Which statement best describes the overall effect of the impeller's swirling action?

• A. It reduces engine power.
• B. It improves the mixing of fuel and air.
• C. It increases exhaust backpressure.
• D. It cools the intake charge.

Answer: (B)

Swirl creates a rotational flow in the incoming mixture, generating turbulence that breaks up fuel droplets and keeps them dispersed. This turbulence increases the contact between fuel and air, leading to a more uniform, well-mixed charge before ignition. With a better air–fuel distribution, combustion becomes more complete and efficient, which is why the swirling action is described as improving the mixing of fuel and air. It doesn’t primarily act to reduce power, alter exhaust backpressure, or cool the intake charge; those effects are not the main impact of the swirl.