1. Intake stroke: The piston moves downward, creating a vacuum that draws air-fuel mixture into the cylinder through an open intake valve.
2. Compression stroke: The piston moves upward, compressing the air-fuel mixture in the cylinder, increasing its pressure and temperature.
3. Power stroke: The compressed air-fuel mixture is ignited by a spark plug (in gasoline engines) or by the high temperature and pressure caused by compression (in diesel engines), causing combustion and a subsequent release of heat and high-pressure gases. This forces the piston downward, generating power that drives the crankshaft.
4. Exhaust stroke: The piston moves upward again, pushing the exhaust gases out of the cylinder through an open exhaust valve.
Therefore, in a four-stroke engine, the piston undergoes four revolutions to complete one full cycle of intake, compression, power, and exhaust strokes.
