Question 93Motor Plants - Assistant Engineer

The correct answer is B) Air/Fuel ratio. As the engine RPM increases from idle to full load speed, the air/fuel ratio will decrease. This is because the engine requires more fuel to produce the increased power at higher RPMs, while the air intake remains relatively constant. The increased fuel flow without a corresponding increase in air flow results in a richer air/fuel mixture, or a decreased air/fuel ratio. The other options are incorrect because: A) Compression ratio is a fixed engine design parameter and does not change with RPM. C) Compression pressure will increase with RPM as the engine is producing more power. D) Lube oil pressure may increase with RPM as the oil pump is running faster.