Internal combustion engine facts

An animation showing a four-stroke engine running.

An internal combustion engine is an engine in which combustion, or the burning of fuel, occurs on the inside. It is a machine that makes large pressure increases inside a sealed box (cylinder). The pressure increase pushes a rod which is attached to a wheel. The rod pushes the wheel and makes it spin around. The spinning wheel is attached to other wheels, such as four car wheels, with a belt or a chain. The engine is very strong and can make all the wheels move.

Engines need oil to make them slippery or the moving parts would grind together and stick. Parts of a car engine are measured to 0.01 of a millimeter and some engine parts fit together very tightly.

Internal differs from external combustion where the fire is outside the engine, such as a steam engine.

Most road vehicles use the internal combustion engine today, and most of those use the four-stroke engine. Rocket and jet engines are combustion engines but they do not turn wheels. The fire in a rocket combustion engine is so strong that it blows a mighty wind out the back, which pushes the rocket forward.

Another type of internal combustion engine is the Wankel engine.


Internal combustion engine Facts for Kids. Kiddle Encyclopedia.