Editing 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|thumb|right|A circa-1970 [[AMC_straight-6_engine#232|AMC 232]] 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 [[Autogas|liquefied petroleum gas]] and [[Common ethanol fuel mixtures|ethanol blends]] (such as ''[[E10 petrol|E10]]'' and ''[[Common ethanol fuel mixtures#E85|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 engine|spark ignition]], unlike [[diesel engine]]s 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]].<ref>{{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}}</ref><ref>{{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}}</ref><ref>{{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}}</ref>

==History==
{{main|History of the internal combustion engine}}
The first practical petrol engine was built in 1876 in Germany by [[Nicolaus Otto|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.<ref>{{cite EB1911|wstitle=Oil Engine |volume=20 |page=36 |first=Dugald |last=Clerk}}</ref>

==Design==

=== Thermodynamic cycle ===
[[File:4StrokeEngine Ortho 3D Small.gif|thumb|right|upright=0.8|Animation of an Otto cycle engine]]

Most petrol engines use either the four-stroke [[Otto cycle]] or the [[two-stroke engine|two-stroke cycle]].<ref>{{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}}</ref><ref>{{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}}</ref><ref>{{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}}</ref> Petrol engines have also been produced using the [[Miller cycle]] and [[Atkinson cycle]].<ref>{{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}}</ref><ref>{{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}}</ref><ref>{{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}}</ref><ref>{{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}}</ref>

=== Layout ===
Most petrol-powered piston engines are [[straight engine]]s or [[V engine]]s. However, [[flat engine]]s, [[W engine]]s and [[Engine_configuration#Other_layouts|other layouts]] are sometimes used. 

[[Engine_configuration#Wankel_(rotary)_engines|Wankel engines]] are classified by the number of rotors used.

=== Compression ratio ===
{{main|Compression ratio#Petrol engines}}

===Cooling===
{{main|Internal combustion engine cooling}}

Petrol engines are either [[Air-cooled engine|air-cooled]] or [[Water_cooling#Internal_combustion_engines|water-cooled]].

===Ignition===
{{main|Ignition system}}
Petrol engines use [[spark ignition]]. [[High voltage]] for the spark this may be provided by a [[ignition magneto|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]].<ref>{{Cite PHAK|year=2023|chapter=7|page=25}}</ref>

== 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 [[Watt#Kilowatt|kilowatts]] or [[horsepower]].

Typically, petrol engines have a [[thermodynamic efficiency]] of about 20-30% (approximately half that of some diesel engines).<ref>{{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}}</ref>

==Applications==
Applications of petrol engines include [[automobile]]s, [[motorcycle]]s, [[aircraft]], [[motorboat]]s and [[small engine]]s (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.

==See also==
* [[Diesel engine]]
* [[Electric motor]]
* [[Hydrogen engine]]
* [[Jet engine]]

==References==
{{reflist}}

{{Automotive engine}}
{{Authority control}}

[[Category:1876 introductions]]
[[Category:Internal combustion piston engines]]
[[Category:Gasoline engines]]
[[Category:German inventions]]