As the piston in an engine moves down, a mixture of fuel and air gets drawn into the cylinder, which causes compression. This compression is ignited by the spark plugs, causing the exhaust valve to open to allow the burned fuel mixture to be sent to the exhaust system. An internal combustion engine needs a gasoline-to-air mixture of around 14.7 parts air to one part gasoline (by weight) in order to run efficiently.
A piston uses four strokes: the intake, compression, power and exhaust. During the intake stroke, the piston moves down and moves back up again for the compression stroke. It moves back down to create the power stroke, and moves up once again for the exhaust stroke. To work properly, the engine must have firing spark plugs, an oil system and an engine cooling system.
Oil is essential to keep the engine parts properly lubricated in all internal combustion engines. It is pumped throughout the entire engine by an oil pump; an engine without oil will soon lock up.
The cooling system is crucial because while the engine is running, it gets extremely hot. Not only does the cooling system, which is comprised of the radiator, fans and hoses, keep the engine components cool, it also keeps the oil cool as it travels around the engine.