Internal Combustion Engines
The exhaust valve in a four stroke cycle petrol engine

Opens at bottom dead center and closes at top dead center
Opens at 50° before bottom dead center and closes at 15° after top dead center
Opens at 50° after bottom dead center and closes at 15° before top dead center
May open and close anywhere

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Internal Combustion Engines
In a four stroke cycle petrol engine, the expansion

Starts at 30° after top dead center and ends at 50° after bottom dead center
May start and end anywhere
Starts at top dead center and ends at bottom dead center
Starts at 30° before top dead center and ends at 50° before bottom dead center

ANSWER DOWNLOAD EXAMIANS APP