As shown in the illustration above, a valved-piston engine would have two crankshafts. There would be two pistons inside each cylinder. One of these pistons is referred to as the intake piston, the other piston is referred to as the exhaust piston. One side of the engine is called the intake side, the other side is called the exhaust side. The illustration above shows the four strokes of the engine: the intake stroke, the compression stroke, the power stroke, and the exhaust stroke.