Scavenging

A basic part of the cycle of an internal combustion engine is the supply of fresh air and removal of exhaust gases. This is the gas exchange. Scavenging is the removal of exhaust gases by blowing in fresh air. Charging is the filling of the engine cylinder with a supply or charge of fresh air ready for compression.

Increasing the density of the charge air by the use of a suitable comprssor between the air intake and the cylinder , the weight of air induced per working stroke is increased. Thereby a greater weght of fuel can be burnt with a consequent increase in the cylinder power output.