VNT,VG Like Turbo setup
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From: Sacramento, CA
VNT,VG Like Turbo setup
Sorry if this has been covered trying to get some info if its been tried before 
The VNT (variable nozzle turbo) and the VG (Variable geometry) turbo use exhaust restriction to help improve turbo response at low rpms.
I was wondering through if anyone has tried restricting the intake of the turbo. All turbos far as i know have a surge line where the turbo is trying to push more air into the system but can't spin up because the engine can't take in the air fast enough.
So I was thinking if the turbo inlet was restricted that would allow the turbo to spin up and thus provide a high air pressure ratios. The entire idea of this simply is to shift the turbos efficiency range to the left a little reducing the surge line. Once some conditions are met then the restrictor could be opened back up putting the lines back to where they were.
Does this sound silly? And has to anyones knowledge has it been tried?
The VNT (variable nozzle turbo) and the VG (Variable geometry) turbo use exhaust restriction to help improve turbo response at low rpms.
I was wondering through if anyone has tried restricting the intake of the turbo. All turbos far as i know have a surge line where the turbo is trying to push more air into the system but can't spin up because the engine can't take in the air fast enough.
So I was thinking if the turbo inlet was restricted that would allow the turbo to spin up and thus provide a high air pressure ratios. The entire idea of this simply is to shift the turbos efficiency range to the left a little reducing the surge line. Once some conditions are met then the restrictor could be opened back up putting the lines back to where they were.
Does this sound silly? And has to anyones knowledge has it been tried?
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Joined: Oct 2005
Posts: 72
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From: RRev Motorsports
Sorry, but this would not work.
What you are proposing would be much like driving a turbocharged car at high altitude (lower compressor inlet pressure). What happens when the compressor inlet pressure is lower is that the turbo would operate at a higher pressure ratio in order to reach the same compressor flow. Because of this it would cause the compressor to operate at a point that is higher on the compressor map (same on x axis (flow), higher on y axis (pressure ratio). This would actually force the compressor into surge instead of reducing the surge margin.
Basically there are two things that you can do to a turbocharger to make it operate at an optimum level, make the compressor inlet pressure as low as possible, and make the backpressure on the turbine side of the turbocharger (largest, straightest exhaust possible).
What you are proposing would be much like driving a turbocharged car at high altitude (lower compressor inlet pressure). What happens when the compressor inlet pressure is lower is that the turbo would operate at a higher pressure ratio in order to reach the same compressor flow. Because of this it would cause the compressor to operate at a point that is higher on the compressor map (same on x axis (flow), higher on y axis (pressure ratio). This would actually force the compressor into surge instead of reducing the surge margin.
Basically there are two things that you can do to a turbocharger to make it operate at an optimum level, make the compressor inlet pressure as low as possible, and make the backpressure on the turbine side of the turbocharger (largest, straightest exhaust possible).
