engine 4 stroke cycle

In order to increase the horsepower of an engine is to first understand the four stroke cycle within the engine. The four stroke cycle consists of intake stroke, compression stroke, power stroke, and exhaust stroke.

Intake stroke

The first stroke is the intake stroke. The piston

moves down the cylinder and creates a partial

vacuum in the cylinder. A mixture of air and fuel

is forced through the inlet valve into the cylinder

by atmospheric pressure, now greater than the

pressure in the cylinder. During this stroke,

the exhaust valve stays closed.

Compression stroke

The second stroke is the compression stroke.

The piston moves up in the cylinder with both

valves closed. The air and fuel mixture is

compressed and the pressure rises.

Power Stroke

The third stroke is the power stroke.

Near the end of the compression stroke,

the air and fuel mixture is ignited by an

electric spark from the spark plug. The

combustion that occurs causes a rise in

temperature and enough pressure to force

the piston down again

Exhaust Stroke

The fourth stroke, or exhaust stroke, the

piston moves up again and forces the burned

gases out of the cylinder and into the exhaust system.