Question

In a four stroke cycle diesel engine, the exhaust valve __________

(a) opens at 30º before bottom dead center and closes at 10º after top dead center

(b) opens at bottom dead center and closes at top dead center

(c) opens at 30º after bottom dead center and closes at 10º before top dead center

(d) may open or close anywhere

This question was addressed to me in exam.

The origin of the question is Advantages of Two Stroke Engines topic in chapter Two Stroke Engines of IC Engine

Answer 1

Answer: (a) opens at 30º before bottom dead center and closes at 10º after top dead center

Explanation: In a four-stroke diesel engine, the exhaust valve typically opens around 30º before bottom dead center (BDC) and closes about 10º after top dead center (TDC). This timing ensures that exhaust gases are fully expelled before the intake process begins for the next cycle.