aei technology report

Powertrain

Ford's all-new 6.7-L VB raises the diesel-engineering barDiesel engine OEMs, herecomes your new medium-dutybenchmark.

Ford Motor Co. is com-pleting validation of its 6.7-LV8, due to enter productionlate next year as an option for2011 Super-Duty trucks. Theall-new V8 is the first Forddiesel engine to be developedentirely in house. It is also thefirst to be certified to operateon 20% biofuel (B20) and thefirst to comply with U.S. EPA2010 emissions standardsthat require an 80% reduc-tion in NOx.

The engine is a showcaseof clever packaging, combus-tion control, and robust de-sign. Code-named "Scorpion"during development, the "SixSeven" as it is now knownfeatures the following keytechnologies:• Compacted graphite-iron(CGJ)cylinder block• Aluminum cylinder headswith dual coolant jackets• Inboard-facing exhaust

The new Honeywell single-sequential turbocharger features variable-pitch impeller vanes, a new bearing design for quieter operation, anda unique compressor system.

ports with outboard-facingintake ports• A single-sequential turbo-charger mounted within the Vof the block

Ford's European diesel enqineerinq team, supported by the company'sResearch and Advanced Powertrain groups, developed the combustionchambers in the new diesel's aluminum heads.

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• Piezoelectric fuel injectorsoperating at 30,000 psi (2070bar) and capable of five injec-tions per combustion cycle.• Ford-patented software con-trols for mixing the urea fluidin the selective catalytic reduc-

Lead NVH engineer Scott DeRaadcredits a clean-sheet approachfor the new VB's near-stealthyoperating qualities.

tion (SCR)exhaust aftertreat-ment system. This will be thefirst North America-designeddiesel to employ SCR.

The engine's power andtorque ratings will be an-nounced later. Output and fuelefficiency are expected to besignificantly greater than thoseof the current 6.4-LPowerStroke diesel V8 sourcedfrom Navistar Internationaland should give the SuperDutyrange class-leading payloadand towing credentials, ac-cording to Lead EngineerAdam Gryglak.

Besidesbeing extremelypackage-efficient for its size, aresult of the intake system de-sign, the new V8 also will setnew classstandards in NVHattenuation. Aft was amongthe first media invited to back-ground discussions withGryglak's team and to hear theengine demonstrated in anF-450 flatbed truck. The soundlevelswe witnessed were stun-ningly low and mechanicalclatter virtually absent. Thiswas all the more impressivebecause the truck was runninginside a huge, echoing garageand was not fitted with anunderhood noise blanket.

Indeed, the new V8'ssound profile is so subduedthat Ford engineers say tradi-tional acoustic blankets willnot be fitted to productionvehicles using this diesel.Likewise, sound levels at thetailpipe from idle throughmiddle-range rpm are on parwith some large-displacementgasoline engines.

"The question of how qui-et do we make it was an on-going debate among the de-velopment team," noted NVHengineer Scott DeRaad. Hisgroup was on the critical pathof the program-since its gen-esis in 2006.

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Developmentkicks offThe new diesel is an impor-tant power unit for Ford. Sixtypercent of the company'sheavy-duty F-250/350 pickuptrucks are purchased with thePowerStroke diesel. The com-pany has produced more than3.5 million of these vehicles inthe last two decades.

According to Gryglak, a20-year veteran of FordPowertrain engineering, theopportunity to develop aclean-sheet diesel was "rareand exciting" for the team-"something a powertrain engi-neer might get one chance todo in their career," he noted.

Combustion system devel-opment began in the early2000s as a Ford Research andAdvanced Powertrain project.But by mid-2006 Ford man-

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agement decided to rapidlyaccelerate the work toward afull-scale engine program.This was due in large part tothe disintegration of its long-time PowerStroke supply rela-tiOnship with Navistar.Production of the Navistar-built Ford V8s ends Dee. 31.

After development of thenew V8 began, Ford also en-tered discussions withGeneral Motors about a po-tential collaboration on dieselV8 engines. GM had its 6.6-LDuramax for heavy-duty pick-ups and was well along in de-veloping an all-new 4.5-L unitfor U.S. light-duty applica-tions. Ford had developed itsown 4.4-L light-duty V8 (cur-rent status is on hold) in addi-tion to the 6.7-L V8 program.

According to engineersfamiliar with the talks, it was

technolo y report

Lead Engineer AdamGryglak has workedon diesels for 9 ofhis 20 years at FordPowertrain. The new"Six-Seven" is his firstclean-sheet engineprogram.

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technology report

Fully dressed, the new6.7-L diesel V8 is morecompact overall than

the 6.4-L Navistarengine it replaces. The

engine features twowater pumps: one for

engine coolant andone to manage liquid

for the air-to-waterintercooler and EGR

cooling system.

thought the two companiesmight create noncompetitivesynergies by replicating theirsuccessful joint six-speed auto-matic transmission program,which has helped each achievesignificant cost savings.

GM's 4.5-L design also fea-tured inboard-facing exhaust,a package solution proven onvarious historic gasoline V8sincluding Cadillac flatheads,Ford's Indianapolis-winningV8 of the 1960s, and the cur-rent BMW twin-turbo gaso-line V8. GM had also settledon a CGI block for its diesel,with a single turbochargernestled in the valley. It dif-fered in having a DOHC valve-train and integral exhaustmanifolds, while Ford chose amore compact OHV designand bolt-on manifolds.

Preliminary discussions be-tween Ford and GM centeredon basic package surfaces.But collaboration wasn't tobe. Both sides ultimately de-cided to pursue independentdevelopment paths. And ear-lier this year, GM killed its 4.5-

24 NOVEMBER 2009 ae;

L diesel program which wasslated for 2010 production.

When the 6.7 programwas approved in late 2007,Ford heavily leveraged itsEuropean diesel engineeringexpertise, particularly in com-bustion-chamber design, ex-plained Gryglak. He said thedevelopment team assembledin Dearborn included stafffrom Research, AdvancedPowertrain, and Navistar ap-plications veterans. The fourlead manufacturing engineersfrom Ford U.K. were co-locat-ed with their design counter-parts to bring experience fromthe European Puma and Liondiesel programs.

InnovationthroughoutThe foundation of the newarchitecture is the deep-skirt-ed CGI block. Its materialproperties-CGI is approxi-mately twice as strong as grayiron-allow for thinner inter-nal walls and major bulk-heads, which help save mass.

The block is cast in Brazil

by Tupy SA and featurescross-bolted main bearingcaps for strength. The 6.7-L isdesigned for a 300,000-mi(483,000-km) duty cycle with-out major maintenance, notedLead Durability Engineer EdWaszczenko. He added thatthe dynamometer test sched-ule calls for 75 million cyclesbetween idle and wide-openthrottle. Among the manydesign changes to reciprocat-ing parts aimed at boostingdurability are the connectingrods. They are more robustoverall and now include small-end bushings; the wrist pins inthe Navistar V8 fit directly onthe rod.

Bore and stroke measure99 x 108 mm (3.9 x 4.3 in),respectively. According toGryglak, the V8's overall dec

sign "has displacement head-room and can also accommo-date smaller-displacementversions. tr

The aluminum heads withfour valves per cylinder areresponsible for most of thenew diesel's 160 Ib (73 kg)

weigbt savings, compared withthe old iron-head 6.4-L V8.The heads are cast by Nemak,while Ford handles final ma-chining at its Chihuahua,Mexico, engine plant, wherethe 6.7 is assembled.

The heads' inboard-facingexhaust ports feed theHoneywell turbocharger sit-ed in the V. Compared withconventional outside-facingports, this tight plumbinghelps reduce the exhaust sys-tem's total volume by 50%,optimizing heat transfer. Italso greatly aids throttle re-sponse by helping the turbospool up faster.

The heads are fixed to theblock by six bolts (two morethan on the 6.4-L) to spreadthe clamping load more even-ly. The heads incorporate dualwater jackets, which provideinternal manifolding. The en-gine uses two coolant pumps.One is for engine thermalmanagement. and the otherhandles the air-to-watercharge-air cooler and EGRcooling system.

The heads are designed tohandle the V8's 2600-psi(179-bar) cylinder pressures.Compression ratio is 16.2: 1.

Ford claims an industry firstwith its application of the sin-gle-sequential Honeywell tur-bocharger, formerly called SSTand now dubbed "DualBoost." It features a singleturbine impeller driving a pairof compressor wheels. Thisarrangement functions like asmall-displacement turbocombined with a large-dis-placement unit, giving imme-diate response at both lowand high engine rpm andsmoother response across theoperating range.

In addition, variable-pitchimpeller vanes are actuatedby means of new turbine-nozzle technology. The choiceof air-to-water charge coolingyields half the system volumeof an air-to-air cooler, with a

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technolo 'Y report aei

significant reduction in chargetemperature-50°C (122°F)compared to 90°C (194°F),said Gryglak.

The turbocharger mount-ing is one of the many holisticdesign elements that makethe 6.7-L diesel's NVH perfor-mance so impressive. The tur-bo housing mounts solidly ona patented pedestal situatedlow in the cylinder valley.

The Bosch fuel injectionsystem also helps reduce noiseby not using post-injectionevents during idling, althoughGryglak admits that the piezo-type injectors are inherentlynoisier 'than solenoid-actuatedtypes. The trade-off was im-proved engine-out emissions,he said.

Asserted NVH boss DeRaad:"Fuel system flexibility, thestiffer block, and good funda-

mental core engine designwere the main drivers for NVHreduction." He explained thatvery detailed analysiswas lav-ished on the engine's timinggears, with experts from Ford'sautomatic transmission groupenlisted to help optimize tooth

The Honeywell single-sequential "Dual Boost"turbocharger is mountedwithin the valley of theV8's cylinder block tocreate a smaller overallpackage, optimizethermal management,and improve turbo .response.

pitch, lash, and helix angles tominimize gear noise.

Other NVH actions includethe use of Helmholtz resona-tors in the intake manifoldand clean-air tube, and acous-tic covers lined with melaminefoam are mounted on therocker covers to reduce high-frequency sounds.

Ford IP is key toaftertreatmentAccording to emissions engi-neer Chris Oberski, the 6.7-Ldevelopment team chose SCRas the primary NOx-controltechnology because it does notrequire periodic rich opera-tion-a fuel-efficiency benefit.

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technology report

i....The CGI.cylinder block design incorporates a patented pedestalmounting for the turbocharger, designed to reduce NVH.

Co-developed by Bosch(which supplies the system'surea pump), the SCRcatalystis the central element of anearly six-foot-Iong aftertreat-ment suite mounted under-neath the truck. It includes adiesel-oxidation catalyst and asilicon-carbide particulate fil-ter providing passive and ac-tive regeneration.

Incorporated with the SCRcat is what Ford engineers callthe "DEF"-diesel emissionsfluid injector. This device in-jects a mixture of demineral-ized water and 32.5% ureainto the exhaust stream todramatically quell NOx.tailpipeemissions.

Oberski explained thatFord has developed "uniqueintellectual property" in theform of software to preciselycontrol the percentage of am-monia vapor within the SCRexhaust stream. His team hassized the onboard urea tankto require replenishment at7500-mi (12,1 OO-km) inter-

26 NOVEMBER 2009 aei

vals. Ford's Motorcraft partsdivision will sell a' Ford-branded urea product, anddrivers will receive audible(chimes) and visual (lights onthe instrument cluster) warn-ing approximately 1000 mi(J 600 km) before the tank isempty.

The Ford engineers tellAEI that more advanced ver-sions of the new V8 are indevelopment, aimed at themore stringent LEV3 emis-sions regulations.

Fifty of the' 11-spec en-gines have been built atChihuahua for prototype andvalidation testing. The plant iscurrently in the process oftooling up for production,which begins fourth quarter2009. Meanwhile, the newdiesel V8 continues to roarcontinuously on the Dearborndynos, often sustaining 4000-rpm speeds to ensure it'sready by this time next year.

Lindsay Brooke

example, the NiMH batterypack in the Ford Fusionweighs around 60 kg (132 lb),with cells accounting forabout 40 kg (88 Ib)

"The cell weight of anequivalent lithium system willbe around 20 kg," said TedMiller, Senior Manager ofEnergy Storage Strategy atFord. The transition to lithiumis planned throughout theindustry. For example, Fordplans to use Li-ion in its elec-tric Transit Connect van, setfor introduction next year.

The transition to Li-ion bat-teries will not depend solelyon production capability.There 'are a number of techni-cal issues that must be ad-dressed to make the transitionfrom NiMH. The NiMH batterypacks cannot be managed bythe control techniques in usetoday.

"We would like to estab-lish the same basic controlstructure for both NiMH andLi-ion batteries," saidToshifumi Takaoka, GeneralManager of Toyota's HybridVehicle EngineeringManagement Division."However, the internal resis-tance and other characteris-tics of these batteries differwidely, and we think thatthese areas will have to becontrolled using separatemodules."

A key factor is that Li-ionbatteries are delicate and areheavily dependent on the con-trol module to ensure thatbattery lifetimes match pow-ertrain life cycles.

"Li-ion batteries willquickly degrade whencharged to 100% full capacityor discharged to 0% state-of-charge," said Greg Zimmer,Product Marketing Engineer

Energy

Move to Li-ion requiresmany technical changes

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Battery technologies recentlygot a huge shot in the armwhen federal grants werehanded out. This portion ofthe economic stimulus pack-age aims to make lithium-ion(Li-ion) the technical base forelectrified vehicles, but it alsounderscores the many techni-cal changes automakers andtheir suppliers must make.

Battery companies got thebulk of $2.4 billion in grantmonies given to transporta-tion companies by the U.S.Department of Energy inAugust. To name a few,A 123Systems got $249 mil-lion, BASF collected $24.6million, EnerDel Inc. received

. $118.5 million, and JohnsonControls was given $299 mil-lion. Many others got fundingdesigned to build an infra-structure for hybrid and elec-tric drive vehicles.

The moves mark a signifi-cant advance in the move toelectrified vehicles, but thetransition also means thatengineers will have to make anumber of changes in theircontrol systems. Li-ion bringssignificant benefits over thenickel metal-hydride (NiMH)batteries now used in hybrids.

Foremost among them isthe ability to deliver morepower from smaller batteries.Most automakers will leveragethat to shrink the size of bat-tery packs.

"The nice thing about lithi-um is that you can get smallerbatteries," said Larry Nitz,General Motors ExecutiveDirector for HybridPowertrains. "We won't uselithium to get more power."

With lithium, mass can beroughly cut in half. That savessome space, but more signifi-cantly it reduces weight. For