VNT-25 too small?

The Garrett VNT-25 is back on eBay. I've seen this turbo installed on a 2.7L Isuzu g@sser, but it would boost creep above 3100rpm@9psi to 15psi.

I'm really thinking of tagging this turbo and having my buddy make a custom manifold set. I just don't want to waste $400 if it's too small. Now my 3K K03 is really dang small but it does the job well (Even if it heats the air more.) The VNT-25 should not be any smaller than this.

The seller returned an e-mail telling me he can "upgrade" this turbo to a T28 for *only* $200. Now, the whole reason for even thinking about this turbo is the VNT design and ease of controling the vanes on this model. I know new VNT turbos can be bought but only for big $$$, even the small ones.

Another thought was dual VNT-15's used on VW TDI's but in the end that would cost WAAAAAAAAY too much for the gains I'd get back.

Am I crazy? My 3K turbo spools pretty well as-is, I get 10psi by 2500 and 13.5 by 3000. Just imagine 13psi @ 2000rpm. *drool*

[tomnik]

[The boost control of the VNT is different!
It is vice versa to the actual wastegate.
The mechanical part works with vacuum which is controlled by the computer.
No vacuum (start or breaking line) the VNT is shut. To realise this with the boost pressure only (without pressure – vac converter and computer) is not easy.
Closing the turbo by boost pressure means full power when starting and worse: full power in case of line breaking.
I found the VNT (taken from a 210 model 270 CDI) but still no solution for the control.

Also my intercooler comes from this model and fits perfectly in the front bumper of my SD.

Tom

The VNT-25, as used on some 89-90 crysler models, uses vacuum and pressure to control the vanes. (See picture) The keyboard in the picture should give you an idea on it's physical size.

My idea of control was to use the stock auto-tranny vacuum device on the IP to "control" the vanes at idle/low throttle for less exhaust restriction. Also to exercise the vanes and prevent carbon sticking of the vanes. (As many babied VW TDI's run into)

From what I have gathered on others that have used this turbo on g@ssers, running manifold boost to the pressure side of the actuator (With a vacuum check valve on gassers) will limit it to 9psi. A standard boost controller should bring this up where I want it.

HERE is a teardown photo gallery of a VNT-25.