General System Description

Turbocharger Operation:

A turbocharger is used to increase power on a demand basis.

As increased power is required and the throttle is opened, more air-fuel mixture flows into the combustion chambers. As this increased flow is burned a larger volume of high energy exhaust gas enters the engine exhaust system and is directed through the turbocharger turbine housing. Some of this energy is used to increase the speed of the turbine wheel. The turbine wheel is connected by a shaft to the compressor wheel. The increased speed of the compressor wheel compresses the air it receives and delivers it to the throttle body unit and the intake manifold. The resulting higher pressure in the intake manifold allows a denser charge to enter the combustion chambers. The denser charge develops more power during the combustion cycle.

The intake pressure (boost) is controlled to a correct maximum value by an exhaust bypass valve (wastegate). The valve allows a portion of the exhaust gas to bypass the turbine wheel, thus controlling turbine speed. The wastegate is operated by a spring loaded diaphragm (actuator assembly) that responds to the wastegate solenoid to adjust boost level. The wastegate solenoid is controlled by the Electronic Control Module (ECM).

Turbocharging allows for increased power as compared to a naturally-aspirated engine of the same displacement. A turbocharged engine is a finely tuned assembly, which can adapt to increases in air-fuel consumption and the balanced increases in exhaust which occur under boost conditions. Any alteration to the air intake or exhaust system, which upsets the air flow balance, may result in serious damage to the turbocharged engine.