What is scavenging?

• A. The blown air charge helps to clear the cylinder of exhaust gases
• B. The intake stroke of the engine
• C. The process of lubricating the cylinder walls
• D. The method of exhaust gas recirculation

Answer: (A)

Scavenging is the process where the incoming air-charge entering the cylinder helps push the burnt exhaust gases out of the cylinder, so the next compression stroke starts with a fresh mixture. In engines that rely on this effect, the fresh charge sweeps through the cylinder and out the exhaust port, clearing spent gases and preventing them from diluting the next charge. That description—the blown air charge helping to clear the cylinder of exhaust gases—captures the essence of scavenging. It’s not simply the intake stroke, not about lubricating the walls, and not a form of exhaust gas recirculation.