Question 163Motor Plants - Assistant Engineer

The correct answer is C) combustion pressure on the power stroke. When a generator diesel engine is operated at partial load, the combustion pressure on the power stroke will decrease compared to full load operation. This is because at partial load, the fuel injection quantity is reduced, resulting in lower peak cylinder pressures during the power stroke. The other options are incorrect because: A) piston speed is not directly affected by partial load, B) fuel injection pressure is typically maintained constant regardless of load, and D) compression pressure on the compression stroke is also not directly affected by partial load.