The biggest difference to notice when comparing figures between a 2-stroke engine and 4-stroke engine is that the spark-plug fires once every revolution in a two-stroke engine but in case of four-stroke engine the spark fires once every other revolution. First of all lets discuss about the working of four-stroke engine...
Today most of the cars use what is called Four-Stroke Combustion Cycle to convert gasoline into motion. The four-stroke approach is also known as the Otto cycle, in honor of Nikolaus Otto, who invented it in 1867. They are-
- Intake Stroke
- Compression Stroke
- Combustion Stroke
- Exhaust Stroke
The piston starts from the top, the intake valve is opened by the Camshaft, and the piston moves down to let the engine take in a cylinder-full of gasoline and air. Only the tiniest drop of gasoline needs to be mixed into the air for this to work.--------This all Process is called Intake Stroke.
Then the piston moves back to compress this fuel & air mixture. This all makes the mixture more denser, internal temperature of the cylinder increases. Hence--------Compression Stroke makes the Explosion more powerful.
And when the piston reaches the top of the cylinder, the spark plug emits a spark and ignites the gasoline. The gasoline charge in the cylinder explodes, driving the piston downwards.-------This is called as Combustion Stroke.
Once the piston hits the bottom of its stroke, the exhaust valve opens and the exhaust leaves the cylinder to go out the tailpipe.-------This is called Exhaust Stroke.