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Discussion Starter #1
Quote taken from here:

http://geneva2006.cars.msn.co.uk/75/news/view_259.htm

The new 911 Turbo features an exhaust gas turbocharger with variable turbine geometry (VTG) that provides control of the exhaust gas flow throughout the entire range of engine speed. The result is a considerable increase in power output, despite the fact that engine capacity has remaining unchanged at 3.6 litres. Power has been increased from 420bhp to 480bhp. Maximum torque, in turn, is up from 560 to 620 Nm (383 to 457lb-ft) and starts in at a very low 1,950 rpm.

Is this available as an aftermarket kit?

Dave.
 

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Discussion Starter #4
Thanks DCD,:)

Should have known someone likeyou would already be in the know;)

Regards,

Dave.

PS message to self, must use the search button more:eek:
 

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Have seen what was described as a prototype VVT from Ford. Turbonetics also have a VVT mod, however it is not intended for the "bigger" turbos such as GT30 series.
The key problem seems to be how do you control the system, the "vanes" are typically driven by a servo of some form, the question is how do you manage the servo system and link into your ECU.
DaveG
 

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There are huge VNT turbos being used, and have for a while now.

I can post pics of VNT GT40s etc if you want...

VNTs are controlled by either electronic controller (Holset ones for example) or by a simple pressure actuator on most (which in turn could be controlled by an electronic controller).
 

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Variable vain geometry had been on diesels for a while, the problem with petrol
engines is the exhaust gases are 100 DegC higher then Diesel, which was up until a
while ago just outside the temperature range of the materials used. :(

I guess some egg heads in some metalogy department has found the answer. ;)
 

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MartinC said:
Nissan have been using VNT turbos for a while now on the diesel range, they keep suffering from overboost/boost spikes
Its a pain in the **** to sort that, seems to not operate fast enough, so almost all people that ive seen whos fitted them as an aftermarket mod have also fitted an external wastegate, rather than just relying on the VNT to control the boost by increasing turbine a/r, and hence stopping the exhaust wheel from spinning faster.
 

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SteveN said:
There are huge VNT turbos being used, and have for a while now.

I can post pics of VNT GT40s etc if you want...

VNTs are controlled by either electronic controller (Holset ones for example) or by a simple pressure actuator on most (which in turn could be controlled by an electronic controller).
Steve, I was meaning ones that work to a spec a high end RB engine requires. The Ford unit had an electronic controller fitted however as far as I'm aware no one has yet perfected a system that provides the desired control granularity and speed. Maybe Porsche are the first!
DaveG
 
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