MikeD.

Well monday I am going in for a tune. The trucks running a stock lq9 longblock, 232/234 .595/.598 112lsa (TV2) cam, 1 3/4 longtubes, NNBS intake w/ 87mm TB. Right now the d1 has a 4.25 pulley on it, I was shooting for 8psi, but looks like thats not going to happen. I have a 3.70 pulley laying around that I can throw on there. What kind of boost would I expect out of that pulley?

Also, I have a k061115 on there right now, which fits but the tensioner is maxed out. If i ran the 3.70, what length belt would that require. In my mind, that pulley is .55 smaller, So i would assume getting a belt that .5" shorter should be close right?

K061110 Sound about right? the 111.5" is maxing out the tensioner as is, so with it being roughly .5" shorter that should put me in the ballpark?

neverstop

go with the 3.7" pulley for sure imo, that should give you an 18% increase in blower speed so I'd just take whatever psi you have now and add that. you'll need an 8 rib of course to run that though I think.

can't help you with the belt but a 0.5" pulley does not make for a belt 0.5" shorter, only way that works for me is to buy a bunch of them and return the ones that don't fit