Engine Performance: System: Turbocharger: Operation

The turbocharger is driven by exhaust gases being expelled from the cylinder combustion chambers. At idle speeds there is no pressurization of incoming air and the engine operates like a normally aspirated engine. When the engine reaches approximately 1000 RPM, turbo boost begins with approximately 1.45 psi (.10 kg/cm² ).

As engine RPM increases, turbo boost pressure increases, depending upon engine load. The greater the load, the higher the boost. Maximum boost pressure is approximately 8.7 psi (.61 kg/cm² ). Turbine speed depends upon engine RPM and temperature. Higher temperatures create more exhaust gas pressure, resulting in higher turbine speeds.

As the cylinders receive their full capacity of incoming air, boost pressure opens the wastegate valve, diverting exhaust gases into the exhaust pipe away from the turbine. This lessens thrust on the turbine and slows it down.