I'm dropping down from 4.25 to a 4.00 pulley on my d1, and just wondering if I just need a belt that's a 1/4" shorter then what I have now to have the same tension I do now?

 

Its not so much about tension, but tensioner travel remaining. As long as the tensioner can take up the slack on the other side then you should be ok.

But for the record, you would need closer to 1/2" shorter to keep it the same.

3.14159*(4.25-4)*0.5 (lets assume the belt has 180 degrees of wrap) = 0.39"

 

Ahh ok, I figured it wasn't that easy. As of right now my tensioner is beyond maxed out, but has worked so far

 

How many pounds were you at with the 4.25, I'm curious to know how much a 4.00 will increase boost. 2-3lbs???

 

You can use a string and run it around the system and get your measurement that way also. Just make sure your tensioner is comperssed.

 

They say roughly 1lbs per .10 of an inch. So I would assume 2-2.5lbs. I'm currently peaking 7-7.5lbs on the 4.25.

 

There you go with that gradeschool math again. Pie, everyone likes pie.

 

That's gradeschool?? I guess I should have stayed in school..