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Turbo pressure regulation, V6

Turbo pressure regulation, V6

The engine is equipped with a Garret VNT turbocharger (Variable Nozzle Turbine). This turbocharger is governed by a set of vanes on the exhaust side.


• The engine develops a high torque even at low engine speeds.

• As the working temperature of the turbocharger can be kept down, the compression of the air to the cylinders is improved, which increases power.

• The turbocharger responds more quickly to the desired torque which means improved drivability.

• The engine consumes less fuel and has reduced emissions.


These vanes control the speed and boost pressure of the turbocharger. At low exhaust flow, the vanes will be adjusted to increase the speed of the turbocharger and thereby increase the boost pressure. This means that a higher engine torque can be attained even at low engine speeds. As the exhaust flow increases, the turbocharger speed will be reduced to avoid overspeeding but it will still deliver the requested boost pressure.


The vanes are adjusted for low exhaust flow so that the inlet area on the exhaust side is reduced. As the inlet area is reduced, the speed of the exhaust flow will increase. In this way, the turbocharger can deliver a high boost pressure even at low engine speeds.


The angle of the vanes is controlled by a ring that is connected to the control rod from the diaphragm unit. The boost pressure control valve receives a signal from the engine control module as to the desired boost pressure. The boost pressure control valve controls the negative pressure required to regulate the vanes.

A potentiometer in the diaphragm box detects the position of the control rod and thereby the inlet area of the vanes. This information means that the engine control module is always aware of the position of the vanes and that their position can be quickly changed. The potentiometer also allows control of the turbocharger's mechanical parts. In order to ensure that there is sufficient vacuum for the turbocharger regulation, there is a vacuum pump mounted on the cylinder head. This is driven by a camshaft.