 Spark-ignition engines  - are a type of internal combustion engines. Unlike the compression-ignition engines, where the heat resulting from compression ignites the fuel mixture, in spark-ignition engines it is ignited with an electrically produced spark.

 Division  There are two types of spark-ignition engines:  two-stroke engine: the thermodynamic cycle is completed in two movements of the piston  four-stroke engine, also known as Otto cycle engine: the thermodynamic cycle is completed in four movements of the piston  Wankel engine: the four piston strokes do not follow one after another, instead they take place simultaneously in different parts of the engine.

 Fuel mixture  Because the fuel mixture typically consists of air and petrol (gasoline or gas in American English), they are usually referred to as petrol engines (gasoline engines or gas engines in American English). However, other fuels can be used as well, such as autogas (LPG), compressed natural gas (CNG), methanol, ethanol or hydrogen. Cars in drag racing usually use nitromethane.  Spark-ignition engines were traditionally distinguished from compression-ignition engines also according to the place, where the fuel is mixed with air. While the compression-ignition engines blend fuel inside the cylinders, in spark-ignition engines it was done outside the cylinders, in a carburettor. However, in modern engines highly pressurized fuel is injected directly into the cylinders, which improves the efficiency of the engines. This process is called gasoline direct injection (GDi).

spark-ignition engine – zážehový motor internal combustion engine – motor s vnitřním spalováním compression-ignition engine – vznětový motor heat – teplo compression – stlačení ignite – zažehnout fuel – palivo fuel mixture – palivová směs spark – jiskra two-stroke engine – dvoudobý motor four-stroke engine, Otto cycle engine – čtyřdobý motor Wankel engine – Wankelův motor piston – píst simultaneously – současně petrol (American English: gasoline, gas) – benzín petrol engine (American English: gasoline engine, gas engine) – benzínový motor blend – smíchat cylinder – válec carburettor (American English: carburetor) – karburátor pressurized – pod tlakem inject – vstřikovat efficiency – výkon direct injection – přímé vstřikování autogas, LPG (Liquefied petroleum gas) – zkapalněný ropný plyn natural gas – zemní plyn hydrogen – vodík drag racing – závody dragsterů cat-away – průřez