I changed the pulley on my rotrex to a 85mm pulley from a 95mm pulley. The 95mm pulley had about a 75% belt wrap with a 2005mm effective length belt. I changed the belt to a 1994mm belt. I have been having some issues with belt slippage and I am guessing at the supercharger. Now at about 5kRPM I see around 7# of boost and then it stalls after from the slippage. I am using Gates belts and having to cut a rib or 2 off. I always thought the 2005mm belt was too long as I would have my alternator pulled back almost to the radiator for correct tightness with the 95mm. I have my alternator about 3/4 back with my current setup. I am considering getting a 10mm larger idler pulley to give me more belt wrap on the pulley. Does anyone know the make of the original idler for the KW system? I plan to continue with the 1994mm belt. The gates belt is not a green stripe HD belt. I have read a lot about the gatorback belts and use in SC setups. I tried one and had to cut a rib off and it shredded on me in park. I can try another one. What belts everyone else using? I know one other person that changed to the 85mm. Havent heard of any issues. I have tried about 4-5 belts and I will not use belt dressing! Any help appreciated. Thanks

 

All fixed. Went to a 1980mm from a 1995mm belt with the alternator about a 1/4 of a inch from the loosest position. It is a actual gates 5 rib belt so no more cutting. Tension is good. I need to bring the rev limiter closer to stock so i don't over spin the S/C. Boost levels have dropped since header and test pipe. Got things flowing through. 11psi at 6900, this is where the limits of the S/C are achieved.

 

Nice! Good to hear that you've finally gotten your drive belt situated.

 

11psi? Wow! Your car should be moving now. Nice! Congrats on the fix.

 

These tires aren't going to last long. I am thinking about redoing the piping from the S/C to the intake next, maybe a different inter-cooler some how. I remember OJ telling me that IC restricts the air flow around 12psi. My air temps are kinda high still and am looking into a CF hood that I could do a scoop or NACA duct to the air breather. I did see a hood that had decorative vents almost where the intake and IC sit. I just worry that the S/C and intake could take on too much water if in the rain.