VALUE TIMING DIAGRAM OF A FOUR STROKE, OTTO CYCLE ENGINE It has already been explained in the operation of four stroke, Otto cycle engine that the inlet valve opens during the suction stroke and the exhaust stroke and the exhaust valve opens during the exhaust stroke. The exact moment at which each of the valves opens and closes with reference to the position of the piston and crank can be show graphically in a diagram. This diagram is known as valve timing diagram. Theoretically, the inlet valve opens exactly at the beginning of suction stroke and closes at the end of the stroke. Both the valves close during power and compression stroke. The exhaust valve opens exactly at the beginning of exhaust stroke and closes at the end of the stroke. The theoretical valve timing diagram for a four stroke Otto cycle engine in shown in diagram. The opening and closing valves with reference to the position of piston and crank shaft during the four strokes are described as follow. 1. ...
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