Engine Performance: System: Turbocharger: Operation

Turbine impeller of turbocharger is driven by exhaust gases expelled from cylinder combustion chambers. At idle, no pressurization of intake air takes place and engine operates like a normally aspirated engine.

With engine under full load, exhaust gases are at maximum pressure, which increases RPM of turbine and compressor impellers to an extremely high speed. Boost pressure of the intake air reaches a maximum.

When pressure in intake manifold reaches 6.08-6.85 psi (.43-.48 kg/cm² ), diaphragm of wastegate controller pushes against linkage which opens wastegate.

Some exhaust gases are then routed directly into main exhaust pipe, by-passing turbine impeller. This maintains boost pressure of intake air at a constant 6.19-7.35 psi (.44-.52 kg/cm² ).

If wastegate fails to function properly, an emergency relief valve located on intake manifold opens to atmosphere when intake manifold pressure reaches 7.35-7.73 psi (.52-.54 kg/cm² ). This prevents engine damage from excessive pressure.