VNT control question

[lucasone]

On a VNT turbo when vacuum is applied to the actuator pulling down on the rod, does this increase turbine speed(boost) or decrease?
Also when this happens are the vane in a closed position or open?

If anyone has any info on this topic, please let me know.

Thanks

[rallydiesel]

When vacuum is increased to the actuator, the vanes close and turbine speed increases . At no vacuum, the vanes are open and turbine speed decreases. Open/close is sort of inaccurate. It's the angle of the vanes that changes, they never actually close off exhaust flow completely, just change the velocity of the exhaust gas going through them.

[lucasone]

Thanks

[lucasone]

Looking at the VNT controll couldn't you replace the vacuum actuator with a boost actuator and controll it with boost?

[rallydiesel]

I think vacuum is more easily controlled with an electronic solenoid. If you are making a mechanical vnt controller, then boost is what you will want instead.

[OM617]

Looking at the VNT controll couldn't you replace the vacuum actuator with a boost actuator and controll it with boost?

Yes but fuel economy and part throttle performance will be extremely poor due to the actuator causing very high exhaust backpressure.

[Rabbit on Roids]

see, i knew you had good information once in a while!

[OM617]

see, i knew you had good information all the time!

Yep, agreed.