Upgrade to VR4 ?

[pavement pounde]

Hello,
Is it possible to upgrade my SN93 to VR4 ?
I allready rebuilt it with a rebuiltkit from Graig and a better impeller and oilcooler.
Thanks

[speedytang]

If you can find a used kit because the last thing we have heard is Craig has no more VR4 kits

[pavement pounde]

So, the VR4 is a complete different blower ?

[speedytang]

It is a different impeller and rear housing and you need to re-shim the bearing race to increase pressure on the ball drive. On your big block you would see a huge increase in performance. The SN-93 was really out of breath on anything larger than 360ci. The only problem I could see is your a TBI on the 454..Correct. You would not be able to increase the TBI rate for the increased CFM even with a chip. You would need something equal to 50lb injectors.

[pavement pounde]

It is a different impeller and rear housing and you need to re-shim the bearing race to increase pressure on the ball drive. On your big block you would see a huge increase in performance. The SN-93 was really out of breath on anything larger than 360ci. The only problem I could see is your a TBI on the 454..Correct. You would not be able to increase the TBI rate for the increased CFM even with a chip. You would need something equal to 50lb injectors.

Thanks man,
I was allready working on a auxillary fuel injector system and an enlarged trottle body.

[pavement pounde]

If you can find a used kit because the last thing we have heard is Craig has no more VR4 kits

I mailed him, he has some VR4 kits left:) $600 ............:weird:
To much for me, for now

[pavement pounde]

I bought a used Vr4 that is very bad on the frontside, just for parts.
So I like to put the rear housing and impeller on my SN93.
Just how do I re-shim the bearing race to increase pressure on the ball drive ?
I have rebuilt my SN93 myself and there where no shims.

[F=MA]

Whut? There are shims behind each bearing race...

You have to pull the races to get at them.

F=MA

[pavement pounde]

So I could use the shims(s) of the busted VR4 ?
I have not opened it up yet.

[F=MA]

I'd guess so.

F=MA

[speedytang]

You can do that and make sure you pull both races on the old unit and don't mix up the shims because mine had no measurements on them. Make sure you measure the total thickness of the shims with a caliper before you install and that way if it turns to hard or soft you can mix and match the shims later. I color coded my shims and made a notebook with the color that equals what thickness.

[pavement pounde]

I'll keep you guys informed !

[pavement pounde]

Pulled the VR4 yesterday and there was 1 thick shim.
How tight must the VR4 turn again?

[pavement pounde]

Ok, instald the vr4 impeller, backside and put the shims over, and everything looks ok.
The pulley turns some what heavier but doable with 2 hands.
I am looking forward for the testdrive.
I also instalt an extra injector plate under the trottle body with 2 injectors what came from a Vortech 454 blower kit for extra fuel.
Thanks everyone for you help !

[speedytang]

Please let us know how it goes.