A spark-ignition engine (SI engine) is an

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal comb ...

, generally a

petrol 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 ...

, where the combustion process of the air-fuel mixture is ignited by a spark from a

spark plug A spark plug (sometimes, in British English, a sparking plug, and, colloquially, a plug) is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air ...

. This is in contrast to compression-ignition engines, typically

diesel engine The diesel engine, named after the German engineer Rudolf Diesel, is an internal combustion engine in which Combustion, ignition of diesel fuel is caused by the elevated temperature of the air in the cylinder due to Mechanics, mechanical Compr ...

s, where the heat generated from compression together with the injection of fuel is enough to initiate the combustion process, without needing any external spark.

Fuels

Spark-ignition engines are commonly referred to as "gasoline engines" in North America, and "petrol engines" in Britain and the rest of the world. Spark-ignition engines can (and increasingly are) run on fuels other than petrol/gasoline, such as

autogas Autogas is liquefied petroleum gas (LPG) used as a fuel in internal combustion engines of vehicles as well as in stationary applications such as generators. It is a mixture of propane and butane. Autogas is widely used as a "green" fuel, ...

( LPG),

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical compound and the simplest aliphatic Alcohol (chemistry), alcohol, with the chemical formula (a methyl group linked to a hydroxyl group, often ab ...

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

, bioethanol, compressed natural gas (CNG),

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

, and (in drag racing)

nitromethane Nitromethane, sometimes shortened to simply "nitro", is an organic compound with the chemical formula . It is the simplest organic nitro compound. It is a polar liquid commonly used as a solvent in a variety of industrial applications such as in ...

Working cycle

The working cycle of both spark-ignition and compression-ignition engines may be either

two-stroke A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes of the piston, one up and one down, in one revolution of the crankshaft in contrast to a four-stroke engine which re ...

four-stroke A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directio ...

. A

spark-ignition engine is an Otto cycle engine. It consists of following four strokes: suction or intake stroke, compression stroke, expansion or power stroke,

exhaust stroke In the context of an internal combustion engine, the term stroke has the following related meanings: * A phase of the engine's cycle (e.g. compression stroke, exhaust stroke), during which the piston travels from top to bottom or vice versa. * Th ...

. Each stroke consists of 180 degree rotation of crankshaft rotation and hence a

cycle is completed through 720 degree of crank rotation. Thus for one complete cycle there is only one power stroke while the crankshaft turns by two revolutions.

References

{{DEFAULTSORT:Spark-Ignition Engine Spark plugs Internal combustion piston engines

Fuels

Working cycle

See also

References