Principles Of Variable Vane Operation
WARNING: This page is about a different car, the 2018 Land Rover Discovery and 2017 Land Rover Discovery. However, it is still accessible from the selected car via links, so may be relevant.
The variable vanes in the VGT are controlled by the PCM and are used to improve the exhaust gas power transfer to the turbine wheel. Adjusting the pitch angle of the vanes by rotating the turbine housing greatly assists the boost pressure increase in the VGT at low engine speeds.
As engine speed, and therefore the exhaust gas velocity increase, the PCM increases the vane opening to avoid overspeed of the turbines and provide a smooth high speed operation.
The VGT vane actuator also provides the PCM with a feedback signal to determine the pitch angle of the vanes. This ensures that the power transfer from the turbine wheel to the compressor wheel is within the VGT speed and boost pressure requirements.