Internal Combustion Engines
Crankcase explosion in I.C. engines usually occurs as

First a big explosion followed by a mil explosion
Never occurs
Both mild and big explosions occurs simultaneously
First a mild explosion followed by a bi explosion

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Internal Combustion Engines
In a typical medium speed 4-stroke cycle diesel engines

Exhaust valve opens at bottom dead center and closes at top dead center
May open and close anywhere
Exhaust valve opens at 35° before bottom dead center and closes at 20° after top dead center
Exhaust valve opens just after bottom dead center and closes just before top dead center

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