I know the UDP underdrives the supercharger, but can't you make up for that by using a smaller S/C pulley? It seems that you could possibly gain some power by having the smaller diameter crank pulley underdriving the accessories, while also getting full boost from the blower.

I'm just curious because I've never heard this discussed. It would be a lot easier to change the s/c pulley and not worry about removing a UDP if you already have one, and might even net some gains
-hype

 

Nah, not really... given the amount of work to install the supercharger, swapping back to the stock drivepulley from the UDP is trivial when you're installing the SC.

 

All that matters is the ratio of drive to driven pulley diameters. So you can go with a UDP if you use a smaller blower pulley. Since it is easier to change the crank pulley than the blower pulley, it would be nice to run the smallest available pulley on the blower and just change to a larger crank pulley when you want to up your boost. You could probably get a machine shop to make you any size crank pulley you want.

 

I don't think the blower pulleys are small enough to make up the difference and
if it did work the difference in crank would probably warrant a different belt size thus requiring you to pull the blower off anyway.

Also crank pulley are more $ than blower pulleys.

 

Good point about the belt - I had forgotten about that little detail. Nevermind what I said.

 

Ok so what is the smallest blower pulley available from vortech?

I'm not planning to supercharge, but I was curious because I have a UDP. Since I already have the crank pulley and belts are cheap couldn't new s/c pulleys be made for the application?
-hype

 

The Vortech website lists the range of 6-rib pulleys that they sell.

http://www.vortechsuperchargers.com/...es/pulley.html

Looks like 2.62" is the smallest diameter.

Keep in mind that the smaller the pulley, the less traction you get from the belt, resulting in increased propensity for belt slip.

 

Furbiss112 had a custom 2.5 in pully made for his S/C for use with the UDP. He doesn't post on here much....but he's a Chicago local.

IIRC he pushed about 8lbs of boost with that set-up....

IMO it's not beneficial...the power freed up by the UDP in NOTHING compared to putting on a smaller S/C pully...

 

2.62" and a stock crank pulley is the way to go