The Spark Ignition Internal Combustion Engine

The four-stroke cycle spark ignition (SI) internal combustion engine (ICE) was initially proposed by Beau de Rockas in 1862 and first built by N. A. Otto in 1876. This engine has become the major piston engine in use today. The PV cycle of the engine is shown in Fig. 4.3 where the four strokes are indicated. 

The efficiency of the engine is a maximum of about 25% at a CR of about 15. Fuel injection, as in the diesel engine, means better control of the air/fuel ratio under variable temperature conditions. 

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