Principles of Operation

The turbocharger is an exhaust-driven centrifugal air compressor. Its purpose is to increase power output by supplying compressed air to the engine.

Expanding exhaust gases drive the turbine shaft assembly to speeds up to 200, 000 RPM. Filtered air entering the compressor side of the turbocharger is compressed and delivered through a Charge Air Cooler (CAC). The very hot compressed air is cooled, then continues on to fill the intake manifold at a higher pressure than atmospheric pressure. Because considerably more air is forced into the intake manifold, the results are increased power, fuel efficiency and the ability to maintain power at higher altitudes.

The turbocharger is governed by a wastegate actuator. The wastegate actuator redirects some of the exhaust gas past the turbine and therefore acts as a governor. The wastegate actuator is preset during manufacture and must not be tampered with. The wastegate actuator is controlled by the turbocharger control valve that is located on the turbocharger compressor housing.

The intake air system is fitted with a turbocharger bypass valve. This vents the intake air system when the throttle is closed and recirculates the air back into the intake air system. It also releases pressure on the turbocharger which will reduce turbo lag and improve acceleration and increase engine performance.

The turbocharger is equipped with a boost control system. The PCM detects 1st or 2nd gear using the engine speed and vehicle speed signals. This information is then used to adjust the pressures applied to the wastegate actuator allowing it to open at a lower boost pressure. This prevents the turbocharger developing maximum boost in 1st and 2nd gears.

The turbocharger housing is both water and oil cooled. The oil supply also lubricates the turbocharger bearings.