It depends on what supercharger you are using Gen III or Gen V and what cam you are using. I've never run the supercharger with a stock pulley but my Gen V with a 3.4" pulley maxes out at 11 psi. At that boost level it was necessary to add an intercooler to control the KR's. There was no way to avoid it. For a stock 3800SC with the Gen III supercharger and the stock pulley, nosracs info is correct.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
I re-routed my belt (with alternator still in the loop) and it has given me more traction.
What is amazing is I did not know how much traction (wrap around the SC pulley) it requires to get the thing to work. I imagine at higher boost levels the SC is very hard to rotate. Also, when I mash the pedal there is going to be some slip. It's avoidable. Cogged pulleys would not be a bad idea, or a wider belt.
I re-routed my belt (with alternator still in the loop) and it has given me more traction.
What is amazing is I did not know how much traction (wrap around the SC pulley) it requires to get the thing to work. I imagine at higher boost levels the SC is very hard to rotate. Also, when I mash the pedal there is going to be some slip. It's avoidable. Cogged pulleys would not be a bad idea, or a wider belt.
GM designed the M90 to be run with a 6 rib serpentine belt dedicated to supercharger use with a specific belt wrap.to provide 6 psi of boost. . ZZ Performance sells an 8 rib conversion pulley system for the more demanding applications. For your shared assets application I would recommend that you try a Goodyear Gatorback ribbed serpentine belt. Cant say that it will solve all of your slipping issues but they offer superior anti-slip properties. Even with your belt reroute you will still need to maintain strong tension on the supercharger belt and if you are sharing the drive with your alternator it may not solve the original issue of alternator. bracket bending.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
I have used the 6 rib with a 2.8 for a couple years now with no problems. I think I have the goodyear belt you mention.
The 6 rib serpentine belt has worked well for me as well and I use a dedicated belt for the supercharger as well. Better results have been obtained with the ribbed Gatorback belt design. The OP had redesigned the belt routing so both the alternator drive and the supercharger run on the same belt. As such he has a different situation. It may work but its hard to say if he will see optimal boost with this configuration. The engine running the supercharger at high RPMS puts real pressure on that belt and I believe thats why he experienced a bent alt bracket. BTW you are running an excellent 1/4 mile with your setup and without an intercooler. AMazing. Did the mileage go down a lot with the XP cam? ------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
[This message has been edited by Dennis LaGrua (edited 12-14-2015).]
The 6 rib serpentine belt has worked well for me as well and I use a dedicated belt for the supercharger as well. Better results have been obtained with the ribbed Gatorback belt design. The OP had redesigned the belt routing so both the alternator drive and the supercharger run on the same belt. As such he has a different situation. It may work but its hard to say if he will see optimal boost with this configuration. The engine running the supercharger at high RPMS puts real pressure on that belt and I believe thats why he experienced a bent alt bracket. BTW you are running an excellent 1/4 mile with your setup and without an intercooler. AMazing. Did the mileage go down a lot with the XP cam?
Thank you. I have the VS cam and did not notice much of a drop - but at the time I was running 92 octane. Now with E85, I get about 17mpg - usually beating the tar out of it.
I might be willing to argue that my routing is more efficient. The bearings in the alternator are no weaker, nor stronger possibly, than the ones in a simple idler pulley. I got a good wrap on my crank pulley and SC pulley. Plus, I believe I've eliminated an idler with my routing. So far it has been good. My bracket needs reinforcing. As mentioned I never knew there were such large forces at play.
