Which statement correctly identifies the role of scavenging in engine operation?

• A. The blown air charge helps clear the cylinder of exhaust gases
• B. It increases fuel consumption
• C. It seals the exhaust pipe
• D. It reduces intake valve lift

Answer: (A)

Scavenging is the process of using the incoming fresh air (often with fuel) to sweep out the cylinder after combustion, so the cylinder starts clean for the next cycle. The incoming charge pushes out or expels the burnt exhaust gases, reducing dilution of the new charge and helping ensure efficient, complete combustion. That’s exactly what the statement about the blown air charge doing—clearing the cylinder of exhaust gases—describes.

The other ideas don’t fit this function. Sealing the exhaust pipe is handled by gaskets and fittings, not scavenging. Scavenging isn’t meant to inherently increase fuel consumption; in fact, proper scavenging aims to improve efficiency by reducing leftover exhaust in the cylinder. And scavenging doesn’t control intake valve lift; valve lift is determined by the valve train and cam timing, not the scavenging process.