Internal combustion engine

“ICEV” redirects here. For the form of water ice, see IceV. For the high speed train, see ICE V.An internal combustion engine (ICE) is a heat engine

Diagram of a cylinder as found in 4-stroke gasoline engines.:C – crankshaft.E – exhaust camshaft.I – inlet camshaft.P – piston.R – connecting rod.S – spark plug.V – valves. red: exhaust, blue: intake.W – cooling water jacket.gray structure – engine block.

where the combustion of a fuel occurs with an oxidizer(usually air) in a combustion chamber that is an integralpart of the working fluid flow circuit. In an internal com-bustion engine the expansion of the high-temperature andhigh-pressure gases produced by combustion apply directforce to some component of the engine. The force is ap-plied typically to pistons, turbine blades, or a nozzle. Thisforce moves the component over a distance, transform-ing chemical energy into useful mechanical energy. Thefirst commercially successful internal combustion enginewas created by Étienne Lenoir around 1859[1] and the firstmodern internal combustion engine was created in 1864by Siegfried Marcus.The term internal combustion engine usually refers to anengine in which combustion is intermittent, such as the

more familiar four-stroke and two-stroke piston engines,along with variants, such as the six-stroke piston engineand the Wankel rotary engine. A second class of internalcombustion engines use continuous combustion: gas tur-bines, jet engines and most rocket engines, each of whichare internal combustion engines on the same principle aspreviously described.[1][2] Firearms are also a form of in-ternal combustion engine.[2]

Internal combustion engines are quite different fromexternal combustion engines, such as steam or Stirlingengines, in which the energy is delivered to a workingfluid not consisting of, mixed with, or contaminated bycombustion products. Working fluids can be air, hot wa-ter, pressurized water or even liquid sodium, heated in aboiler. ICEs are usually powered by energy-dense fuelssuch as gasoline or diesel, liquids derived from fossil fu-els. While there are many stationary applications, mostICEs are used in mobile applications and are the domi-nant power supply for vehicles such as cars, aircraft, andboats.Typically an ICE is fed with fossil fuels like natural gasor petroleum products such as gasoline, diesel fuel orfuel oil. There’s a growing usage of renewable fuels likebiodiesel for compression ignition engines and bioethanolor methanol for spark ignition engines. Hydrogen issometimes used, and can be made from either fossil fuelsor renewable energy.

1 History

Main article: History of the internal combustion engine

2 Etymology

At one time, the word engine (from Latin, via Old French,ingenium, “ability”) meant any piece of machinery — asense that persists in expressions such as siege engine. A“motor” (from Latinmotor, “mover”) is any machine thatproduces mechanical power. Traditionally, electric mo-tors are not referred to as “Engines"; however, combus-tion engines are often referred to as “motors.” (An electricengine refers to a locomotive operated by electricity.)

1

2 4 CLASSIFICATION

3 Applications

Reciprocating engine as found inside a car

Reciprocating piston engines are by far the most com-mon power source for land and water vehicles, includ-ing automobiles, motorcycles, ships and to a lesser ex-tent, locomotives (some are electrical but most use Dieselengines[3][4]). Wankel engines are used in some automo-biles and motorcycles.Where very high power-to-weight ratios are required,internal combustion engines appear in the form ofcombustion turbines. Powered aircraft typically uses anICE which may be a reciprocating engine. Airplanes caninstead use jet engines and helicopters can instead employturboshafts; both of which are types of turbines. In addi-tion to providing propulsion, airliners employ a separateICE as an auxiliary power unit.

Big Diesel generator used for backup power

ICEs drive some of the large electric generators thatpower electrical grids. They are found in the form ofcombustion turbines in combined cycle power plants witha typical electrical output in the range of 100 MW to 1GW. The high temperature exhaust is used to boil and su-perheat water to run a steam turbine. Thus, the efficiencyis higher because more energy is extracted from the fuelthan what could be extracted by the combustion turbinealone. In combined cycle power plants efficiencies in therange of 50% to 60% are typical. In a smaller scale Diesel

Combined cycle power plant

generators are used for backup power and for providingelectrical power to areas not connected to an electric grid.Small engines (usually 2‐stroke gasoline engines) are acommon power source for lawnmowers, string trimmers,chain saws, leafblowers, pressure washers, snowmobiles,jet skis, outboard motors, mopeds, and motorcycles.

4 Classification

There are several possible ways to classify internal com-bustion engines.Reciprocating:

By number of strokes

• Two-stroke engine• Four-stroke engine (Otto cycle)• Six-stroke engine

By type of ignition

• Compression-ignition engine• Spark-ignition engine (commonly foundas gasoline engines)

By mechanical/thermodynamical cycle (these2 cycles do not encompass all reciprocating en-gines, and are infrequently used):

• Atkinson cycle• Miller cycle

Rotary:

• Wankel engine

Continuous combustion:

• Gas turbine

5.1 Structure 3

• Jet engine

• Rocket engine

The following jet engine types are also gas turbinestypes:

•Ramjet •Turbojet

• Turbofan• Turboprop

5 Reciprocating engines

See also: Diesel engine and Gasoline engine

5.1 Structure

Bare cylinder block of a V8 engine

The base of a reciprocating internal combustion engine isthe engine block, which is typically made of cast iron oraluminium. The engine block contains the cylinders. Inengines with more than one cylinder they are usually ar-ranged either in 1 row (straight engine) or 2 rows (boxerengine or V engine); 3 rows are occasionally used (W en-gine) in contemporary engines, and other engine config-urations are possible and have been used. Single cylinderengines are common for motorcycles and in small enginesof machinery. Water-cooled engines contain passages inthe engine block where cooling fluid circulates (the waterjacket). Some small engines are air-cooled, and instead ofhaving a water jacket the cylinder block has fins protrud-ing away from it to cool by directly transferring heat tothe air. The cylinder walls are usually finished by honingto obtain a cross hatch, which is better able to retain theoil. A too rough surface would quickly harm the engineby excessive wear on the piston.The pistons are short cylindrical parts which seal oneend of the cylinder from the high pressure of the com-pressed air and combustion products and slide continu-ously within it while the engine is in operation. The top

Piston, piston ring, gudgeon pin and connecting rod

wall of the piston is termed its crown and is typically flator concave. Some two-stroke engines use pistons with adeflector head. Pistons are open at the bottom and hollowexcept for an integral reinforcement structure (the pistonweb). When an engine is working the gas pressure in thecombustion chamber exerts a force on the piston crownwhich is transferred through its web to a gudgeon pin.Each piston has rings fitted around its circumference thatmostly prevent the gases from leaking into the crankcaseor the oil into the combustion chamber. A ventilationsystem drives the small amount of gas that escape pastthe pistons during normal operation (the blow-by gases)out of the crankcase so that it does not accumulate con-taminating the oil and creating corrosion. In two-strokegasoline engines the crankcase is part of the air–fuel pathand due to the continuous flow of it they do not need a

4 5 RECIPROCATING ENGINES

separate crankcase ventilation system.

Valve train above a Diesel engine cylinder head. This engine usesrocker arms but no pushrods.

The cylinder head is attached to the engine block by nu-merous bolts or studs. It has several functions. The cylin-der head seals the cylinders on the side opposite to thepistons; it contains short ducts (the ports) for intake andexhaust and the associated intake valves that open to letthe cylinder be filled with fresh air and exhaust valves thatopen to allow the combustion gases to escape. However,2-stroke crankcase scavenged engines connect the gasports directly to the cylinder wall without poppet valves;the piston controls their opening and occlusion instead.The cylinder head also holds the spark plug in the case ofspark ignition engines and the injector for engines that usedirect injection. All CI engines use fuel injection, usuallydirect injection but some engines instead use indirect in-jection. SI engines can use a carburetor or fuel injectionas port injection or direct injection. Most SI engines havea single spark plug per cylinder but some have 2. A headgasket prevents the gas from leaking between the cylin-der head and the engine block. The opening and clos-ing of the valves is controlled by one or several camshaftsand springs—or in some engines—a desmodromic mech-anism that uses no springs. The camshaft may press di-rectly the stem of the valve or may act upon a rocker arm,again, either directly or through a pushrod.The crankcase is sealed at the bottom with a sump thatcollects the falling oil during normal operation to be cy-cled again. The cavity created between the cylinder blockand the sump houses a crankshaft that converts the recip-rocating motion of the pistons to rotational motion. Thecrankshaft is held in place relative to the engine blockby main bearings, which allow it to rotate. Bulkheadsin the crankcase form a half of every main bearing; theother half is a detachable cap. In some cases a singlemain bearing deck is used rather than several smaller caps.A connecting rod is connected to offset sections of thecrankshaft (the crankpins) in one end and to the piston inthe other end through the gudgeon pin and thus transfersthe force and translates the reciprocating motion of thepistons to the circular motion of the crankshaft. The end

Engine block seen from below. The cylinders, oil spay nozzle andhalf of the main bearings are clearly visible.

of the connecting rod attached to the gudgeon pin is calledits small end, and the other end, where it is connected tothe crankshaft, the big end. The big end has a detachablehalf to allow assembly around the crankshaft. It is kepttogether to the connecting rod by removable bolts.The cylinder head has attached an intake manifold andan exhaust manifold to the corresponding ports. The in-take manifold connects to the air filter directly, or to acarburetor when one is present, which is then connectedto the air filter. It distributes the air incoming from thesedevices to the individual cylinders. The exhaust manifoldis the first component in the exhaust system. It collects theexhaust gases from the cylinders and drives it to the fol-lowing component in the path. The exhaust system of anICE may also include a catalytic converter and muffler.The final section in the path of the exhaust gases is thetailpipe.

5.2 4-stroke engines

Main article: 4-stroke engineThe top dead center (TDC) of a piston is the posi-tion where it is nearest to the valves; bottom dead center(BDC) is the opposite position where it is furthest fromthem. A stroke is the movement of a piston from TDCto BDC or vice versa together with the associated pro-cess. While an engine is in operation the crankshaft ro-tates continuously at a nearly constant speed. In a 4-strokeICE each piston experiences 2 strokes per crankshaft rev-olution in the following order. Starting the description atTDC, these are:[5][6]

1. Intake, induction or suction: The intake valves areopen as a result of the cam lobe pressing down on thevalve stem. The piston moves downward increasingthe volume of the combustion chamber and allowingair to enter in the case of a CI engine or an air fuelmix in the case of SI engines that do not use directinjection. The air or air-fuel mixture is called the

5.3 2-stroke engines 5

Diagram showing the operation of a 4-stroke SI engine. Labels:1 ‐ Induction2 ‐ Compression3 ‐ Power4 ‐ Exhaust

charge in any case.

2. Compression: In this stroke, both valves are closedand the piston moves upward reducing the combus-tion chamber volume which reaches its minimumwhen the piston is at TDC. The piston performswork on the charge as it is being compressed; as aresult its pressure, temperature and density increase;an approximation to this behavior is provided by theideal gas law. Just before the piston reaches TDC,ignition begins. In the case of a SI engine, the sparkplug receives a high voltage pulse that generates thespark which gives it its name and ignites the charge.In the case of a CI engine the fuel injector quicklyinjects fuel into the combustion chamber as a spray;the fuel ignites due to the high temperature.

3. Power orworking stroke: The pressure of the com-bustion gases pushes the piston downward, gener-ating more work than it required to compress thecharge. Complementary to the compression stroke,the combustion gases expand and as a result theirtemperature, pressure and density decreases. Whenthe piston is near to BDC the exhaust valve opens.The combustion gases expand irreversibly due to theleftover pressure—in excess of back pressure, thegauge pressure on the exhaust port—; this is calledthe blowdown.

4. Exhaust: The exhaust valve remains open whilethe piston moves upward expelling the combustiongases. For naturally aspirated engines a small partof the combustion gases may remain in the cylin-der during normal operation because the piston doesnot close the combustion chamber completely; thesegases dissolve in the next charge. At the end ofthis stroke, the exhaust valve closes, the intake valveopens, and the sequence repeats in the next cycle.The intake valve may open before the exhaust valvecloses to allow better scavenging.

5.3 2-stroke engines

Main article: 2-stroke engine

The defining characteristic of this kind of engine is thateach piston completes a cycle every crankshaft revolution.The 4 process of intake, compression, power and exhausttake place in only 2 strokes so that it is not possible todedicate a stroke exclusively for each of them. Starting atTDC the cycle consist of:

1. Power: While the piston is descending the com-bustion gases perform work on it—as in a 4-strokeengine—. The same thermodynamical considera-tions about the expansion apply.

2. Scavenging: Around 75° of crankshaft rotation be-fore BDC the exhaust valve or port opens, and blow-down occurs. Shortly thereafter the intake valve ortransfer port opens. The incoming charge displacesthe remaining combustion gases to the exhaust sys-tem and a part of the charge may enter the exhaustsystem as well. The piston reaches BDC and re-verses direction. After the piston has traveled ashort distance upwards into the cylinder the exhaustvalve or port closes; shortly the intake valve or trans-fer port closes as well.

3. Compression: With both intake and exhaust closedthe piston continues moving upwards compressingthe charge and performing a work on it. As in thecase of a 4-stroke engine, ignition starts just beforethe piston reaches TDC and the same considerationon the thermodynamics of the compression on thecharge.

While a 4-stroke engine uses the piston as a positive dis-placement pump to accomplish scavenging taking 2 ofthe 4 strokes, a 2-stroke engine uses the last part of thepower stroke and the first part of the compression strokefor combined intake and exhaust. The work required todisplace the charge and exhaust gases comes from eitherthe crankcase or a separate blower. For scavenging, ex-pulsion of burned gas and entry of fresh mix, two mainapproaches are described: 'Loop scavenging', and 'Uni-flow scavenging', SAE news published in the 2010s that

6 5 RECIPROCATING ENGINES

'Loop Scavenging' is better under any circumstance than'Uniflow Scavenging'.

5.3.1 Crankcase scavenged

Diagram of a crankcase scavenged 2-stroke engine in operation

Some SI engines are crankcase scavenged and do not usepoppet valves. Instead the crankcase and the part of thecylinder below the piston is used as a pump. The intakeport is connected to the crankcase through a reed valve ora rotary disk valve driven by the engine. For each cylin-der a transfer port connects in one end to the crankcaseand in the other end to the cylinder wall. The exhaustport is connected directly to the cylinder wall. The trans-fer and exhaust port are opened and closed by the pis-ton. The reed valve opens when the crankcase pressureis slightly below intake pressure, to let it be filled with anew charge; this happens when the piston is moving up-wards. When the piston is moving downwards the pres-sure in the crankcase increases and the reed valve closespromptly, then the charge in the crankcase is compressed.When the piston is moving upwards, it uncovers the ex-haust port and the transfer port and the higher pressureof the charge in the crankcase makes it enter the cylin-der through the transfer port, blowing the exhaust gases.

Lubrication is accomplished by adding 2-stroke oil to thefuel in small ratios. Petroil refers to the mix of gasolinewith the aforesaid oil. This kind of 2-stroke engines hasa lower efficiency than comparable 4-strokes engines andrelease a more polluting exhaust gases for the followingconditions:

• They use a total-loss lubrication system: all the lubri-cating oil is eventually burned along with the fuel.

• There are conflicting requirements for scavenging:On one side, enough fresh charge needs to be intro-duced in each cycle to displace almost all the com-bustion gases but introducing too much of it meansthat a part of it gets in the exhaust.

• They must use the transfer port(s) as a carefullydesigned and placed nozzle so that a gas currentis created in a way that it sweeps the whole cylin-der before reaching the exhaust port so as to expelthe combustion gases, but minimize the amount ofcharge exhausted. 4-stroke engines have the bene-fit of forcibly expelling almost all of the combustiongases because during exhaust the combustion cham-ber is reduced to its minimum volume. In crankcasescavenged 2-stroke engines, exhaust and intake areperformed mostly simultaneously and with the com-bustion chamber at its maximum volume.

The main advantage of 2-stroke engines of this type ismechanical simplicity and a higher power-to-weight ratiothan their 4-stroke counterparts. Despite having twice asmany power strokes per cycle, less than twice the powerof a comparable 4-stroke engine is attainable in practice.

5.3.2 Blower scavenged

Using a separate blower avoids many of the shortcom-ings of crankcase scavenging, at the expense of increasedcomplexity which means a higher cost and an increase inmaintenance requirement. An engine of this type usesports or valves for intake and valves for exhaust, exceptopposed piston engines, which may also use ports for ex-haust. The blower is usually of the Roots-type but othertypes have been used too. This design is commonplace inCI engines, and has been occasionally used in SI engines.CI engines that use a blower typically use uniflow scav-enging. In this design the cylinder wall contains severalintake ports placed uniformly spaced along the circumfer-ence just above the position that the piston crown reacheswhen at BDC. An exhaust valve or several like that of 4-stroke engines is used. The final part of the intake man-ifold is an air sleeve which feeds the intake ports. Theintake ports are placed at an horizontal angle to the cylin-der wall (I.e: they are in plane of the piston crown) togive a swirl to the incoming charge to improve combus-tion. The largest reciprocating IC are low speed CI en-gines of this type; they are used for marine propulsion

5.4 Ignition 7

Diagram of uniflow scavenging

(see marine diesel engine) or electric power generationand achieve the highest thermal efficiencies among inter-nal combustion engines of any kind. SomeDiesel-electriclocomotive engines operate on the 2-stroke cycle. Themost powerful of them have a brake power of around4.5 MW or 6,000 HP. The EMD SD90MAC class of lo-comotives use a 2-stroke engine. The comparable classGEAC6000CWwhose primemover has almost the samebrake power uses a 4-stroke engine.An example of this type of engine is the Wärtsilä-Sulzer RTA96-C turbocharged 2-stroke Diesel, used inlarge container ships. It is the most efficient and pow-erful internal combustion engine in the world with athermal efficiency over 50%.[7][8][9][10] For comparison,the most efficient small four-stroke engines are around43% thermally-efficient (SAE 900648); size is an advan-tage for efficiency due to the increase in the ratio of vol-ume to surface area.See the external links for a in-cylinder combustion videoin a 2-stroke, optically accessible motorcycle engine.

5.4 Ignition

Internal combustion engines require ignition of the mix-ture, either by spark ignition (SI) or compression ignition(CI). Before the invention of reliable electrical methods,hot tube and flame methods were used. Experimental en-gines with laser ignition have been built.[11]

5.4.1 Gasoline Ignition Process

Gasoline engine ignition systems generally rely on a com-bination of alternator or generator and lead–acid batteryfor electrical power. The battery supplies electrical powerfor cranking, and supplies electrical power when the en-gine is off. The battery also supplies electrical power dur-ing rare run conditions where the alternator cannot main-tain more than 13.8 volts (for a common 12V automotiveelectrical system). As alternator voltage falls below 13.8volts, the lead-acid storage battery increasingly picks upelectrical load. During virtually all running conditions,including normal idle conditions, the alternator suppliesprimary electrical power.Some systems disable alternator field (rotor) power dur-ing wide open throttle conditions. Disabling the field re-duces alternator pulley mechanical loading to nearly zero,maximizing crankshaft power. In this case the batterysupplies all primary electrical power.Gasoline engines take in a mixture of air and gasolineand compress it to not more than 12.8 bar (1.28 MPa).When mixture is compressed, as the piston approachesthe cylinder head and maximum stroke, a spark plug ig-nites the mixture.The necessary high voltage, typically 10,000 volts to over30,000 volts, is supplied by an induction coil or trans-former. The induction coil is a fly-back system, usinginterruption of electrical primary system current throughsome type of synchronized interrupter. The interruptercan be either contact points or a power transistor. Someignition systems are capacitive discharge types. CD igni-tions use step-up transformers. The step-up transformeruses energy stored in a capacitance to generate electricspark. With either system, a mechanical or electrical con-trol system provides a carefully timed high-voltage to theproper cylinder. This spark, via the spark plug, ignites theair-fuel mixture in the engine’s cylinders.While gasoline internal combustion engines are mucheasier to start in cold weather than diesel engines, theycan still have cold weather starting problems under ex-treme conditions. For years the solution was to park thecar in heated areas. In some parts of the world the oilwas actually drained and heated over night and returnedto the engine for cold starts. In the early 1950s the gaso-line Gasifier unit was developed, where, on cold weatherstarts, raw gasoline was diverted to the unit where partof the fuel was burned causing the other part to becomea hot vapor sent directly to the intake valve manifold.

8 5 RECIPROCATING ENGINES

This unit was quite popular until electric engine blockheaters became standard on gasoline engines sold in coldclimates.[12]

5.4.2 Diesel Ignition Process

Diesel engines and HCCI (Homogeneous charge com-pression ignition) engines, rely solely on heat and pressurecreated by the engine in its compression process for igni-tion. The compression level that occurs is usually twiceor more than a gasoline engine. Diesel engines take in aironly, and shortly before peak compression, spray a smallquantity of diesel fuel into the cylinder via a fuel injec-tor that allows the fuel to instantly ignite. HCCI typeengines take in both air and fuel, but continue to relyon an unaided auto-combustion process, due to higherpressures and heat. This is also why diesel and HCCIengines are more susceptible to cold-starting issues, al-though they run just as well in cold weather once started.Light duty diesel engines with indirect injection in auto-mobiles and light trucks employ glowplugs that pre-heatthe combustion chamber just before starting to reduce no-start conditions in cold weather. Most diesels also have abattery and charging system; nevertheless, this system issecondary and is added by manufacturers as a luxury forthe ease of starting, turning fuel on and off (which canalso be done via a switch or mechanical apparatus), andfor running auxiliary electrical components and acces-sories. Most new engines rely on electrical and electronicengine control units (ECU) that also adjust the combus-tion process to increase efficiency and reduce emissions.

5.5 Lubrication

Diagram of an engine using pressurized lubrication

Surfaces in contact and relative motion to other surfacesrequire lubrication to reduce wear, noise and increase ef-ficiency by reducing the power wasting in overcoming

friction, or to make the mechanism work at all. At thevery least, an engine requires lubrication in the followingparts:

• Between pistons and cylinders

• Small bearings

• Big end bearings

• Main bearings

• Valve gear (The following elements may not bepresent):

• Tappets• Rocker arms• Pushrods• Timing chain or gears. Toothed belts do notrequire lubrication.

In 2-stroke crankcase scavenged engines, the interior ofthe crankcase, and therefore the crankshaft, connectingrod and bottom of the pistons are sprayed by the 2-strokeoil in the air-fuel-oil mixture which is then burned alongwith the fuel. The valve train may be contained in a com-partment flooded with lubricant so that no oil pump isrequired.In a splash lubrication system no oil pump is used. In-stead the crankshaft dips into the oil in the sump and dueto its high speed, it splashes the crankshaft, connectingrods and bottom of the pistons. The connecting rod bigend caps may have an attached scoop to enhance this ef-fect. The valve train may also be sealed in a flooded com-partment, or open to the crankshaft in a way that it re-ceives splashed oil and allows it to drain back to the sump.Splash lubrication is common for small 4-stroke engines.In a forced (also called pressurized) lubrication system,lubrication is accomplished in a closed loop which carriesmotor oil to the surfaces serviced by the system and thenreturns the oil to a reservoir. The auxiliary equipment ofan engine is typically not serviced by this loop; for in-stance, an alternator may use ball bearings sealed with itslubricant. The reservoir for the oil is usually the sump,and when this is the case, it is called a wet sump system.When there is a different oil reservoir the crankcase stillcatches it, but it is continuously drained by a dedicatedpump; this is called a dry sump system.On its bottom, the sump contains an oil intake covered bya mesh filter which is connected to an oil pump then to anoil filter outside the crankcase, from there it is divertedto the crankshaft main bearings and valve train. Thecrankcase contains at least one oil gallery (a conduit insidea crankcase wall) to which oil is introduced from the oilfilter. The main bearings contain a groove through all orhalf its circumference; the oil enters to these grooves fromchannels connected to the oil gallery. The crankshaft has

5.7 Diesel cycle 9

drillings which take oil from these grooves and deliver itto the big end bearings. All big end bearings are lubri-cated this way. A single main bearing may provide oil for0, 1 or 2 big end bearings. A similar system may be usedto lubricate the piston, its gudgeon pin and the small endof its connecting rod; in this system, the connecting rodbig end has a groove around the crankshaft and a drillingconnected to the groove which distributes oil from thereto the bottom of the piston and from then to the cylinder.Other systems are also used to lubricate the cylinder andpiston. The connecting rod may have a nozzle to throwan oil jet to the cylinder and bottom of the piston. Thatnozzle is in movement relative to the cylinder it lubricates,but always pointed towards it or the corresponding piston.Typically a forced lubrication systems have a lubricantflow higher than what is required to lubricate satisfacto-rily, in order to assist with cooling. Specifically, the lubri-cant system helps to move heat from the hot engine partsto the cooling liquid (in water-cooled engines) or fins (inair-cooled engines) which then transfer it to the environ-ment. The lubricant must be designed to be chemicallystable andmaintain suitable viscosities within the temper-ature range it encounters in the engine.

5.6 Cylinder configuration

Common cylinder configurations include the straight orinline configuration, the more compact V configuration,and the wider but smoother flat or boxer configuration.Aircraft engines can also adopt a radial configuration,which allows more effective cooling. More unusual con-figurations such as the H, U, X, and W have also beenused.Multiple cylinder engines have their valve train andcrankshaft configured so that pistons are at different partsof their cycle. It is desirable to have the piston’s cy-cles uniformly spaced (this is called even firing) espe-cially in forced induction engines; this reduces torquepulsations[13] and makes inline engines with more than 3cylinders statically balanced in its primary forces. How-ever, some engine configurations require odd firing toachieve better balance than what is possible with evenfiring. For instance, a 4-stroke I2 engine has better bal-ance when the angle between the crankpins is 180° be-cause the pistons move in opposite directions and inertialforces partially cancel, but this gives an odd firing patternwhere one cylinder fires 180° of crankshaft rotation afterthe other, then no cylinder fires for 540°. With an evenfiring pattern the pistons would move in unison and theassociated forces would add.Multiple crankshaft configurations do not necessarilyneed a cylinder head at all because they can instead havea piston at each end of the cylinder called an opposedpiston design. Because fuel inlets and outlets are posi-tioned at opposed ends of the cylinder, one can achieveuniflow scavenging, which, as in the four-stroke engine is

efficient over a wide range of engine speeds. Thermal ef-ficiency is improved because of a lack of cylinder heads.This design was used in the Junkers Jumo 205 diesel air-craft engine, using two crankshafts at either end of a sin-gle bank of cylinders, and most remarkably in the NapierDeltic diesel engines. These used three crankshafts toserve three banks of double-ended cylinders arranged inan equilateral triangle with the crankshafts at the corners.It was also used in single-bank locomotive engines, and isstill used in marine propulsion engines and marine auxil-iary generators.

5.7 Diesel cycle

Main article: Diesel cycleMost truck and automotive diesel engines use a cycle

p

VV2

p4p1

0 V1V3

1

2 3

4

p2

p: pressureV: specific volume

Qin

Qout

Wout

Win

isentropic

isentropic

P-v Diagram for the Ideal Diesel cycle. The cycle follows thenumbers 1–4 in clockwise direction.

reminiscent of a four-stroke cycle, but with a compres-sion heating ignition system, rather than needing a sep-arate ignition system. This variation is called the dieselcycle. In the diesel cycle, diesel fuel is injected directlyinto the cylinder so that combustion occurs at constantpressure, as the piston moves.Otto cycle: Otto cycle is the typical cycle for most of thecars internal combustion engines, that work using gaso-line as a fuel. Otto cycle is exactly the same one that wasdescribed for the four-stroke engine. It consists of thesame four major steps: Intake, compression, ignition andexhaust.PV diagram for Otto cycle On the PV-diagram, 1–2: In-take: suction stroke 2–3: Isentropic Compression stroke3–4: Heat addition stroke 4–5: Exhaust stroke (Isen-tropic expansion) 5–2: Heat rejection The distance be-tween points 1–2 is the stroke of the engine. By dividingV2/V1, we get: r, where r is called the compression ratioof the engine.

10 6 COMBUSTION TURBINES

5.8 Five-stroke engine

In 1879, Nikolaus Otto manufactured and sold double ex-pansion engine (the double and triple expansion princi-ples had ample usage in steam engines), with two smallcylinders at both sides of a low-pressure larger cylinder,where a second expansion of exhaust stroke gas tookplace; the owner returned it, alleging poor performance.In 1906, the concept was incorporated in a car builtby EHV (Eisenhuth Horseless Vehicle Company) CT,USA. (ref: 'The Romance of Engines’, Takashi Suzuki,Ph.D., pags: 87-94, SAE, 1997), and in the 21st cen-tury, ILMOR designed and successfully tested a 5-strokedouble expansion internal combustion engine, with highpower output and low SFC (Specific Fuel Consumption).

5.9 Six-stroke engine

The six-stroke engine was invented in 1883. Fourkinds of six-stroke use a regular piston in a regularcylinder (Griffin six-stroke, Bajulaz six-stroke, Velozetasix-stroke and Crower six-stroke), firing every threecrankshaft revolutions. The systems capture the wastedheat of the four-stroke Otto cycle with an injection of airor water.The Beare Head and “piston charger” engines operate asopposed-piston engines, two pistons in a single cylinder,firing every two revolutions rather more like a regularfour-stroke.

5.10 Other cycles

The very first internal combustion engines did not com-press the mixture. The first part of the piston downstrokedrew in a fuel-air mixture, then the inlet valve closed and,in the remainder of the down-stroke, the fuel-air mix-ture fired. The exhaust valve opened for the piston up-stroke. These attempts at imitating the principle of asteam engine were very inefficient. There are a numberof variations of these cycles, most notably the Atkinsonand Miller cycles. The diesel cycle is somewhat different.Split-cycle engines separate the four strokes of intake,compression, combustion and exhaust into two separatebut paired cylinders. The first cylinder is used for intakeand compression. The compressed air is then transferredthrough a crossover passage from the compression cylin-der into the second cylinder, where combustion and ex-haust occur. A split-cycle engine is really an air compres-sor on one side with a combustion chamber on the other.Previous split-cycle engines have had two majorproblems—poor breathing (volumetric efficiency) andlow thermal efficiency. However, new designs are beingintroduced that seek to address these problems.The Scuderi Engine addresses the breathing problem

by reducing the clearance between the piston and thecylinder head through various turbo charging techniques.The Scuderi design requires the use of outwardly open-ing valves that enable the piston to move very close tothe cylinder head without the interference of the valves.Scuderi addresses the low thermal efficiency via firing af-ter top dead centre (ATDC).Firing ATDC can be accomplished by using high-pressure air in the transfer passage to create sonic flowand high turbulence in the power cylinder.

6 Combustion turbines

6.1 Gas turbines

Main article: gas turbine

A gas turbine is called a gas turbine because it compressesa gas, usually air. There are three stages to a turbine: 1)air is drawn through a compressor where the temperaturerises due to compression, 2) fuel is added in the com-buster, and 3) hot air is exhausted through turbines bladeswhich rotate a shaft connected to the compressor.A gas turbine is a rotary machine similar in principle to asteam turbine and it consists of three main components:a compressor, a combustion chamber, and a turbine. Theair, after being compressed in the compressor, is heatedby burning fuel in it. About⅔ of the heated air, combinedwith the products of combustion, expands in a turbine,producing work output that drives the compressor. Therest (about ⅓) is available as useful work output.

6.2 Jet engine

Main article: Jet engine

The jet engine takes a large volume of hot gas from acombustion process (typically a gas turbine, but rocketforms of jet propulsion often use solid or liquid propel-lants, and ramjet forms also lack the gas turbine) andfeeds it through a nozzle that accelerates the jet to highspeed. As the jet accelerates through the nozzle, this cre-ates thrust and in turn does useful work.

6.3 Brayton cycle

Main article: Brayton cycleA gas turbine is a rotary machine somewhat similar inprinciple to a steam turbine. It consists of three maincomponents: compressor, combustion chamber, and tur-bine. The air is compressed by the compressor where atemperature rise occurs. The compressed air is furtherheated by combustion of injected fuel in the combustion

11

Fuel

Fresh Air Exhaust gasses

Combustion

Work out

Compressor Turbine

P

v

q in

q out

s = const.

s = const.

1

2 3

41

2 3

4

P-v Diagram

T

s

q in

q outp = const.

p =

cons

t.

1

2

3

4

T-s Diagram

Brayton cycle

chamber which expands the air. This energy rotates theturbine which powers the compressor via a mechanicalcoupling. The hot gases are then exhausted to providethrust.Gas turbine cycle engines employ a continuous com-bustion system where compression, combustion, and ex-pansion occur simultaneously at different places in theengine—giving continuous power. Notably, the combus-tion takes place at constant pressure, rather than with theOtto cycle, constant volume.

7 Wankel engines

The Wankel cycle. The shaft turns three times for each rotationof the rotor around the lobe and once for each orbital revolutionaround the eccentric shaft.

Main article: Wankel engine

The Wankel engine (rotary engine) does not have pistonstrokes. It operates with the same separation of phases

as the four-stroke engine with the phases taking place inseparate locations in the engine. In thermodynamic termsit follows the Otto engine cycle, so may be thought of asa “four-phase” engine. While it is true that three powerstrokes typically occur per rotor revolution, due to the3:1 revolution ratio of the rotor to the eccentric shaft,only one power stroke per shaft revolution actually oc-curs. The drive (eccentric) shaft rotates once during ev-ery power stroke instead of twice (crankshaft), as in theOtto cycle, giving it a greater power-to-weight ratio thanpiston engines. This type of engine wasmost notably usedin the Mazda RX-8, the earlier RX-7, and other models.

8 Forced induction

Main article: Forced induction

Forced induction is the process of delivering compressedair to the intake of an internal combustion engine. Aforced induction engine uses a gas compressor to increasethe pressure, temperature and density of the air. An en-gine without forced induction is considered a naturallyaspirated engine.Forced induction is used in the automotive and aviationindustry to increase engine power and efficiency. It par-ticularly helps aviation engines, as they need to operate athigh altitude.Forced induction is achieved by a supercharger, where thecompressor is directly powered from the engine shaft or,in the turbocharger, from a turbine powered by the engineexhaust.

9 Fuels and oxidizers

All internal combustion engines depend on combustionof a chemical fuel, typically with oxygen from the air(though it is possible to inject nitrous oxide to do more ofthe same thing and gain a power boost). The combustionprocess typically results in the production of a great quan-tity of heat, as well as the production of steam and carbondioxide and other chemicals at very high temperature; thetemperature reached is determined by the chemical makeup of the fuel and oxidisers (see stoichiometry), as wellas by the compression and other factors.

9.1 Fuels

The most common modern fuels are made up ofhydrocarbons and are derived mostly from fossil fuels(petroleum). Fossil fuels include diesel fuel, gasolineand petroleum gas, and the rarer use of propane. Ex-cept for the fuel delivery components, most internal com-bustion engines that are designed for gasoline use can

12 9 FUELS AND OXIDIZERS

run on natural gas or liquefied petroleum gases with-out major modifications. Large diesels can run with airmixed with gases and a pilot diesel fuel ignition injec-tion. Liquid and gaseous biofuels, such as ethanol andbiodiesel (a form of diesel fuel that is produced fromcrops that yield triglycerides such as soybean oil), can alsobe used. Engines with appropriate modifications can alsorun on hydrogen gas, wood gas, or charcoal gas, as well asfrom so-called producer gas made from other convenientbiomass. Experiments have also been conducted usingpowdered solid fuels, such as the magnesium injectioncycle.Presently, fuels used include:

• Petroleum:

• Petroleum spirit (North American term:gasoline, British term: petrol)

• Petroleum diesel.• Autogas (liquified petroleum gas).• Compressed natural gas.• Jet fuel (aviation fuel)• Residual fuel

• Coal:

• Gasoline can be made from carbon (coal) us-ing the Fischer-Tropsch process

• Diesel fuel can be made from carbon using theFischer-Tropsch process

• Biofuels and vegetable oils:

• Peanut oil and other vegetable oils.• Woodgas, from an onboardwood gasifier usingsolid wood as a fuel

• Biofuels:• Biobutanol (replaces gasoline).• Biodiesel (replaces petrodiesel).• Dimethyl Ether (replaces petrodiesel).• Bioethanol and Biomethanol (wood alco-hol) and other biofuels (see Flexible-fuelvehicle).

• Biogas

• Hydrogen (mainly spacecraft rocket engines)

Even fluidized metal powders and explosives have seensome use. Engines that use gases for fuel are called gasengines and those that use liquid hydrocarbons are calledoil engines; however, gasoline engines are also often col-loquially referred to as, “gas engines” (“petrol engines”outside North America).The main limitations on fuels are that it must be easilytransportable through the fuel system to the combustionchamber, and that the fuel releases sufficient energy in

the form of heat upon combustion to make practical useof the engine.Diesel engines are generally heavier, noisier, and morepowerful at lower speeds than gasoline engines. Theyare also more fuel-efficient in most circumstances and areused in heavy road vehicles, some automobiles (increas-ingly so for their increased fuel efficiency over gasolineengines), ships, railway locomotives, and light aircraft.Gasoline engines are used in most other road vehicles in-cluding most cars, motorcycles, and mopeds. Note thatin Europe, sophisticated diesel-engined cars have takenover about 45% of the market since the 1990s. Thereare also engines that run on hydrogen, methanol, ethanol,liquefied petroleum gas (LPG), biodiesel, paraffin andtractor vaporizing oil (TVO).

9.1.1 Hydrogen

Main article: Hydrogen internal combustion enginevehicle

Hydrogen could eventually replace conventional fossil fu-els in traditional internal combustion engines. Alterna-tively fuel cell technologymay come to deliver its promiseand the use of the internal combustion engines could evenbe phased out.Although there are multiple ways of producing free hy-drogen, those methods require converting combustiblemolecules into hydrogen or consuming electric energy.Unless that electricity is produced from a renewablesource—and is not required for other purposes— hydro-gen does not solve any energy crisis. In many situationsthe disadvantage of hydrogen, relative to carbon fuels,is its storage. Liquid hydrogen has extremely low den-sity (14 times lower than water) and requires extensiveinsulation—whilst gaseous hydrogen requires heavy tank-age. Even when liquefied, hydrogen has a higher specificenergy but the volumetric energetic storage is still roughlyfive times lower than gasoline. However, the energy den-sity of hydrogen is considerably higher than that of elec-tric batteries, making it a serious contender as an energycarrier to replace fossil fuels. The 'Hydrogen on Demand'process (see direct borohydride fuel cell) creates hydro-gen as needed, but has other issues, such as the high priceof the sodium borohydride that is the raw material.

9.2 Oxidizers

Since air is plentiful at the surface of the earth, the oxi-dizer is typically atmospheric oxygen, which has the ad-vantage of not being stored within the vehicle. This in-creases the power-to-weight and power-to-volume ratios.Other materials are used for special purposes, often to in-crease power output or to allow operation under water orin space.

13

One-cylinder gasoline engine, c. 1910

• Compressed air has been commonly used intorpedoes.

• Compressed oxygen, as well as some compressedair, was used in the Japanese Type 93 torpedo.Some submarines carry pure oxygen. Rockets veryoften use liquid oxygen.

• Nitromethane is added to some racing andmodel fu-els to increase power and control combustion.

• Nitrous oxide has been used—with extra gasoline—in tactical aircraft, and in specially equipped cars toallow short bursts of added power from engines thatotherwise run on gasoline and air. It is also used inthe Burt Rutan rocket spacecraft.

• Hydrogen peroxide power was under developmentfor German World War II submarines. It may havebeen used in some non-nuclear submarines, and wasused on some rocket engines (notably the Black Ar-row and the Me-163 rocket plane).

• Other chemicals such as chlorine or fluorine havebeen used experimentally, but have not been foundpractical.

10 Cooling

Main article: Internal combustion engine cooling

Cooling is required to remove excessive heat—over heat-ing can cause engine failure, usually from wear(due toheat-induced failure of lubrication), cracking or warp-ing. Two most common forms of engine cooling are air-cooled and water-cooled. Most modern automotive en-gines are both water and air-cooled, as the water/liquid-coolant is carried to air-cooled fins and/or fans, whereaslarger engines may be singularly water-cooled as they arestationary and have a constant supply of water throughwater-mains or fresh-water, while most power tool en-gines and other small engines are air-cooled. Some en-gines (air or water-cooled) also have an oil cooler. Insome engines, especially for turbine engine blade coolingand liquid rocket engine cooling, fuel is used as a coolant,as it is simultaneously preheated before injecting it into acombustion chamber.

11 Starting

Main article: Starter motor

An internal combustion engine is not usually self-startingso an auxiliary machine is required to start it. Many dif-ferent systems have been used in the past but modern en-gines are usually started by an electric motor in the smalland medium sizes or by compressed air in the large sizes.

12 Measures of engine perfor-mance

Engine types vary greatly in a number of different ways:

• energy efficiency

• fuel/propellant consumption (brake specific fuelconsumption for shaft engines, thrust specific fuelconsumption for jet engines)

• power-to-weight ratio

• thrust to weight ratio

• Torque curves (for shaft engines) thrust lapse (jetengines)

• Compression ratio for piston engines, overall pres-sure ratio for jet engines and gas turbines

14 13 AIR AND NOISE POLLUTION

12.1 Energy efficiency

Once ignited and burnt, the combustion products—hotgases—have more available thermal energy than theoriginal compressed fuel-air mixture (which had higherchemical energy). The available energy is manifested ashigh temperature and pressure that can be translated intowork by the engine. In a reciprocating engine, the high-pressure gases inside the cylinders drive the engine’s pis-tons.Once the available energy has been removed, the remain-ing hot gases are vented (often by opening a valve or ex-posing the exhaust outlet) and this allows the piston toreturn to its previous position (top dead center, or TDC).The piston can then proceed to the next phase of its cycle,which varies between engines. Any heat that is not trans-lated into work is normally considered a waste productand is removed from the engine either by an air or liquidcooling system.Internal combustion engines are primarily heat engines,and as such their theoretical efficiency can be calculatedby idealized thermodynamic cycles. The efficiency of atheoretical cycle cannot exceed that of the Carnot cycle,whose efficiency is determined by the difference betweenthe lower and upper operating temperatures of the en-gine. The upper operating temperature of a terrestrialengine is limited by the thermal stability of the materialsused to construct it. All metals and alloys eventually meltor decompose, and there is significant researching intoceramic materials that can be made with greater thermalstability and desirable structural properties. Higher ther-mal stability allows for greater temperature difference be-tween the lower and upper operating temperatures, hencegreater thermodynamic efficiency.The thermodynamic limits assume that the engine is op-erating under ideal conditions: a frictionless world, idealgases, perfect insulators, and operation for infinite time.Real world applications introduce complexities that re-duce efficiency. For example, a real engine runs best at aspecific load, termed its power band. The engine in a carcruising on a highway is usually operating significantlybelow its ideal load, because it is designed for the higherloads required for rapid acceleration. In addition, factorssuch as wind resistance reduce overall system efficiency.Engine fuel economy is measured in miles per gallon orin liters per 100 kilometres. The volume of hydrocarbonassumes a standard energy content.Most steel engines have a thermodynamic limit of 37%.Even when aided with turbochargers and stock efficiencyaids, most engines retain an average efficiency of about18%−20 %.[14] Rocket engine efficiencies are much bet-ter, up to 70%, because they operate at very high temper-atures and pressures and can have very high expansionratios.[15] Electric motors are better still, at around 85−90 % efficiency or more, but they rely on an externalpower source (often another heat engine at a power plant

subject to similar thermodynamic efficiency limits).There are many inventions aimed at increasing the effi-ciency of IC engines. In general, practical engines are al-ways compromised by trade-offs between different prop-erties such as efficiency, weight, power, heat, response,exhaust emissions, or noise. Sometimes economy alsoplays a role in not only the cost of manufacturing the en-gine itself, but also manufacturing and distributing thefuel. Increasing the engine’s efficiency brings better fueleconomy but only if the fuel cost per energy content isthe same.

12.2 Measures of fuel efficiency and pro-pellant efficiency

For stationary and shaft engines including propeller en-gines, fuel consumption is measured by calculating thebrake specific fuel consumption, which measures themass flow rate of fuel consumption divided by the powerproduced.For internal combustion engines in the form of jet en-gines, the power output varies drastically with airspeedand a less variable measure is used: thrust specific fuelconsumption (TSFC), which is the mass of propellantneeded to generate impulses that is measured in eitherpound force-hour or the grams of propellant neededto generate an impulse that measures one kilonewton-second.For rockets, TSFC can be used, but typically other equiv-alent measures are traditionally used, such as specific im-pulse and effective exhaust velocity.

13 Air and noise pollution

13.1 Air pollution

Internal combustion engines such as reciprocating inter-nal combustion engines produce air pollution emissions,due to incomplete combustion of carbonaceous fuel. Themain derivatives of the process are carbon dioxide CO2, water and some soot — also called particulate mat-ter (PM). The effects of inhaling particulate matter havebeen studied in humans and animals and include asthma,lung cancer, cardiovascular issues, and premature death.There are, however, some additional products of the com-bustion process that include nitrogen oxides and sulfurand some uncombusted hydrocarbons, depending on theoperating conditions and the fuel-air ratio.Not all of the fuel is completely consumed by the com-bustion process; a small amount of fuel is present aftercombustion, and some of it reacts to form oxygenates,such as formaldehyde or acetaldehyde, or hydrocarbonsnot originally present in the input fuel mixture. Incom-plete combustion usually results from insufficient oxygen

13.3 Idling 15

to achieve the perfect stoichiometric ratio. The flame is“quenched” by the relatively cool cylinder walls, leavingbehind unreacted fuel that is expelled with the exhaust.When running at lower speeds, quenching is commonlyobserved in diesel (compression ignition) engines that runon natural gas. Quenching reduces efficiency and in-creases knocking, sometimes causing the engine to stall.Incomplete combustion also leads to the production ofcarbon monoxide (CO). Further chemicals released arebenzene and 1,3-butadiene that are also hazardous air pol-lutants.Increasing the amount of air in the engine reduces emis-sions of incomplete combustion products, but also pro-motes reaction between oxygen and nitrogen in the airto produce nitrogen oxides (NOx). NOx is hazardous toboth plant and animal health, and leads to the productionof ozone (O3). Ozone is not emitted directly; rather, itis a secondary air pollutant, produced in the atmosphereby the reaction of NOx and volatile organic compoundsin the presence of sunlight. Ground-level ozone is harm-ful to human health and the environment. Though thesame chemical substance, ground-level ozone should notbe confused with stratospheric ozone, or the ozone layer,which protects the earth from harmful ultraviolet rays.Carbon fuels contain sulfur and impurities that eventuallyproduce sulfur monoxides (SO) and sulfur dioxide (SO2)in the exhaust, which promotes acid rain.In the United States, nitrogen oxides, PM, carbonmonox-ide, sulphur dioxide, and ozone, are regulated as criteriaair pollutants under the Clean Air Act to levels wherehuman health and welfare are protected. Other pollu-tants, such as benzene and 1,3-butadiene, are regulatedas hazardous air pollutants whose emissions must be low-ered as much as possible depending on technological andpractical considerations.NOx, carbon monoxide and other pollutants are fre-quently controlled via exhaust gas recirculation which re-turns some of the exhaust back into the engine intake, andcatalytic converters, which convert exhaust chemicals toharmless chemicals.

13.1.1 Non-road engines

Main article: Non-road engine § Emission standards

The emission standards used by many countries have spe-cial requirements for non-road engines which are used byequipment and vehicles that are not operated on the pub-lic roadways. The standards are separated from the roadvehicles.[16]

13.2 Noise pollution

Significant contributions to noise pollution are made byinternal combustion engines. Automobile and truck traf-

fic operating on highways and street systems producenoise, as do aircraft flights due to jet noise, particularlysupersonic-capable aircraft. Rocket engines create themost intense noise.

13.3 Idling

Main article: Idle reduction

Internal combustion engines continue to consume fueland emit pollutants when idling so it is desirable to keepperiods of idling to a minimum. Many bus companiesnow instruct drivers to switch off the engine when the busis waiting at a terminal.In the UK (but only in England), the Road Traffic VehicleEmissions Fixed Penalty Regulations 2002 (Statutory In-strument 2002 No. 1808) [17] introduced the concept ofa "stationary idling offence". This means that a driver canbe ordered "by an authorised person ... upon productionof evidence of his authorisation, require him to stop therunning of the engine of that vehicle" and a "person whofails to comply ... shall be guilty of an offence and be li-able on summary conviction to a fine not exceeding level 3on the standard scale". Only a few local authorities haveimplemented the regulations, one of them being OxfordCity Council.[18]

14 See also• Adiabatic flame temperature

• Air-fuel ratio

• Bore

• Component parts of internal combustion engines

• Crude oil engine - a two-stroke engine

• Deglazing (engine mechanics)

• Diesel engine

• Dieselisation

• Direct injection

• Dynamometer

• Electric vehicle

• Engine test stand - information about how to checkan internal combustion engine

• External Combustion Engine

• Fossil fuels

• Gasoline direct injection

• Gas turbine

16 17 FURTHER READING

• Heat pump

• Hybrid vehicle

• Indirect injection

• Jet engine

• Magnesium injection cycle

• Piston engine

• Petrofuel

• Reciprocating engine

• Stroke

• Turbocharger

• Variable displacement

15 References[1] “History of Technology: Internal Combustion engines”.

Encyclopædia Britannica. Britannica.com. Retrieved2012-03-20.

[2] Pulkrabek, Willard W. (1997). Engineering Fundamen-tals of the Internal Combustion Engine. Prentice Hall. p.2. ISBN 9780135708545.

[3] James, Fales. Technology Today and Tomorrow. p. 344.

[4] Armentrout, Patricia. Extreme Machines on Land. p. 8.

[5] Stone 1992, pp. 1-2.

[6] Nunney 2007, p. 5.

[7] Low Speed Engines, MAN Diesel.

[8] “CFX aids design of world’s most efficient steam turbine”(PDF). Retrieved 2010-08-28.

[9] “New Benchmarks for Steam Turbine Efficiency - PowerEngineering”. Pepei.pennnet.com. 2010-08-24. Re-trieved 2010-08-28.

[10] Takaishi, Tatsuo; Numata, Akira; Nakano, Ryouji; Sak-aguchi, Katsuhiko (March 2008). “Approach to High Ef-ficiency Diesel and Gas Engines” (PDF).Mitsubishi HeavyIndustries Technical Review 45 (1). Retrieved 2011-02-04.

[11] “Laser sparks revolution in internal combustion engines”.Physorg.com. 2011-04-20. Retrieved 2013-12-26.

[12] “Gasifier Aids Motor Starting Under Arctic Conditions”.Popular Mechanics: 149. January 1953.

[13] Nunney 2007, p. 15.

[14] “Improving IC Engine Efficiency”.Courses.washington.edu. Retrieved 2010-08-28.

[15] Rocket propulsion elements 7th edition-George Sutton,Oscar Biblarz pg 37-38

[16] “2013 Global Sourcing Guide” (PDF). Diesel & Gas Tur-bine Publications. Retrieved 2013-12-26.

[17] “The Road Traffic (Vehicle Emissions) (Fixed Penalty)(England) Regulations 2002”. 195.99.1.70. 2010-07-16.Retrieved 2010-08-28.

[18] “CITY DEVELOPMENT - Fees & Charges 2010-11”(PDF). Oxford City Council. November 2011. Retrieved2011-02-04.

16 Bibliography

• Nunney, Malcom J. (2007). Light and Heavy Ve-hicle Technology (4th ed.). Elsevier Butterworth-Heinemann. ISBN 978-0-7506-8037-0.

• Stone, Richard (1992). Introduction to InternalCombustion Engines (2nd ed.). Macmillan. ISBN0-333-55083-8.

• Anyebe, E.A (2009). Combustion Engine and Oper-ations, Automobile Technology Handbook 2.

• Singal, R. K. Internal Combustion Engines. NewDelhi, India: Kataria Books. ISBN 978-93-5014-214-1.

• Ricardo, Harry (1931). The High-Speed InternalCombustion Engine.

• Patents:

• ES 156621• ES 433850, Ubierna Laciana, “Perfec-cionamientos en Motores de Explosion,con Cinco Tiem-Pos y Doble Expansion”,published 1976-11-01

• ES 230551, Ortuno Garcia Jose, “Un NuevoMotor de Explosion”, published 1957-03-01

• ES 249247, Ortuno Garcia Jose, “Motor deCarreras Distintas”, published 1959-09-01

17 Further reading

• Singer, Charles Joseph; Raper, Richard (1978).Charles, Singer; et al., eds. AHistory of Technology:The Internal Combustion Engine. Clarendon Press.pp. 157–176.

• Setright, LJK (1975). Some unusual engines. Lon-don: The Institution of Mechanical Engineers.ISBN 0-85298-208-9.

• Suzuki, Takashi (1997). The Romance of Engines.US: Society of Automotive Engineers. ISBN 1-56091-911-6.

17

• Hardenberg, Horst O. (1999). The Middle Ages ofthe Internal Combustion Engine. US: Society of Au-tomotive Engineers.

• Gunston, Bill (1999). Development of Piston AeroEngines. PSL. ISBN 978-1-85260-619-0.

18 External links• Combustion video - in-cylinder combustion in anoptically accessible, 2-stroke engine

• Animated Engines - explains a variety of types

• Intro to Car Engines - Cut-away images and a goodoverview of the internal combustion engine

• Walter E. Lay Auto Lab - Research at The Univer-sity of Michigan

• youtube - Animation of the components and built-upof a 4-cylinder engine

• youtube - Animation of the internal moving parts ofa 4-cylinder engine

• Next generation engine technologies retrieved May9, 2009

• MITOverview - Present & Future Internal Combus-tion Engines: Performance, Efficiency, Emissions,and Fuels

• Engine Combustion Network - Open forum for in-ternational collaboration among experimental andcomputational researchers in engine combustion.

• Automakers Show Interest in an Unusual EngineDesign

• How Car Engines Work

• A file on unusual engines

• Aircraft Engine Historical Society -AEHS

18 19 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

19 Text and image sources, contributors, and licenses

19.1 Text• Internal combustion engine Source: https://en.wikipedia.org/wiki/Internal_combustion_engine?oldid=691417552 Contributors: Mag-

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19.2 Images• File:18XER_engine_block.jpg Source: https://upload.wikimedia.org/wikipedia/commons/3/30/18XER_engine_block.jpg License: CC

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• File:Overhead_cam_engine_with_forced_oil_lubrication_(Autocar_Handbook,_13th_ed,_1935).jpg Source: https://upload.wikimedia.org/wikipedia/commons/0/07/Overhead_cam_engine_with_forced_oil_lubrication_%28Autocar_Handbook%2C_13th_ed%2C_1935%29.jpg License: Public domain Contributors: Scan from <a href='//en.wikipedia.org/wiki/The_Autocar'class='extiw' title='en:The Autocar'>The Autocar</a> (Thirteenth edition, circa 1935) Autocar Handbook, London: Iliffe & Sons. Originalartist: Andy Dingley (scanner)

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