The gasoline engine is a device to convert the chemical energy stored in gasoline into mechanical energy to do work—to mow a lawn; chainsaw a tree; propel a car, boat, or airplane; or to perform myriad other tasks. The energy in the gasoline is transformed into heat within the engine through combustion, so the gasoline engine is an internal combustion engine.

Because combustion is normally initiated by an electric spark, the gasoline engine is also frequently known as a spark-ignition engine.

A number of different kinematic mechanisms have been used to extract mechanical work from the heated products of combustion. The preferred option is the slider-crank mechanism, which is incorporated into the gasoline-engine cross section of figure 1. In the slider-crank mechanism, the piston reciprocates up and down within a cylinder, alternately doing work on...