Principles Of Operation

Turbocharger

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. The internal components are oil and air cooled. Engine oil is circulated through the housing, which acts as a heat barrier between the " hot" turbine and the "cold" compressor. Bearings are sleeve type and lubricated by engine oil. Oil is pumped directly from the oil filter base, then circulated to the turbocharger housing and returned to the sump through an oil drain in the turbocharger center housing.

The electronic turbocharger variable vane hydraulic control valve utilizes the PCM to control intake manifold pressure. The turbocharger uses a set of moveable vanes in the turbine housing to change the flow of the exhaust gases through the turbocharger. These vanes can be positioned to change the angle or direction and the velocity of flow to the turbine wheel, depending upon the conditions in which the engine is operated. As power demands increase, exhaust gas velocity increases in direct relation, as does intake manifold boost pressure. Conversely, as the flow of exhaust gas diminishes, intake manifold boost pressure is also reduced at the same rate.

Expanding exhaust gases drive the turbine shaft assembly to speeds over 100,000 rpm. Filtered air entering the compressing 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 pressure higher 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.