Question 29Motor Plants - Assistant Engineer

The correct answer is C) after TDC (Top Dead Center). In a diesel engine, the highest pressure in the cylinder normally occurs after Top Dead Center (TDC) during the power stroke. As the piston reaches TDC, the fuel is injected and ignited, causing the rapid increase in pressure and temperature that drives the piston down during the power stroke. The peak pressure occurs slightly after TDC, as the expanding gases continue to push the piston downward. The other options are incorrect because: A) the pressure peaks after TDC, not at TDC; B) the pressure peaks after TDC, not before; and D) air starting is a separate process not related to the peak cylinder pressure during normal engine operation.