What is scavenging in an engine?

Scavenging in an engine refers to the process where fresh air or a fuel-air mixture enters the combustion chamber, particularly emphasized during the valve overlap period. This overlap occurs when both the intake and exhaust valves are open simultaneously for a brief moment, allowing for the efficient expulsion of exhaust gases while simultaneously drawing in fresh air. This is crucial in two-stroke engines and some four-stroke engines, as it enhances the intake charge and promotes better combustion efficiency.

The process of scavenging is essential for maximizing power output and reducing emissions. By ensuring that the combustion chamber is cleared of exhaust gases, there is a greater likelihood of a more complete combustion of the fresh air-fuel mixture, which contributes to the overall performance of the engine.

In contrast, the other options relate to different functions within engine operation but do not accurately describe scavenging. For instance, removing carbon buildup is a maintenance procedure aimed at keeping the engine clean, flushing oil involves lubricating and cleaning engine parts, and cooling engine components refers to the thermal management necessary for optimal performance. Each of these processes plays a role in engine efficiency but does not define scavenging.