What is the hp and tq difference b/t the ur underdrive and stock diameter pulleys. dynos would be helpful.

thanks for the responses

 

I've heard that there is hardly any difference at all.

 

Most of the power gains from any of these pulleys is from the lower weight, not the underdrive effect. The UR website has a white-paper on this explaining the details.

 

I think it's like a 1.5-2whp/tq difference

IMO it's worth having the stock diameter anyway for better alternator and A/C performance

 

Plus you get to keep the stock belts!

 

I have them, they don't offer very much in the form of extra power like they do on...lets say an LS1. But it is a little bit more. They biggest advantage is the decrease in rotational mass which allows for a noticeably quicker rev speed. I like them, plus its a pretty blue....um.... I didn't say that....

 

thanks for the feed back....anyone else? can i hear from someone that has the stock diamater ur pulley.

 

one thing to consider is that the stock steel pulley is 5 lbs. heavier than the much lighter one piece UR pulley, the stock pulley is actually welded together from two pieces.

 

QFT.

 

UR offers a stock diameter pulley and pulley set as well as underdriven

http://www.z1auto.com/prodmore.asp?m...ine&prodid=718