What does scavenging refer to in engine operation?

Scavenging in engine operation specifically refers to the process of removing the exhaust gases from the combustion chamber and replacing them with fresh air or fuel-air mixture. This occurs particularly in two-stroke engines, where the timing of intake and exhaust is crucial. Since these engines do not have valves, scavenging plays a critical role in ensuring that spent gases do not mix with incoming fresh charge, thereby maximizing efficiency and performance.

By effectively clearing the cylinder of combustion by-products, scavenging prevents engine knocking and contributes to more complete combustion of the new intake charge. This enhances the overall power output and efficiency of the engine. In this context, the accurate understanding of scavenging as the replacement of combusted gases with fresh air is essential for optimizing engine operation and performance.