A more effective, though complex, method of turbocharging
uses a turbine stage where the swallowing capacity is automatically
varied while the engine is running. This permits turbine
power to be set to provide just sufficient energy to drive
the compressor at the desired boost level wherever the engine
is operating.
This is achieved by varying the area of a nozzle, a set of
guide vanes that control the flow through the turbine. Conventional
designs pivot the vanes to achieve different nozzle areas.
The Holset VGTTM is unique in that the vanes
do not pivot but slide axially. This innovative approach ensures
a high level of durability and reliability, essential for commercial
diesel applications.
VGTTMurbocharging yields several benefits in engine matching:
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Good transient response. |
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Good fuel economy. |
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Increased useful engine operating speed range. |
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Enhanced compression brake capability. |
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Reduced engine swept volume and package
size for a given rating. |
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High pressure ratio compressors. |
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