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4
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Turbocharger
5
Turbocharger retaining nuts
6
Exhaust manifold stud (note orientation of stud)
Variable Vane Turbocharger The engine is fitted with twin variable vane Turbochargers, electronically controlled, one to each bank. The turbochargers are fixed to the exhaust manifold by a three hole flange. The turbocharger consists of two elements, a turbine and a compressor both installed on a single shaft.
The turbocharger bearings are supplied with oil from the engine.
The turbine uses the flow of the exhaust gas to drive the compressor. The compressor draws air through the air cleaner and forces it into the intake manifold. Principles of Operation - Variable vane turbocharger The turbocharger is designed to improve engine induction and engine performance. The list below details the concerns relating to turbocharger performance. High engine speed produces excessive turbine speed and therefore creates excessive turbocharger boost pressure. Low engine speed does not produce sufficient turbine speed and therefore not enough turbocharger boost pressure is achieved. The turbocharger does not have a wastegate control valve. Instead, it has variable turbocharger vanes which are located in the turbocharger turbine housing and these direct the air flow into the turbocharger turbine. The turbocharger vanes act as the control for the turbocharger boost pressure.
The turbocharger produces its full turbocharger boost pressure over the entire engine speed range, not just at high engine speed. This is achieved through the adjustment of the vanes and the resulting change in the flow of the exhaust gas.
The speed of the exhaust gas flow within the turbocharger is increased independent of engine speed by varying the intake cross section in front of the turbocharger turbine. This is achieved by adjusting the angle of the vanes controlling the air flow into the turbocharger turbine and this then drives the turbocharger turbine faster. The higher turbocharger speed produces a high turbocharger boost pressure at all engine speeds.
The engine control module (ECM) controls the turbocharger vanes by means of an electronic vane adjustment solenoid attached to the turbocharger. |