Web animation: Four-stroke petrol engine

The following animation illustrates the processes that take place in a four-stroke spark ignition engine. All 4 strokes are shown. In addition to gas exchange and combustion, the movements of the valves, the piston, the connecting rod and the flywheel can also be seen.

The animation is suitable as a basic introduction to the functioning of a four-stroke petrol engine

Description of the animation

1. Intake: The valves open. The piston moves downwards. The vacuum fills the cylinder with air and fuel. Both components mix to form a fuel-air mixture.

2. Compression: The valves are closed. The piston moves upwards. This increases the pressure and temperature inside the combustion chamber.

3. Combustion: Shortly before the piston reaches the top dead centre, the fuel-air mixture is ignited by the spark plug. The fuel-air mixture burns from top to bottom. The flame front hits the piston and pushes it downwards.

4. Exhaust: The fuel-air mixture is completely burnt. The valves open again. The piston moves upwards. The combustion gases are expelled.


PlatformPC/Mac bzw. Tablet
Resolution(min)1280 x 720


C. Hein, S. Rikowski


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