petrol engine

{{short description|Internal combustion engine designed to run on gasoline}}

File:American Motors AMC modern era inline six on stand at Rambler Ranch.jpg automotive engine]]

A petrol engine (gasoline engine in American and Canadian English) is an internal combustion engine designed to run on petrol (gasoline). Petrol engines can often be adapted to also run on fuels such as liquefied petroleum gas and ethanol blends (such as E10 and E85). They may be designed to run on petrol with a higher octane rating, as sold at petrol stations.

Most petrol engines use spark ignition, unlike diesel engines which run on diesel fuel and typically use compression ignition. Another key difference to diesel engines is that petrol engines typically have a lower compression ratio.{{Cite web |title=How do car engines work? |url=https://www.kia.com/dm/discover-kia/ask/how-do-car-engines-work.html#:~:text=As%20a%20result,%20the%20gasoline,of%20the%20gasoline%20engine%20operate. |access-date=2024-11-11 |website=Kia British Dominica |language=en-DM}}{{Cite web |title=Alternative Fuels Data Center: How Do Diesel Vehicles Work? |url=https://afdc.energy.gov/vehicles/how-do-diesel-cars-work |access-date=2024-11-11 |website= |language=en}}{{Cite web |title=Unterschied zwischen Diesel- und Benzinmotoren |trans-title=The difference between diesel and gasoline engines |url=https://www.autodoc.de/info/diesel-oder-benzinmotor-was-ist-der-unterschied |access-date=2024-11-11}}

History

The first practical petrol engine was built in 1876 in Germany by Nicolaus August Otto and Eugen Langen, although there had been earlier attempts by Étienne Lenoir in 1860, Siegfried Marcus in 1864 and George Brayton in 1873.{{cite EB1911|wstitle=Oil Engine |volume=20 |page=36 |first=Dugald |last=Clerk}}

Design

= Thermodynamic cycle =

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Most petrol engines use either the four-stroke Otto cycle or the two-stroke cycle.{{cite web |title=What is Otto Cycle - Complete Explaintion on P-v & T-s Diagram |url=https://www.theengineerspost.com/otto-cycle/ |website=The Engineers Post |access-date=14 August 2022 |language=en-us |date=10 September 2019}}{{cite web |title=What is Two Stroke Engine?- Types, And Working |url=https://www.engineeringchoice.com/what-is-two-stroke-engine/ |website=Engineering Choice |access-date=14 August 2022 |language=en-us |date=12 November 2020}}{{cite web |title=Two Stroke Engine - Internal Combustion Engines (IC) - Automobile Magazine |url=https://www.motortrend.com/news/two-stroke-engines-expected-revival/ |website=MotorTrend |access-date=14 August 2022 |language=en |date=16 December 2009}} Petrol engines have also been produced using the Miller cycle and Atkinson cycle.{{cite web |title=How does a Miller-cycle engine work? |url=https://auto.howstuffworks.com/question132.htm |website=HowStuffWorks |access-date=14 August 2022 |language=en-us |date=1 April 2000}}{{cite web |title=Mazda 2.3L Miller-cycle DOHC V-6 |url=https://www.wardsauto.com/news-analysis/mazda-23l-miller-cycle-dohc-v-6 |website=WardsAuto |access-date=14 August 2022 |language=en |date=1 January 1998}}{{cite web |title=Why does Toyota use Atkinson cycle engines? |url=https://mag.toyota.co.uk/toyota-use-atkinson-cycle-engines/ |website=Toyota UK Magazine |access-date=14 August 2022 |date=14 January 2015}}{{cite web |date=4 April 2016 |title=Engine Types: Atkinson Cycle vs Otto vs Miller |url=https://enginehoist.net/engine-types-atkinson-cycle-vs-otto-vs-miller/ |access-date=9 June 2023 |website=EngineHoist}}

= Layout =

Most petrol-powered piston engines are straight engines or V engines. However, flat engines, W engines and other layouts are sometimes used.

Wankel engines are classified by the number of rotors used.

= Compression ratio =

=Cooling=

Petrol engines are either air-cooled or water-cooled.

=Ignition=

Petrol engines use spark ignition. High voltage for the spark this may be provided by a magneto or an ignition coil. In modern car engines, the ignition timing is managed by an electronic Engine Control Unit. Ignition modules can also function as a rev limiter in some cases to prevent overrevving and the consequences of it, such as valve float and connecting rod failure.

= Primer =

Primers may be used to help start the engine. They can draw fuel from fuel tanks and vaporize fuel directly into piston cylinders. Engines are difficult to start during cold weather, and the fuel primer helps because otherwise there will not be enough heat available to vaporize the fuel in the carburetor.{{Cite PHAK|year=2023|chapter=7|page=25}}

Power output and efficiency

{{main|Engine power|Engine efficiency#Gasoline (petrol) engines}}

The power output of small- and medium-sized petrol engines (along with equivalent engines using other fuels) is usually measured in kilowatts or horsepower.

Typically, petrol engines have a thermodynamic efficiency of about 20-30% (approximately half that of some diesel engines).{{Cite news|url=http://www.greencarreports.com/news/1091436_toyota-gasoline-engine-achieves-thermal-efficiency-of-38-percent|title=Toyota Gasoline Engine Achieves Thermal Efficiency Of 38 Percent|work=Green Car Reports|access-date=2017-10-07|language=en}}

Applications

Applications of petrol engines include automobiles, motorcycles, aircraft, motorboats and small engines (such as lawn mowers, chainsaws and portable generators). Petrol engines have also been used as "pony engines", a type of engine used to start a larger, stationary diesel engine.