Turbocharger Description and Operation

A turbocharger is a forced induction device used for increasing power output of an internal combustion engine. By using the exhaust gas forces to compress intake air, a turbocharged engine is more powerful and efficient than a naturally aspirated engine with the same displacement. The dual-scroll turbocharger is mounted on the exhaust manifold and the lightweight turbine is driven by the waste energy generated by the flow of the exhaust gases. The turbine is connected by a shaft to the compressor which is mounted in the induction system of the engine. The compressor vanes compress the intake air above atmospheric pressure, thereby greatly increasing the density of the air entering the engine.

The turbocharger incorporates a wastegate that is controlled by the ECM, by means of a pulse width modulated (PWM) solenoid, to regulate the pressure ratio of the compressor. An integral turbocharger bypass valve, controlled by the ECM through a remotely mounted solenoid, is used to prevent compressor surging and damage by opening during abrupt closed throttle conditions. The bypass valve opens during closed throttle deceleration conditions, which allows the air to recirculate in the turbocharger and maintain compressor speed. During a wide open throttle command, the bypass valve closes to optimize turbo response.

The turbocharger is connected to the engine oiling system by a supply and drain tube and synthetic oil is installed at the factory. Synthetic oil is required for its friction-reducing capabilities and high-temperature performance. There is a cooling system circuit in the turbocharger that utilizes the engine coolant to further reduce operating temperatures.