Cadillac STS-V Series Forum Discussion, Anyone with a smaller pulley PLEASE enter in Cadillac V-Series Forums; Ok, so I could not figure out what was going on in my car since the pulley swap. In 3rd ...
Ok, so I could not figure out what was going on in my car since the pulley swap. In 3rd gear I could only get to 106mph before I would hear what sounded like a turbo blow off valve opening and I would loose a couple pound of boost.
Well, I figured it out. It was massive belt slip. The reason I did not catch it before is that the belt I was using had so much shellac on it that it did not make a sound when slipping or create any dust. After I got it off I saw it is sooooo shiney!! I am sure some of that shine is the slipping since I got the smaller pulley. So I got a Goodyear Gatorback belt to replace what I had. The belt I was using was the stock belt with 68000 miles on it. I know, I know, why didn't I change it when I did the pulley? Well I tried but got the wrong size. I got the 4080535 which was too small. I now have the 4080537 and it fit perfect.
SO this post is 2 fold. One, replace your belt if you get a new pulley and two the correct size to use. With a 2.4 pulley you will need a 4080537 and with a 2.5 or 2.55 use a 4080540 belt. Stock is a 8PK1380 and Goodyear does not make a Gatorback in that size. Closest is a 4080545 and 1/4" longer than stock. It was costing me about 40rwhp when it slipped or about 50 horsepower at the crank! My midrange is crazy now and top end is ridiculous!! I will be changing to a 2.3 soon and when available I will team that with an oversized crank pulley (hint hint Tim). So if I just change the top pulley I should be able to use the 4080535 that is taking up room in my work area. Or with the combo I will have to figure it out.
Disclaimer (For Boomys10): Individual results may varry
Good to know, I just re-used my stocker when I dropped pulleys. Does the 2.3 require any special machining to the snout? I machined mine down with the zzp rental tool and was wondering if the 2.3 would fit.
From fairly extensive knowledge of this stuff now, everyone has different results with pulleys and belts as far as sliggage is concerned. I'm running the gatorback 540 on mine with the 2.55, which will be getting changed soon enough to the 2.3, BUT!!! You won't be able to use the 535 for the smaller upper AND bigger lower. You'll either need what you hav now, or a step larger. The lower is going to add a lot more than the upper loses. Just my two cents.
im done pga. so over this relationship and it never started. lol. but in all seriousness, i think youll have an issue with the smaller upper and larger upper as far as belts are concerned. might be in the realm of idler pulley at that point.