Four Stroke Cycle

     The main format of engines used in cars today is the four stroke design. These types of engines are called four stroke because the piston must go in an up and down motion four times in order to create power to the wheels. The first stroke that the engine must go through is called the intake stroke. This stroke is when a valve opens up and the piston pulls the fuel air mixture into the cylinder. The next stroke is the compression stroke. This is when the piston is in an upward position compressing the gas in the cylinder while the valves are closed. When the piston reaches the top of the cylinder the gas is under extreme pressure and is ignited by a spark plug. The third stroke is called the power stroke because the fuel is ignited by the spark plug which forces the piston downward. When this vital stroke occurs the piston turns the crankshaft which imparts a rotational force (torque) to the wheels of the car. And the last stroke is when the opposite valve opens up and the piston pushes out all of the exhaust from the burnt fuel. After those steps are taken they start all over again until the engine is shut off or fuel is cut off.

** For more photos of the 'four stroke' engine go to the photo gallery and look under Four Stoke Engine**