Variable Geometry Turbos

[southern_tango]

Just crossed my path with this in youtube

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Opinions?

[SimonR32]

Been out for a long time in non petrol applications, seems to be a good idea and Porsche are now running it in 911 turbos

http://www.porsche.com/microsite/technology/default.aspx?pool=uk&ShowSingleTechterm=PTVTG&Category=&Model=&SearchedString=&SelectedVariant=PMT911TurboAll

Edited December 31, 2010 by SimonR32

[The Mafia]

Thats pretty awesome. I wonder how to operate the vaible part, as in, via boost or vacuum, maybe revs?

Also wonder how big the scope is.

[Adriano]

Scope is big enough. My Iveco has one and its 7 years old. If you manually move the actuator it gets 15psi at idle. No wastegate. The problem is geting the exhaust housing to hold together with petrol egt's

[GTRNUR]

They use a stepper control with an electronic controller on the porsches. There is a lot more to it than just controlling boost as well. When the engine is off boost the electronics cycle the veins back and fourth to stop them jaming up. Its safe to say the porsche versions are a fair bit different than the VGT's that are used on diesals.

[Adriano]

Mine uses a PWM soleniod controlling a vacuum can actuator.

[KEBAB_DRIFTER]

http://forums.nicoclub.com/holset-vgt-electronic-controller-project-t463902-80.html

good read

[Rolls]

I have always wondered why we don't see these in the form of garret performance turbos that we can purchase. I know they do make them, but I have never seen an aftermarket one for sale.

edit: After some reading apparently the issue is they don't run a wastegate causing excessive back pressure at high revs, great for a factory car but not so great for a performance race car.

I'm sure you could adapt a wastegate with one but controlling the vayne and the wastegate to control boost would be very difficult, you couldn't just do it by trial and error, you'd need to have someone work out the maths before hand, I believe porsche is the only company that has successfully done this so far.

Edited January 1, 2011 by Rolls