Turbocharging:

Turbocharging an engine occurs while the engines own exhaust gasses are forced by a turbine (impeller) that rotates and is linked to a second impeller located in the fresh air intake system. An impeller in the fresh air intake system compresses the fresh air. The compressed air serves two functions. First one, it rise the engine's available power through increasing the maximum amount of air (oxygen) which is forced within each cylinder. This permits more fuel to be injected and more power to be generates through the engine. The second one function is to increase intake pressure. That improves the scavenging of the exhaust gasses out of the cylinder. Turbocharging is generally found on high power four-stroke engines. It could also be used on two-stroke engines whereas the increase in intake pressure produced through the turbocharger is needed to force the fresh air charge within the cylinder and help force the exhaust gasses out of the cylinder to enable the engine to run.