Engine 4 Stroke Cycle

Engine 4 Stroke Cycle: "4 Stroke Cycle
The 'cycle' as in two or four, of an internal combustion piston engine is defined by how many strokes of different direction must be accomplished to complete one cycle of combustion. One cycle is defined as the time between two ignitions of combustible material. The cycles are often divided into strokes. Each stroke is motion in one direction. The following is the cycle of a four cycle engine:
Intake Stroke
This is the first movement of the piston. This is a downward motion of the piston that develops a vacuum in the cylinder. This vacuum pulls the air and fuel mixture into the cylinder through the open intake valve.


Compression Stroke
During this second stroke, all valves are closed. This allows all of the piston's force to be used to compress the air and fuel mixture. As it is compressed, the mixture becomes more dense creating a more potent mixture for detonation.


Power Stroke
Just before the piston reaches top dead center, the mixture is ignited by a spark plug. The third stroke, the power stroke harnesses the energy of the explosion by allowing the piston to be forced downward from top dead center. This linear motion is changed to rotational motion by the crankshaft.


Exhaust Stroke
The last stroke is the exhaust stroke. During this last upward movement of the piston the exhaust valve is open. The piston forces all of the burned gasses from the previous explosion out of the cylinder. The cycle is completed and can begin again."