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What is a four stroke engine?

What is a four stroke engine?

Most car engines are four-stroke, which means that each piston moves up and down twice (two up-strokes, and two down-strokes, making four strokes), to produce one pulse of power. In a four-stroke engine, the four strokes are:

01 Intake

The piston moves down the cylinder, sucking air/fuel mixture from the inlet manifold into the cylinder and combustion chamber through the inlet valve.

02 Compression

The valves are closed and the piston moves up the cylinder, compressing the mixture until it’s ignited in the combustion chamber at the top of the stroke.

03 Power

The valves stay closed as the piston is pushed down the cylinder due to the expansion of the burning mixture.

04 Exhaust

The piston moves back up the cylinder (because of the momentum produced during the power stroke), and the burnt gases are pushed out through the open exhaust valve. The cycle then starts again, with another intake stroke.