How Does Gas Make an Engine Run?

Compression of Air and Gas

Most gasoline engines use combustion technology. The majority of today's automobiles use four-stroke engines, also called the Otto cycle. The first two strokes are the intake and compression strokes where gas (vaporized) and air are mixed together in the combustion chamber and pressure is added to compress them.

Combustion

After the air and small amount of gas are compressed, a spark plug produces a spark that ignites the pressurized mixture, causing combustion. This controlled explosion is the force that provides power to move the vehicle.

Pistons

The pistons in the engine are the parts that are moved by the combustion process. When the air/gas mixture is being compressed, the piston moves to the top of the combustion chamber. Combustion forces the piston down which drives the crankshaft. The useful mechanical energy produced is then transferred to the axles and eventually the tires on the ground.