byat least some, that large truckswouldsoongoautomaticaswell.Economicsmakesthosedecisionstoday,whichiswhyclutch/shift/throttleautomationhasbecome the preferred direction.Eventhough car automatics are beingbuilt

withuptoeightspeeds,therebykeepingengine rpmatmoreefficient numbersmoreofthetime,thereisnothingwithequallyhightorquecapacitytobeattheefficiencyofwell-madegears,generallyestimatedas“morethan98%.”

Eventhingsasmundaneasheadlightsarebeingupgradedtoconserveenergy.As the fluorescent-light crowd nevertireoftellingus,ordinaryincandescent(glowingwirefilament)bulbs turnonly5%ofthesuppliedenergyintothelight,therestbeingwastedasheat.Addingasmidgeofhalogenandmakingthebulbout of high-melting quartz allows thefilamenttorunhotterwithoutevaporating(yes,that’sjustwhathappens),makingmore light. Most efficient of all arethe new gas discharge lamps filledwith noble gas (incapable of formingchemical compounds), excited byshowersofelectrons.Byvaryingthegaspressureorvoltageacrossthedeviceitsemittedspectrumcanbevaried.

Damn, those humans are clever.Andtheyneverletup.


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Today’sengineerscandesignawholevirtualmachineinProEorSolidWorks,then examine it in three-dimensionalrenderings that can be rotated to anydesired angle of view.They can alsosubject it to simulated stresseswithfiniteelementanalysis(FEA),orcheckinternal or external aerodynamicswithcomputedfluiddynamics(CFD).Enginesimulationsallowmanybadideastobeevaluatedveryquickly.

Lifewassimplerinthe1960s.Ourwintersport was to order in all known andrelevant catalogs of speedparts, andthen toporeover themwhile the frostgrewthickonthewindowpaneandlogscrackledonthefire.

Cams were a favorite and it wasimpossible not to be inflamed by thedescriptionsofthevariousgrinds.

“TheCruiser:mild,streetablegrindgivestractableboostoverstock.”

“Three-Quarter Race: cuts loose bigpowerandacceleration.”

“Super-StompDouble-ThrowdownFull-Race: the cam for outstanding trackperformance.”

AndthentheGrandFinale,“All-OutTop-End-Only:ultimatepowerforBonnevilleandlongstraightaways.”

After reading through this pulse-accelerating litany, who could orderanyof that pedestrian stuff at the topof the page? That was for nancy-boys.WeHADTOHAVE the “TriggerBurke Killer Super Eliminator,” eventhoughchildhoodmemoriesassociatedelimination with something moremundanethancamshafts.

Oneofthegoodthingsaboutsurvivingearlyadulthoodisthatonemayactuallylearnafewthings.Seriousracersneveruse any items that actually appear incatalogs.Littledidweknowin1966,butactualraceswerewonwithconservative

cam timingsmuch like those of therejected “Cruiser,” butwith a lotmorelift.

Itwouldtakeyearstolearnthis—yearsspent stalling at stoplights, clashingvalvesonoverlap,andfindingthattheactualtimingsofthecamthatcameintheboxwerenothinglikethenumbersonthetimingcard.Desperateclosing-time phone calls brought the helpfuladviceto,“Justlineupthedotsandrunit.Forgetthetimingcard.”

The truthwas the junk in the catalogpaidthecamgrinder’soverheadscostofdoingbusiness.Helavishedhisrealattentiononthepeoplewhoknewwhattheyweredoing.That’s how it has tobe.Thoseweretheguyswhothoughtnothingofsettingupthepistonsinthemillingmachineandsinkingtheirvalvepockets an extra .020”.Nothing to it.Talkingonthephonewhiledoingvalvedropcheckswithlightsprings.Skimmingthe head to compensate for the lostcompressionvolume.Hotlicks.

What shall I say of ten years spentwanderinginthewildernessofmyownignorance?Thatgettingtherewashalfthefun?ThatIwouldhavemademoremoneyinrealestate?

The1970swerethebigdecadeoftwo-strokemotorcycle racing in theUnitedStates. Two-strokes are a mysteryto a lot of people, but theywanted tofeel theyweremoving toward higherperformance—somehow. One outfitmadeasuper-lightswingarmthatflexedsomuchthatthebikewouldhardlygostraight on top end.Anothermade aradicalseatwithaflipped-uptailsection,based on a casual observation thatsomecarshavedecorativespoilersontheirreardecklids.Itsurelyincreaseddragover stock, butmanywere sold.Stock brake lines had to be replacedwithdash-3braidedstainlessflexfromtheaerospacesurplusplace.Hot.AndhowaboutthisLexanwindscreen?Onandonitwent—stuffthatsoldwell,but

Coffee Table Engineering – My Too-Real Experiences

nevermadeanyoneevena tenthofasecondquicker.

Everyenthusiasmhasitsself-appointedpreacherswhogreetanyonewhohasvisiblymodifiedanythingonhismachineby saying, “You know, it’s completelymeaningless to test more than onemodification at a time—because younever knowwhat’sworking andwhatisn’t.Itcouldbeanything”.

It sounded convincing. So onewell-heeledCalifornia enthusiast orderedfortyreplacementcylindersforhis250-ccengine(roughly$11,000-worth).Hetook them to a noted cylinder portingspecialist and had just one change made to each cylinder. Like, raisingthe exhaust port 0.5-mmon this one,widening theport1.0-mmon thenextone,andsoon.Thenall thecylinderswere runon theengine,oneafter theother, in an exhaustive test program.Notebookswerefilled.

Whenthedatawereallin,theconclusionwas thatstock isbest.Notoneof themodifications producedmore power.This was not satisfactory, becausepeople with stock engines were allbackmarkers.Stockmanifestlydidnotwinraces.

Therefore I went to someone whoknewsomething,andaskedhisadvice.“Well,youknow,youcouldkindaraisetheexhausta little,but ifyoudidthat,theenginewouldwanttorevmore,soyou’dhaftatakemaybe20-mmoflengthoutof theexhaustheadpipes to let itdothat.Andifyouraisetheports,thatshortensupthecompressionstroke,soyouproblyoughttatakemaybe.025”offtheheadtogetthecompressionback.Andthen,iftheengine’sturningfaster,thoselittlestockcarbsaren’tgoingtocutit,somaybeyoucouldgoupacouplemillimeters.” It took him less than aminutetosaythis.

His discoursewasall very folksy andcasual, but themessage was clear.

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Everything you do to the engine hastowork cooperativelywith everythingelse—ithastobeapackage.Anengineisasystem,notapartslist.

So we tried it—at Daytona. In firstpractice our brand-new bikewas adroner,sooutcamethedie-grinderandIraisedthetopedgesoftheexhaustports amillimeter, andwidened thetops of the ports almost 10%.Thenwe took the hacksaw to the pipesandshortenedandre-mountedthem.Onwent a spare head, pre-modifiedfor higher compression. In the nextpracticetherevswentupby300—onthesamegearing.Then Idecided toretardtheignitiontimingfrom2.0-mmto 1.7.Another 200 extra revs.Thatnight we put on 36-mm carbs anddid all we could off the track to getthem responding properly. The nextday—another200revs.Bytheendofpractice,wewere third fastest.Onebikeaheadofuswasa factoryentryandtheotherbelongedtooneoftherealwizardsof250racing.Intherace,thebikeranlikeanairlinerandasthefinallapsranout,IsangtoitfromwhereIstoodbehindpitwall,andattheendwewerethird.Weweredizzy.Howdidwegethere?

We had got there by finally havinglearned some basic things aboutengines.Wehadreadthesignsonthesparkplugsandonthepistoncrowns,and had corrected the fuel mixtureaccordingly.Wehadbeenbold to theedgeoffoolhardiness,butthegambleswere supported by goodprobabilities.Wehad learned to talk to theengine.Andtolistentoit.

Wealsolearnedthatthestockengine’sspecificationwasadisguisecreatedbythemanufacturertoprotecttheamateurracer from himself. Everything wasconservative.Itwaslikeallthoseback-numbercamsinthecatalog—intendedonly to pay the overhead cost at thecam shopwhile the serious businessofracingwouldbecarriedonbypeoplewho knewwhat theywere doing.Wewere,bydegrees,becomingmorelikethosepeople.

We found the same when seekingadvicefrom“TheChampionMan”—thetuningadvisorsenttotheeventsbythesparkplugmaker. Ifyouwererunningadroningstocker,hewouldlookatthebusinessendsofyourplugs.Ifoilyblackliquiddidnotactuallydripoutofthem,he’dsay,“Thatlooksgood.I’drunthat.”Thiswashisroleas“hewhokeepsthepluguserfromhavingabadtimewithourbrand.”

But we later discovered that he hadanotherpersonalityaswell—ifheknewyourbikewasrunninginthetopthreein practice. Then he’d look into theplugsand say something like, “I thinkyoucouldadvancethetimingmaybeaquarter-degree.Maybeahalf.”

“Howcanyoutell?”

Hehandedmethemagnifier.“Lookatthe end of the center-wire. They cutthosewith a shear at the factory, sowhenthey’renew,theedgesaresharp.Whenyourengineisrunningjustright,thatcenter-wireshouldgethotenoughthat thoseedges juststart tosoftenalittle—they looka little rounded.Yoursdon’t—they’restillsharp.”

Thepoint here is that there is alwaysmore to be learned, more ways torecover information fromengines thatwill point to how they can best beimproved.Ittakestimetolearn,andittakescuriosityandcarefulobservation.Dynoroompeopleknowadifferentsetof thingsaboutenginesfromwhat theengineersupstairs know.Users in thefieldhaveyetanothersetofexperiencesandconclusions.Allofthisisuseful.

Once a dyno operator friend phonedand askedme this question, “Whenan engine starts to detonate (knock),what happens to the exhaust gastemperature?”

TherewasalongsilenceonthelineasI thought about this.Practically everygo-kartracer intheworldhasanEGTgaugeonhis/herengine,basedontheideathatifthetemperaturegoestoohightheenginemustbedetonating.Canfifty-

millionFrenchmenbewrong?

“TheEGTshoulddrop,” I said, a littleanxiously, hoping realitywould agree,yetfearfulthatitmightnot.

“Well,itdoes,butIwanttoknowwhy.”

Sowediscussedit.Webothknewthatwhen a liquid-cooled engine starts todetonate, its coolant temp goes upmaybe five degrees for no apparentreason.Thatenergyhastocomefromsomewhere,andthehotcombustiongasistheonlysourceofenergyinanengine.ThereforetheEGTshouldfall.

Whydoesthecoolanttempgoupwhendetonationbegins?Normally,hotpartsofenginesareinsulatedtoadegreebyanaturalboundarylayerofstagnantgasthatliesnearallsurfaces.Itisstagnantbecause its molecules lose energyin collidingwith the surface. Normalcombustion is too smooth to disturbthislayer,butthesonicshockwavesofdetonationscouritaway.Unprotected,themetalheatsupmore thannormal,andwe see this on the temperaturegauge.

Experiencegraduallybuildsusamodelofhowthingsworkinengines,andthatmodelhelpsusplanchangesbyroughlypredictingtheireffects.Ourfirstthoughtsarenotalwaysreliable—it’sworthtakingaminute to run itpast theexperiencewehavebehindoureyes.Whenthere’ssomeonetoask,doit—there’snoshameinadmitting thatnoneofusknowsasmuchasheorshewouldliketo.Wisestof all are the engineers and otherswho have broken lots of parts.Aftereachdisastercomehoursofstaringatpistons,valves,piecesofturbinewheelsor other parts, hoping for clues.Theyarethere,andtheWiseOnescanseethem.Andtherearevolumesofbooksthat belong on the conference roomtable—inspirationalreadingthatcanaddmeaningtowhatwe’veseen.

Anengineisasystem,notapartslist.


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Rudolph Diesel (1858-1913) cameto his idea for a compression-ignitionengineasaresultoftheoryratherthanofcut-and-try.Thiswasanaturalmatterfor aGermanof this period.Otto vonBismarck created a unified industrialGermanyfromacollectionofagriculturalprincipalities.As a basis for futurenationalpower,anindustrialrevolutionwas required. Such a revolution hadhappenedbyaccident inEngland,butBismarckplannedGermany’s version.Toenticepeopleawayfromagricultureto industrial employment in cities, heprovided free public education andworkman’s compensation.To providetheknowledgenecessaryforindustrialleadership,asystemofhighereducationwascreated,baseduponfirstprinciples.Dr.DieselandtheotherGermaninternalcombustion engine pioneers wereproductsofthissystem.Theirworkwasbased uponwell-understood physicalprinciples rather than on back-yardintuition.DieselgraduatedfromMunichTechnicalUniversityin1880,andin1893publishedabookletoutlininghistheoriesof how a new andmore economicalenginetypecouldbedesigned.

OneofDiesel’searlyengines—thatusedfor original acceptance testing—canbeseen in theDeutschesMuseum inMunich.Itisabeautifully-madeverticalsingle-cylindermachinetenfeettallthatsuggests thatDiesel and his backerswere very sure of what the resultswouldbe.Hisbackerswere influentialindeed—Fritz Krupp andAugsburgMaschinenfabrik. He had told them,“The whole of my engine must bemadeofsteel.”Atitsfirsttest,aviolentcombustion detached an accessorypartathighspeed.Thosepresentwerenot disappointed; something big hadhappened.Nowthejobwastocontrolit. Soon it was operating, deliveringpowerataspecificfuelconsumptionof0.52lb/hp-hr.

A new engine type was very muchneeded.Ottohaddemonstratedthatthefour-strokeprinciplecouldgreatlyimproveupontheheavyfuelconsumptionoftheearlygasengines.Yetevenfour-strokegasolineenginesneededimprovement

because combustion knock on earlyandlow-gradegasolinesrequiredthemtooperateatlowcompressionratiosofthreeorfour-to-one.

Diesel’s engine was quickly verysuccessful and so was he. SomehistoricalaccountssuggestthatDieselthen mismanaged his wealth. Hemysteriouslydisappearedfromachannelsteamermaking a quiet crossing toHarwich,England,inSeptember,1913.We are offered our choice of threeexplanations—that he fell, jumped, orwaspushedintothesea.Anaccidentona calmnight?Asuicide?The thirdchoicerequiresthatwebelieveagentsactingforderKaiserdisposedofDieseltopreventhisknowledgefromservingontheBritishsideinWorldWarOne.

Britainhadactuallybuiltsteam-poweredsubmarines,andseveralnationshadtriedtopowersubswithgasolineengines.Thesteamsubhadadisqualifyingwindowofvulnerability—themotionlesshalf-hourneededtoraisesteamaftersurfacing.Gasolinefumesincapacitatedcrewmeneven if they failed to blow the boatto pieces fromany stray spark.Subsneededabetterpowerplanttobecomesomethingmorethancuriosities.

Most naval authorities dismissedsubmarinesascoastalvesselsatbest,unabletokeepupwithfleetsbecauseof their limitedspeed,and lacking therangeforoceancrossings.

Germany changed all that.AlthoughGermanymade great efforts to keepup in the1890s-1910naval racewithBritain, therewas ultimately no hopeof equaling the British surface fleet.The submarine, on the other hand,hadalltheingredientsofacompletelynovelwarstrategy.England,anislandnation,washighlydependentuponseacommerce.

Existing Diesel engines weighedhundreds of pounds per horsepowerandwere not obvious candidates assubmarine powerplants.Yet there arealwaysthosewhoseethingsnotastheyare,butastheymaybeinfuture.

Diesels at seaDieseldevelopmenttookmanyformsinGermany,quicklyrunningthroughmanyconcepts—two-stroke,four-stroke,evendouble-acting,with combustion takingplaceonbothsidesofeachpiston.Wayshadtobefoundofcreatingthenecessarystrength in engine structure to supporta long, slendercrankshaft—butwithoutexcessive weight. This developmentwas a very large undertaking but itwas successful—German submarineDiesel enginesbecame themodels forUSdevelopment afterWorldWarOne.In this early period fuel injectionwasaccomplished by blasting the fuel intothe engine cylinder using compressedair.Fuelwasmeteredintoapre-chamber,thencarriedthroughmultiplesmallorificesintothecombustionchamber.Thissystemachievedexcellentatomizationbecausethe fuelmust pass through two sonicshocksonitswayintothecylinder.Asaresultignitionwasprompt.LatermarineDieselstypicallycarriedtwoormoreairpumpsforthis,oneofwhichwouldbeinservicewhiletheother(s)wereonstandbyorinrepair.Theairpumpinjectionsystemwasbulkyaswellastroublesome.

In1904MAN(MaschinenfabrikAugburg-Nuernburg) Diesels weighed 75-100poundsperhorsepower,andweretooheavy and bulky for consideration assubmarinepowerplants.Atthistimetheleading shipyardGermaniawerft (GW)wasusingKortinggasolineengines inits submarine experiments, andwasenjoying considerable export tradebecause of the wide interest in thesubmarine.AyearlaterGWagainaskedMANforenginesandwasshownafourcylinderfour-strokeDieselof300-hpat500-rpm,tobereadyfordemonstrationin1907.Afterconsideration,thisenginewasorderedin1908.

Meanwhile,GW,much as theWrightBrothers had done, decided it wouldhavetodesignitsownengine.Thiswasatwo-strokeoffourcylindersand300-hp,madetobereversible.ItwasruninMarch,1908.In1906,requestsforbidweremadetoFIAT,Korting,andMAN.

Germannavy authoritieswere at thistimeattractedtothetwo-strokebecause

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ithadnoexhaustvalveproblem.Valvematerials were in a primitive stateand required frequent re-grindingeven if they did not fail outright bycracking or breaking.At this time“All firms experienced great difficultyin manufacturing lightweight dieselengines.”

This isn’t surprising.The problem ofsubmarine powerwas clearly one ofadding cylinders, resulting in longercrankshafts, because of the limiteddiameter of submarinehulls.The firstauto engineswith six cylinders in-linehadplenty of “difficulty” asa result oftorsional oscillations—the back-and-forthtwistingofthecrankasaresultoftheappliedtwistingpulsesfromcylinderfirings.MAN’s first proposal as a subenginewas,likesomanyautoenginesof that time, an in-line four. WhenMontagueNapierhadrunhisfirstsix-cylinderautomobilein1903,crankshafttorsionalvibrationcreatednoiseinthecamshaftdrive.Napier’sablesalesmanS.F.Edgesimplycalledthenoise“powerrattle”andturneditintoasellingpoint.

Another problemwasmaterials. Theheaviest part of any engine is itsstructure,butcast iron isn’tknown forlightweightor fatigue resistance.Thiswasatimeofdiscoveryinsteelalloys,andGermanyandFrancewerethemostadvancednationsinthisendeavor.IntheUS,steelmillshadmadegreatstridesinraisingprofitbyeconomiesofscaleandlaborsaving,buttheirproductremainedplainoldcarbonsteel.

Everything had to be learned for thefirst time—all the smallest details,for example, of how to design cast-steel pistons that did not have stressconcentrations that would causecracking.Engineerscoulddesignenginecrankcases strictly according to firstprinciples derived frombridgeor shipdesign, but nature always had thelastword.Muchofthisworkhadtobeaccomplished by trial and error, andsuchexpensivemeansofresearchanddevelopmentcouldonlybeaffordedbythe largest organizations.MAN nowcommandedworld-widesales.

MANhada“lightweight”enginereadyfortestinAugustof1910,afteratwo-yearbuildperiod.GW’senginewasalsoof300-hp and four cylinders, butwas areversibletwo-stroke.

FIATandKortingwerenotquickenoughwith product to be considered, so thefour-strokeMANandtheGWremained.The four-stroke’s economywas 0.42lb/hp-hr,whilethatoftheGWtwo-strokewas0.48(comparethesenumberswiththe0.35-0.38ofmoderntruckDiesels).Thefour-strokewaslessnoisybutpoorlybalanced—probablytheresultoftorsionalvibrations,whichwereonlykepttolerableby useof a thicker, heavier shaft thantheengineerswouldhaveliked.Afour-stroke’spowerpulsescomehalfasoftenandarethereforeroughlytwiceaslargeasthoseofatwo-stroke,thusbeingbetterabletoelasticallytwistcrankshaftsandsotosetthemintopotentiallydestructivevibratorymotion.Thetwo-stroketurnedabitfaster,wasnoisierandsmoother,andstartedmoreeasily.

In 1912 eleven Diesel boats wereordered from GW, powered by theGW two-strokeof 925-hpat 430-rpm.ThedecisiontotryGWfirstmayhavebeenrelatedtotheproblemoftorsionalvibrations.Yet in the same year fourboats were ordered withMAN four-strokesof1000-hp.

ByJulyof1914,with thebeginningofWWIonlyamonthaway,the850-hpGWtwo-strokewas judged unsatisfactoryand theMAN found superior, butGWimproveditsproductsteadily.TheMAN

four-strokeSV4/42engineof 1200-hpwould becomeGermany’s foremostWW I submarine engine.After thewar,examplesofthisenginewouldbestudied in theUS and a very similarengine produced forUS submarines.Other engines removed fromGermanU-boats would see postwar servicedriving electricity-generating plants inEngland.WhysuchGermanprimacy?Engineersworldwidemightunderstandthe principles of Diesel engines aswell as theGermans did, but it wasthe accumulated experience of thebuild/test/improve cycle, energeticallypursued, which were unique to theGermanenginesofthistime.

Froma position trailing in number ofsubmarinesattachedtoitsfleet,Germanyachievedarevolutioninpropulsion.AsEberhard Rossler observes in “TheU-Boat,”“ItwasthedieselenginethatchangedtheroleoftheGermanU-boatfromadefensivetoanoffensiveoneandmadepossibleitssuccessfulapplicationinawarofblockade.”

It is theweight and bulk, not of theenginealone,butoftheengineandthefuel required for the job at hand, thatdeterminethechoiceofpowerplantforvehiclesoflongrange.BeforetheendoftheFirstWorldWar,Germanengineerswould be planning submarines of13,000-mile range, thanks to the fast-developingfueleconomyandreliabilityoftheDieselengine.


Bibliography

“TheU-Boat;theEvolutionandTechnicalHistoryofGermanSubmarines”,byEberhardRossler.Arms&ArmourPress,London1981ISBN0-85368-115-5

“MarineDieselEngines”,byC.C.Pounder,Newnes-Butterworths,London,1972ISBN0-408-00077-5

“EnginesAfloat”,Vol. II; theGasoline/DieselEra,byStanGrayson,DevereuxBooks,Marblehead,Mass.,1999.ISBN0-9640070-7-x

“InternalFire”,byLyleCummins,SAE,Warrendale,PA,1989ISBN0-89883-765-0

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Getting It RightWhen a semiconductormanufacturerbegins pilot production of a new-generationcomputerchipwitharadicallysmallerfeaturesize,theengineersknowtheymustweatheraperiodofdifficultdevelopment, high costs, and a yieldofusablechipsthatmaybeatfirstlessthanonepercent.Inthisworktheyhavetheseadvantages:

1.Theyhavebeenthroughthisprocessbeforeandhavecome through it toachieve profitable production.Theyknowtheprocessworks.

2.Thecompanyhasearlierproductsinprofitable production, providing thefinancialresourcesnecessarytopushthroughandsolvetheproblemsofthenextgeneration.

When prospective Diesel enginemanufacturersofthe1930stackledtheproblemofairlessDieselinjection,theylackedthecomfortof(1)above,andinallcasesthedifficultiestheyencounteredmadeat leastaseveredent in (2)aswell.

All modern Diesel engines employairless(oftencalledsolid)fuelinjection,but when Dr. Rudolf Diesel did hisoriginaldevelopmentatMaschinenfabrikAugsburg,hismanyingeniousattemptsat solid injection ended in failure.In real desperation he resorted tousing the injectionpumptometer fuelquantity into a pre-chamber. Thenthe fuel was atomized by blasting itinto the main combustion chamberbymeansof a secondary injection ofhighly-compressedair.Two-andeventhree-stage air pumpswere thereforean added expense and complicationofallearlyDieselengines.Becauseofthe very highpressure required, suchpumpsgeneratedalotofheatandhadtobecoolediftheywerenottofail.Lines,storagetanks,andcheckvalvesallhadtobeof theveryhighestquality if thesystemweretowork.Allsuchdetailshadtobeworkedoutbylongtesting.

It is interesting tonote thatoneof thetechnologies that was successfullyusedtocreateverylow-emissionstwo-

strokegasolineenginesisarepriseofthisair-blastmethoddevelopedbyDr.Diesel.TheOrbitalEngineCompanyofAustraliafoundinthe1980sthatitcouldproducevery fine fuel particle sizebymeteringfuelintoapre-chamber,thenblastingthatfuelthroughanorificeintothemain combustion chamberwith ashot of compressed air from a smallpoppetvalve.Severaltwo-strokemakersincludingMercurymarineboughtOrbitallicenses and built two-stroke enginesusingthistypeofdirectfuelinjection..

TheearlyhistoryoftrueDieselengineshasbeencomplicatedbytheexistenceofanotherenginetype—the“oilengine”—mainly produced from 1890 to 1900.While theDiesel cycle requires thatthe compressionof air in theworkingcylindergenerateheatsufficienttoignitetheinjectedfuel,theoilenginesofthatearly periodwereOtto cycle enginesadaptedtoburnheavyfuelsbymeansofahotevaporatorofsomekind.

The incentive to devise suchengineswas the lowercostandgreatersafetyofheavyfuelsinthattime,ascomparedwithgasoline.Agreatmanythousandsof suchengines as theAkroydStuartand thePriestmanwere produced forstationary ormarine power.AfterDr.Diesel’s vindication and success in1897, such engineswere sometimesreferredtoas“semi-Diesels.”Theywerenothingofthekind.

Inourownerathisconfusionisfosteredbysuchthingsastheannoyingsparklessrunning-on of car engines of the later1970saftertheignitionwasswitchedoff,ortheoccasionalrunning-awayofatwo-stroke,whichdoesnotstopevenwhenitssparkplugwireispulledoff.Peoplerefertosuchrunning-onas“Dieseling,”but,infact,thecompressionofairtoheatitbeyondtheignitiontemperatureofthefuelisnotinvolved.Thecauseofsuchrun-onisalwaystheretentionofhotgasorreactivechemistryinthecylinderfromthepreviouscycles.

The need for high-pressure air wasa great drawback for early Dieselsbecause it was anything but trouble-

free.A skilledmechanicwas requiredin attendance to keep all systems inoperation.Air-blast injection Dieselswerenotturn-keypowersystems.

Wheninthelater1920sthisdrawbackwasaddressedbyattemptstodevelopsolid injection, Mother Nature washer usual generous self in doling outproblems and failures. Fuel injectionlinesflexed,causingfuelto“dribble”attheendofinjection,asthedilatedsteellinescontracted.The fueloozing fromtheinjectorscarbonizedthere,buildingupdeposits that soonblockednormalinjection.Sharpinjectioncut-offseemedimpossible to achieve. Soundwavesbouncedbackand forthupanddownthrough the fuel in the injector lines,causingcylinder-to-cylindervariationsintheamountoffueldelivered.Individualadjustments failed to correct thisbecause the variations themselvesvariedwith engine speed. Fuel lineswereerodedfromwithinandpuncturedbycavitation,focusedoncertainspotsbycombinationsofwavereflectionsandinjectionlinegeometry.Wetellourselvesthat fluids are not compressible—butthey are. The Englishmanufacturerofaircraft landinggear,Dowty,makesa device called a “solid spring”whichmakesuseofthecompressibilityofoil.Themore fuel therewasbetween theinjectionplungerandthespring-loadedinjectionvalveattheenginecylinder,themorethespringinessofthefuelhadtobeallowedforaswellasthespringinessoftheinjectionline.

The desired result, of course,was toinject fine sprays of fuel at very highspeed—750 feet per second was acommonnumber.Assuchfast-movingdropletshit thedensecompressedairin theDiesel engine’s cylinder, theyflattened, punched in, and broke upintocircletsofsub-droplets.Thelargestofsuchsub-dropletswerebrokenupintheirturn,thefinalproductbeingahugeincrease in total droplet number andsurfacearea.This greatly acceleratedfuelevaporation.

Evaporation is a cooling process, sodroplet evaporation’s first effect is to

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coolthecompression-heatedairintheDieselcylinder.Thisisthecauseofthecelebrated“Dieselignitiondelay”ofuptotencrankdegreesfromthetimeoffirstinjectionoffueltothetimeofmeasurablepressure rise from combustion. Theusual description ofDiesel ignition isthatfuelignitesasitisinjectedintothecompression-heatedairinthecylinder.Infact,theevaporationoffueldropletstakes time and initially cools the airaround them.Only as fuel-rich vaporcomes in contactwith hotter regionsdoesignitionactuallytakeplace.

Onesolutiontotheproblemsofirregularinjectionwastomakeall fuel injectionlines between a plunger pump andthe injectionnozzles thesame length.Anotherwasthe“unitinjector”—togiveeach cylinder its own injection pump/nozzle unit mounted directly on thecylinderhead,andeachoperatedbyitsownpushrodand rocker from its ownlobeonthecamshaft.

Injection plunger to bore clearancesmeasure in millionths, so plungersinitiallyseizedtoboresfrequently.Anycontaminantsinthefuelhadthesameeffect.Thelubricationcharacteristicsofthefuelvaried,soagivenexperimentalsystemmightworkwell on fuelAandseize after a few hours of operationonfuelB.Manymaterialsandsurfacetreatments had to be tested. Theexperimentsgulpedmoneyandtime.Abodyofknowledgewasbeingdevelopedateachcompanythatwasseekinganairlessinjectiontechnology.

The greatest single attraction of theDiesel engine is its fuel efficiency, somakersknewthatreliableoperationatone speedand loadwasn’t enough—although thiswas the best that someearly marine Diesels could deliver.Standard engine testmethodswouldreveal any deficiencies. Few buyerswantedanenginethatwaseconomicalat¾ loadbutusedasmuchfuelasagasolineengineat¼load.

Todayelectronically-controlledcommon-rail injection systems perform five ormore separate injection events per

cylindercombustion,buttheseconceptsare not new—just their successfulapplication.

Early attempts at solid injection oftenbeganwith a common-rail system, inwhichahighpressurepumpmaintainedinjectionpressureinadeliverypipeor“rail” that suppliedall injection valves.Unfortunately, early injection valvescouldnot cutoff flowsharplyenough,allowingthemto“dribble”andtocarbonup,ruiningtheinjectionspraypatterninjustafewhundredhoursofoperation.

Cam-drivenmechanical injectorshavebeendesigned todeliver a small pilotinjection before themain fuel spray.Becauseofignitiondelay,ifaninjectionsystem simply begins spraying fuel,quiteabithasbeeninjectedbythetimesomepartofitactuallyignites.Theresultisasharpthumpastheconsiderablefuelinthecylinderlightsupatonce.ThisisthetraditionalDieselknockwhichmakesolderDieselssoloud.

A pilot injection sprays a tiny amountof fuel into the cylinder, andwhen itlightsup,themainspraycanbeignitedpromptly by it.As a result, withoutsudden ignition of quite a bit of fuel,operation ismuch quieter. No doubtyou’ve noticed this as theCumminsengineinyourpickuphasevolvedfrom12-valve,to24-valvetothe5.9HPCRandnowtheevenquieter6.7HPCR.

Modernelectromagneticorpiezoelectricinjection valves also provide a pilotinjection, and once the f lame isestablished, they are able becauseof theirspeedto follow itwithmultiplemain injections. In engines using anexhaustcatalyst,theremaybeasinglelateinjectionaswell,whosepurposeistomake the exhaust gas hot enoughto keep the catalyst “lit” (that is, hotenoughtopromotecompleteburningofunburnedhydro-carbonintheexhauststream).

Answeringall themyriadquestionsonthewaytosuccessfulsolidinjectiontookserious amounts of time andmoney,which is why it usually happened in

large organizations likeMAN,GM, orDaimler-Benz. In this game, havinggoodideaswasjustabeginning.Thenyou needed ultra-precisemachiningfacilities to turn ideas into hardware,plus the cash to afford long series ofinstrumentedrunningenginetests.Withthedualconstantdemandsforgreatereconomyandloweremissions,thisworkneverends.


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hitting the New NumberWhatisthepriceoffuelinyourarea?Wenaturallyhope thatgasolinewillhoveraround$3agallon,buteachtimeithasrisen above that,we havewondered“Is this the last time?Willwe, in threeyears,lookbackon$3gasaswenowdoupongasat$1.65?”Arisingchorusofvoicesspeaksof“PeakOil”—theyearinwhichmaximumworldoilproductionwillbe/hasbeenattained,andafterwhichproductionwill drop.Read the booksandarticlesandseewhatyoumakeofthem.We’dliketobelievewe’llalwaysbemiddle-aged,healthy,andhappytoo,butweknowthateverythingchanges.IfPeakOilisnow,ourfuturecouldseefuelriseto$4,then$5,andthenwho-knows-how-high.This is a high-stakes gameinwhichtherearebidderspreparedtogoasfarastheyhaveto.China,India,and Indonesia need oil to fuel theirfast-industrializingeconomies.TheUSandWesternEurope, accustomed tohundredsofyearsofasplithave/have-notworldwiththemselvescomfortablyon top,may be on a collision coursewith highly productive and ambitiousneweconomies in theEast.Haveweall theunderstandinganddiscipline tonegotiateequalaccesstoenergy?

ThePacificWar, 1941-45,was foughtoverresources.TheUSsuppliedJapanwithoilandscrapmetalsbetweenWWIandWWII,whileJapancarvedherselfever-larger pieces ofManchuria (coalandironore)andChina(foodandlabor).TheUSwarnedJapanthatChinamustnotbecomea“greaterJapan.”Wedidthis so often and so toothlessly thatJapanese planners dismissed theUSasapaper tiger, its citizensdecadentfrom soft living. Must we call thisappeasement?UShandsweretiedbytheGreatDepression of 1929, and astrongnationalmoodofisolationism.

When the Japanese seized controlof Indochina from the French in July1941,theUSfinallytookaction,cuttingoffJapan’soil.USleadersandanyonewho read past page one in nationalnewspapersknewinthatmomentthattherewouldbewar.Japan’sstrategicoilreservewas small. Japanese leaderssaidclearlythattheywouldnotstandidly

byasJapanwasreducedtoathird-ratepowerbyenergystarvation.Warwouldcomesoon,butwhere?

Intruth,USplannersdidtheirshareofunderestimating theirpotentialenemy.The idea of a Japanese trans-Pacificnavalstrikewasinconceivabletothembecause theAmerican “PlanOrange,”forsimilaractionagainstJapanwasitselfknowntobeunworkable.Ifwecouldn’tdoit,howcouldthey?

Japanese carrier pilots arriving overPearlHarborcouldnotbelievetheirluck–herewerethepapertiger’sWorldWarIbattleshipsdrawnupinaneatrow,andoverthereweresimilarrowsofequallyvulnerable B-17s and other aircraft.Simultaneously,JapaneseforceseasilytookoverDutchoilfieldsinwhatisnowIndonesia,brushedasideUSforcesinthePhilippines,anderasedlocalBritishpowerbyseizingSingaporeandsendingtwoBritishbattle-cruiserstothebottominminutesbylong-rangeairattack.TheJapanese strategywas to hope thattheir new access to resourceswouldgivethemthestrengthtorepelWesternresponses.

This historical example reveals thatenergy is deadly serious business.Today there isn’t quite enough to goaround, and theremay be even lessin the future.Thatdrives thepriceup.Congresshasdecidedthatconservationcanbeausefultoolinmakingenergygofarther.One result is thenew35-mpgCAFEstandard.

CorporateAverage Ffuel Economy(CAFE)forautosandlighttrucksisnowmandatedbyCongresstorisein2020from the current 27.5-mpg cars/22.5-mphlighttrucks,toanewstandardof35-mpgaverageforboth.

Thereisnoserioustechnicalprobleminmeeting this standard. Low-emissionssmallturbo-Dieselautosandsomeofthenewgasolinedirectinjection(GDI)autoswillmeetthisstandardnow.The2020dateallowsplentyof timetoconsumethevalueofexistingproductiontoolingand tomake a transition to the new

equipmentthatwillberequired.

Therealproblemswillbesocial.Welikeourlargishcars,SUVs,andpickupsasthey are, somanufacturerswill straineveryfibertocreateamixoflargeandsmall vehicles thatwill averageout tothe35-mpgstandard.Evennow,electricmotorsarebeingintegrateddirectlyintonew-designautomatictransmissions,sothatexistingSUVsandpick-upscanbehybridizedwithoutmuchchangeotherthanfindingspace for thebatteryandextendingthefloor’strannybulgeevenfartheraft.

Manyof us havenowdriven thenewbreed ofEuropean turbo-Diesel auto.Never revving over 2600-rpm, theyacceleratehardanddeliverwonderfuleconomy,whilehavingEuropeandesignflair.Suchcarshavebeenlatearrivingin the US, where tighter emissionsrequirements prevail. Currently, EPA-compliantnewDieselsfromMercedes,BMW, Honda, andAudi are eitherbeginning to arrive or will soon behere.ForUSmakers, the trickwill beto find ways to manufacture small,economical cars in numbers sufficienttoletthemearnmostoftheirprofit—asusual—fromlarger,morefully-equippedmodels.Theywillgetsomehelpinthisby such controversial measures asthe exceptions for flex-fuel vehicles.The economy of such machines—able to burn E85 gasoline/alcoholmixture—can legally bemultiplied byfivebefore inclusion in theCAFEmix.Ingeneral,Detroithaschosentomakelarge,expensive,relativelyfuel-hungryvehicles perform this role, therebyimprovingtheirnumbers.Nodoubttherewillbeother,similarfudgingprovisionsinfutureemissionslaw.

Dieselswere the heroes in the early1980sbecause theywereeconomical(very important inavoiding longfilling-stationlinesinthesecond“oirushokku”ofthattime)andemittedlittleunburnedhydrocarbon. Then came a freshunderstandingofDieselparticulates—whichbecomevisibleasblacksmokewhen injector sprays deteriorate orwhenanowner-operator racks-out an

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old-techinjectorpumpinhopeofextrapower.Thesmokeisnotjustclumpsofcarbonatoms, left over from the coolfringesofcombustion.Italsocarriesaburdenofadsorbedmultiple-carbon-ringhydrocarbonstructures,someofwhichmimicbiologicalmoleculesandmaybemetabolizedinhumans.Someofthesestructures are proven promoters ofcancer.Herotozero.

Since then thepriceofUSadmissionforDieselshasincludedfilteringouttheparticulatesandremovingorpreventingtheformationofnitrogenoxides.Noneof uswishes to be bundled off to thecancerward or to die coughing in anNOx-facilitatedsmoginversion,butwedon’texactlywelcomethe ideaof fuelsoexpensivethatallvehiclesmustsitstilluntilallseatsarefilledwithpayingcar-poolers.We like ourmobility andprivacy!

Particulate filtration is becoming amature technology,which leaves theproblemof nitrogen oxides.The bestplan is not tomake them in the firstplace,whichiswhynew-designDieselsincorporate heavy, cooledEGR.Themorecoolinertgaswecanmixwiththeair in our engine, the lowerwill be itscombustiontemperature,andthelowertheproductionofNOx.IseethepagesofautoengineeringmagsfillingupwithadsforDieselexhaustcoolerssoIknowthisisnicelymakingtheleapfromtheorytopractice.

That leaves the problemof removingenoughNOxfromtheresultingexhauststreamtodropthecontentcomfortablybelowthecurrentstandard—andkeepingthevaluedownthereasthevehicleagesover a specified lifetime.This kind ofpainstakinganddetailedworkiswhytheautomotiveindustryisthenumber-oneconsumerofresearchanddevelopmentfundingintheworld.Notspaceships.Notbio-tech.Notweapons.

I recentlyattended the riding testofanewmodelofItalianmotorcyclewheretheirengineer,discussingtheproblemsoffuelandignitioncalibrationforracing,said, “Of course for racing this is so

easy,butforproduction,itbecomesverycomplicated.”

TheGermanautomakershavepresentedtheirBlue-TecsystemtotheUSEPA.ItinjectsureawhichreactswiththeNOxtoproduceharmlessatmosphericnitrogenandoxygen.Theproblemisthattheureatankmustbe refilled,andEPAdoubtsdrivershavetheself-disciplinetodothis.DoestheengineECUthereforeshuttheenginedownwhentheureatankrunsdry?Doesitsoundabeeperorilluminatea redwarning light? Does it reducepowertoa“limp-home”mode?

Hondaandothers (yourTurboDieselis includedinthisgroup)havechosenthe other leading technology, whichadsorbsnitrogenoxidesononesurfaceofamulti-layercatalysttrap.Periodicallythe engine’s ECU orders it into briefrichoperation,providing fuel topowera reaction that reduces the NOx toharmlessform.Noureaiscarried.

As experiencewith these systems isgained,we can hope that economiesofbothscaleandofimprovedpracticewill cut their cost so that compliantDiesels lose their laboratorycharacterand becomeenduring and affordablesolutions. Not so fast! Engineerscurrently speak of a possible $6000-7000 surcharge for 2020-compliantvehicles.Butwait—isthisthetruth,orisitgametheory?AretheyreallyspeakingtoCongress,hopingthestandardmaybeback-pedaledforeconomicreasons?EveryoneknowsthattheUSeconomywouldstagger(andmightevenfall)ifthedomesticautoindustrycollapsed.

Other Diesel technologies that willcontributetothispossiblefutureareveryhighpressure,multi-squirtcommon-railinjectionsystems,theirinjectionvalvesactuated either by electromagneticor piezoelectricmeans. It is easy tovisualize aDiesel’s high compressionratiocontributingtoitsefficiency,butapracticalmatterintrudes;howlongdoesittaketoinjectthefuel?Ifittakesmanydegrees,thelastpartofthefueltoenterthe cylinderwill burn after the pistonhas descended some distance from

TDC. In otherwords, the late-injectedfuelwill burn at a lower compressionratio—andtheexpansionoftheresultingcombustion gaswill begin at a lowerpressureandwillexpandashortertotaldistance.Thismotivates engineers tousefasterinjection,whichcallsformorepressure.The nature of this problembecomes somewhat clearerwhenwereflectthatpeakcombustionpressureinariflecartridgemaybe50,000-psi,whilecurrent common-rail injection systemsareat24,000-29,000-psi.

Multiple squirts—asmanyas five perfiring cycle—are employed.A small-volumepilotinjectionquietscombustionbylimitingtheamountoffuelpresentinthecylinderwhenlight-uptakesplace.Thisiswhyrecently-designedDieselsnolongerproducethetraditionalandnoisy“Diesel knock,” either at idle or underway.Thenthreemaininjectionsdispersefuel in the combustion chamber, eachtimestoppingshortofdrivingthesprayplumeallthewaytothecylinderwalls.Finallyalate-cycleinjectionaddsheattokeeptheexhaustcatalysthotenoughtofunction.

High injection velocity—over 1100-ft/sec—ensuresbreak-upofthefuelsprayinto particles so small that their hugesurface area translates tomaximumevaporation and rapid burning ofremainingdroplets.Dieselcombustionisdescribedasadiffusionflame,inwhicheach fuel droplet is surrounded by ahaloofevaporationfromitssurface,andtheoutwarddiffusionoffuelmoleculesbringsthemintocontactwiththeoxygenof the air charge. Combustion takesplaceinthismixingzone.Thepresenceofcooled,recirculatedexhaustgasinthisprocesslowersitsflametemperature—enough,ideally,topreventtheformationofmuchNOx.

The greater the percentage of fueldroplets that are consumed in thediffusionflameprocess,thesmallertheresidueofpyrolyzedfuelresiduethereislefttoclusterasparticulates(liketheblackstuffinthebottomofthetoaster).Nothing is perfect! Engineers strivefor uniform conditions throughout the

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chamber, but richand leanzonesareinevitable.Ifcombustionisimprovedwithaviewtocuttingparticulateproduction,itburnshotter,increasingNOxgeneration.If temperature is successfully loweredenoughbycooledEGRtoresultinverylowNOx,combustionislesscompleteandparticulate formation accelerates.Pick your poison. In development,engineersmake a best estimate ofthe relative costs of dealingwith thetwokindsofemissions,andsteertheircombustion compromise accordingly.Truthhereisrelative—tomorrowafreshtechnologymayshifttheequation,andnewchoicesmustbemade.

Want uniform mixture above all?Maybe the thing to do iswait for thecomingHCCIengine,whichpromisesnear-Diesel efficiency with very lowemissions.Thatmightmeanbigsavings,for suchanenginewouldneedmuchless exhaust aftertreatment. This isHomogeneousChargeCompressionIgnition,aprocessinwhichapre-mixedchargeiscompressedataspecifichightemperature, such that it auto-ignitesquickly but not explosively, burning topeakpressureattheusual14-degreesATDC. Late stock-car great SmokyYunickplayedwith this concept yearsago, using a heated intakemanifold,but today’s implementations ofHCCIrevolvearoundtherecirculationofjustthe right amount of uncooled exhaustgas.Whenthisisdoneright,theresultis that theaddedheatofcompressioninthecylinderisjustenoughtocauseauto-ignition at the right point in thecycle. Because the charge lights upeverywhere in “a thousand points oflight,” there is no flame front as thereiswith spark ignition.Without a flamefront, there is no compression of endgas ahead of it, so there can be nodetonation. That allows use of highcompressionratioforefficiency—withoutknock.

Unfortunately,HCCI presently cannotwork at either very lowor high loads.Atidlethereistoolittleheattoachieveignition, and at high load there is toomuch fresh charge in the cylinder tobeheatedtoeventualignitionbyEGR.

Therefore the current developmentscenteronemployingHCCIinconstant-load devices such as stationarygenerators, or usingHCCI to achievehigh economy in vehicles that spendmostof their timeat highwaycruisingspeed.Theconcept is toovaluable toignorebecauseitisabletooperatesolean that economy is very high, andthatwithverylowemissions.Therewillsurely beaplace for it—perhaps in a“multi-combustion-mode” system—inmeetingthe2020standards.

We humanswant and need to knoweverything,butnature resistsstrongly.Hermost potentweapon is thatwithevery new thing we learn, we alsouncover new ignorances. These areDon Rumsfeld’s famous “unknownunknowns,” and there are enough tolast the lifetimeof our species. In themeantime,wearegoing to learna lotmoreaboutthetiniestdetailsofDieselcombustion.ThatmaygetusdowntheroadjustaheadoftheEPA.


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Legal Force and a Crazy QuestionBeforewe know it, 2020will behere,andwithitwillcomelegalforcebehindCongress’s new 35-mile-per-gallonCorporateAverage Fuel Economy(CAFE) standard. The old standardhadbeen27.5mpg.Thislawessentiallyrequires that the fuel economy of anautomaker’smodelyear,averagedoverallvehiclesproducedandmeasuredbya specified driving cycle,must equalor exceed the mandated number.Manufacturersarefinedinproportiontodeviationsfromthisrule.

Naturally,therehasbeenalotoffiddling,for organizationsas largeas theautoindustrycanaffordalotoflawyers.Oneof themost notable is the “FlexFuel”provision,whichgrants amazing relieftothosewhoproducevehiclesabletoswitchautomaticallybetweengasolineandE85 (85%alcohol,15%gasoline)fuels.Outwardly,thissoundslikeafinething—encouragingmakerstoproducevehicleswhich can be fueled in thismostlyrenewable-energymanner.Nowfor the fine print. Themeasured fueleconomyofaFlexFuelvehiclemaybemultipliedtimes fiveforitsinclusionintheCAFEaverage.Thereforethe industryincludesthistechnologymainlyaboarditsmost fuel-hungry andprofitable-to-sellmachines—largeSUVs.Insteadofcomputingwiththeiractualfueleconomy(let’ssayit’ssomethinglike17mpg),theybecomepart of themaker’sCAFEasfivetimesthat—inourexample,85mpg.Lookin’good!Poof—apainfulfinancialfinetotheautomakerdisappears!

The influence of suchwork-aroundspales when compared with today’s$4.25/gallon Diesel fuel and $3.80gasoline.*Nolegalsleight-of-handcantransforma$130tankof fuel intoonethat costs yesterday’s $50.The extrawe are nowpaying for vehicle fuel islargeenoughthat,unlessweareverycomfortablywell-off,weare having togiveupsomething, somewhere, tobeable to afford to continue driving aswemust.Thathurts.Beforepetroleumbustedthroughthe$100-a-barrellevel,wethoughtof30mpgcarsaseconomical.Nowthatitcosts$40tofilltheirdinkygastanks,wearesuddenlyinterestedinthe

detailsoffueleconomyandwhatis,orcouldbe,donetoincreaseit.

We’ve all heard about checking tirepressureandwheelalignment,avoiding“jackrabbit starts” (lovely PR phrasefromthe1950s),driving10mphslowerthanusual,andnotcarryingwintertime’straction sandbagsaroundall summer.Whatwill all that get us?Oneor twomiles per gallon—maybe.And yes,we’veheardalltheblatherabout“IfallAmericanswouldturndowntheirwaterheaters, dry their clothes outdoors,andwashwith a damp rag insteadoftakingshowers,wecouldsave80zilliongallonsofthisorthat.”JusttrygettingallAmericanstodoanything.

Anotherredherringisoverblowntalkof“alternativeenergy.”GetontheInternetanddoa little research.Yousoonfindthattheenergycategoriesareoil,gas,coal, nuclear, and “other.”Other is averysmallnumber,and includeswind,tidal,geothermal,compostedcarpetfluff,and fry oil begged fromgreasy-spoonrestaurants.Otherincreasesveryslowly.Politicians talk loudly of hydrogenandcrowdsapplaud just as loudly.But doweseetelevisedceremonies,showinggiant coal-fired electricity generatingplants being shut down because somuchwind,geothermal,andotherhascomeon-line that their “dirtypower” isno longerneeded?No,andyouwon’tseesuchathingforalongtime,ifever.That’s because it takes a lot of windfarms, carpet fluff, and fry oil to equaltheenergyintwo trainloadsofcoal—the24,000tonsofblackrocksthatabigcoal-electricplantburnsinoneday.Energyuseinanyindustrialnationwithahighstandardoflivingishuge.Oilisnotan“addiction”—it isanabsolutenecessityforsuchnations.Iftheycutdownonoiluse, they justhave toburnmorecoal,findmoregas,orbuildmoreoftheever-popular and easy-to-manage nuclearplantswhichareperfectlysafe.

Editor’s note: Kevin’s hit upon an idea that I believe makes sense to the majority of TDR readers. But, we’ve pounded this drum before—where is the US’s national energy plan?

Should we not demand more from our elected officials?

Excuse me while I ponder the national fuel tax holiday idea.

What will/can the vehicle industrydo in response to the new CAFEstandard? Naturally, they get theirlawyers, lobbyists, andother types ofgoodbuddiesonthecasetoseewhatkindofinterpretivehair-splittingwillbuythemhowmuchtimebeforethefullforceof the law collideswith their absoluteneedtokeeprightonsellingtheirmostprofitablevehicles—namely,largeSUVsandpickuptrucks.Somearm-twistingislikelytoworkhereforatleastawhile,asexperiencedfolkingovernmentknowthatthelastthingthecurrenteconomyneeds is to hear thatBMW is buyingCadillacdivisionofGM,orthatChryslerhasclosedorbeensoldtoaconsortiumofChinesebuyers.Thereforethedealwill probably not be as clean as the35mpgnumbermakesitsound.Every system of laws—national, religious,sporting—generatesanactivesystemofhair-splittingthatsoftensitseffects.

Every engine now in production hasbeenthroughspecificfuelconsumptiontesting.The result of such testing issummed up in a performancemap,relating specific fuel consumption(calledbrakespecificfuelconsumption[BSFC]itismeasuredinpoundsburnedper horsepower developed, per hourof operation) to engine rpmand load(throttleopeningoraveragedcombustionpressure).TheresultofsuchmappingisaseriesofcurvesofconstantBSFC,androughlyattheircenteristhe“island”ofminimumSFC.Thisistheengine’smostefficientpointofoperation,anditcanforavarietyof reasonsbeasmuchas2½timesmorefuelefficientatthispointthanitisatitsleastefficientpoints.Whyshould this be so? Isn’t compressionratio the principal determinant of fuelefficiency?

Here’s how it works. Friction risesrapidlywith rpmbecause inertia loadson pistons and bearings increaseas the square of speed.Thatmeans

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operationathigherrpmsacrificesever-risingpowertofriction.Wealsohavetokeepaway from very low rpm—whenheavily-loadedpartssuchascamlobesandvalvetappetsoperateatthebottomof their speed range, there is time formostoftheoilfilmbetweenthemtobesqueezedout.Whydoesn’tthisruinthepartsimmediately?Modernoiladditivestake upwhere the oil filmmarginallyleaves off—but friction rises becausethe additives are solids, not liquids.This iswhyautomakersare turning toroller tappets—to avoid some of thefriction rise that occurs at low rpm inthisway.An engine’s friction curve issometimesdescribedasa“bucket”—lowinthemiddle,higheratthesides.Thatleaves us somewhere in themiddle.Howabout throttle opening, or “load,”astheengineerstermit?Well,againthenewsisthatthemiddleisbetterthantheextremes.Atveryhigh load,heat lossincreases.Atverylowload,muchofthemoderate combustion pressure beinggenerated is used up in overcomingpiston-ring and other friction.Worseyet,ingasolineengines,intakethrottlingcauses so-called “pumping loss” toincrease—the power consumed inpullingapartialvacuuminthethrottledcylinders.

Incidentally, you can see from thisparagraphwhy it ismore efficient toturbochargeasmallerenginethanitistoeitherrevtheenginehigherormakeitbiggerasameansofgettingmorepowerfromit.Thehighertheenginerevs,themore power it loses to friction, and abigger enginehasbigger andheaviereverything,whichalsoincreasesfriction.Turbochargingismorallygood!

Theresultofallthesepushingandpullingvariables is that there is this islandofminimum BSFC somewhere in theroughly left-middleof theperformancemap.Wouldn’t it be lovely ifwecouldsomehowoperate the engineonly atthatspeedandload?

Theobvious problemwith this is thatthe vehicle’s transmissionhasa finitenumber of speeds, so the engine’srpmmust rise and fall—often across

a ratherwide range—in the processof accelerating the vehicle from restto cruising speed.Economy cars aregeared to operate their rather smallenginesrightontheirislandofminimumBSFCathighwayspeed.Thisispartofthereasonwhysuchacargetsitsbestfueleconomyontheopenroad,notonlocal two-lane roadswhere averagespeedsarelower.

Aradicalsolutionwouldbetoconnecttheenginetoagenerator,operateitonlyat itspointofbestBSFC,andusetheresultingelectricpowertobothdrivethevehicleandchargeanon-boardbattery.When the batterywas fully-charged,the combustion enginewould simplyshutdown,startingupagainonlywhenneeded. This is a rough descriptionof so-called “series hybrids” such asChevy’sawaitedVolt.Theyattempt tooperate their combustion engine onlyat or very near to itsmost efficientoperatingpoint.

Anotherapproachistouseanon-boardbattery-electric drive to power thevehiclemainly in conditions inwhichthe combustion engine’s efficiency isespecially bad. This is roughly how“parallelhybrids”suchasToyota’sPriusoperate.Eitherpowersourcecandrivethevehicleseparately,orbothmaydosotogether.Thecombustionengine’sfuelefficiencyispooratlowpart-throttle,sotheelectricdriveoperatesatsuchlowloads,withthecombustionenginetakingoverastheloadrequiredmovesintoitsmoreefficientrealms.

Inbothcases,thecombustionengineisdownsizedbecausereducedpeakpowercanbeatleastpartlymadeupbyusingboththecombustionengineandbatterypowerduringtimesofpeakload,suchasaccelerationuphighwayon-ramps.This downsizing helps to avoid theworstfeatureoftraditionalV8-poweredAmericancarsandlighttrucks—namely,thatoftheirtypical300horsepower,only10%wasusedathighwayspeeds.Thispushedtheiroperatingpointdowntoaninefficientzone.Thinkof itaspushing300hpworth of friction tomake only30hp-worthofactualpower.

Much ismade of the hybrid’s abilityto recover some energy by so-calledregenerative braking. Rather thanalways relying on normal dry frictionbrakes fordeceleration, suchvehiclescan employ their drive motors asgenerators, converting vehicle kineticenergybackintochemicalenergystoredin theirbattery.The less-shiny truth isthatonlyabout30%energyrecoveryiscurrentlyachievedinthisway.Anothertruth is that your useof thebrakes isminimal as you practice conservativedrivingtechniques.

Themostnotoriousproblemofhybridsis that the buyermust purchase twoengineswith the vehicle, not one asformerly. The cost penalty for this iscurrentlyestimatedat$6000forasmallautomobile. Ifhybridizationboosts theaverage fuel economyof a small carfrom 25mpg to 40, with gasoline at$3.80agallonthatamountstoasavingsof$.057permile,orona15,000miledrivingyear,$855.Soundsprettygood!Butwhenwedividethat$855intothehybrid’s $6000 cost premium,we findwemust keep the car seven years tobreakeven(because$6000,dividedby$855,=7).

We fret about the trickypoliticsof oil-producingnations (SaudiArabia, Iran,Iraq, UnitedArab Emirates, Kuwait,Venezuela, Russia, just for starters),but the batteries presently used inhybrids (nickelmetal hydride) containfairamountsofcobaltand lanthanum.ThereissomecobaltintheUSbutlargeramounts are found inRussia and theCongo.AprincipalsourceforlanthanumisChina.Why does everything haveto be so complicated?Good luck tousall.

Theautomakersdon’t like theoptionstheyhaveforincreasingfueleconomy.Hybridscostmorebecause theyhavetwo engines instead of the traditionalone,andDieselscostmorebecausetheirturbochargersaremadeoftrickmetals,their structure andmovingparts havetobeextra-beefyandmadeofpremiummaterials,andtheirfuelinjectionsystemoperatesathugepressuresandsocosts

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moretomakethandoesgasolinefuelinjectionequipment.Oh,anddon’tforgetall the emissions problems—Dieselsneed particulate exhaust filters andsomemeansoftrappingorreactingtoharmlessnessthenitrogenoxidestheynaturallygenerateinabundance.

OnlyafewEuropeanDieselcarsandtheplannedHondaDieselmeetcurrentUSemissions requirements, but high fuelpriceswillencourageotherstobelievetheycanaffordtosellcompliantDieselsintothismarket.

Meanwhile considerable researchand development is being expendedon a combustion scheme thatmightdeliver near-Diesel fuel economy butat lower equipment and emissionscost.Thecurrentdirection ingasolineengine development is toward veryleanoperation, but becauseuniformlyleanmixturesare sodifficult to ignite,theeasywaytosuccesshasbeenwithmixturesthatarenon-homogeneous—rich enough to ignite in the vicinityof the spark plug, but lean overall.The troublewith this is that thehottercombustionwherethemixtureisricheralwaysgeneratessomehard-to-removenitrogen oxides. Isn’t there away toigniteuniformlyveryleanmixtures?

Untiltheearly1990s,theofficialanswerwasno, andprofessional engineeringsocieties were tempted to reject forpublication papers that suggestedotherwise(ignorantforeigncrackpots!).When thedambroke,people realizedthat if a very leanmixtureof gasolineand air were properly heated beforecompression,itwouldreliablyandrapidlyignite at a certain point in the stroke.(OneofthepeoplewhoworkedonthisideawasthelateSmokyYunick.)ThisiscurrentlycalledHCCI,whichstandsforHomogeneousChargeCompressionIgnition, a process very different fromDieselcombustion.InDieselcombustion,pure air is compressed until it is hotenough that fuel injected into it as aspraywillignite.InHCCI,itisaheatedanduniformleanmixtureofairandfuelthatiscompressed.

Because Diesel combustion is aprocess of droplet evaporation, withfuelmoleculesdiffusingawayfromthedroplet until they encounter enoughoxygentobeginburning,allfuelmixturesfrompure fuel (in thedroplet) to pureair (far from the droplet) are present.Thatmeans that at least some veryhot,chemically-correctcombustionwilltakeplace,whichiswhatgeneratesthetroublesomenitrogenoxides inDieselexhaust.

Because fuel and air are uniformlypremixed in HCCI combust ion,combustionisvery leaneverywhere—lean and therefore cool. This canessentiallystopnitrogenoxideproduction,saving the engine developers fromhaving to tack on expensive exhaustpost-treatmentdevicestoremoveit.

There’salwaysacatch.HCCIismadetoworkbyaddingmeasuredamountsofhotexhaustgastothefreshcharge,sothatitignitesattheproperpointneartheendofthecompressionstroke.Butat idle or low load the tiny amount offreshchargecanbecomesodilutedthatit doesn’t ignite.And near full throttlethereissomuchchargeinthecylinderthatitcoolstheaddedhotexhaustgas,again causing ignition to cease.So itappears—atleastforthemoment—thatHCCImayhave tobeused inadual-mode engine that switches to sparkignitionandnormalmixtureatthebottomandtopofitsloadrange.

Afterawhile,theconstantlyincreasingcomplexityofwhatmustbedonetomeetemissionsbeginstoseemself-defeating.To clean upDiesels or spark-ignitionengines,ortomakeHCCIwork,itseemswemust createwhole new industriesand technologies, whose factories,product shipping, and commutingworkersconsumepowerandmaterialswhilegeneratingwaste.Canwesayforsurewhether thisresults inanetgaininqualityofhuman life,and inbenefitto the environment?Maybe it’s just acrazyquestion—like“Is ithotter in thecity,orinthesummer?”andIshouldjustshutup,getwith themainstream,and

helptomakethismagazine,too,justananthologyofcheerleadingpresskits.


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shooting up For Diesels?Whileweawaittheresultsofindependenttestingtoconfirmordenythevalueofwater-methanol injection for Dieselpowerandeconomy(seeDougLeno’s“WaterMethanol for Fuel Economy,”page126),let’shavealookatthelonghistoryofsuchinjection.

Firstofall,theuseofalcoholasfuelforinternalcombustionenginesgoesbackalongway—tospecialethanolracesheldinFrancearound1908,asapossiblemeans of boosting the profitability ofagriculture.(Soundfamiliar?)SomethingmoresubstantivewasdonebyenginepioneerHarryRicardo around 1920.Hewasstrugglingwiththecoolingandcombustionproblemsof spark-ignitionengines,andhisassociateFrankHalfordcommissionedaspecialtopend,tobefittedtoHalford’ssingle-cylinderTriumph500-cc racingmotorcycle.At this timealmost allmotorcycles had air-coolediron heads and cylinders, and ranpistonscastofironorsteel.Thelowheatconductivityofironmadetheseenginesrunveryhot,andthat,combinedwiththelowknockresistance(wenowcallthisOctaneNumber)ofavailablegasolines,dictatedthatcompressionratiostayatlownumberslike4or5-to-one.

Ricardo attacked the problem fromall points of the compass. He dealtwith engine temperature bymakingpiston and cylinder of aluminum andthe headof aluminum-bronze (a 48%improvement inheatconductivityoveriron). The aluminum cylinder had anironliner.Hedealtwithoctanenumberby brewing up an alcohol-rich fuelthat strongly resisted detonation.Theresulting“Triumph-Ricardo”raceenginewasable to run8-to-onecompressionfromwhich it derivedhigh torqueandgood fueleconomy,beatingmachinestwice as large in both short and longraces.Naturallyeveryonewantedsomeof that, so Ricardo craftily arrangedtwo sources for his patent fuel—bothmakinganidenticalblend.Inamannerreminiscent of thearguments of partypolitics,racersendlesslydebatedwhichofthesetwofuelswasthebetter—littleknowingthattheywerethesame.

If we now pull out our “Handbook ofChemistryandPhysics”andcomparetheenergycontentofgasolinewith thatofalcohols,wewillbepuzzled.Thealcoholscontainonlyabout2/3oftheenergyofthegasolinehydrocarbons,byvolume.Alcohols are structurally hydrocarbonswith substitution of anOH- group foroneofthehydrogens.Thelowerenergyof alcohols as compared with theircorrespondinghydrocarbonsarisesfromthepresenceofthisoxygen—ineffect,analcoholisapartially burned hydrocarbon.Someof its original energy has beenusedupbycombiningwithoxygen.

Nowwe’reevenmorepuzzled.Ifalcoholscontain only 2/3 asmuch energy asgasoline,howdidtheTriumph-Riccywinallthoseraces?Andwhydodragstersinalcohol-fueledclassesmakemorepowerthan their gasoline-fired equivalents?And alcohol-class racers report thattheirenginesrunmuchcooler.Howcanalcoholyieldlessenergy,yetmakemorepower,while resulting in lower enginetemperature?

Theanswer lies in a special propertyof alcohols: their high latent heat ofevaporation. It takes some heat toevaporategasoline—that’swhy, if yougetgasolineonyourfingers, they feelcool.Butmuchmoreheat is requiredto evaporate alcohols.Now it gets abitmorecomplicated.Becausealcoholcontains less chemical energy thangasoline, we have to use a lotmoreof it to burn up all the air our engineis pumping.This need to usea lot ofalcoholaddsevenmoretothisheat-of-evaporationaffair.Indeed,thecompleteevaporation of the alcohol necessarytomake a chemically-correct fuel-airmixturerefrigeratestheairbymorethan400-degreesF.

Theextrapowerfromtheuseofalcoholfuelcomesfromthisrefrigerationeffect,which shrinks the fuel-air charge sothatmuchmoreofitcanbefedintotheengine’scylinders.Thecoolrunningofalcohol-fueledenginescomefromtheirlowerflametemperature—alsotheresultofthesevererefrigerationoftheinitialfuel-aircharge.

Now let’s jump to the 1930s.Aircraftenginemakersarestrugglingwith theproblemsofheatanddetonationmorethananyoneelsebecausetheirenginesmust givemaximum power for a fullfiveminutesduring take-off, thengivesomethinglike85%powerduringclimbtoaltitude.Ifanengineisevergoingtooverheatanddetonateitselftopieces,this is when! This wasmade all theworsebythecomingofsupercharging.Thoseweredesperatetimes—somuchso thatmany engineers thought theDieselengine—itstorquenotlimitedbydetonation-dictated low compressionratio—mightbetheonlywayforward.

Then new technologies came to therescue.ThomasMidgley,overatDelco,came up with the anti-knock agenttetraethyl lead, and S.D. Heron atMcCookFieldcameupwiththesodium-cooledexhaustvalve.Thoseadvanceseasedthedetonationsituationalot.

As supercharging raised enginetemperature and pushed conditionstoward detonation, engineers hit onthe idea of enriching the fuelmixtureduring take-off.Theextra fuelcouldn’tburn—therewasn’t enoughoxygen inthecylindersforthat.Butitsevaporationwould reduce the temperature of thecharge reaching the cylinders—andthatallowedmoresuperchargerboosttobeusedwithoutpushingtheengineintodetonation.

Therewerelimitstothis.Thebiggestofthemwasthatmixturesofgasolineandair richer thanabout10-to-onecannotnotbeignitedbyanormalspark.Thatmeantthatyoucouldenrichthemixturebyabout 40%,butmake it any richerthanthatandmisfiringwouldbegin.

TheHandbookofChemistryandPhysicshasbeenonalotofshelvesformanyyears,soitwasn’tlongbeforeengineerslookedintoitforsomethingtheycouldinject into engines running on take-off power that would have an evengreatercooling,anti-detonanteffectthanordinarymixtureenrichment.Waterwasaleadingcandidatebecauseitrequiresawhackinggreatamountofenergyto

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evaporate (that is, to boil). For eachgram of water evaporated, wemustsupply540caloriesofheat.

Ah, but airplanes may fly up highwhere theair temperature isvery low.It wouldn’twork toowell to have thewater/anti-detonant system freezeup,orevenburstitstankageandplumbing.An anti-freezewas needed, and theconvenientonewasmethylalcohol—ina50/50mixture.

Now as pilots eased their throttlesforward to take-off power, the controldiaphragmofawater-injectionregulatorsensed the high manifold pressureand began to flowwater.Despite thesupercharger,stuffingthecylinderswithextramixtureandheatingthechargeairbycompression,nodetonationoccurredbecauseevaporationofwater-methanolwaspullingdownthetemperatureofthechargeairsomuch.

Once take-off and initial accelerationwere complete, the pilot made thefirst power reduction and, at the newconditionsdetonationbecamelesslikelysothewaterregulatorshutoffthewater-methanolinjection.

EvenmorerecentlywehavethecaseoftheRenoairracers,withtheir4000-hpP-51sand4500-hpBearcats.Tomakemorepower, theyperformmiraclesofmachine-shop improvisation to adapta three-gear supercharger drive to an18-cylinder radial, enablingmost of1000-hptobesenttothesupercharger,tocompressandcrammixtureintothecylinders.Now,howdotheykeepthisoverstuffedenginefromdetonating?Allthatcompressionhasheatedtheintakechargealot.Toavoiddetonationitmustbecooled,andbycooling thecharge,itisalso“shrunk”involumeandmadeeasiertopushintothecylinders.

Howshallwecoolit?Onewayistoinjectever-morewater-methanol.Theotheristodirectlycoolthechargewithanair-to-airintercooler.Injecttoomuchwaterandyoubecomethefiredepartment—everygramofwatertakesaway540caloriesthatcouldhavebeenmakingpower.But

scoopingairthroughanintercoolercanveryeasilycosthundredsofhorsepowerinaerodynamicdrag.Damnedifyoudo,damnedifyoudon’t.

Okay, now we’ll leave those guyssweatingthatproblemoutinthedesert,andwe’llturntoourownTurboDieseltrucks.Whywould you inject water-methanolintoaTurboDieselengine?

Dieselsdon’tdetonate,sowe’renotdoingit to suppress detonation.What otherreasonmightwehave?Well,Dieselsdesignedtomeetemissionsregulationsburntheirfuelinthepresenceofabout20%excessair.AtBonnevilleandotherracingvenues,wheretherearenoclean-air teams fromWashington DC andDieselracersadjusttheirfuelsystemstodeliverextrafuel,somepowerismadewiththat20%extraair.Youcantellwhenthey’re doing it because, as the songsays,their“exhaustisblowin’blackascoal.”TheyearIwenttoBonneville, ittookmostofanhourforthelongblackcloudtodriftawayafteraV-16-poweredstreamlinedtruckmadea250-mphrun.InsteadofaddingextraDieselfuel,youcouldaddanyother fuel thatwouldn’tdetonate,tocombinewithsomeofthatexcess air, release extra energy, andmakeabitmorepower.

Anotherreasonyoumighthaveisthatyourchargeairtemperatureisstillhighdespite filling yourwhole under-hoodspacewith intercoolers and hot andcoldairductstoservethem.Liketheairracers,youmightwantto“shrink”yourcharge a bit by cooling itwithwater-methanolinjection.

Or, ifyou’rearacerandhaverun intosome special piston or exhaust valvetemperatureproblems,youmightinjectthestuffasageneralcoolant.

And,lastbutnotleast,lighttruckDieselsdon’t run on full throttle 100%of thetime, andwhen they don’t, they haveevenmorethan20%excessairpresentintheircylinders.Itwouldbetempting,withDieselsellingfor$4.50agallon,tosquirtinsomethingthatis(a)cheaper,(b) contributes useful power, and (c)

doesn’tdetonateasaresultoftheDieselengine’sveryhighcompressionratio.

Objections?Thefirstwouldcomefromthe predictable emissions standpoint.EverythinginDieselcombustiontodayis most carefully monitored so thatthe fuel control canperform its seriesof 4, 5, ormore separate injectionsper power stroke, timed and sized toresult in emissionswithin legal limits.Water-methanol injectionwill changeat leastsomeof thevariables(chargetemperature, timing of first ignition,rateofheatrelease),anditwouldbeamiracleifeverythingstayedthesame.

Alivelydebateatthemomentconcernsthe EPA’s skept ic ism about theautomakers’claimthatbuyersofDiesel-powered vehicleswith the upcomingSelectiveCatalytic Reduction (SCR)emissions controlwill always faithfullyremembertofilluptheureatankaswellasthemainfueltank.Somesaythatawarning lightwill do the trick.Otherscall for a power reduction and limp-homemode if theurea tankbecomesempty. Hard-liners want the engine(and its emissions) to stopwhen theurea runsout. IfDiesel engineswereemissions-optimized to operate withwater-methanol injection,whynot justhave them switch to a Diesel-onlyprogramwhentheW-Mtankempties?Because that requires two expensiveemissions development programsinsteadofone.Who’spaying?

I’m not saying this can’t or shouldn’tbedone—just that therewillbea fewobjections. Until the police take topatrolling the highways with remoteemissions sensingequipment, or untilmandatoryon-boardsystemsreportviacellphone all the details of operationto thedealerormanufacturer,youwillremainfreetodoasyouwishwithyourownequipment—exceptatmotorvehicleinspectiontime.


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hopingBack in the old dayswe couldmakepowerbyturbocharginganenginetothedesiredairdensityandinjectingfueluptojustshortofthesmokethreshold.Thenwediscoveredtheeffectsofparticulatesandthesmog-formingpowerofnitrogenoxides. The first response was touse after-treatment devices to filterout, burnup, or chemically convert toharmlessnesstheunwantedemissions.Butasitismoreefficientnottomaketheunwantedstuffinthefirstplace,majorefforthasgoneintofiner,higher-velocityfuel injection sprays,multiple sprayevents,andaccurateprocesscontrolbymeansofelectronics.Thiswasgood,buttherewasmoretocome.Nowtheytellusthatfutureenginesmustoperateatmuchhigherpressures.Thisisbecause(a)engineswillbemadesmallerwhileremainingjustaspowerfulasameansofcuttingfriction’sshareoftheaction,and (b) lotsmore cooledexhaust gaswillbeaddedtothecylinderchargeasameansofloweringflametemperatureinordertocutnitrogenoxidegeneration.Lotsofgasinasmallerengineaddsuptoincreasedpressure.

I hope that the necessary researchand development (R&D)workwill beperformedhereintheUSbyAmericanengineers.VWrana$200millionprogramtodevelopthenecessaryruggedbutlowfrictionbottomendrequiredforthiskindof operation.DoAmerican companieshave what it takes to push throughsuchprograms?Doctorsnowroutinelye-mailtheirX-raystoIndia,wheretheyareinterpretedat lowercostbyIndiandoctors.AreAmericanindustrieslookingat proposals from Indian or ChineseuniversitiesorconsultingfirmstohandleUSengineeringR&D?

Here we are split against our ownrhetoric.On theonehand,100% red-bloodedAmericans are required tobelieve that the freemarket uniquelydeliversthegoodsatthelowestpossiblecost.Thatmaymeangiving theR&Dcontracttowell-trainedandhard-working(not tomentiondeserving) personsatShenyangEngineering Institute, andtelling ourUSengineers their price istoohigh.

Ontheotherhand,commonsensetellsus that if toomanyAmerican incomestakethedownelevatorinthisway,thereare fewer people able to buywhat ismanufactured.Whatisworse,ifvaluableknowledge-centered employment isoffshoredasmuchofourmanufacturinghasbeen,ournationwillbecomelessand less technically capable as timepasses.Whenyoungpeopleseekcareerplanning advice today, they are nolongertoldtostudyengineeringandthesciences.Theyaretoldthehotareasarenursing,lawenforcement,andbusinesscomputerservices.

We had it good for 25 years afterWW II becausewhile other industrialnationshadbeensmashedbywar,ourproductive capacitywasnever higher.TheUSremainedtheproduceroflowestcost—sellingeasilyallovertheworld—untilaround1970.Thatisapproximatelyhow long it tookEuropeanandAsianproducerstopickthemselvesup,rebuildatfirstbyhand(cheaplabor!),andthenusewhat they’d earnedand saved toinstalltheverymostefficientautomatedproductionsystemsandR&Dequipmentavailable.Theninoneareaafteranother,foreignnationsreplacedtheUSastheproducersoflowestcost.

The result was reduced sales andincome formanyUS producers, andbankersrespondedbyred-liningwholeareasofmanufacturing.Hmm,maybewecouldreturntoprofitabilitybyreplacingouroutdated1950sequipment?

“Nope,sorry,wecan’tlendyoumoneyforthatsortofthing—thereturnscan’tevenbeatinflation.”

Just as engineerswork to solve theimmediate problems stopping theirprogress, investors responded byshiftingtheirmoney intonewactivitiesoffering higher returns.Mergers andacquisitionsheatedup.Buycompanies,usetheircashtopaythenote,sellwhatcanbesoldandclosedowntherest—afewlossesprovideusefulredinkattaxtime. But be careful—bankerswatchyourstockprice.

Whenpuzzled citizens askedwhy somany familiar industrieswere closingdown, theywere toldwe’veenteredasensibleneweraof“globalization.”

“Y’see,iftheSouthKoreanshavethebestpriceforsteel,theybecomesteelmakerstotheworld.IfJapanorGermanyhasageniusforautomaking,theybuildallthecars.Nationswithlessefficientsteelorautoindustrieswillnaturallyclosetheirsdown.Here inAmerica,we’vemovedpast your granddad’s smokestack,rust-belt industries to a fresh, sunnyupland—the ‘service economy.’ Sure,there’llbemomentaryhardshipforsomeofus,butinthelongrunit’llallcomeoutjustright.Waitandsee.”

We’ve been waiting. One piece ofadvicewe’veheardisthatwemust“allbecomeentrepreneurs.”Haven’tIheardsomethinglikethisbefore,reverberatingthroughhistory?Whyyes—itwasformerpresidentHerbertHoover,implyingthatAmericans thrownout ofwork by theGreatDepression of 1929might “sellapplesonstreetcorners.”

Afterthemergersandacquisitionscameourpresentday,whensomuchmoneyis to bemade simply by speculatingin money—derivat ives, currencyspeculation,andthemysterious“CDOs,”orcollateralizeddebtobligations.Theytellusthatinternationalflowsofcapitalexceedworldtradebyabout50-to-one.Andhistorysuggeststousthatwhensomuchmoney-making is disconnectedfrom useful products and services,little market oscillations or shifts inconfidencecanquicklydevelopintobiggolly-wobbles.

I want verymuch to see the comingdevelopments inDiesel engines, andI amhoping that this fascinatingworkwill be published in a language I canread. I amproud to see thatCadillacgathereditselfup,shookoffitspastof6000-poundroad-rollerswith8mile-per-gallon500-inchcast-ironpushrodV8s,anddevelopedentirelynewenginesandsystems that earned public trust andrecoveredadecentmarketshare.If—asappearslikely—theUSneedsfleetsof

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moderately-pricedsmall,highly-efficientautospoweredbylow-emissionsturbo-Diesel engines, I hope to see themdevelopedandmanufacturedhereintheUS,byAmericanengineersandfactoryworkers.Whiletherearestillenoughofthemwiththeeducationandexperiencetogetthejobunderway.


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Disel alternatives – Making the ChoiceOver the past few years a number ofcompeting combustion systems haveenteredthearenaofchoice.Originallythe choicewas only between spark-ignition andDiesel, but nowwe readabout gasoline firect injection (GDI),homogeneous charge compressionignition (HCCI), stratified-charge, andlean-burn.At first, research seemedto be seeking ultimates—the lowest possiblefuelconsumption,theminimum ofemissions.Today,withcostloomingever-largerasthecontrollingfactor,andunder thecontinuingpressureofsuchinitiativesasthecorporateaveragefueleconomy(CAFE),ultimatesmeanlessthanfindingtheleastexpensivewaytopowerwholefleetsofvehiclesacrossarangeofweightsandapplications.

Dieselenginesarehighly fuel-efficientand generatemighty torque, but theyare also fairly heavy for their power,requireanextremelyhigh-pressurefuelinjection system, and need complexand expensive technologies withtongue-twister names to cleanup thenitrogenoxidesthattheirhotcombustionproduces,andtoremoveparticulates.

HCCI promisesDiesel-like economyfrom a lighter, cheaper engine—butwhen?Thebasicconceptistomixjustenoughstill-hotexhaustgaswithfreshcharge,thenletcompressionauto-igniteit almost uniformly. Because ignitiontakes place throughout the chargevolumeandnotatasinglepoint,thereisnoflamefrontandthereforetherecanbenodetonation.Becauseofitsexhaust-dilutedcharge,HCCIcombustioniscool,generating littleNOxand so requiringonlymoderate emissions technology.Butprogressinextendingtherangeofitsabilitytofireinthiswaydowntoidleanduptofullloadisslow.Suchenginesmayalwaysbedual-mode,withsparkassistat full load.Development continues—whichmeansproducibleenginesareatleastacoupleofyearsaway.

GDI is attractive because it can beadaptedtoexistingengines,butitdoesrequireafine-particle-size injector thatisalsofastenoughtoformthemixtureinside the combustion chamber—not

upstreamintheintakeflow,asisthecasewith ordinary electronic fuel injection.GDI increases volumetric efficiencyby taking in only air during the intakestroke—no fuel.At one time it wasbelieved that adding fuel to the intakeair well upstream from the cylinderrefrigeratedtheairbythecoolingeffectof fuel evaporation, allowingmore airmasstofitintothecylinder.Butinfactitturnsoutthatthepresenceofliquidfuelin the intakestreamefficientlygathersheat frommanifold interior surfaces,heating the charge and reducing, notincreasing,itsdensity.Air—anexcellentinsulator—picksup lessheat by itself.The resulting cooler charge ismoretolerant of higher compression ratios,makingpossibleincreasedtorque.

Cadillac,aspartofitsprogramtogainayoungermarketwithhigher-techenginesandvehicles,developeditsCTSV6enginearoundGDI.Thehigherair-takingabilityofthisenginegaveitthepowerofa20%larger non-GDI powerplant. Now Fordis combiningGDIwith turbocharging inwhattheyarecalling“EcoBoost.”Makingan engine smaller reduces friction bycutting the number and size of friction-generatingcomponentssuchaspistons,pistonrings,bearings,andvalvegear—butitalsoreducespowerandtorqueaswell.Adding a turbocharger allows the lostpower and torque to be recovered, sothere can be a net savings of friction.The result is amore fuel-efficient, butjustaspowerfulengine.Combiningsucha downsized, but turbocharged, enginewithGDIrecoversevenmorepower.Theresult,Fordclaims,isV6swiththepowerofV8s, butwith “up to 20%”better fueleconomy.Becausesuchenginesarestillfairlyeconomicaltobuild,theoverallresultcanbevaluable,affordablegainsinCAFEforthemanufacturerandattractivelylowerfuelconsumptionfortheenduser.

The stratified-charge engine achieveseconomygainsbymakingitpracticaltooperateatveryleanair-fuelratios.Sadto say, as combustion ismademoreandmore intense—for example, bysuperchargingaspark-ignitiongasolineengine—wedon’t gain power in directproportiontothemassofchargeburned.

Whathappensisthattheconversionofcombustionheatintocylinderpressurebecomeslessefficientthemoreintensethatcombustionbecomes.Wenormallythink of temperature as the averageenergyof thezillioncolliding,zoominggasmolecules in the hot combustiongas—butthisisonlyanidealization.Thiszoomingmotionofthemoleculesiswhattranslatesintothepressurethandrivespistons—the sumof all themolecularcollisionswith thepistoncrown.But infact, as the combustion gas ismadehotter,moreandmore thermalenergygoesintorotationofthemolecules,andinto their internal vibrations. Becausethesemotions translate lesswell intopressureonpistons,hottercombustionislessefficientthancoolercombustion.Andthemorewediluteourfuelwithair(providedwecanstillmakeitburn)thecoolerwillbetheresultingcombustion,and the more efficiently this coolercombustionheatwilltranslateintopistonpush.

Then troublebegins.Becausea lean-burn engine adds less fuel to eachcylinder-fulofair,itneedstobebiggerto equal the power of a conventionalengine.Thatmeansextraweight.Andaleanmixtureishardtoignite,requiringspecialtechnology.Theanswerwastostratifythecharge—tomakeitquiteleanoverall, but locally rich enough to beignitedbyaconventionalsparkplug.

That leads tomore potential trouble,becauseany timeyouburnanormal,chemically-correctmixture you burnhot—and generate NOx that istroublesometocleanup.

Roundandrounditallgoes.Thegameistofindthetechnologyorcombinationof technologies that requires the leastoverall cost—costof research,costofmaterials,costofproduction,costoffuelconsumed.Today,thescarcityofmoneymakes basic research less attractivethan somehow improvising ways toadaptwhat isalready inproduction toperform in newwayswith aminimumof technology.The probable result isthat basic researchwill continue, butat a reduced pace,while companies

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concentrateonstayingafloatandsolvingtheir technological problems in thecheapestwaysandintheshortesttime.Later,when(if?)economiesrevive,basicresearchcanreturntoafasterpace.


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Cummins, Chrysler, FiatAccording to a recent press release,Fiathopestotripleitsautoproduction,which isnow2.2millionperyear.Thecompany already has branch or jointventure production operating inSouthAmerica, India, China, Russia, andEasternEurope.The obvious goal isto emerge from the present turbulenttimes as one of a reducednumber ofverylargesurvivingworldmanufacturers.Theirpendingplantotakea35%shareof failing Chrysler would give themexpandedaccesstotheUSmarket,andwouldbringtoChryslerFiat’sknow-howinsmallcarconstruction.FiatwithdrewfromtheUSmarketin1983.

Fiat’s truck division, Iveco (IndustrialVehicleCorporation), operates in 19countriesworldwide and has 31,000employees. Annual production is200,000commercialvehiclesandcloseto500,000Dieselengines

In 1996Fiat,CaseNewHolland andCumminsentered intoa joint venture.That joint ventureended in 2008withFiat’s engine development operation,FiatPowertrain,takingcompletecontroloftheEuropeanEngineAlliance(EEA),ofwhichCummins formerlyhada1/3share. The goal of the alliancewas,according to a 2008 piece byMikeBrezonickinDieselProgress,tojointlydevelop“anewgenerationof4,5and6-literdieselengines.”

Brezonick’spiececontinues“…ItbecameincreasinglyclearthatchangesinFiat’sdirection,particularly itsgrowingfocusonitsownenginesales,wouldaffectthelong-termviabilityofthealliance.

“Thefirstwritingonthewallmayhavecome as early as 1999, when NewHollandN.V.,ownedbyFiat,purchasedCaseCorp. as part of its foundationof CNH (CaseNewHolland)Global.Then inmid-2005, Iveco’sengineandpowertrain activities were mergedinto Fiat Powertrain Technologies(FPT),whichmoreaggressivelybeganpursuinggrowth inenginesales.ThatputCumminsandFPTincompetitionformuchofthesamebusiness—hardlyanidealsituationforalliancepartners.”

Quoting froma late-January piece byAlanBuntinginAutomotiveWorld.com:“Byallaccounts,relationsbetweentheEEA partnerswere far from smooth.CumminsallegedlyaccusedtheItaliansof reneging on an agreement thatFiat would not tout for outside, on-highwaybusiness.Althoughnotpubliclyacknowledgedatthetime,cooperationwasstrainedandtheEEAwasquietlydissolved about five years ago.AndwhenCummins embarked on an ISBupdateprogramtomeetEuro4emissionlaws—which involved, fundamentally,an increase in bore and stroke—thecompany bent over backwards topreventFiatengineersgettingaccesstothefinerdetails,includingthosecylinderdimensions.”

Asofthiswriting(5/6/09),ChryslerowedCummins $44million and CumminsenginesalestoChrysleraredown45%ascomparedwith lastyear,accordingtoareportonIndystar.com’sbusinesspage.AlaterreportsuggestsaFederalprogramwillpayCumminswhatChryslerowesthem,butsalesofCumminsmid-rangeenginesdoappearunderthreatfromChrysler’sdifficulties.

The current turbulence in the worldeconomyisonlyacceleratingaprocessthathasbeenmaterializingforyears—the consolidation of large excessproduction capacity in theworld autoindustry.Togrowor toshrinkappearstobethechoice.Scratch-and-scrabblewillbethemethod.

Fiat is one of the great original autocompanies, dating back to July 1899when former cavalry officerGiovanniAgnelli,twocounts,andabankerjoinedforces for the purpose. In 1900 theCorsoDantefactoryopened,employing150 people and building 24 cars. In1903their12-horsepowerfour-cylindercar soldwell inFrance,England, andAmerica. Therewould follow classicyearsinautoracingbeforeWorldWarOne,theconstructionofmanytypesofaircraftengines,andofcarsandtrucks.FiatexpandedsteadilytobecomeandremainoneofEurope’slargestvehiclebuilders. Fiat currently owns Ferrari,

but they are known best for buildingsmall, economical automobiles on alargescale.

USautomakershavebeenunable toresist themoney to bemade in largevehicles likeSUVsandpickups,whileknowingthatultimately,theworldmustturn to smaller cars.WhenEuropeanandAsianeconomyautosfirstappearedin the US, industry heavies wereamused.

“Thesoonerthesebeginnerslearnthatsmallcarsequalsmallprofits,themorelikelytheyaretosurvive.”

Companies such asVW,Toyota, andHonda did learn how to earn a profitonsmallcars,buteach timehigh fuelpricesdroveDetroit to consider doingsothemselves,crudeoilwoulddropandthequickprofitswereseentobeoncemoreinlargevehicles.

Thisbecameacyclicprocess,operatingratherlikearatchet.Whengasolinejumpedin price in 1974,Honda respondedwiththeAccordmodel,whichwasasmallbutfeature-laden car.ManyAmericans sawtheAccordas the small carwith big-carluxury—andtheyboughtit.Whenfuelwasagainplentiful,manyofthosewhoboughtAccord remainedHonda buyers, whileothersreturnedtobuyinglargeAmericancars. Japanese andEuropean cars hadby now earned the reputation of beingreliable and of good quality.When fuelpricesjumpedagainin1979,anewgroupofAmericans bought smaller,more fuel-efficientcars,andwhenpricesmoderated,some of them remained smaller-carbuyers.

WhenUSmakers decided theymustafter all offer smaller cars, their initialofferings of the 1980s were hastily-designedandmanyofthemperformedpoorlyandwereindifferentlyconstructed.Valuable brand identities forged overmany yearswere sacrificed in amadscramble to produce generic “DetroitToyotas.” Some of the least-popularoftheseweretheChryslerK-carsandGM’s “Chevrolac.”While the importsoffered higher-performing engines

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andchassiswithmodernhandlingand“feel,”manyofthenewUSofferingwerepoweredby stodgy two-valve fours orV6sthatwereconceptuallyadaptationsofantiqueironV8s.Inthe1990sDetroitbegan tomend fences by developingmoremodern technologies, but in themeantimethedamagehadbeendone.Americanshadcometo regard importcarsasofgenerallyhigherquality,andAmericancarsassecondbest.Theup-and-downratcheteffectofrepeatedfuel-pricecrisesalternatelyforcedDetroittotoolup forsmaller cars, then temptedthemtodropsmall-carplansinfavorofareturntoquickprofitsfrombigvehicles.InthecourseofthesecyclesDetroitlostabouthalfofitsmarket.

Meanwhile, the import brands refinedtheirability toearnaprofitonsmallercars.Fiat’slongsurvivalintheEuropeanmarketplaceindicatesthattheyhavethatabilityaswell.Theyappeartobebettingthatthecurrentperiodofmoderatefuelpriceswon’tlastforever.Ifpricesjumpagain,whoeverisbestpreparedtoofferattractivesmallcarsataffordablepriceshasachancetoearnmoney.CouldthatbeFiat,buildingwhattheyknowbest,inChryslerfactories?


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GTL RevisitedI havediscussedgas-to-liquids (GTL)Dieselfuelinthiscolumnbefore(Issue49,August‘05).Geologicaloildepositscontain some liquids that assumegaseous state once released frombelow-ground pressures, and of thiswhatwecallnaturalgasconsistsmainlyofmethane.Amoment’sthoughtaboutwhatmight happen to petroleumovermillionsofyearsofundergroundstoragereveals that less-stable arrangementsof carbon and hydrogen atoms aregradually broken apart by thermalmotion and reform intomore stableforms.Among the most stable aremethane (one carbon atom, joined tofourhydrogens)andtheringstructuresoraromatics(whichmakeupsomuchofDieselfuels).

GTLismadeunderprocessconditionswhich favor the assembly ofmultiplecarbon atoms into chains. Chains,having loose ends, aremore easilybrokenapartortheirhydrogensknockedoffbyheat,andsoGTLDiesel ignitesmore promptly (higher cetane rating)andburnsmorecompletely thandoesthemore stable ring-structuredDieselfuel. It also costs about 10%more.Moreaboutthatcostlater.Mostofthecombustionandemissionsbenefits ofGTLarepreservedevenwhenitiscut50%withconventionalDieselfuel.

Gasisaproblemintheoilfields.Whatdoyoudowithit?Formanyyearsitwasflared off—simply burned up—ratherthan solve the difficult problems ofgettingittomarket.Gasformsexplosivemixtureswith air, so there is hazardin its presence. Compressing andcompactlystoringitrequiresexpensiveand specializedequipment—andLNGshipsforoverseastransit.ButpipingitshortdistancestoGTLconversionplantsisalsopossible.Currently, I learn, thetwomarketing options cost about thesame.

For a time, gaswas regarded as themiracle fuel of the future. It burnsrelatively cleanly and can be used topower compact gas turbine-drivenelectricitygeneratingstations.Ithaslesscarbon in relation to its heating value

thandoheavierfuels,soitisattractiveonthebasisofreducedcarbondioxideemissions. Lots of powerplants—boththermalandgasturbine—begantoburnthestuff.Ohjoy.

Then the price of gas went up—abunch.Powercompaniesdependuponstockholderswhomove theirmoneytomore profitable investments if thenumbers start to look bad. To keepthe numbers good, expensive gas-fired plants were quicklymade lessnumerous and coal-fired plantsmorenumerous. Stockholders may drivePriusesandhelptheirschool-agesonsand daughters recycle bottlecaps onSaturdays, but they are very seriousaboutstockprices.Asonelong-departedUSpresidentoncesaid,“Gentlemen,thebusiness of this country is business.”Currently,themiracletrustedtooptimizethe compromise between costs andemissions iscalled “capand trade.” Ithastodowithbuyingandsellingrightstoemitcarbon.Ihavenoideawhatcapandtradewilldoforus,butitsurelywillnotexistforlongifitfailstoearnseriousmoneyforsomefolks.

GTL is very attractive, but gas isexpensive,andinmanycasesit is faraway, across oceans.And there areothercapablebidders.

Thescaleofenergyuseinthiscountryisenormous.Pleasekeepthisinmindthenexttimeyoureadabouthowwindenergyusehasdoubledinthelasttwoyears. Bravo, but wind energywas supplying one-tenth of one percentof this nation’s electricity. Now it issupplying two-tenths of one percent.Coalnowsupplies50percent,andone largecoal-firedstationburnstwo10,000ton trainloads of coalevery day.Thatisonetonofcoalevery fourseconds,burnedineachsuchbigplant.Andtherearehundreds,socoalminingisfastandfurious.

Hand-waverstellusthesolutionistogetoutofourcarsandontobicycles,toshutoff our air conditioners, and to put onwarmcashmeresweaterswhilekeepingourhousesat55-degreesinwinter.You

sayyouhaveatwenty-milecommute?Moveclosertowork.Liveefficientlyinemissions-optimizedurbandorms.

Getserious.Thecitiesandindustriesofnorthandsouthalikearemade possible byairconditioningandspaceheating.Twenty percent of our nation’s yearlyelectricity consumption goes for airconditioning.Manyofthisaudienceareold enough to rememberwhole officebuildings-fullofpeoplesenthomeinJulybecause peoplewere fainting in theiroffices.Oldor infirmpeople in un-air-conditionedapartmentsdiedorrequiredhospitalization.Onlyafewcanremembertrying to get theirmanufacturing jobsdoneinsun-roastedplants,orheatingonly the kitchen of the farmhouse inwinter.Onlyasmallnumberofwell-to-dosuper-environmentalistscanaffordsuchretrochanges.

Sure,wecansavesomefuelbyjudiciouseconomy,butwecan’tjustshutofflifeas we know it and switch on somenew, better, andmore responsible lifeovernight.Whopays the large capitalcosts?Whowouldmakeallthebrand-newdetailsmesh?Whoorwhat—shortof a draconianWorldGovernment—wouldmake us all do this?A vaguesense of responsibility? That senseof responsibility hasn’t put an end todrunkdrivingorcheatingontaxes.Whywould it change our oil consumptionovernight?

Well,then,isn’tittruethatvastenergyresourcesawait usasoil shale, deepunder the Four Corners region oftheAmericanSouthwest?And aren’trecovery operations in progress inAlberta,Canadaontheirvasttarsands?Yes,inbothcases,butguesswhat?Pricerules.Whatdoesthatmean?Itmeansthatoilcompanieswillkeeppumpingtheeasiestoilfirstforaslongasitischeaperthanthealternatives.(RememberthosePrius-driving stockholders, all readingthe WallStreetJournal.)Theoilshaleis hard to get at and requires lots ofwater (an availability problem in theSouthwest)andlargephysicalplantforits conversion to liquid fuels.The tarsandshave tobeheated tomake the

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glop runout, andonce theyhave thestuff, it requiresquitedifferent refinerymethodsandequipmentfromtraditionalpetroleum.Thelandiswreckedbytheextraction and itswaste products.Allthistacksonextracosts.Stockholders—even as they public-spiritedly switchfrom paper towels towashable linennapkins—hatethat.

Sothesearchforpumpableoiliswhereit is at—for the foreseeable. GTL isjustaminor,ifinteresting,detailinthatlargerpicture.Andlittlethoughwemaylikeit,theUSisjustoneplayeramongplayersintoday’sinternationaloilquest.Whoeveroffers thebestdealgets thegoods.Regrettably,thegameismadeharderbyhistory.JustafterWWIItheUSwon theday inSaudiArabiaoverBritish oil interests because theArabworldhadlongnegativeexperiencewithBritishcolonialism.(AfterWWIBritainparceledouttheremnantsoftheMuslimOttomanEmpire,keepingthebestbitsforherself.)Today,theUSislookeduponbymanyforeignnationsasaninterferinguncle, just as Britain was then.Weearnestly try to be BFFs (that’s kid-speakforbestfriendsforever—groovy,eh?)simultaneouslywithIsraelandtheArabworld.Goodluck.Wehavetolivewithallthis.

Meanwhile, China finds fair successplaying the “good cop” role, buildinginfrastructure in oil-rich nations thatagree to supply her swelling industry.It’s reallyannoying todiscover thatallnationshaveclever,resourcefulbusinessmindswho negotiate just as hard asoursdo.Chinesebusinessmenarenotweak-mindedCommunist ideologues,brandishingLittleRedBooks.Whattheywantismoney,whichsalutesnoflags.

Just forget the idea that oneof thesePresidents will finally deliver on hispromise to end US dependence onimportedoil.Theycan’t.Thestockholderswon’t let them.Can’t let them.This isbusiness.

Alsoforgetthecrackpotideathatliberalloveforspottedowlsorbabysealsisallthatkeepsusfrom“unlimitedoil” from

vast,off-limitsoffshoreorAlaskafields.Oilisseriousbusinessandthestrongestplayerwins.Hundredsofthousandshavediedtoprovethis.HitlerinsistedthathisArmyGroupSouthkeeppushingtowardthe Soviets’ Baku oil fields—despitethree Soviet armiesassembling tocutthemoff.Hitlerfinallyrelented,butnotintimetosave300,000GermansencircledatStalingrad.BecauseGermanywasunable to seize Baku oil, it becamenecessarytosynthesizeliquidfuelsfromcoalforGermantanks,submarines,andaircraft.Itwasnotthecheapestsolution.Itwastheonlyone.ManyaUSB-24orB-17crewmanmethisfateattemptingtodestroytheresultingGermansyntheticfuelplants.Hitlercomplainedconstantlythathisgenerals“hadnounderstandingofeconomics.”

InthePacific,JapanwenttowaragainsttheUS,Britain,andHollandwhentheUS—supplierof80%ofJapan’soil—cutofftheflowtoshowextremedispleasureattheJapaneseoccupationofVietnaminthespringof1941(FrenchIndochinaat the time).AsJapanhadcutherselfbigger and bigger slices of Chinathrough the 1930s, theUS sent herdisapprovingnotes, but could takenoactionbecauseitwasthedepthsoftheGreatDepression.Historybooksdon’tcall this“appeasement,”but ithadthesameeffect.

If you read the history that Japaneseschoolchildrenreadtoday,itsaysthattheUSactionforcedJapantochoosebetween (1) accepting the status ofa poor third-rate nation or (2) takingmilitary action to secure a reliablepetroleumsupply.JapanhadseentheindustrialpowerscutupaweakChina(whiletakingplentyherself—Manchuria,rich in coal and iron). Japan had nodesire to become anyone’s colony.ThishadbeenthedrivingforcebehindrapidJapaneseindustrialization.Intheirview,oilwaspower,andtheymeanttohaveit.

The Japanese therefore planned toseize the richDutch oil fields inwhatis today Indonesia, but that wouldinstantly trigger strong and probably

unmanageable military responsesfrom thewestern powers.Todelay orsoftenthoseresponses,theJapanesesentalargetaskforceofsevenaircraftcarrierstoknockouttheUSnavalbaseat Pearl Harbor, and sent JapaneseArmy units to seize theBritish navalbaseatSingaporeandUSbasesinthePhilippineIslands.

Thepoint?Nationsaredeadlyseriousaboutoil.Spottedowls?Readthepapers.Inless-jollypartsoftheworldjournalistsmeetwithmysterious accidentswhentheyuncoverembarrassinginformationabout the high bid,whomade it, andwhat the numbers were.We get tosee the ripples on the surface, readabout the variousmaneuverings overNiger,Somalia,Chechnya,theSpratlyIslands—alltheplaceseitherproducingoilnow,orwithpromisingseismicreportson file at Slumberger, Halliburton, orother respected petroleum surveyfirms.Mostofall,weseethepetroleumand stock prices. You’ll know oil isnearingitsrealendwhenShell,Exxon-Mobil, Lukoil, and the others shiftmajorinvestmentmoney—many,manybillions—tootherenergyschemes.Untilthen,wecanconfidentlyassumethere’splentytocome.WecanhopeasadetailthatDieselpowerfindsaplaceincurrentUStransportationplanning.(There’salotoftalkaboutelectriccars,buttrytoimaginewhat anelectric truck wouldlooklike.Whatcoulditcarry,besidesitsownbatteries?)Andsomewherewithinallthatplanningmayberoomforsomerefreshing, crystal-clear, clean-burningGTLDieselfuel.


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smokeI wonder if there is any coherent“Diesel lobby” in this country. Thedomestic automakers’ interest in thisis proportional to the amount of theirbusinessthatisDiesel-powered—whichisquitesmall.The truckbusinesshaslittlereasontopushitspositionbecauseit’snotasthoughthereisanycompetingpowerplant for them. (Try to imagineYellowFreight’s payload fraction afterswitchingtoelectric.)SotheresultisthatDieselpowerisprettyquietintheUS.

Meanwhile Honda and the Germanautomakers aremoving forwardwithUS-compliant Diesel autos, but theyare swimmingagainst a tideof publicopinion that thinks “Diesels are dirty,”or“Dieselfuelisaninherentlypollutinghydrocarbon.”Iwantthatkindofpublicopinion to consider that all the late-model Diesels operating in the USmeetthelawsofthelandwithrespecttonoiseandemissions.Diesel-poweredvehiclessoldintheUSare100%okaywithpublicpolicyandareequalpartnerswith gasoline-powered counterparts incutting emissions. Indeed, the resultsproduced by 2007-compliant Dieselsaresaidtobemuchbetterthanplanned.But there is noDiesel lobby bringingthis information to theattentionof thewholepublic.

Yes,thegreatertheaveragemolecularweightofahydrocarbonfuel,themoredifficultitistoburncompletely,whichiswhyDiesel engines have traditionallyhadtheproblemofexhaustparticulates.Current technologies work on thisproblem from both ends. Ultra-high-pressure,multi-strikefuelinjectionworksfrom thecombustionend todrive fueldropletsthroughcompressedchargeairatclosetothespeedofsound,causingrapiddropletbreakupandevaporation.Thesearekeystoimprovedandmorecompletecombustion,fortheclosertheinjected fuelcomes to thevaporstateat the timeof combustion, the likelierit is that each and every hydrogenandcarbonatomwillbemarriedofftooxygen.Thatmeanslessleftoverintheformof the fearedpolycyclic aromatichydrocarbons (PAHs), riding on theclumps of uncombined carbon atoms

thatweknowasparticulates.

Andwhat there is of those leftoversmustnowpassthroughparticulatefilterswhere the legally-mandated fraction istrapped, held, and then burned.Thatmeans nomore black exhaust, andforourlungsitmeansgreatlyreducednumbersofairbornePAHmolecules,withtheirpotentialascarcinogens.(ThinkofPAHsasakindofTinkertoy,madeupof hexagonal 6-carbon rings, linkedtogetherbysharedsides.Carbonringsarenot“dirty”andtheyarenot“evil,”astheyareemployedbyplantsasstructuralelements of cellwalls. Inconveniently,some structures are carcinogenic.Curare,adeadlypoison,is“all-natural”anditisdemonstrably“organic”—butit’spoisonnevertheless.)

Ihadalookatthefacultyparkinglotatthelocalcommunitycollege.Nopickuptrucks—zero.ButonlytwoHondaInsighthybrids.What I did seewas lots andlots of small economy sedans—thekind that the Europeans power withsmall turbo-Diesels, enabling themto use30-40% less energy thangas-powered equivalents.Maybe this justmeanscommunitycollegefacultyaren’tpaid enough to affordmany LincolnNavigators.

Currentlythereismuchdiscussionof“80in ‘50,”whichmeans reducing carbondioxide emissions by 80% by 2050.Setting aside the question of globalwarmingitself,whatdoesthisimply?Mypresentcar—aChevyCobalt—averages27mpginmixeddriving.IfItradeditfora two-seat Insight and drove only onfour-lane highways, using the “pulse-and-glide” ultra-mileage technique offull-fanatic econo-drivers, Imight get95mpg. Sorry, not good enough—I’dhave to get 135-mpg to hit that 2050goal.

IliveintheSnowBeltandhavetoheatmyhouseOctobertoApril.Howwillmydescendants cut their heating bill by80%? I have six inches of fiberglassinsulation on the south side and teninches on the north.Will I have toincrease that times four?Two feet of

insulationonthesouthandthree-and-a-halfonthenorth?Andfilltheatticrighttotheroofwithlayersofbatts?Impractical.My great-granddad’s generation hada simplerway—they lived only in thekitcheninthewinter,andworewoolenunion suits to bed. Is this the futureAmericanWayofLife?

Nowhowabout thecities?Everythingcity-dwellerseatorotherwiseconsumecomes in by truck or train, and isdistributedbyDieseltrucks.Canwecuttheirfueluseby80%?

Atthispointtheinformedenvironmentalistchimes in, “Of coursewedon’tmeanstarving the cities by cutting truckfuel 80%. We mean converting toclean, zero-emissions electric powerfor these uses. By that time, electricpower generationwill have switchedto nuclear or to gas, clean coal, andcarbonsequestration.Why,evenaswespeak,agiantcoalplantinWestVirginiaisrunninganexperimentalprogramtoremovecarbondioxidefromstackgas,coolandcompressittoliquidform,andpumpitmilesdeepintotheearthwhereitcanneverescapetotheatmosphere.”

Let’staketheitemsonebyone.Electrictrainsarefine,andhaveexistedfor2-3generations, allowing goods to entercitiesinsmokelessfashion.Butelectrictrucks?Unlesstheyareonlygoingafewmilesoneachtrip, it’sfairtoaskwhattheycouldcarryinadditiontotheirownbatteries.A BMWMini, converted tobattery power andwith approximately100miles range, gives up two of itsfour seats to batteries, and its rangeiscutsignificantlyifthebatterieshaveto supply cabin heat inwinter.. In-citydeliverymightbeanelectricapplication,but long-distance trucking certainly isnot.Aircraft are not.Ocean shippingis not.Arm-waving about magicallybringingback the railroadsflies in thefaceofthethousandsofmilesofroadbedthathasbeentornuptomake“rail-trails”for snowmobilers, four-wheelers, andmountain-bikers.

Clean,zero-emissionselectricpower?Yes, at the point of use there is only

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a faint smell of hot insulation. But atthe point of power generation at thispresentmoment coal supplies 48.5%of the nation’s electricity,with nuclearandgasvyingforsecondat19or20%each.Gas is attractive, especially forcities because a bunch of compactgas-turbine-powered alternators canbe brought in on railcars, plugged-in,andstartedupwithouttheusualtwentyyearsofwranglingoversiting,permits,environmentalimpactreportsandlongseries of wonderfully boring publicmeetings.But gas is expensive.Onlycoalischeap,whichiswhyitsuppliesessentiallyhalfofourelectricity.

Atthispointthesuper-environmentalistcuts in and says, “Coal is green.”Our collective, hydrocarbon-burningjaws drop. How? He explains that“Hydrocarbon fuels have hiddenenvironmental costs,suchasoffshorepolitics, refining, disposal of wastes,and transportation half-way aroundthe globe.Coal is here and requiresalmostnoprocessing.Coalcutscarbonemissions.Coalisgreen.”

Beforewegetsuckedintothisone,takeadeepbreath.Mostofwhatpassesforenvironmentaldebateissloganswhichneithersideunderstands,butjustrepeat,asloudlyastheirpromotionalbudgetsallow. Like presidential elections, thisis an arm-wrestle of television time,clever publicists, and slogans.Gosh,folks, last I checked, strip-mining ofthe kind that extracts all that coalinWyoming was widely consideredenvironmentally nasty.Now it’s okay?Howaboutremovingthewholetopsofmountains inWestVirginia, and howaboutmenwithblackfacesand lungsdescendingintotheearthinconditionsofponderablerisk, forwagesthatcanonly be called “extremelymoderate?”This is green, just because someoneneeds tomake it look thatway—theendsjustifyingthemeans?

Andwhat is “cleancoal”? It isa suiteof technologieswhich could be usedto extract undesirable matter fromthe stack gas of coal-burning electricplants—analogous toDiesel exhaust

aftertreatment. It hasbeendiscussed,but is not currently in use because itcostsmoney.

Oh, no!Another large contingent ofwould-beproblem-solversspeaksupatthispoint.Theseare the“free-market-will-solve-everything” people. Justmakeelectricityabuck-fiftyakWhandgasoline$20agallonandtheworldgetssqueaky-clean overnight.That’s okayforthosewhocancomfortablyaffordit,buthavealookatwhat’shappeningtomanyof our cities—endlessblocksofemptybuildings,windowsgone,coveredwith graffiti.Make everything super-expensive and lotsmore people dropoffthebottomofthefood-chain.Icouldbeoneofthemunderthoseconditions,because Iwas too shiftless and lazyto become a vice-president of Enronor aMadoff partner. It’s socially riskytohavetoomanyangrypeopleonthebottom—managingthebalancebetweenpleasant living in gated communitiesandgrittyurban realities isoneof thetrickiest tasksofgovernment.Theso-called “free-market solution,” with its$20gasoline(and$24Diesel,let’snotforget!)wouldmakeitinfinitelytrickier.Butitcouldhappenanyway.

Howaboutcarbonsequestration?Turnsout that pilot plant inWestVirginia isprocessing2%ofoneplant’sstackgas—amodest but significant experiment.They may learn whether the highestimate—that sequestrationwill add30%tothecostofelectricity—orthelowestimateof5-15%,istrue.Willwebetoldtheresults?I’mnotsure,becausesomeone in a responsible position inbusinessorgovernmentmaydecidethatan “adjusted”message—even thoughit’safib—representahighermoralgoodthantruth.Sadtosay,ithashappenedbefore now.Makesme think of thoselong-agodebatesovernuclearpower,inwhichteamsofbright,well-paidmenand women, educated at the sameprestigious universities and trained inthe same arcane specialties, argueoppositesidesofeverypoint.Whatdoesthissuggesttothelayperson?Nothinggood,exceptmaybe thatopinionsareforhireandthattruthmaybeirrelevant

totheoutcome.

Howdowegettoafutureworldinwhichwe use less energy,where the leastamong us aren’t tempted to becomedesperaterevolutionaries,andtheothersarenotcrowdedintosmallkitchensjustbecauseit’scoldoutside?Bygolly,that’sagoodquestion.Here,helpmeteartheglassineaddresswindowsoutoftheseusedbillingenvelopessoIcanputthemintherecyclingwithaclearconscience.Nowwearegoodchildren.

I’d l ike to hear lots more from aDiesel lobby,becauseDieselpower isdefinitelygoingtobeanimportantpartoffutureenergy-savinginthiscountry.“Electric”hasabigheadstartinbuildingpropagandapower,butDieselpowerispracticalnow.


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By Golly, You Don’t say!JustrecentlyIwasattheNewEnglandAirMuseumand cameupon a groupofyoungpeoplelookingatabig1940saircraftpistonengine.Oneofthemwassaying;

“And you knowwhat ELSE is JUSTAMAZING?TheydesignedthesethingswithSLIDERULES.”

Is thatso,sonny? In fact,mostof theworld’sgreatbridgesandtallbuildingsweredesignedinthesameway,aswerethe atomic bomb, the transistor, andradar.Thesliderulewasjustadeviceformakingquicknumericalestimates.Therealworkofdesigntookplacethroughunderstanding the physics involved in the problem,andusingthatasaguidetonewsolutions.Understandingisthekey,notrawcomputation.

It is important toknow justhowmuchcomplex instrumentation went intoacquiring that understanding.When Iwasbarelyoutofcollege,IvisitedMIT’sSloanAutomotive lab,where theMITbalanced-diaphragmengine indicatorwas still in use. This was a devicewhichenabledtheactualcompression,suction,andcombustionpressuresinanengine cylinder to bemeasuredwhilefiring.Onesideof thediaphragmwasconnected to theengine’scombustionchamber and the other to a variablesourceofpressure.As theengineranonadynamometer,pressureononesideofthediaphragmwasslowlyvaried,andthepointofcrankrotationatwhichthediaphragmchangedsidesinitshousingwasnoted.Gradually,point-by-point,acompletepressure-volumecurveoftheenginecyclecouldberecorded.

WiththisP-Vcurveitwasthenpossibletocalculatethepowertheenginewouldmakeiftherewerenobearingorpistonfriction.Itwasalsopossibletoderivethespeedofflamepropagation,andtoseethebeginningsofdetonation.

Today, an engine indicator takes theformofan$8000water-cooledpressuretransducer that screws into the head,sendingitssignaltoapre-ampthatthenfeedsdata toacomputer.Same idea,

fastermeasurement,newequipment.

Howmuch stress do you suppose isacting on this connecting-rod duringoperation?Todaycomputersareusedtorunrapidanalysisofthisbaseduponconceptually breaking the rod up intoan assembly ofmany small regions(finite elements), then computing theforcesgeneratedby,andactingupon,each such region. Millions of suchcomputationsproduceapredictedstresspattern in the rodateachpoint in theenginecycle.Backinthe1980safrienddescribedseeingsuchafiniteelementanalysis(FEA)inprogressatanenginemanufacturer.Computerswereslowerthen,sothefalse-color“stresspicture”oftheconnectingrodwastakingminutestofillup themonitor’sscreen, line-by-line,startingatthebottom.Meanwhiletheengineerwenttothecoffeeroomtorefreshhimselfwithahotdrinkandthemorning’sgossip.

Thisnewbreedofengineerissometimescalleda“screenjockey”andhedependsmore onmachine computation andmodeling thanonunderstanding.Thatishowhewaseducated.Thisbecomesever-more true as older engineers—thosewithlongexperience—areofferedearly retirement and are replaced bymuchyounger(andlesser-paid)personsseated at rows of high-end computerworkstations. Why think through aproblemwhen themachinewill crankoutasolution?

How did engineers of the past knowwhether a cylinder blockwas strongenough? Or too strong? Today adynamicFEAwouldbeused.Butlongago,E.S.Taylorcameupwithasimpletechnique that gave direct answers.Thiswas “brittle lacquer”—to coat thepartinquestionwithabrittlepaint,thensubjectittostress(suchaspressureincylinders).Whereverthestrainexceededacertainvalue,thelacquerwouldflake.Afewcyclesofthistechnique,combinedwithchangestothecasting,resultedinastrongpart.

Metalpropellersdrivenbyaircraftpistonengines were vulnerable to fatigue

failurescausedbybladeflexuredrivenby the engine’s firing impulses.Oneapproach to a solutionwas to designcrank counterweights as pendulums,whosemotionwouldabsorbenergyfromthecrankasacylinderfired,thenswingbackandgivethatenergybacktothecrankasfiringpressurediedaway.Suchpendulous counterweights smoothed-outtheengine’storquevariationwithoutactuallyconsumingpower.

Buthowmuchstress remained in thevarious parts of the propeller blades?Bladeswere instrumentedwith straingauges adhered to their surfaces,with thewires from thegauges led toa slip-ring assembly.Then theenginewasrunorthewholeairplaneflowntorecordthestresslevelsatvariousrpmand load, determiningwhether or nota given engine-prop combinationwassafetofly.

Moving parts of engines have beensimilarly instrumented. Piston ringshavebeeninsulatedfromtheirpistoninordertostudytheextentoftheircontactwith the cylinder wall by electricalconductivity. Connecting rods havebeencoveredwithstraingauges,theirleadsfedthroughribbonwireorafeedarm.Temperaturesofcriticalpartscanbemeasured either electrically, withthermocouples, thermally with plugsof metal alloys that melt at varioustemperatures, or bymeans of paintswhich change color over a scale oftemperatures.

Longago,inabout1903,theautomakerNapierinEnglanddevelopeditsfirstin-linesix.Thegreaterlengthandtorsionalspringiness of this crank allowed theengine’sfiringimpulsestoexciteitintotorsionalvibration,makingitstiminggearrattleloudly.Thisproblemwas“handled”by thefirm’sPRman,S.F.Edge,whocheerfullycalledthenoise“powerrattle.”ButwhenRollsproduceditsownsixin1905,theytackledtheproblemdirectly,placingaspringdrivebetweenthecrankandgearbox,andplacingaLanchesterfrictionaldamperonthefreeendofthecrank.Clearly,someonethoughtaboutwhatmust be going on and cameup

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withaseriesofexperimentalsolutionsquickly leading to a practical fix.Thesame company was able to pacifytorsionalvibrationinthecrankshaftsofitsMerlinandGriffonaircraftenginesastheirpowerwasdevelopedfrom900hpin1939to2250hpattheendofWWII.Allwithoutcomputers.

In the 1930s this same problemwastackled more directly by use of aninstrumentcalledthe“torsiograph”.Thisemployedaninertialflywheel,freetoturnon itsownbearings,but restrainedbysprings.Asthecrankspun,theflywheelturnedsteadilyasthecrankrotated initsseriesofjerksandvibrations.Thesejerksandvibrationswererecordedbyacapacitorwhosevaluewaschangedbythe positional difference between thecrank and the torsiograph’s flywheel.This,inturn,controlledthefrequencyofanelectronicoscillator,whichwasthenrecorded.By thismeans theextentofthecrank’storsionalvibrationcouldbemeasuredquiteaccurately.

Diesel engines for submarineshad tobe ofmuch lighter construction thanwereDieselsforindustrialapplications,andtheyhadtobeslenderenoughtofitwithinthehulls.Torsionalvibrationwasimmediatelyaveryseriousproblem,aslightercrankslackedtorsionalstiffness.Asaresult,operationofsuchenginesat certain speeds led rapidly to crankbreakage.At first, the solutionwas toprovide tables of vibration amplitude,measured in engine trials, and toforbidoperationatthosespeedswhichespecially excited crank torsionals.Conducting a night surface attack isnerve-wrackingenoughwithoutworryingaboutcrankshaftforbiddenspeeds,sothiswasnotapracticalsolution.Whatdidworkwas tocouple theDiesels togenerators,operatethemataconstantsafe speed, and vary propeller rpmelectrically.

All thiswas donewithout computers.Indeed, math ana lys ts createdprocedures bywhich any crank couldbereducedtoan“assemblyofspringsandmasses,”whosemotionscouldbeanalyzed by computations performed

eitherwithslideruleormechanicaldeskcalculators.Thisworkwaslaboriousbutproducedusefulresults.

Engineshavebeenbuiltwith“floating”cylinder liners,byuseofwhichpistonring friction forces were measuredat all points in the engine cycle.Thisenabled validation of mathematicallubricationmodels, which could thenbeusedtopredictfutureperformance.Suchmodels are still in use, but therequired computations are performedmuchmorequicklytodaybycomputers.Yettheoriginalunderstandingofsuchphenomenawas generated by usingexperimental rigs to ask nature therelevantquestions.Thisrequiredactualthought—not just loading data into a$40,000 software package and thenhitting“run.”

From at least the 1930s, engineswith transparent cylinderwallsmadeof quartz have been used to studycombustion and flame propagation.Rowsof ionizationgaugeshavebeenscrewed into cylinder heads to recordthe velocity and direction of flamepropagation. Even before that,HarryRicardo used an in-cylinder pinwheeldevicetomeasuretherateofairswirlin combustion chambers. This wasdone to determine just how muchturbulencewas required to completecombustion in a given time, or as ameansofavoidingcombustionsorapidas toresult inroughness.Eventoday,Ducati in Italy use such a device toassisttheirengineersinfindingcorrectanglesfor intakeportsandshapesforcombustionchambers.Therearehopesthatcomputedfluiddynamicswillsoontake over such analytical tasks, butthecomplexityofturbulentcombustionrequires either extreme computationspeed or unrealistic simplifications tothemathmodelthatisused.Itsdayiscomingsoon.

Engineers from theearly yearsof the20th-century“motored”engines—turnedthemwithelectricmotors—asameansofmeasuring friction andair pumpingloss.Theymotoredenginesinvariousstates of assembly—for example,

without valve gear—as ameans oflearningjustwhatshareoffrictioneachclassofenginepartscontributes.

Details of airflow into the cylinders oftwo-strokeDieselswasstudiedbyusing“rakes”ofimpactprobes,movedinsmallsteps through headless cylinders asscavengeairwasblown through theirports.Through such experiments theflowpatternsnecessary tomakebesttorquewereworkedout.

Even with computers there remainsthe argument between those whojust want answers, and those whoalsowantunderstanding. Iattendedasymposium on flight in ground effectand listened to a Russian engineerdescribeamathematicalmethodknownas “matched asymptotic expansions.”During the question period a listenerraised his hand and said in a boredvoice, “Whygo toall this trouble?WehavefastcomputershereintheUS.WhynotjustrunNavier-Stokescodeandletthemachinegrindouttheanswers?”

TheRussianreplied,“Becausematchedasymptoticexpansionsnotonlygiveyouanswers,theyalsogiveyouinsightintowhat the flow is doing.Andwith thatinsight you canmove directly towardimprovement.”

Computers are wonderful ly fastcomputational aids,andusingmodelsof real phenomena they can predictsome things that were previouslybeyond our understanding. Yet themodels themselves cannot be perfector infallible, aswe are seeing in therecent controversy overwhether dataused tomodel global warming wascorrectly used.Human thought is stillrequired!Or,asonecrustyoldengineeronceputittome,“Garbagein,garbageout.Always do amanual back-of-the-envelope calculation as a check oncomputerresults.”


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on holdBadthingsdon’tgoawayjustbecausewe takecarenot to thinkabout them.Rightnowwe’re inaglobaleconomicdepressionthatsqueezedtheretirementfundsofthosewhohavethemtoabouthalftheirprevioussize.Therearesignsofsomerecoveryhere,butinEuropeitisstillatitsworst.USautomakershavehadaterribleshockandit’sfarfromclearwhere their “recovery” isheaded.But,wewhistlepastthegraveyard.

AsimilarsituationistheweaponryoftheColdWar.Itstillexists—atleast50,000warheads—but because the formerSovietUnionhasnewofficestationery,wehave stopped thinking about suchthings.Infact,theirlatestICBM,called“Topol-M”,hasmaneuveringwarheadsintendedtododgeanti-missilesastheycrashthroughtheatmosphere.YouTubeoffersavideowithRussiannarration.Agiantmulti-axle (andDiesel-powered,you can be sure!) transporter-erectorsplashesthroughastream,itsdriver’selbowjauntilyouttheopenwindowofthecab.Itclimbsalongawoodedpathwayand takesup its firingposition.Thereisa loud “BONK”as thecappopsoffthe storage tube.Then it takes about30 seconds to bring the tube vertical,followedbya rushofgasas the tubeispressurized.Themissileisblownupoutofthetubewithathump,itssolid-fueledengineigniteswitharoar,andthehorriblebrightthingrisesoutofsightintotheeveningsky.

But it’s not real because since 1991we’ve stopped thinking about suchthings. Likewisewe are not thinkingabouthowlittlemoneyUSautomakershavetoplaywith,andhowimpressedthey arewith the fragility ofmarkets.By golly, folks, what if we wake uptomorrow to hear the news-readersintoning, “TheFed shocked theworldtodaybyannouncingUScurrencywillsplit three-for-one?”What if terribleinflationwipesoutallvaluesinresponseto the take-no-prisoners rate atwhichthemintsareprintingmoney?What ifChina,Japan,andEurope,each in itsown suicidal desperation, decide todumpbigamountsoftheUSpapertheyare holding?Business plannersmay

not takesuchdrasticoutcomes100%seriously (let’s call it a “risk-weightedthreat analysis”) but they see stockprices dithering and hear the punditspredictinganotherdivetocome.Nooneknows.Everyonefears.

Wouldyou,inresponsetotheabove,planexpensive research and developmentprojectsthatdependedfortheirsuccessongamblingthatAmericanswillchangethewaytheydrive?Youwouldnot.Youwould hunker down and reserve allyourassets to “attending toyourcorebusiness.”

So it iswith theambitiousDieselautoengineprojectsfortheUSfromHonda,Ford,Nissan,andChevrolet.WithmanyAmericanstravelingtoEuropeandAsia,itwasthought,therewaswideexposureof influential buyers to the powerful,quiet,andhighlyeconomicalnewDieselcarsinthosemarkets.Ihavehadsuchexperiencesmyself, and knowmanyothers in the sameboat—peoplewhowould,inbettertimes,behappytobuyoneofthenew-technologyDieselautosorlighttrucks.Multi-strikeinjectionhasquieted “Diesel knock” and selectivecatalytic reduction have taken careof theDiesel’smost difficult emissionproblem—nitrogen oxides.And thebetenoirof1980’sairscience—Dieselparticulates—has yielded to DieselParticulateFiltrationsystems.Withthefulltechnologypackage,Dieselenginesarecleanandconsumer-friendly.

Troubleis,thoseemissionssystemsareexpensive.Many sophisticatedworldtravelers have a lot less disposableincome than two years ago, and theprice ofDiesel fuel gives no comfort.InEurope,Diesel use is encouragedby taxpolicy,butnotso in theUS. InEurope,over60%ofnewcarssoldareDiesel powered, but here themajorityofdriverscontinuetothinkoftheDieselasan“industrialengine”orsomekindof third-world economy scheme. Lookaround and see that Hummers andother large and fuel-thirsty vehiclesare back, encouraged by gasoline’sdrop from$4.35 to$2.86.WhenmostAmericans—not the world-traveling

kind—thinkofDieselcars,theythinkoffunny-hat friends in the1980s,drivingquaint, faded VWGolf Diesels andresolutelyrefuelinginthesmellypartoftheserviceplazawherethepavementisslipperyandbigtrucksdrivenbymeninmysteriouscheckedshirtsaregrowlingthrough.

AsIseeit,aUStrendtowardat leastsomeDiesel autoshadbegun, basedpartlyonfueleconomy(whichhastwocomponents—oneisthe“green”ideologyandtheother ismoney)andpartlyongradually increasing familiarity. Thecurrentdepressionhasforthemomentsquashedthat,puttingtheautomakers’USDieselprojectsonhold.That’snotthe end—it’s just a hold, becauseweknowthatbothJapanandEuropearefuriously developing small economypowerplantsfortheemergingmarketsthat they seeas a hedgeagainst theshrinkageofthepreviouslyreliableandlargeUSmarket.

Thebigdebatehere isover the likelyshape of the depression.One set ofopinionspredictsitwillbeV-shaped—adecline,abottoming,followedbyaclimbbacktothepreviouslevelofeconomicactivity.Allbetternow!Letushopethisiscorrect,ormanyofuswillhavetoplanonbeingretiredonlyhalfaslong,orathalftheplannedeconomiclevel.

Theotheropinionsetmodelstheworldeconomyasastepdownward—fortheforeseeable future.This discouragingview suggests that investors haveretreated from risk like slugs fromsalt,andthatitwilltakealongtimetopersuade them that it isagainsafe toplanonbuyingcheapandsellingdear.Planonlong-termunemployment.

But,ineithercase,thebasicproblemsoftheworld—limitedresources,pollution,regional strife—carry on regardless.Thatmeansthatinthelongrun,whetherwe are comfortably prosperous orbumpingalong justabove thepovertyline,ifweneedtransportationitwillhavetobeincreasinglyeconomical.NothingismoreeconomicalthantheDieselengine.Lettheideologuesofelectric-everything

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continue the strip-mining ofWyomingcoalandthesendingofmenintodeepanddustycoal-holesinWestVirginiaandTennessee.Intheabsenceofanationalenergypolicythiswill taketheformofan economic struggle—coal versuspetroleum—andmaythecheaper,moreconvenientfuelwin.

Bear in mind that we have trillionsinvestedinaworkabledistributionsystemforpetroleumfuels.Arm-wavers,inandoutofgovernment,seemtoimaginethatanequallypervasivesystemforquicklyrecharging the batteries ofmillions ofelectric vehicles can be quickly andcheaply summoned into existence.Thinkofthemanyadditionalcoal-firedpowerplants thatwould be necessarytoprovide thatelectricity.Thinkof thepresent difficulty of fast-charging ofbatteries (three hours seems to bewhatittakesrightnow)withthebatteryelectrodesystemsinproduction.Thinkof thepredictionsofwhen theenergydensity of batteries will reach threetimeswhat it is now—typically five ormore years.California did its famousKingCanuteact,theequivalentofsittingin thesurfandordering the tide togoback.Technologydoesn’tobeyourplansfor “scheduled breakthroughs,” so theelectric technologyCalifornia soughtwas not forthcoming. Lotsmoreworkmaydothejob,oritmaynot.

Ontheonehandwehavepetroleum,withits associated refinery, transportation,and political costs, being burned inDiesel engines that are 35%or even40%(insomeconditions)efficient.

On the other we have coal (nowgenerating almost 50% of nationalelectricity),movingoutfromtheminesin innumerable 10,000-ton trainloads,beingburnedforconversiontoelectricityatanaverage35%efficiency,andthenpassingthroughtransformer,line,moretransformers,batterycharge/dischargeefficiency,andthenmotorefficiencytodrivea vehicle.When youmultiply allof these together, you get an overallsystemefficiencyof17-22%.

Petroleumdoeshavepolitical costs—

keepingwatch in theMiddleEastandCentralAsia,biddingagainstfuel-hungryChinaandJapan,arm-wrestlingcrankynations while carefully avoiding anyresemblance to an old-time colonialpower—theusualhigh-wireact.

Costswillruledespiteideology.Yes,wecanimagineaworldmotivatedbygreenthinking insteadof by profit, but in itsbattlewithcosts,whichwillwin?

High-techDieselswillbebackbecausethere is no viable alternative to theirefficiency.But,intheUS,temporarilyatleast,theyareoneconomichold.


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More Than one WayDiesel engines have been designedandmanufactured in a great varietyof forms.Manyof thesecanbe foundinA.W. Judge’s “High SpeedDieselEngines,” a bookwhich also coversolder fuel injection equipment. TwofavoritesofminefromthisvolumearetheSulzeropposed-piston four-stroke,andNapier’s “Nomad,” a two-stroke,turbo-compoundaircraftengine.

TheSulzer has its crankshaft locatedbelow its cylinders, with connectingrods oriented to right and left. Eachcon-rod drives a rocker-arm, and theupper armof each rocker operates apiston.Each cylinder has twopistonswhicharedriventowardeachotherbytherockerstocompressair,afterwhichfuelisinjectedinthenormalmanner.Theadvantageofthisdesignisthattheheatlossnormally associatedwith cylinderheadsiscompletelyeliminated.Thisisalsoafeatureofthe“EcoMotor”currentlyunderdevelopment.

TheNapierNomadwasa flat-12withpiston-ported liquid-cooled cylinders.Exhaustgasdroveaturbinewhichcouldsendpowertoboththecrankshaftandto the scavenge blower that suppliedcharge air to the cylinders.A Beiervariable-ratio drivewas employed tocontrolthisflowofpower.

TheNomadwasbynomeansthefirstDieselaircraftengine.Duringthe1920stherewasconsiderablepessimismoverwhetherthespark-ignitionengineevenhadafutureinaviation.Onereasonforthiswasdetonation,whichcouldbecomeuncontrollablewiththepoorfuelsofthetime, especially when engines weresupercharged.Dieselswereessentiallyimmunetodetonation,soanumberofaircraftDieselprojectswereundertaken.Theymighthavebeenthewayforward,butthenThomasMidgleyofDelcoLabsdiscovered the powerful anti-knock,tetraethyl lead, and spark ignitionreceivedanewleaseonlife.

CertainGermanaircraftwerepoweredby Junkers two-strokeDiesels.Theseengines had two crankshafts—anupper and a lower—with six open-

endedcylindersbetweenthem.Ineachcylinder two pistons compressed airbetween them. Exhaust ports in thecylinderwallwereopenedbyonepiston,whichmovedabout15crankdegreesinadvanceoftheother.Freshairportswereopenedbytheotherpistoninthesame cylinder. Fresh air entered thecylinderatoneendinaspiralpattern,chasingtheexhaustgastotheotherendwhereitexitedthroughexhaustports.

Locomotive and submarine Dieselsmade by Fairbanks-Morse operatedunder the same principle. Napier, intheir“Deltic”engine,madeeachofthreecrankshaftsdodoubledutybyplacingthemat theapexesof a triangle.Thethreesidesofthistriangleconsistedofopen-endedcylinderswithtwopistonsineach,asabove.

Largemarine Diesels, made at onetime by Doxford, implemented theopposed-piston concept differently.Onecrankshaftdrovethelowerpistonineachverticalcylinderconventionally,andmovedtheupperpistonbymeansofaslidingframedrivenupanddownbyapairofsecondaryconnecting-rods.

Inallofthesetwo-strokesthescavengeairwassuppliedbyaseparatescavengeblowerofsomekind,justasitisintwo-stroke truck enginesmade byDetroitDieselcompany.

Afewsimplifiedtwo-strokeDieselshavebeenbuiltusingcrankcasepumpingjustasfoundinthesimplespark-ignitiontwo-strokesthatpowerchainsaws.

FascinatingdetailonDieseldesignandperformance—withmanyillustrations—istobefoundin“DieselEngineReferenceBook,”editedbyLillyandpublishedbyButterworths.

The complex story of the developmentofDieselenginesforsubmarinescanbefound in LyleCummins’s encyclopedic“Diesels for the First StealthWeapon;Submarine Power 1902-1945.” It isfascinating to follow the developmentas engines light enough to be usefulproved too light to survive. Just aswith

aircraft engines, detail design had tobe refined and conditions of operationsmoothed before engines capable ofreliableoperationonan11,000-milepatrolcameintobeing.

Today nobody likes to design powergearingifhecanpossiblyavoidit—theconsequencesof failurearetoogreat.Gearing is also heavy, and everypoundofweight added to ship, truck,orairplaneisapoundlesspayload.ForthosereasonslargemarineDieselsarenowdirectlycoupledtotheirpropellersand rotate at propeller speed—60 to80rpm.Tomakethenecessarypoweratsuchlowrevsrequiresthattheenginemake the largest possible number ofpowerstrokes.Today,thatmeanstwo-strokeengines.

Yearsago,ambitiousdesignershopedtofiretheirenginesevenmorefrequently– by compressing air and burningfuel on both faces of each piston.Suchadouble-actingenginewasverycommon in steampistonpractice, butthehighertemperaturesofcombustionas comparedwith steammadepistoncooling and piston-rod lubrication justtoodifficult.Double-actingDieselswerebuilt,butfailedtoreachadesirablelevelofreliability.

Thetinymodelenginesthathavebeensoldas“Diesels”areactuallycloserinoperatingprinciple to the “running-on”ofgasolineenginesaftertheirignitionisturnedoff.Run-onwascommonintheearlydaysofemissionscontrols.

In the t rue Diesel cycle, a i r iscompresseduntil itstemperatureriseshigh enough that injectedDiesel fuelignites spontaneously (after a shortdelaywhiledropletsevaporateandtheresultingvaporgetshotenough)uponcontactwithit.Inthemodel“Diesels”itisactuallytheheatofresidualexhaustgas,mixingwith fresh fuel-air charge,thatcausesignition.Enginesoperatingonthisprincipleareaverytrendybranchofresearchnow,underthenameHCCI,forHomogenousChargeCompressionIgnition.Itishopedthatenginesofthistypemayonedaycombinemuchofthe

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economyofaDieselwiththelowNOxoflean-burnspark-ignitionengines.

WhydidNapierdesignaDieselaircraftenginejustafterWWII,whenjetswerethehotnewtechnology?Atthetime,itwasbelievedthatdecadeswouldpassbeforejetengineslosttheirextravagantthirstforfuel.Inthemeantime,theyusedfueltoofasttoflytheAtlanticdirectly.TheplannedrouteforearlyjetssuchastheDeHavillandCometthereforeincludedarefuelingstopatGander,Newfoundland.TheNapierNomad-powered airplane,beinghighlyefficient,butnofasterthanany other propeller aircraft, could flyLondon-to-NewYorkdirectly.Becausetherewasnoneedforrefueling,itwouldarriveinNewYorkfirst.

Historytookadifferentdirection,astheindustrial nations of the earth pouredresourcesintojetenginedevelopment,eachvyingwith theother in thegreatgame.Soon, Boeing 707swithmoreefficient engines had slammed thewindowofopportunityforDieselenginesincommercialaircraft.

But not so fast. Today, with aviationgasolinedowntoatrickle,concernoverleadhasremovedmuchofitsdetonationresistance.ThathasputtheemphasisbackontheDieselasawayforward—atleastforfuturelightaircraftpowerandforsomestealthycruisemissilesordronesthatneed the lowestpossibleexhausttemperature (which turbo-Diesels candeliver).

AsIwasdrivingpastworkonBoston’snewtunnelssomeyearsago,Iheardapiledriverbangingaway,anditsexhaustrevealedittobeaDiesel.Asthesnarledtrafficcrepton,Itriedtoimaginehowthisworked.As it turnsout, likeaStenormanyaircraftguns,it“firesfromanopenbolt.”Theheavypistonisraisedtostartthemachine,drawinginfreshairthroughcylinderwallports.Tostart,thepistonisdropped,compressingairbelowitandthenstrikingthepilecap,whichhasasmallcombustionchamberinitscenter,justasmanyDieselengineshavetheircombustionchamberintheirpistons.Themotionofthefallingpistonhas“cocked”

afuel injector,whichnowdeliversfuelintothechamberwhereitignitesintheusualway.Theinitialimpactofthepistonagainstthepilecaphasstartedthepilemoving, and the added strong pushof Diesel combustion simultaneouslycontinues thepile’s downwardmotionandthrowsthepistonupward.Asitrises,thepistonfirstuncoversexhaustports(youguessed it—this is a two-stroke)andthenfreshchargeports,allowingthecycletorepeat.PresumablytodaythesemusthaveDPF,SCR,andalltheotheracronymsofpollutionabatement.

The Diesel engine was a GermaninventionandtheGermanswerequicktoseetheadvantagesofthisengineforshipandsubmarinepropulsion.Anenergy-richfuelandhighefficiencycombinedtousefullyreducethevolumeoncedevotedto coal bunkers.Germany’s infamous“pocketbattleships”ofthebetween-the-warsperiodwerethereforeremarkablypowerful for their tonnage,whichwaslimitedbytheVersaillesTreaty.

Thismakes it strange that inWWIIGermantankswerepoweredbygasolineengines,notbythatideal-for-the-jobhightorquepowerplant,theDiesel.ItwastheRussians who saw the advantagesof Diesel tank engines, giving theiroutstanding T-34 a four-stroke V-12Diesel that increased range,deliveredwidetorque,andatleastmoderatedthehazard of fire.Everybody else seemsto have rushed into production withwhateverhappenedtoalreadybetooledfor some other purpose. Germany’sfamousTiger tankwas powered by alargeMaybachgasolineenginewhoseoriginal purposewas surely Zeppelinpower.ItsheavythirstledtoaleadingAlliedstrategy fordefeating this thick-armored behemoth, armed as it waswiththefeared88-mmgun—waitforittorunoutofgas.

TheAmericans,thenatthepeakoftheirslap-leather productivity and “can do”attitude,weresurprisinglynobetteroffthantheGermans.Americantankswerealsolargelygasoline-powered,somebyconverted air-cooled airplane radials(actuallynotabadenginefortheNorth

Africandesert)andsomebyastrangecluster of fiveDodge flathead sixes.TheM4Shermanwasnot called “theRonson”byitscrewsoutofaffection.

Turbocharg ing t ransformed theautomot ive Diesel . Wi thout theturbo, aDiesel is an overweight andunderpoweredengine,attractiveonlyforitslowfuelconsumption.Withtheturboitbecomesessentiallywhateveryouwantittobe—aLeManswinner,aluxurycarengine, a super economy-car engine,anenginefortrucksofanysize.AllthatcurrentlyholdsDieselsbackintheUSmarket iseconomicsandattitude.It iseconomics thathasstoppedoverseasmakers from payingwhat it costs tocertifymoreDieselautoshere,anditisanoutwornattitudethatregardsDieselsas“industrialengines.”Giveittime.


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Purely academicTheUS apparently lacks an energypolicy,butitneedsone.Whatisneededis some common sense about whatchangesarepossible,andrealismwithregard to what can be done now toconserveenergy.

Instead,whatwehearisunrealisticcallsto switch to romantic, but impractical,non-solutions such as electric or fuelcellvehiclesforwhichthereisnonation-widerefuelingscheme.

Proponentsofelectricvehicleswillreplythattheycanbepluggedinanywhere,butonlyyesterdayIreadthatChevy’snew Volt gasoline/electric hybrid (inaveragecommuterservice)willneedtorechargefortenhourson110Vorfourhourson220V—notexactlyawelcomeinterruptionintheChristmasroadtriptothegrandparents’house.

Hydrogenasafuelavailableforuseincombustion or fuel-cell use does notexist. There is no free, uncombinedhydrogen. Hydrogenmust either bebrokenoff of petroleumhydrocarbons(discarding the 30% of the energypresent in the carbon) or electrolyzedfromwaterinaprocessthatputsinmoreenergythancanlaterberecovered.

What thismeans is that there is nopractical alternative to combustion-poweredvehiclesforall-arounduse.Themarketforelectricsandplug-inhybridswillbeonlyas“thirdcars”forverywell-offfamilieswhocanusethepick-upfortowingthehorsetrailer,drivetheinternalcombustion-engined sedan for over-the-roadtravel,andstillhavecashleftovertoaddabitof“green”byparkinga$40,000Voltnexttotheoutdoorplugforthehedgetrimmer.

Let’sthinkaboutwhatcouldbebehindthis push for electrics.We know that48.5% of US electricity comes fromcoal-firedplants,andweknowthatthecoaliseitherstrip-minedinWyomingortunneledoutofthemountainsinWestVirginiaandTennessee.Doesthismeanthatthepushforelectricvehiclesisreallyintended to switch some energy use

from imported petroleum to domesticcoal?

Mygreen friends tellme that “coal isgreen”becausepetroleum-basedfuelshavehiddencosts thatcoaldoesnot.And theyareserious.Petroleummustbe refined,which involves applicationof heat and catalysts in expensiveand specialized plants. It must betransported inhugeshipsonvoyagestaking up to two weeks. The singletwo-strokeDiesel engine that powersmanysuchshipsmakesmoreor less100,000-horsepower and burns justover30,000-poundsofheavy residualfuelperhour.

Why does that figure sound familiar?Why, it’s the amount of fuel burnedper hour by aBoeing 747 in cruisingflight.The747weighscloseto400tonsat take-off, but the oil shipweighs aquarter-of-a-milliontons.Hmm.

Petroleumhaspoliticalcosts.Togetit,wemayhavetostationmilitary forceshere and there around theworld.Wemay have to out-bid theChinese tobuy it.Wemay have to keep aircraftcarriers cruisingnearby to discourageany“negativethinkers”whomayhaveotherideas.Okay,okay,Igetit,butdon’twealreadypaythosecostsonApril15th ofeveryyear?

YesterdayI listenedtoadebateaboutall this, and fast-talking headsweretellingmewhat oil ought to cost.Atthepump,Ilearned,thereoughttobea long list of hidden costs—refining,transportation,political,health(bysomeformofmath theyhad computed thatcoal-fired electricity plants kill 13,000Americans annually, and that Dieselengineexhaustannuallykillssomeotherterriblenumber),education,etc.

This academic stuff is great fun, butI have practical needs inmy life thatcan’t wait 20 yearswhile everythingis ideally restructured.All these futuretransportation schemes sound tomelike theGI’s lament inWW II—“Ifwehadsomeham,wecouldhavehamand

eggs, ifwehad someeggs.”MywifeandIhavetogettothegrocerystore.Myyoungestsonhastodrive20milestocollegeclasses(Itis$11,000moreifhelivesinthedorm).Ihavetopickupthemiddle sonat an airport 67milesaway, home on leave for Christmas.Weall have to live—andnot in someideal, theoretical, academic tomorrowway,butinado-it-todaypracticalway.ThereforeifImakebread,Idoitintheelectric breadmachine (thinking ofthe 13,000people I’m condemning todeathbyusingelectricityfromcoal-firedplants!), rather thangoingout into thebright, sunny front yardwith a zero-emissionssolarcookertodomybakingintheenvironmentally-perfectVandanaShivaway.(SheisanIndianidealistwhoproposes thatwecanall liveperfectlywell by subsistence agriculture, usingone bullock per family as our powersource.)

Idon’thaveabullock,andit’s18°inmyfront yard.Therefore I am interestedinsolutionsthatworkandareactuallyavailable to me this minute. If ourpoliticians inWashingtonDC thoughtalong these lines instead of foolishlybelieving in unattainable academicnonsense, they would do as theEuropeans do and encouragewideruseofhighlyefficientDieselvehicles.

Yesterday I lookedat listsof theagesofUScoal-firedelectricityplants.Somewere built in the 1920s and are stilloperating. Inmyresearch,76%of theplants, it toldme, were built before1980.Andratherthanbuildnewplants,theexistingonesarebeingoperatedathigherpercentagesofcapacity.Whyisthis? It is becausenewenergyplantsof any kind are very expensive, thepolicy future regarding such plants isuncertain,andnobodywantstobetthecompany on the proposition that thisadministration’senvironmentalpolicieswillbesmoothlycontinuedbythenextadministration.Arm-waversspeakofabrightnewfutureof“clean,100%safenuclearpowerplants.”Noonewantstobuildnuclearplantsbecausetheprocessfor approving their construction takes

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25years.Plus,manypeoplerememberbeing told about “clean, 100% safe”before,andnothavingthingsquiteturnoutthatway.

Automakers tell us that 40%of theirresearchanddevelopmentbudgetsarespent onwhat they call “contingencyengineering.” Brain-stormers sit inDetroit conference rooms, dreamingup the kinds of safety and emissionsfeatures theEPA,NHTSA, and otheragenciesmayinfutureinsistupon.Themore likely of these are then fundedfor limited development in hope thatsuchheadstartswillsavemoneyiftheconceptsbecomelawinfuture.

Somethingsimilarmusthappen in thepower industry.What if zero sulfuremissionsbecomelawforallcombustionpowerplants?Whatifcarbonrecoveryismandated?(WhatIreadyesterdaysaidthiswilladd40%tothecostofelectricity,but there are lower figures bandiedabout—believethemifitpleasesyou—no one really knows.)What if powerdemandincreasesby25%becauseofvehicleelectrification?Whatiftoughnewenvironmentallawsarepassedbywell-meaninggreen coalitions inWyomingorWestVirginia legislatures, pushingupthepriceofcoal?Powercompanieshavenoideawhatliesahead,sotheysittight,keepcostsundercontrol,andcross theirfingers. Ifmyelectricbill isjustunder$200amonthIthinkI’mdoingwell.Sorryaboutthe13,000people.

It is precisely becausewe can’t knowwhat liesahead thatourbeststrategyisconservation,andnotsomeidealistictotalchange-overtoelectricorfuel-cellvehicles.An element in conservationisuseofthebestavailabletechnologyfor vehicle fuel economy—theDieselengine.

Somefolksjustdon’tgetit...


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Diesels in the usaI thought it time to drop you a line. “Exhaust Note” is always the first article I read when my TDR comes in the mail. The reason is that I know that the Cummins under the hood is the heart and soul of my 2007 Ram. Every time I drive that truck, I am amazed and impressed by the power and efficiency of it. A gas engine with the same displacement wouldn’t get near the mileage nor have the power to haul my trailer with horses.

After reading “Purely Academic” in Issue 71, I recalled my first experience with diesel power. It was 1982 when the price of gas shot up to a whopping 65 cents a gallon. The truck I was driving at the time was getting about 10mpg. I needed to know what my options were, for there was no way I was going to pay that much for fuel.

One day at work a friend and fellow employee told me about a new truck he had just purchased which was getting 40mpg. My response was, “No way.” That evening in the parking lot after work he showed me his new ride. It was a new Chevy LUV (light utility vehicle) truck, purchased at a nearby dealership. A few days later I decided to check them out at the dealer and drive one. I soon realized it was an Isuzu, only with a little difference to the grill and other minor details. The engine was 2.2-liter, naturally aspirated, four-cylinder with a six-speed manual transmission. It took me little time to decide this was the answer and to make the purchase, and yes, it did get 40mpg. I was happy as a clam shifting through all those gears knowing I was saving money on fuel. The power was lacking a bit, but I could run circles around the diesel rabbit. Did I mention, it got 40mpg?

At the time I didn’t know I would have that little truck for ten years with need for a larger one only on a few occasions. I did regular maintenance on it and had to change the glow plugs in it twice. It got 40mpg. When the odometer read 175K miles I thought it might be time to get rid of it. I put a “for sale” sign on it and another friend at work bought it. He drove it another 100K miles and sold it having had no trouble with it. It still got 40mpg.

Since I got rid of that little truck, I’ve seen a few still on the road. One day I followed one into a mini-mart to ask the owner if he would sell it to me. The man laughed and said he had been approached before with the same question. I knew no auto manufacturers sold anything close to this little wonder and often wondered why. The Isuzu engine has been around forever and has other applications, so I thought the reason they were no longer sold was they couldn’t meet the EPA’s pollution requirements. It got 40mpg.

So here is the deal: why hasn’t Cummins, or any other manufacturer, designed a 2.5-liter, or thereabouts, in-line, four-cylinder, aspirated 16-valve diesel engine for a mid-sized truck (Dakota)? With a six-speed manual transmission the combination would sell like hotcakes. Mileage would be fantastic and the power would be all you could want. For daily use and commuting it would perform most of the tasks required of a truck. The Japanese knew this 30 years ago, and even lacking the technology that we have today, still sold huge numbers of small diesel trucks.

Would you pass this on to your friends at Cummins and Dodge to get the ball rolling before the foreign market does. We need to buy “American made” now more than ever. I’ll be the first in line to buy one, not to replace my Ram but in addition to it. And, oh, did I mention that little truck got 40mpg?Doug Tourville

Doug’sletterexpressesadisappointmentthat,asapro-Diesel(aswearewritingin the “ExhaustNote” column, pleasenotethecapitalD)audienceweallfeel.If youwantKevinCameron’s chapterandverseaboutthepoliticalaspectsofDieselpowerinAmerica,IwillreferyoutotheTDR’swebsiteandtheleftcontrolpanel.Clickonthe“CameronCollection”andfocusyourattentiononnumbers35,39,40,60,67,69and,mostrecently,70.DougalsomentionsthattheIsuzuenginewas“aroundforever,”butallthosemadeinDieselenginesareturbochargersinthe“CameronCollection”numbers42,47,50and70.

While this audience can agree andappreciate themarvels of theChevyLUV truckwith the little Isuzuengine,themanufacturers’number-crunchersat

GM,Ford,Chrysler,Toyota,Fiat,Nissan,Mercedes,BMW,etal,wouldnotbeabletoarguetheprofitabilityofasmallDiesellightutilityvehicle.

Yet,toaddressyourdesireforaLUV-typeproduct,theanswercouldbeMihindra.Thereisalreadyanenthusiastwebsiteforthetruck,www.mahindratruckforum.com.However,aswereportedinIssue57,page70(fouryearsago),andagaininthisissueonpage___,thistruckismired in government and distributionredtape.

Thereisprogress.AsG.R.Whalenoted,the recently releasedmiles-per-gallonratingfromtheEPAonthistruckis19/21.Butwhatadisappointment.Thisdoesnotmatchthe40mpgoftheChevyLUV.Whalehassuggestedthatitislikelytheactualmpg numberswould be betterthantheEPAestimates,bringingtheminlinewithagasoline-poweredToyotaTacomaat19/25.Nevertheless,whatadisappointment.

And,sinceIhavealludedtothesmallishToyotaTacoma,letusreflectonvehiclesalesandconjectureaboutimplicationsinmakingacaseforasmalltruck.Thenumbers: ’09 ’10 ’11ToyotaTacomaFordRangerDodgeDakotaChevyColorado

Noticeatrend?Ifweweretocalculatethecurrentpricepremiumfordieselfueleating awayat the cost advantageofaDiesel power plant, and thedeclinein sales of light utility vehicles, as abusinessmanI’mnotstandinginlineforaMihindradealership.Maybethat’swhythere has beenmore talk than actionaboutMihindraforfour-years?

There ismy logic. I forwardedDoug’slettertoKevinCameronandKevingivesthefollowingresponse:

What happened is that at one time, Diesel was the darling of the EPA, and during that time some fairly economical vehicles were offered for sale in the US. Then, in the later 1980s it was discovered that terrible carcinogens were attaching themselves to carbon clusters in Diesel particulates. Eek! Overnight, diesels became anathema,

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and a long list of emissions limits were “added to their bill.” Because these requirements are not technically easy to meet, and because the solutions are not cheap, few companies want to bet that a significant number of Americans can overcome their prejudices (Don’t even walk near the Diesel pumps at service plazas—the whole place is slippery! Just touch the pump and your hand stinks all day. Diesels rattle and smoke! Diesels are environmental disasters! Diesels are low-class—only for working-class stuff like ships and trains) to buy enough to pay the R&D bill.

So, no Diesels for the mass market. The perception is that they’re just for frickin’ intellectuals. Those who buy diesels are likely to be people who can’t just pull the lever on voting day and let responsible persons tell them what’s best for them.

It’s a propaganda problem. Greens think electricity is in the wall, and is clean and pure, not generated half from coal, one-fifth from natural gas, and one-fifth from nuclear. The people pushing electric cars are delighted that this is so. Hey! Want everlasting life? Sure ya do! Well, forget Baptist, Catholic, and the rest of that. And buy electric! Electric is salvation.Kevin CameronTDR Writer

Ouch,IthinkweknowhowKevinfeels.Wemusthavehitarawnerve.

Forfurthercommentaryabouttheplightof the Diesel engine, I refer you toexcerpts froma column inAutoWeek,9/13/10bywriterDeniseMcCluggage.

“Scene:A clutch of motoring pressgatheredbeforeanintoningcar-companyguy.Guysingingthepraisesofitsmodelelectric.Ah,so.Allcarsongsthesedaysseem to be in the key of E. Electricsmelectric.Igrowweary.ButthecarsofcarmakersareturnedtoconsultantsandfocusgroupswhopersistentlywhisperthereinthatAmericancarbuyerswanttobepluggedin.

“I ask Guy what is his company’sexcusefornotatleastofferingadieselengine.Soacontinuing largenumberofAmericancarbuyersstillbelievethatdieselsarenoisy,dirtyand trucklike—doesn’titmatterthattheyarewrong?

“No, these focus-group folks simplycollect anymisinformedmutteringsas if theyweregemsandglitter themon to their clients.Their professionalconclusion:Americanswon’tbuydiesel.Thus,moreelectricsareannouncedandmoredieselsarecanceled.

“‘Well,’Guyanswersme in a scriptedtone,‘ourresearchshowsthatwiththeadditionalcostofadieselengineandtheuncertaintyindieselfuelprices,itwouldtakesevenyearstoachievepayback.’Ergo:Americanswon’tbuydiesels.

“Later,one-on-onewiththeGuy,Isay,‘You’re wrong about seven years topayback.’Hisantennaebristle.‘Withadiesel,paybackisimmediate—it’scalledtorqueand range.’ (Tohis credit,GuyacknowledgesthatIhaveapoint.)

“About that ‘payback’ business, doesanyone ever talk about the paybacktimeon,say, leatherseats?Andwhatabouthigh-endsoundsystems?Oronasunroof?WiththeDieselyouexperiencereal-timepayback.Likewhenyourrightfoot prompts a diesel engine to swellquicklyintoactionandthenrollonalldaywithouteverwhiningtobefed.

“Nottomentionthegoodadieselenginedoes for your resale value. Payback,indeed.”

But let’s be practical and considerthe bottom-line: If Mr. Big, the autoexecutive,weretoaskyoutoapprovetheDieselprojectforanewincarnationoftheLUV,andthesuccessofthisLUVwoulddetermineyourcontinuedtenureattheautocompany,wouldyousignonthedottedline?

IthinkI’llletMihindragofirst.

Robert PattonTDR Staff


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Conflicting InterestsThismorning Iwas reading that threegroups with environmental interestshave written to President Obamaurginghimtoadoptthestrictestoffourproposedratesofimprovementforfuelconsumption in light vehicles. Suchvehiclesarealreadyhavingtostepupfromtheold27.5mpgtothenew2016standardof 35.5mpg. (Thesemileagenumbers are CAFÉ, or CorporateAverage Fuel Economy, measuredin laboratory driving cycles.) Suchimprovementsaresensiblenationalself-defense inaworldof risingpetroleumpriceanduncontrolleddeficitspending.Fortheperiod2017-2025,lightvehiclefuel economy may be required toimprove at a yearly rate between 3and6%—thenumber tobechosen inupcoming deliberations. The highestnumber would eventually raise therequiredfueleconomyto62mpg.

Automakersaresaying(withtheirvoicessuitablyamplifiedbythebestavailablepublicists and lobbyists) that the newtechnology required to meet thesestandardscouldpushcarownershipoutof reachofmanyAmericans. Like thePresident, business has its legitimateinterestswhichitmustdefend.Sohaveconsumers.

Whatwouldthatnewtechnologybe?Toalargeextent,thatmightbedeterminedby the (bankrupt) State ofCalifornia,whose influentialAirResourcesBoard(CARB)willmake relevant decisionsthiscomingNovember.BackacoupleofyearsagoitlookedasthoughCARBwould follow its usual path—seekingaboveall to reduceemissionswithoutmuch concern over technology costor fuel consumption.Remember thatCalifornia’s legitimate interest overthe past 45 years has been to dealwithgreenandyellowairoveritsauto-clogged cities. However, there havebeen some rays of a different kindof sunlight, aswhenCARB, formerlydead-setagainstanykindoftwo-strokeengine, actually read the specs onBombardier’sdirect-injectionwatercrafttwo-strokes and decided they lookedprettyokay.

CARB’s decision on their 2016 LowEmissions Vehicle III standard wasexpectedtoholdDieselstosuchdifficultemissions standards as to amount toforbidding them. Industry observersregarded this as part of a “push” tomakeelectricvehicles(asif,afterEnron,Californiahaselectricitytospare)moreattractive.Now some are saying thatCARBmaybe considering that highlyefficient Diesel engines do have alegitimate place in the nation’smix ofprimemovers.CARB’sdecisionwillcarryalotofinfluence,forEPAoftenfollowsCARB’slead.Asofterposition,balancingtheneedforimprovedfuelconsumptionagainst endless improvements in airquality, would bewelcome news forDieselusers.

If you sit down at your computer andGoogle, “Dieselcombustion lift-off,” youwill be presented with nice four-colorillustrationsof thecombustionofDieselfuelsprays.“Lift-off”isthepointinthespraybeyondwhichlightisbeinggeneratedbythebeginningsofcombustion.Thespraybillowsoutafterthatpointasheatreleasecausesrapidgasexpansion.Whatcomesoutoftheinjectorisanarrowconeoftinydroplets—mostsizedbetween.0002and.001-inchdiameter—movingatbetween650and1650feetpersecond(whichiswhythesprayfromaninjectorwillcutyourskin).This jetofdropletsentrainsairatitssurface,draggingitalong,andsomedropletsevaporateintothatentrainedairtoformamixtureofairandfuelvapor.Thispre-mixedair andvapor is like thepre-mixedchargeinaspark-ignitionengine.The usual explanation of Dieselcombustion is that pure air is drawninto an engine cylinder and is thencompressed(intruckenginesatypicalcompression ratio is 16-18:1—muchhigher than is possiblewithout knockin gasoline-fired engines) until itstemperatureiswellabovethefirepointofthefuel.Fuelistheninjected,anditignitesfromcontactwiththehotair.

Notquite!Heatisrequiredtoevaporateliquids,andinthecaseofthespeedingdropletsofDieselfuel,thatheatcomesfrom the hot air into which they areinjected. Evaporation of some fuel

coolstheair,delayingthebeginningofcombustion.Thisiswhythefuelcannotignitethemomentitentersthecylinder,butinsteadmovessomedistance(the“lift-offlength”)beforecontactwithfreshhot air brings the temperature of thefuel-air vapor up enough to result inactual combustion.The timebetweenthe beginning of injection and theappearanceofflameisveryreasonablycalledthe“ignitiondelayperiod”andisafewcrankdegrees—say5to7.

As the surface of the spray ignites,(Don’tevenaskaboutthechemistry—it’swonderfulstuff,withchainsofeventsclangingawaythatonlythestrangestofexpertsbegintounderstand.)theflameoriginates and propagateswhere themixtureisclosetochemically-correct—and is very fast. This part of Dieselcombustionisthepremixedcombustionphase—the very short, intense timeduringwhichthatpartofthefuelthathaspreviouslyevaporatedandmixedwithairflashesintoflame.Energyreleaserateisveryhighandthisphasemaytakejust5crankdegrees.

Meanwhile, elsewhere in the spray,conditions are settling in for the long-haul part of Diesel combustion—thediffusion flame. Imagine a cluster ofdroplets, rapidly evaporating in thehot air, and being further helped toevaporate by infrared energy comingfromanearbyflame.Closetotheclusterthere is only fuel vapor,which cannotburnwithoutatmosphericoxygen.Farfromthedroplet,thereisonlyair,whichcannot burnwithout fuel. Fuel vapordiffuses away from the droplet, itsmoleculesdriven thiswayand thatbytheconstantbuzzofcollisionsinthehightemperature gas.Oxygenmoleculesdiffuse toward the fuel droplet.Wherethey meet and form a combustiblemixture,flameoccurs.

Thatflamecannotformamovingflamefrontasitdoesinthepre-mixedfuel-aircharge of a spark-ignition (gasoline)engine.Iftheflameweretomovetowardthe fuel droplet, itwould encounter amixture too rich to burn, and itwouldgo out. If itwere tomove away from

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the droplet, it would bemoving intoleaner conditions, andagain, itwouldbeextinguished.Sotheflamesitsstill,fedby thesteadyoutwarddiffusionoffuel vapor and the inwarddiffusionofatmospheric oxygen. This “diffusionflame”consumesitsreactantsattheratetheydiffuse.Forthisreason,thispartofDiesel combustion takesmuch longerthanthepremixedcombustionphase.Itgoesonandonataverymoderaterateofenergyrelease,asthecrankrotatesthroughperhaps40degreescenteredaroundTDC.

Ifyou thinkabout thismodel,youcanimaginedifferentscenarios.Oneisthesingle-droplet case, anotherwould bea cluster of droplets surrounded by adiffusionflame,andyetanothermightbethattheentirevolumeofthedropletspray is so fuel-rich that flameoccursonlyonitsoutersurface.

In combustion, hydrocarbon fuelmoleculesmustbebrokenupbythermalenergy—that is, their hydrogens areknocked loose by the billiard-ball-likecollisionswithotheragitatedand fast-movingmolecules.Thesamehappenstothetwo-atom(“diatomic”)moleculesofoxygen.Oncesetloose,thesefragmentscancombinetomakedozensofpossible“relationships,”someofwhich liberatea lotofenergy.Hydrogenandoxygencombinetoformwaterfairlyeasily,butthecarbonchainbackbonesofthefuelmoleculesaren’tsofast.Thelongerthecarbonsbakeinsideofdropletclustersor within the cooler fuel spray, thegreaterthechancethatinsteadoffindingtrue love by combining with oxygenatoms (forming carbonmonoxide andcarbondioxide),theywillfindonlyeachotherand formcarbon-atomclusters.Thisistheoriginof“Dieselparticulates”orsoot.Carbonisveryattractivestuff,which iswhy it isusedtoextractbad-tastingactivecompoundsfromwhiskeyorcigarettesmoke.Rich,hotregionsinthefuelspraycontaincarbonrings,oneormoreofwhosehydrogenshavebeenknockedoff.Whenringsbondtoeachothertoform“polycyclics,”someoftheresultingcompoundsturnouttobenastycarcinogens.

Wheredothecarbonringscomefrom?A large percentage of themolecularstructures inDiesel fuelarebasedonsuchrings—probablybecause(a)ringstructuresarehighlystable,andhavepersisted in underground petroleumreservoirsformillennia,and(b)becauseplants—theprecursorsofpetroleum—employringstructuresintheircellwalls.Polycyclicsareattractedtothecruisingcarbon balls, and unless combustionturbulence carries those balls tosomeplacehotandoxygen-richenoughtoburnthemup,theywillsailrightonoutthroughtheexhaustvalvewhenitopens,andbecomepartoftheexhauststream.

You can sort of see from this generalpicturewhyDieselmanufacturers areraising injection pressure, providinginjectorswithgreaternumbersofever-tinier holes, and injecting in short,multipleeventsratherthaninonelongspray.Thelastthingtheywantislong-lasting hot, rich zones inwhich sootforms easily. Multiple spray eventsdistribute fuel into freshregionsofair,discouraging the formation of long-lastingrichzones.HighinjectionvelocitypenetratescompressedairmadeevenmoredensebybothturbochargingandbystuffingincooledEGR.Thatdenseairislikeanarrayofheavy-dutyfootballlinemen,and it’sgoingto takea lotofenergytobreakthroughtheirline.

Thenthere’sthelittlematterofnitrogenoxides—NOx in the official language.NOx is a step in a complex smog-formation process that results in thecreationofozone(moleculesconsistingofthreeratherthantheusualtwooxygenatoms). Breathing becomes difficultandurbanair assumes that greenish-yellowcastthatIsawforthefirsttimeinSouthernCaliforniain1971.

Normally, nitrogen is highly stableand stays that way. Fortunately forthewholeworld, it takes about twiceasmuch energy to separate the twoatomsofanitrogenmoleculeasitdoesto separate two oxygens. If it wereeasiertoknocknitrogenapart,thenextlightningboltcouldsettheaironfire.(Itis78%nitrogenand20%oxygen.)This

issomething thatworriedsomeof theatomicscientistsin1945astheymadereadytotesttheirfirstA-bomb.

Nitrogenremainsintheformoftwo-atommolecules until heated to somethinglike2800°,abovewhichpoint therateof thermalmolecule-busting increasesrapidly.Whatthismeansforcombustionin engines is that some loose, singlenitrogenandoxygenatomswillbesetfree in the hottest parts of the flame,andmay combinewith each other toformnitrogenoxides.Threepathways,called the “Zel’dovichmechanism,” allleadtoNOxformation.Asweknow,onescheme forpreventing its formation istocool thingsoffbydelaying injection(which normally begins ~ 20-degreesBTDC) until TDC, but that naturallyreduces power and increases fuelconsumption.Another is to dilute theair charge in the cylinderwith cooledexhaustgasrecirculatedfromapreviouscycle. This “cooled EGR” is mostlycarbon dioxide and water, and socannotburnorcontributetopower.Itspresence reduces flame temperature,thereby stopping a lot of NOx at itssource. Stuffing this extra inert gasinto the cylinders requiresmoreworkfrom our busy turbocharger, but thelessNOxweproduceinthecylinders,the lessexpensive technologywewillhave to tack on downstream to reactthat smog-forming stuff intoharmless,normaldiatomicnitrogenandoxygen.

Conflicting interests are not confinedto politics. The unpalatable truth isthatwhateverwedo tosuppresssootformationfostersNOxproduction,andvice-versa.Themorevigorouslywestirthe fuel droplets into theair andheatup combustion in an attempt to burnup carbon before it forms soot, themore fuel burns at high temperatureand themoreNOx is formed.Whenwe cool things off to suppress NOxformation,more soot forms becausecarbonburnsbest in hotter flame.Sofar,nowayhasbeenfoundtoimproveeverything at once—sowe are stuckwith particulate filters to collect andperiodicallyburnthesoot,andwitheitherSCR (SelectiveCatalyticReduction—

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thefamousammonia-from-ureaprocessforrenderingNOxintoharmlessform)or with NOx trap-and-burn. None ofthesetechnologiesischeap,especiallyas lowerand lower levelsofsootandNOxarelegislated.Goodperformancein the lab isn’t enough—themakersalsohave toprove toCARBandEPAthat systemswillmanage themselves(lots of computers and sensors!) andcontinue to function reliably for yearsand years (gold-plated connectors,fancywater-exclusion seals, durablecatalysts!).Thoseregulatorybodiesarealsoskepticalthatpeoplewillremembertofilltheirureatanks.

Thereforewehope that (a) the cleverfolks in themanufacturers’ emissionslabs will learn wonderful new andcheaperways to clean up emissions,and(b)thatthefolksatCARBwillshowsomerestraint inNovemberandallowthepowerfulfuel-savingabilityofDieselenginestofindwiderapplicationintheUStransportationmix.


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A basic appeal of theDiesel enginehas been its rugged simplicity. IwasremindedofthisrecentlywhenwatchingavideoofillegalAmazon-basinhydraulicminers, starting a big truck enginecoupled to awater pump.Abig ropewaswrappedaroundtheengine’sclutchdrumseveraltimes,andthenagroupoflustyladsjustwalkedoffwithit,spinningtheengine fast enough to start it.Nobattery,nostarter,nomicroprocessors,no sensors. If ourworld comesapartasfinancierMr.GeorgeSorosislatelypredicting, the few jerk-pumpDieselsstill inexistencecanbestarted in thesamemanner,andwillgooncarryingthefreightaslongasfuelcanbefound.Hydraulicminingusesajetofwaterfromabig pump to blast away vegetation,topsoil—everythinginitspath—tofindabitofgold.Itisnotthefavoredmethodofenvironmentalists,butIreckonthosefellows pulling that big starting-ropearemore concerned with their ownday-to-daysurvival thantheyarewithMr.Gore’smovieor themathematicalmodelingofclimate.

WeallknowthatDieselcombustionisdifficulttomakecomplete.Asaresult,clusters of unburned carbonatoms—Diesel particulates—are blownout ofthe cylinder, each perhaps carryingsomemolecules of PAH—polycyclicaromatic hydrocarbons—sticking to it(fancytermis‘adsorbed’,meaningstuckonto).Thesearecompoundsmadeupoftwoormore(hencethe‘poly’)joinedcarbonrings(hencethe‘cyclic’).Someof these, bymimic-ing the chemistryof compounds used in our bodies’metabolism,canbecomeincorporatedwithin us to act as carcinogens. Theword‘aromatic’meansmadeupofsixcarbons in a ring, and it so happensthat the structure of plant cell wallsismade of such compounds. So it’snot surprising that we find them inpetroleum—then in Diesel fuel, andfinally,inDieselexhaust.

When crude petroleum is refined toproduce products such as gasoline,

Diesel,etc.,itisrunthroughadistillationtower.Thebasicideaisthesameasintheoperationofthemoonshiner’sstill.Whenyouheatamixtureofcompoundsdif fering in molecular weight, thelighter compounds, consisting of thefewest atoms, boil away first. Then,at higher temperatures come theheavier fractions. The petroleum stillseparatesethylalcoholfromthewater-and-alcoholmixture in themash. Inthedistillationtowersofthepetroleumindustrycondensationpansaresetatvariousheightsinthetower.Crudeoilis heated at the bottomof the tower,and vapor rises from it. The lightestfractions—gasessuchasmethane—gorightoutthetopofthetower.(Iusedtoseesuchgasesbeing“flared”fromNewJerseyrefinerieswhenIwasalittleboyridinginmyparents’carontrips.)

Compounds in the gasoline range,consistingofchainsor ringsof5 to8carbons,condensenearthetopofthetower, andarepipedaway for furtherprocessing.No.1fueloilhasarangeof chain lengthsof9-16carbons,No.2 is 10-20, and so on down to No.6 residual fuel, with 20-70 carbonchains.Condensing in the lowestpanis asphalt—really heavy stuff thatwemake roadsout of. Thanks to theinsightsofchemistry,anyoftheheavierdistillates can be “cracked”—that is,broken down into lighter fragments—through a combination of heat andcatalyst. Think of the catalyst as themuggerwho grabs you frombehind,allowinghishelpertofeelforyourwallet.The catalystmomentarily grabs ontoandchangestheshapeofthemolecule,causingastrainthatmakesthedesiredchemicalchangealotmorelikely.Oncethe targetmolecule is broken in thisway,thepiecespopoffofthecatalystmolecule,whichisthenreadytorepeat.The problem with these higher-molecular-weight hydrocarbons iscombustion. Ifyouwereassigned thetask of taking apart simpleTinkertoystructures in limited time, it wouldbe easy. But if we supply Tinkertoy

structuresmadeupofmoreandmoreknobsandsticks,youwoulddoalessandlesscompletejobofdisassemblingtheminthatlimitedtime.

Combustion is just the same.Beforethecarbonandhydrogenatomsinanyhydrocarbonmolecule can unitewithoxygen, theymust first be knockedaparttomakethemavailable.Themorecomplex thestructure, the longer thatdisassemblytakes.Aswegotolongerchain-length fuels, the result ismoreunburnedparticulates in the exhaust,and less-complete combustion. Ifwewant to run our engine near otherpeople, the lawhasnowdecided,wehavetofilteroutthoseparticulates.Theequipmentthatcandothiscostsmoney,andwemiddle-class folkhaveonlyalimitedamountof that.Automakers intheUShavegenerallydecidedthatthecostofDieselemissionscomplianceisjust toohigh for theautomobilemassmarket.

Outontheoceans,giantmarineDieselsdoanefficientjobofmovingtheworld’sgoods over vast distances. Chinaimports ironore fromSouthAmerica,JapanimportsoilfromtheMiddleEastandAlaska,andmanufacturedgoodsgooutinalldirections.SoefficientisthisprocessthatVLCCs(verylargecrudecarriers)useavolumeofheavyresidualfuelthatislessthan1%ofthevolumeofcrudeoiltheyarecarrying.However,burningbigfuelmoleculesthatare20-70carbonatomsinlengthpresentsspecialproblems.TheStateofCaliforniawantsDieselmotorshipsoperatingwithin200milesofitscoasttoswitchtoalower-molecular-weight fuel so that shipexhaustwill contain fewer big, black,gooeychunks.Understandable,andweknowbyreading industrypublicationsthatmakersofsuchmarineDieselsarehardatworkontechnologiestocleanuptheircombustion.Everyoneknowsthatwhenitcomestoemissionsregulations,“AsgoesCalifornia,sogoestheworld.”Another thingwenotice is thatDieselfuel pricegoesupanddown, andup

simplicity and something to Think about

134

again.Even consoling ourselveswiththefactthatthereismoreenergyinagallonofDieselthaninagallonofgas,thepriceisnevereasytopay.ThesaladdayswhentheoilmajorsestimatedtheproductioncostofabarrelofArabianlight crude at a nickel, are over andtheyaren’tcomingback.Todaywehavetopay thesecompanies tooperate inunfriendly places like amile down intheseaor(dareIsayit?)jollyoldIraq,places inwhichyouneverknowwhatlittle disaster tomorrowmay bring. Agiantblowoutwith incalculable lossofcorporatereputation?Angryfolkswithautomaticweapons, little disposed tocompromise?As the old phrase hasit,“Theypassalongthesavingstous.”All of the abovemakes it especiallyinterestingtoreadintheAugust8,2011issueofAutoweekMagazine that theUSDepartment ofEnergy’sArgonneNationalLabhasa littleprojectgoingto investigate the operation ofDieselengines on gasoline. If the inevitableproblemofgasoline’sverypoorcetanerating (its ability to autoignite) couldbe solved, the lowmolecularweightof gasoline could instantly erasemuch of the Diesel’s problem withparticulates and PAHs. The enginewouldcontinuetodisplay theDiesel’slowfuelconsumption.Couldthisbethebestofbothworlds?

Thismightveryeasilycometonothing—lotsofresearchendsbecausethegrantthatbacksitisnotrenewed,orbecausezealousgovernmentcost-cuttersclosethe research institute and sell itsequipmenttotheChinese,orbecauseproblemsuncoveredresistedsolution.The investigator atArgonne isSteveCiatti, and his testing beganwith a1.9-literGMautomotiveDiesel.Resultsare said to have been encouraging.Basic changes to the engine wereunnecessary—the trickery is in thedetailsoffuelinjection.TheshortarticlenotesthatsuccessinoperatingDieselson gasoline (or a gasoline-like fuel)mightleadtosubstantialreductioninthe

costofnecessaryemissions-reductionequipment.

Somethingtothinkabout.


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