HELP - how do I get the pulley off of my SN89?!?

[Michael]

Still we need to know what you crank pulley size is.

Sorry about that. It's stock sized - 7.2"dia.

[Dirk Diggler]

Pavement Pounde has the VR4 impeller.

[Michael]

Pavement Pounde has the VR4 impeller.

Oh! :shocked:

Well, that would explain the difference between the stock grey one I have and the one he's using. See? I told you I was a novice. :)

Any idea if that's the impeller that Paradise Wheels sells customers that opt for the upgraded when they send their blowers into them for a rebuild?

[Red350DropTop]

No, the pink impeller in pavement pounde is the upgraded impeller for the SN series from Paradise Wheels. He took those pictures before he upgraded to the VR-4 impeller and scroll cover. Those pictures were taken when he was rebuilding his SN-93 a while ago (before the VR-4 conversion)

[Michael]

No, the pink impeller in pavement pounde is the upgraded impeller for the SN series from Paradise Wheels. He took those pictures before he upgraded to the VR-4 impeller and scroll cover. Those pictures were taken when he was rebuilding his SN-93 a while ago (before the VR-4 conversion)

Thanks Red350DropTop! That clears things up a bit (for me, at least).

So if I understand you correctly, when upgrading to a VR-4 impeller, the scroll also has to be replaced with the VR-4 specific one?

[pavement pounde]

impellor, ticker rearplate and extra shim

[5.0 Chero]

Getting hear a little late but a taper lock has far superior holding power over just keys and eliminates key walk. Used all the time in industrial applications.

[Michael]

impellor, ticker rearplate and extra shim

Hi Pavement Pounder! So the scroll cover DIDN'T have to be replaced to upgrade to a VR-4?

[Red350DropTop]

Changes:

Scroll Cover- You can identify a VR-4 cover by its smooth surface on the rear vs. ribs on a SN-series.
Impeller
Longer bolts to hold scroll cover (it is thicker)
Inlet and Outlet bigger
Reshimming of impeller off output shaft to get proper scroll to impeller clearance

[Red350DropTop]

[Michael]

Changes:

Scroll Cover- You can identify a VR-4 cover by its smooth surface on the rear vs. ribs on a SN-series.
Impeller
Longer bolts to hold scroll cover (it is thicker)
Inlet and Outlet bigger
Reshimming of impeller off output shaft to get proper scroll to impeller clearance

http://tinypic.com/bh0tio.jpg

SWEET! Thanks Red350DropTop. I think I misunderstood Pavement Pounder when he said "ticker rear plate", he was actually talking about the scroll cover.

You'll have to forgive the question, but is all that stuff in the photo available as a stand-alone kit, or does someone have to buy like a VR-4 supercharger and rip it appart to us all those items in their SN series charger? If it is a kit, who sells it?

[Red350DropTop]

Well, Dirk Diggler has the last "new" kit from Craig at Paradise Wheels. That picture is a kit I bought off Dirk Diggler last summer. It was supposed to be the last VR-4 kit available, but Craig at Paradise found some more. He told Dirk Diggler when he ordered his current kit that this was the last one for real, and he almost didn't sell it to him.

You can physically bolt a VR-4 into a SN bracket. A VR-4 is a SN series blower with the special impeller and scroll cover with tightened clearences in the ball drive.

Your only option to get one is to buy the kit of Dirk Diggler, or find a used one on ebay.

[Michael]

Well, Dirk Diggler has the last "new" kit from Craig at Paradise Wheels. That picture is a kit I bought off Dirk Diggler last summer. It was supposed to be the last VR-4 kit available, but Craig at Paradise found some more. He told Dirk Diggler when he ordered his current kit that this was the last one for real, and he almost didn't sell it to him.

You can physically bolt a VR-4 into a SN bracket. A VR-4 is a SN series blower with the special impeller and scroll cover with tightened clearences in the ball drive.

Your only option to get one is to buy the kit of Dirk Diggler, or find a used one on ebay.

I've actually corresponded with Dirk Diggler via email, and while it is tempting to pick up his VR-4 kit (especially knowing it's the last of it's kind...) I've had to pass on it. I think the rebuild of my SN89 is going to be enough of a strain on the wallet as it is, without adding the cost of the VR-4 kit. Who knows, if in a few months Dirk still has the kit, I may take him up on it...:D

But now I think I realize what's going on. The VR-4 was an actual model supercharger that was based on the SN series, and as such the impeller was interchangeable with any SN supercharger (as long as you replaced the scroll cover and re-shimed the impeller). And as an upgrade, all the parts required to turn a standard SN series supercharger into a VR-4 (ie. impeller, scroll cover, bolts, shims, etc) were made available by Paxton and then eventually by Paradise Wheels. Do I have it right now?

So how does the upgraded impeller (the one I call the "pink" impeller) that Paradise Wheels currently sells for the SN series superchargers compare to the VR-4 impeller?

[Red350DropTop]

You got it pretty much right. A VR-4 was a SN-93 or SN-92 ect. that Paxton took and put the special impeller and scroll cover on. You must also tighten up the ball drive because if not it will slip under the strain of pushing all the CFM the VR-4 impeller does. This requires you to run an oil cooler on the VR-4.

A VR-4 pushes 1400 CFM. The pink impeller SN will only put out about 850 CFM. Less boost.

The pink impeller is "supposed" to give 1-2 psi over a stock SN-89 impeller. But that is nothing like the VR-4 impeller. You can compare the pictures and see how much bigger the VR-4 impeller is than the pink.

[Michael]

You got it pretty much right. A VR-4 was a SN-93 or SN-92 ect. that Paxton took and put the special impeller and scroll cover on. You must also tighten up the ball drive because if not it will slip under the strain of pushing all the CFM the VR-4 impeller does. This requires you to run an oil cooler on the VR-4.

Whoo Hoo! I finally got something right!

This may be heading off-topic a bit, but since you brought up the oil cooler, does that mean that if I run an oil cooler system on a "stock" SN89, that I should see a dramatic increase in overall reliability and life-expectancy of the supercharger? Assuming normal street use, not all-out racing.

A VR-4 pushes 1400 CFM. The pink impeller SN will only put out about 850 CFM. Less boost.

1400CFM vs. 850CFM :shocked: ?!? HOLLY JEEBAS!!! That's a major difference - the VR-4 is almost DOUBLE!!! No wonder everyone with a ball-drive supercharger wants one.

The pink impeller is "supposed" to give 1-2 psi over a stock SN-89 impeller. But that is nothing like the VR-4 impeller. You can compare the pictures and see how much bigger the VR-4 impeller is than the pink.

You're right, the VR-4 is substantially bigger. Man, that 1-2psi over the stock SN89 impeller is starting to look pretty minescule compared to the VR-4.

But on a relatively stock 350 TPI (L98) engine, is it worthwhile to go with a VR-4, or will the upgraded "pink" impeller be fine?