Turbocharger - Diesel: Operation

The turbine impeller of the turbocharger is driven by the exhaust gases expelled from the cylinder combustion chambers. At idle speeds there is no pressurization of intake air and the engine operates like a normally aspirated engine.

With engine under partial load, the throttle valve opens and the speed and volume of exhaust gases increases which turns the turbine impeller at a faster RPM. The increased RPM of the compressor impeller boosts the pressure of the intake air.

With engine under full load, the exhaust gases are at maximum pressure and increase the RPM of the turbine and compressor impellers.