The automobile engine

Internal combustion engines are engines (or motors) in which the fuel is burnt inside the engine itself, as compared with external combustion engines like the steam engine where the fuel is burnt outside the working cylinder of the engine. The petrol engine and the diesel engine as used in modern automobiles are both internal combustion engines. The chemical energy of the fuel is converted into heat energy by combustion, and part of this heat energy is converted into mechanical energy by the engine.