Four Stroke Engine working

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Four-stroke engine 1 Four-stroke engine See also Four-stroke internal combustion engine Four-stroke cycle used in gasoline/petrol engines. 1 - Intake, 2 - Compression, 3 - Power, 4 - Exhaust. The right blue side is the intake and the left brown side is the exhaust. The cylinder wall is a thin sleeve surrounded by cooling liquid. A four-stroke engine (also known as four-cycle) is an internal combustion engine in which the piston completes four separate strokesintake, compression, power, and exhaustduring two separate revolutions of the engine's crankshaft, and one single thermodynamic cycle. There are two common types of four-stroke engines. They are closely related to each other, but have major differences in design and behavior. The earliest of these to be developed is the Otto cycle engine developed in 1876 by Nikolaus August Otto in Cologne, Germany, [1] after the operation principle described by Alphonse Beau de Rochas in 1861. This engine is most often referred to as a petrol engine or gasoline engine, after the fuel that powers it. [2] The second type of four-stroke engine is the Diesel engine developed in 1893 by Rudolph Diesel, also of Germany. Diesel created his engine to maximize efficiency, which the Otto engine lacked. There are several major differences between the Otto cycle engine and the four-stroke diesel engine. The diesel engine is made in both a two-stroke and a four-stroke version. Otto's company, Deutz AG, now primarily produces diesel engines. The Otto cycle is named after the 1876 engine of Nikolaus A. Otto, who built a successful four-stroke engine based on the work of Jean Joseph Etienne Lenoir. [1] It was the third engine type that Otto developed. It used a sliding flame gateway for ignition of its fuel a mixture of illuminating gas and air. After 1884, Otto also developed the magneto to create an electrical spark for ignition, which had been unreliable on the Lenoir engine. Today, the internal combustion engine (ICE) is used in motorcycles, automobiles, boats, trucks, aircraft, ships, heavy duty machinery, and in its original intended use as stationary power both for kinetic and electrical power generation. Diesel engines are found in virtually all heavy duty applications such as trucks, ships, locomotives, power generation, and stationary power. Many of these diesel engines are two-stroke with power ratings up to 105,000 hp (78,000 kW). The four strokes refer to intake, compression, combustion (power) and exhaust strokes that occur during two crankshaft rotations per power cycle. The cycle begins at Top Dead Centre (TDC), when the piston is farthest away from the axis of the crankshaft. A stroke refers to the full travel of the piston from Top Dead Centre (TDC) to Bottom Dead Centre (BDC). (See Dead centre.) 1. INTAKE stroke: on the intake or induction stroke of the piston, the piston descends from the top of the cylinder to the bottom of the cylinder, increasing the volume of the cylinder. A mixture of fuel and air, or just air in a diesel engine, is forced by atmospheric (or greater) pressure into the cylinder through the intake port. The intake valve(s) then closes. The volume of air/fuel mixture that is drawn into the cylinder, relative to the maximum volume of the cylinder, is called the volumetric efficiency of the engine.

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Transcript of Four Stroke Engine working

Page 1: Four Stroke Engine working

Four-stroke engine 1

Four-stroke engineSee also Four-stroke internal combustion engine

Four-stroke cycle used in gasoline/petrol engines. 1 - Intake, 2 -Compression, 3 - Power, 4 - Exhaust. The right blue side is the

intake and the left brown side is the exhaust. The cylinder wall is athin sleeve surrounded by cooling liquid.

A four-stroke engine (also known as four-cycle) is aninternal combustion engine in which the piston completesfour separate strokes—intake, compression, power, andexhaust—during two separate revolutions of the engine'scrankshaft, and one single thermodynamic cycle.

There are two common types of four-stroke engines.They are closely related to each other, but have majordifferences in design and behavior. The earliest of theseto be developed is the Otto cycle engine developed in1876 by Nikolaus August Otto in Cologne, Germany,[1]

after the operation principle described by Alphonse Beaude Rochas in 1861. This engine is most often referred toas a petrol engine or gasoline engine, after the fuel thatpowers it.[2] The second type of four-stroke engine is theDiesel engine developed in 1893 by Rudolph Diesel, alsoof Germany. Diesel created his engine to maximizeefficiency, which the Otto engine lacked. There areseveral major differences between the Otto cycle engineand the four-stroke diesel engine. The diesel engine ismade in both a two-stroke and a four-stroke version.Otto's company, Deutz AG, now primarily producesdiesel engines.

The Otto cycle is named after the 1876 engine ofNikolaus A. Otto, who built a successful four-stroke engine based on the work of Jean Joseph Etienne Lenoir.[1] Itwas the third engine type that Otto developed. It used a sliding flame gateway for ignition of its fuel — a mixture ofilluminating gas and air. After 1884, Otto also developed the magneto to create an electrical spark for ignition, whichhad been unreliable on the Lenoir engine.

Today, the internal combustion engine (ICE) is used in motorcycles, automobiles, boats, trucks, aircraft, ships, heavyduty machinery, and in its original intended use as stationary power both for kinetic and electrical power generation.Diesel engines are found in virtually all heavy duty applications such as trucks, ships, locomotives, powergeneration, and stationary power. Many of these diesel engines are two-stroke with power ratings up to 105,000 hp(78,000 kW).The four strokes refer to intake, compression, combustion (power) and exhaust strokes that occur during twocrankshaft rotations per power cycle. The cycle begins at Top Dead Centre (TDC), when the piston is farthest awayfrom the axis of the crankshaft. A stroke refers to the full travel of the piston from Top Dead Centre (TDC) toBottom Dead Centre (BDC). (See Dead centre.)

1. INTAKE stroke: on the intake or induction stroke of the piston, the piston descends from the top of the cylinderto the bottom of the cylinder, increasing the volume of the cylinder. A mixture of fuel and air, or just air in adiesel engine, is forced by atmospheric (or greater) pressure into the cylinder through the intake port. The intakevalve(s) then closes. The volume of air/fuel mixture that is drawn into the cylinder, relative to the maximumvolume of the cylinder, is called the volumetric efficiency of the engine.

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2. COMPRESSION stroke: with both intake and exhaust valves closed, the piston returns to the top of the cylindercompressing the air or fuel-air mixture into the combustion chamber of the cylinder head. During the compressionstroke the temperature of the air or fuel-air mixture rises by several hundred degrees.

3. POWER stroke: this is the start of the second revolution of the cycle. While the piston is close to Top DeadCentre, the compressed air–fuel mixture in a gasoline engine is ignited, usually by a spark plug, or fuel is injectedinto a diesel engine, which ignites due to the heat generated in the air during the compression stroke. Theresulting pressure from the combustion of the compressed fuel-air mixture forces the piston back down towardbottom dead centre.

4. EXHAUST stroke: during the exhaust stroke, the piston once again returns to top dead centre while the exhaustvalve is open. This action expels the spent fuel-air mixture through the exhaust valve(s).

History

Otto cycle

An Otto Engine from 1920s US Manufacture

Nikolaus August Otto as a young man was a traveling salesman for agrocery concern. In his travels he encountered the internal combustionengine built in Paris by Belgian expatriate Jean Joseph Etienne Lenoir.In 1860, Lenoir successfully created a double-acting engine that ran onilluminating gas at 4% efficiency. The 18 litre Lenoir Engine producedonly 2 horsepower. The Lenoir engine ran on illuminating gas madefrom coal, which had been developed in Paris by Philip Lebon.[1][3]

In testing a replica of the Lenoir engine in 1861 Otto became aware ofthe effects of compression on the fuel charge. In 1862, Otto attemptedto produce an engine to improve on the poor efficiency and reliability

of the Lenoir engine. He tried to create an engine that would compress the fuel mixture prior to ignition, but failed asthat engine would run no more than a few minutes prior to its destruction. Many other engineers were trying to solvethe problem, with no success.[3]

In 1864, Otto and Eugen Langen founded the first internal combustion engine production company, NA Otto and Cie(NA Otto and Company). Otto and Cie succeeded in creating a successful atmospheric engine that same year.[3] Thefactory ran out of space and was moved to the town of Deutz, Germany in 1869 where the company was renamed toDeutz Gasmotorenfabrik AG (The Deutz Gas Engine Manufacturing Company).[3] In 1872, Gottlieb Daimler wastechnical director and Wilhelm Maybach was the head of engine design. Daimler was a gunsmith who had workedon the Lenoir engine. By 1876, Otto and Langen succeeded in creating the first internal combustion engine thatcompressed the fuel mixture prior to combustion for far higher efficiency than any engine created to this time.[1]

Daimler and Maybach left their employ at Otto and Cie and developed the first high-speed Otto engine in 1883. In1885, they produced the first automobile to be equipped with an Otto engine. The Petroleum Reitwagen used ahot-tube ignition system and the fuel known as Ligroin to become the world's first vehicle powered by an internalcombustion engine. It used a four-stroke engine based on Otto's design. The following year Karl Benz produced afour-stroke engined automobile that is regarded as the first car. [4]

In 1884, Otto's company, then known as Gasmotorenfabrik Deutz (GFD), developed electric ignition and thecarburetor. In 1890, Daimler and Maybach formed a company known as Daimler Motoren Gesellschaft. Today, thatcompany is Daimler-Benz.See Otto engine for more detail.

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Diesel cycle

Audi Diesel R15 at Le Mans

The diesel engine is a technical refinement of the 1876 Otto Cycleengine. Where Otto had realized in 1861 that the efficiency of theengine could be increased by first compressing the fuel mixture prior toits ignition, Rudolph Diesel wanted to develop a more efficient type ofengine that could run on much heavier fuel. The Lenoir, OttoAtmospheric, and Otto Compression engines (both 1861 and 1876)were designed to run on Illuminating Gas (coal gas). With the samemotivation as Otto, Diesel wanted to create an engine that would givesmall industrial concerns their own power source to enable them tocompete against larger companies, and like Otto to get away from therequirement to be tied to a municipal fuel supply. Like Otto, it tookmore than a decade to produce the high compression engine that could self-ignite fuel sprayed into the cylinder.Diesel used an air spray combined with fuel in his first engine.

During initial development, one of the engines burst nearly killing Diesel. He persisted and finally created an enginein 1893. The high compression engine, which ignites its fuel by the heat of compression is now called the Dieselengine whether a four-stroke or two-stroke design.The four-stroke diesel engine has been used in the majority of heavy duty applications for many decades. Chiefamong the reasons for this is that it uses a heavy fuel that contains more energy, requires less refinement, and ischeaper to make (although in some areas of the world diesel fuel costs more than gasoline). The most efficient OttoCycle engines run near 30% efficiency. The Volkswagen Jetta TDI 1.9 liter engine achieves 46%. It uses anadvanced design with turbocharging and direct fuel injection. Some BMW ship Diesels with ceramic insulation haveexceeded 60% efficiency.Both Audi and Peugeot compete in the endurance races of the Le Mans Series with cars having diesel engines. Theseare four-stroke turbocharged diesels that dominate largely due to fuel economy and having to make fewer stops.

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Thermodynamic Analysis

The idealized four-stroke Otto cycle p-V diagram: the  intake (A)  stroke isperformed by an isobaric expansion, followed by the  compression (B)  stroke,

performed by an adiabatic compression. Through the combustion of fuel anisochoric process is produced, followed by an adiabatic expansion, characterizingthe  power (C)  stroke. The cycle is closed by an isochoric process and an isobaric

compression, characterizing the  exhaust (D)  stroke.

The thermodynamic analysis of the actualfour-stroke or two-stroke cycles is not asimple task. However, the analysis can besimplified significantly if air standardassumptions[5] are utilized. The resultingcycle, which closely resembles the actualoperating conditions, is the Otto cycle.

Octane Requirements

Fuel octane rating

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Otto Engines

A Refractory Tower showing the differing weights of various products.

The fuels used in four-cycle engines aretypically fractions of crude oil, coal tar, oilshale, or sands produced in a process calledPetroleum Cracking. The ignitiontemperature of the fuel that is refracted isrelated to its weight. It is separated by beingheated and is extracted at different heightsin the refractory tower. The higher the fuelvapor rises in the tower, the lower its weightand the less energy it contains. In refractingpetroleum, there is a standard weight offuels and products that are withdrawn andassociated with a specific extracted material.Gasoline is a light refractory product and iscalled a light fraction. As a light fraction ithas a relatively low flash point (that is thetemperature at which it starts to burn whenmixed with an oxidizer).

A fuel with a low flash point may self-igniteduring compression, and can also be ignited

by carbon deposits left in the cylinder or head of a dirty engine. In an internal combustion engine self ignition canoccur at unexpected times. During the normal operation of the engine as the fuel mixture is being compressed anelectric arc is created to ignite the fuel. At low rpm this occurs close to TDC (Top Dead Centre). As engine rpm risesthe spark point is moved forward so that the fuel charge can be ignited at a more efficient point in fuel chargecompression to allow the fuel to start burning even while it is still being compressed. This produces more effectivepower based on the rising molecular density of the working medium, since this is the essence of efficiency in thecompressed charge IE engine. A denser working medium (the air fuel mixture) experiences a greater heat, andtherefore pressure, rises on less when its molecules are more densely packed together.We can see this in two Otto engines designs. The non-compression engine operated at 12% efficiency. Thecompressed charge engine had an operating efficiency of 30%. A Diesel engine can reach as high as 70% (Diesel'slab engine tested at 75.6% efficiency, VW TDI is at 46%).The problem with compressed charge engines is that the temperature rise of the compressed charge can causepre-ignition. If this occurs at the wrong time and is too energetic, it can destroy the engine. Fractions of petroleumhave widely varying flash points (the temperatures at which the fuel may self-ignite). This must be taken intoaccount in engine and fuel design.In engines, the spark is retarded when the engine is being started, and progresses only to an appropriate amountbased on engine rpm. This is determined by laboratory research. As the engine revolves faster it can accept earlierignition since the moving flame front does not have time to be destructive.In fuel, the tendency for the compressed fuel mixture to ignite early is limited by the chemical composition of the fuel. There are several grades of fuel to accommodate differing performance levels of engines. The fuel is altered to change its self ignition temperature. There are several ways to do this. As engines are designed with higher compression ratios the result is that pre-ignition is much more likely to occur since the fuel mixture is compressed to a higher temperature prior to deliberate ignition. The higher temperature more effectively evaporates fuels such as gasoline, and is factor in a higher compression engine being more efficient. Higher Compression ratios also mean

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that the distance that the piston can push to produce power is greater (which is called the Expansion ratio).So there must be a standardized test and a standard reference system to describe how likely a fuel is to self-ignite.The octane rating is a measure of the fuel's resistance to self-ignition. A fuel with a higher numerical octane ratingallows for a higher compression ratio, which extracts more energy from the fuel and more effectively converts thatenergy into useful work while at the same time preventing engine damage from pre-ignition. High Octane fuel is alsomore expensive.

Diesel Engines

Diesel engines by their nature do not have concerns with pre-ignition. They have a concern with whether or notcombustion can be started. The description of how likely Diesel fuel is to ignite is called the Cetane rating. BecauseDiesel fuels are of low volatility, they can be very hard to start when cold. Various techniques are used to start a coldDiesel engine, the most common being the use of a glow plug.

Design and engineering principles

Power output limitations

The four-stroke cycle1=TDC2=BDC

 A: Intake  B: Compression 

 C: Power  D: Exhaust 

The maximum amount of power generated by anengine is determined by the maximum amount of airingested. The amount of power generated by a pistonengine is related to its size (cylinder volume), whetherit is a two-stroke or four-stroke design, volumetricefficiency, losses, air-to-fuel ratio, the calorific value ofthe fuel, oxygen content of the air and speed (RPM).The speed is ultimately limited by material strength andlubrication. Valves, pistons and connecting rods suffersevere acceleration forces. At high engine speed,physical breakage and piston ring flutter can occur,resulting in power loss or even engine destruction.Piston ring flutter occurs when the rings oscillatevertically within the piston grooves they reside in. Ringflutter compromises the seal between the ring and thecylinder wall, which causes a loss of cylinder pressureand power. If an engine spins too quickly, valve springscannot act quickly enough to close the valves. This iscommonly referred to as 'valve float', and it can resultin piston to valve contact, severely damaging theengine. At high speeds the lubrication of pistoncylinder wall interface tends to break down. This limitsthe piston speed for industrial engines to about 10 m/s.

Intake/exhaust port flow

The output power of an engine is dependent on the ability of intake (air–fuel mixture) and exhaust matter to movequickly through valve ports, typically located in the cylinder head. To increase an engine's output power,irregularities in the intake and exhaust paths, such as casting flaws, can be removed, and, with the aid of an air flowbench, the radii of valve port turns and valve seat configuration can be modified to reduce resistance. This process iscalled porting, and it can be done by hand or with a CNC machine.

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Supercharging

One way to increase engine power is to force more air into the cylinder so that more power can be produced fromeach power stroke. This can be done using some type of air compression device known as a supercharger, which canbe powered by the engine crankshaft.Supercharging increases the power output limits of an internal combustion engine relative to its displacement. Mostcommonly, the supercharger is always running, but there have been designs that allow it to be cut out or run atvarying speeds (relative to engine speed). Mechanically driven supercharging has the disadvantage that some of theoutput power is used to drive the supercharger, while power is wasted in the high pressure exhaust, as the air hasbeen compressed twice and then gains more potential volume in the combustion but it is only expanded in one stage.

Turbocharging

A turbocharger is a supercharger that is driven by the engine's exhaust gases, by means of a turbine. It consists of atwo piece, high-speed turbine assembly with one side that compresses the intake air, and the other side that ispowered by the exhaust gas outflow.When idling, and at low-to-moderate speeds, the turbine produces little power from the small exhaust volume, theturbocharger has little effect and the engine operates nearly in a naturally aspirated manner. When much more poweroutput is required, the engine speed and throttle opening are increased until the exhaust gases are sufficient to 'spinup' the turbocharger's turbine to start compressing much more air than normal into the intake manifold.Turbocharging allows for more efficient engine operation because it is driven by exhaust pressure that wouldotherwise be (mostly) wasted, but there is a design limitation known as turbo lag. The increased engine power is notimmediately available due to the need to sharply increase engine RPM, to build up pressure and to spin up the turbo,before the turbo starts to do any useful air compression. The increased intake volume causes increased exhaust andspins the turbo faster, and so forth until steady high power operation is reached. Another difficulty is that the higherexhaust pressure causes the exhaust gas to transfer more of its heat to the mechanical parts of the engine.

Rod and piston-to-stroke ratioThe rod-to-stroke ratio is the ratio of the length of the connecting rod to the length of the piston stroke. A longer rodreduces sidewise pressure of the piston on the cylinder wall and the stress forces, increasing engine life. It alsoincreases the cost and engine height and weight.A "square engine" is an engine with a bore diameter equal to its stroke length. An engine where the bore diameter islarger than its stroke length is an oversquare engine, conversely, an engine with a bore diameter that is smaller thanits stroke length is an undersquare engine.

Valve trainThe valves are typically operated by a camshaft rotating at half the speed of the crankshaft. It has a series of camsalong its length, each designed to open a valve during the appropriate part of an intake or exhaust stroke. A tappetbetween valve and cam is a contact surface on which the cam slides to open the valve. Many engines use one ormore camshafts “above” a row (or each row) of cylinders, as in the illustration, in which each cam directly actuates avalve through a flat tappet. In other engine designs the camshaft is in the crankcase, in which case each cam contactsa push rod, which contacts a rocker arm that opens a valve. The overhead cam design typically allows higher enginespeeds because it provides the most direct path between cam and valve.

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Valve clearance

Valve clearance refers to the small gap between a valve lifter and a valve stem that ensures that the valve completelycloses. On engines with mechanical valve adjustment, excessive clearance causes noise from the valve train. A toosmall valve clearance can result in the valves not closing properly, this results in a loss of performance and possiblyoverheating of exhaust valves. Typically, the clearance must be readjusted each 20,000 miles (32,000 km) with afeeler gauge.Most modern production engines use hydraulic lifters to automatically compensate for valve train component wear.Dirty engine oil may cause lifter failure.

Energy balanceOtto engines are about 30% efficient; in other words, 30% of the energy generated by combustion is converted intouseful rotational energy at the output shaft of the engine, while the remainder being losses due to waste heat, frictionand engine accessories.[6] There are a number of ways to recover some of the energy lost to waste heat. The use of aTurbocharger in Diesel engines is very effective by boosting incoming air pressure and in effect provides the sameincrease in performance as having more displacement. The Mack Truck company, decades ago, developed a turbinesystem that converted waste heat into kinetic energy that it fed back into the engine's transmission. In 2005, BMWannounced the development of the turbosteamer, a two stage heat recovery system similar to the Mack system thatrecovers 80% of the energy in the exhaust gas and raises the efficiency of an Otto engine by 15%.[7] By contrast, asix-stroke engine may convert more than 50% of the energy of combustion into useful rotational energy.Modern engines are often intentionally built to be slightly less efficient than they could otherwise be. This isnecessary for emission controls such as exhaust gas recirculation and catalytic converters that reduce smog and otheratmospheric pollutants. Reductions in efficiency may be counteracted with an engine control unit using lean burntechniques.[8]

In the United States, the Corporate Average Fuel Economy mandates that vehicles must achieve an average of 35.5miles per gallon (mpg) compared to the current standard of 25 mpg. As automakers look to meet these standards by2016, new ways of engineering the traditional internal combustion engine (ICE) could have to be considered. Somepotential solutions to increase fuel efficiency to meet new mandates include firing after the piston is farthest from thecrankshaft, known as top dead centre, and applying the Miller cycle. Together, this redesign could significantlyreduce fuel consumption and NOx emissions.

Starting position, intake stroke, and compression stroke.

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Ignition of fuel, power stroke, and exhaust stroke.

References[1] (http:/ / www. essortment. com/ nikolaus-august-otto-inventor-internal-combustion-engine-21765. html), Nikolaus August Otto: Inventor Of

The Internal Combustion Engine.[2] Brittanica (http:/ / www. britannica. com/ EBchecked/ topic/ 226592/ gasoline-engine), Britannica Gasoline Engine.[3] (http:/ / www. nicolaus-august-otto. de/ node/ 15), NA Otto Museum.[4][4] Ralph Stein (1967). The Automobile Book. Paul Hamlyn Ltd[5] Best Place for Engineering and Technology (http:/ / www. betp. net/ 2011/ 04/ air-standard-assumptions/ ), Air Standard Assumptions.[6] Otto Engine Efficiency (http:/ / www. ecen. com/ content/ eee7/ motoref. htm), Efficiencies of Internal Combustion Engines.[7] BMW Turbo Steamer Gets Hot and Goes (http:/ / www. autoblog. com/ 2005/ 12/ 09/ bmw-turbosteamer-gets-hot-and-goes/ ), Autoblog,

December 9, 2005.[8][8] Air pollution from motor vehicles By Asif Faiz, Christopher S. Weaver, Michael P. Walsh

General sources• Hardenberg, Horst O. (1999). The Middle Ages of the Internal combustion Engine. Society of Automotive

Engineers (SAE). ISBN 978-0-7680-0391-8.•• scienceworld.wolfram.com/physics/OttoCycle.html• Cengel, Yunus A; Michael A Boles, Yaling He (2009). Thermodynamics An Engineering Approach. N.p. The

McGraw Hill Companies. ISBN 978-7-121-08478-2.• Benson, Tom (11 July 2008). "4 Stroke Internal Combustion Engine" (http:/ / www. grc. nasa. gov/ WWW/ K-12/

airplane/ engopt. html). p. National Aeronautics and Space Administration. Retrieved 5 May 2011.

External links• U.S. Patent 194,047 (http:/ / www. google. com/ patents?vid=194047)• Detailed Engine Animations (http:/ / www. animatedpiston. com)• How Car Engines Work (http:/ / auto. howstuffworks. com/ engine. htm)• Animated Engines, four stroke (http:/ / www. animatedengines. com/ otto. shtml), another explanation of the

four-stroke engine.• CDX eTextbook (http:/ / www. cdxetextbook. com/ video/ video. html), some videos of car components in action.• Video from inside a four-stroke engine cylinder (http:/ / www. liveleak. com/ view?i=73e_1192001762)

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Article Sources and Contributors 10

Article Sources and ContributorsFour-stroke engine  Source: http://en.wikipedia.org/w/index.php?oldid=550897675  Contributors: 10metreh, 11Maxx11, 2002:8161:E968:0:0:0:8161:E968, A7N8X, AGToth, Aboalbiss,Achalmeena, Adambro, AdjustShift, Aiken drum, Alasdair, Amp71, Andy Dingley, Anobo, Anthony Appleyard, Aristeaus, Arthena, Arunsingh16,Asdflkjasdflkjasdflkasjdlfkjasdflkasjdlfkjasdlfk, Autodidactyl, Avono, AySz88, BD2412, Bcartolo, Beano, BeowulfNode, Bevo, Biker Biker, Blathnaid, BlckKnght, Blehfu, Bloodshedder,BobJones, Bobo192, Boschk, Brianhe, CanisRufus, Canyouhearmenow, Canzo, Capricorn42, Cbraga, Ccr1567, Ce1984, CesarB, Chris 42, Chris the speller, Chrisbolt, Chrislonghurst, Cklostsword, Closedmouth, Colin Kimbrell, Conversion script, Corvus cornix, Crecy99, Cremepuff222, Crenner, CsDix, D, DMahalko, DVdm, DaCoolBro, Darguz Parsilvan, Davewho2, David R.Ingham, Deer Assassin, Dellium, DerHexer, Dethroned Buoy, Dhollm, Dunc289, ESkog, EagleFan, EdJogg, Elassint, Eleschinski2000, Eloquence, Engineman, Enigmaticus, EoGuy, Ericd,Evanherk, Excirial, ExportRadical, Farosdaughter, Father Goose, FerdinandFrog, Flyhighplato, Foochar, GCarty, GRAHAMUK, Gaius Cornelius, Gchiorato, Geologyguy, Gingaman, Glenn,Gmaxwell, Gogo Dodo, Goldom, Graham87, Graibeard, Greglocock, Greudin, Guinness27, Gurch, Gzkn, Gzuckier, HDP, Hadal, HannesJvV, Harold f, Headbomb,HemperorOfSmokeLandVillez.dum, Heron, Heryu, Hobartimus, Hoodman93, Hooperbloob, Hotlorp, Hsxavier, Hu, Hu12, Idontknowgohome, Ilikepie2221, Immunize, Infrogmation, Inwind,Iridescent, Ithunn, J.delanoy, JDIAZ001, JForget, Jakohn, James086, Japanscot, Javierito92, Jdmitr2nr, Jebba, Jeepday, Jeeves52, JeremyBoggs, Jeremyukreading, Jim1138, Jimbosworldorg,Jm51, Jobstbrandt, Jodis, John Vandenberg, Jokl, Jossi, Joy6233, Jpc4031, Jschnur, JzoJames, Jóna Þórunn, KVDP, Kaiba, Kanonkas, Kglavin, Kjkolb, KnightRider, Kowey, Krontach,Kunjan-NJITWILL, Kuru, LAX, Lasta, Latka, Leptictidium, Liftarn, Lightmouse, Longhair, Lucideer, Lumos3, MHotwagner, MaNeMeBasat, Mad.martian999, Mada15, Marj Tiefert,Martin-vogel, Mattjpt1100, Melchoir, MercuryFree, Merqurial, Michael Hardy, Michael Zimmermann, Mild Bill Hiccup, Minimac, Mion, Mlynch001, Monosynthluv, Motorhead, Mrholybrain,Msmi121, Myscrnnm, NJGW, NaBUru38, Nasula, NawlinWiki, NewEnglandYankee, Nimbus227, Nposs, OSX, OffsBlink, Ottawaresident, OverlordQ, Oxfordwang, Oxymoron83, PAR,Paneevolpe, Passw0rd, Paulluap10, Peppoj, Peter Horn, Petrb, Pfalstad, Philip Trueman, Phs72, Pironman, Pixelface, Polymerbringer, Proofreader77, Qball369, Qw442, Qxz, R, R.Mann66, RJP,Racer Dude, RattusMaximus, Ray Yallop, Rdsmith4, Re7aaa2010, Rediscoverer, Reliableforever, Remember, Retaggio, Rizzardi, Rjwilmsi, Rocker Arm Guru, Rohnadams, Ron Ritzman, Roo72,Rtyq2, SGGH, Sam, Sango123, Sasigokul, Scott Paeth, Scottyferguson, Seanconradie, Shoy, Shyronnie69, Sidhu gm, Sigmundg, Sitethief, Size J Battery, Skizzik, Sladen, Slb nsk, Son36,Sonett72, South Bay, Spalding, Spettro9, Staeiou, Starrek, Stephan Leeds, Suyash1994, T.a.k., TSylvester, Takamaxa, TarenGarond, Tarrow, Terraflorin, The Illusive Man, The undertow,TheNewPhobia, Thedude808, Thehelpfulone, Thekingofazle, Thorney¿?, Timpicerilo, Tommy2010, Traveletti, Typ932, Tysto, Ucucha, Ultramandk, Vaughan Pratt, Vic0, Victorvp, VikasGorur,Vtibs, Wapcaplet, Warlord88, Waywardhorizons, Wdl1961, White Ash, Whocares26, Why Not A Duck, WikHead, Wikibofh, Williamsburgland, Wimt, Wjejskenewr, XB-70, Xcentaur, Xornok,Ymk108, Yonir, Yurkov DN, Zavoorchik, Zephyris, आशीष भटनागर, 681 anonymous edits

Image Sources, Licenses and ContributorsFile:4StrokeEngine Ortho 3D Small.gif  Source: http://en.wikipedia.org/w/index.php?title=File:4StrokeEngine_Ortho_3D_Small.gif  License: Creative Commons Attribution-Sharealike 3.0 Contributors: ZephyrisFile:PSM V18 D500 An american internal combustion otto engine.jpg  Source:http://en.wikipedia.org/w/index.php?title=File:PSM_V18_D500_An_american_internal_combustion_otto_engine.jpg  License: Public Domain  Contributors: Andy Dingley, IneuwFile:1 Audi R15.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:1_Audi_R15.jpg  License: Creative Commons Attribution-Sharealike 2.0  Contributors: Mike Roberts from London,United KingdomImage:diagrama pv de ciclo 4tempos.png  Source: http://en.wikipedia.org/w/index.php?title=File:Diagrama_pv_de_ciclo_4tempos.png  License: Creative Commons Attribution-Sharealike 3.0 Contributors: Henrique S. XavierFile:Crude Oil Distillation.png  Source: http://en.wikipedia.org/w/index.php?title=File:Crude_Oil_Distillation.png  License: GNU Free Documentation License  Contributors: Users Psarianos,Theresa knott on en.wikipediaImage:Ciclo del motore 4T.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Ciclo_del_motore_4T.svg  License: Creative Commons Attribution-Sharealike 3.0,2.5,2.0,1.0 Contributors: A7N8XImage:Four stroke cycle start.png  Source: http://en.wikipedia.org/w/index.php?title=File:Four_stroke_cycle_start.png  License: GNU Free Documentation License  Contributors:User:WapcapletImage:Four stroke cycle intake.png  Source: http://en.wikipedia.org/w/index.php?title=File:Four_stroke_cycle_intake.png  License: GNU Free Documentation License  Contributors:User:WapcapletImage:Four stroke cycle compression.png  Source: http://en.wikipedia.org/w/index.php?title=File:Four_stroke_cycle_compression.png  License: GNU Free Documentation License Contributors: User Wapcaplet on en.wikipediaImage:Four stroke cycle spark.png  Source: http://en.wikipedia.org/w/index.php?title=File:Four_stroke_cycle_spark.png  License: GNU Free Documentation License  Contributors:User:WapcapletImage:Four stroke cycle power.png  Source: http://en.wikipedia.org/w/index.php?title=File:Four_stroke_cycle_power.png  License: GNU Free Documentation License  Contributors:User:WapcapletImage:Four stroke cycle exhaust.png  Source: http://en.wikipedia.org/w/index.php?title=File:Four_stroke_cycle_exhaust.png  License: GNU Free Documentation License  Contributors:User:Wapcaplet

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