What would be the easiest way to underdrive the blower on my '95? I know the 94/95 pulley should already be driving it slower than if it had a 89-93 pulley.
For what purpose do you want to underdrive what you have?
Ken
I think the easiest way is to buy a jackshaft pulley to overdrive the blower. You have the ability to make the supercharger spin faster on these cars three different ways. The supercharger pulley, jackshaft pulley or crank pulley. I think the jackshaft is easiest to change. I recommend no more than 5% overdrive on a fairly stock car.
He wants less boost if I read this correctly. There are a few 1 to 1 jackshaft pulleys floating out there. Mike Tuck can machine one for you if you want him to. I use to have one but sold it off.
Ken
the Pontiac supercharger uses a huge pulley. not sure if they are inter-changeable though. ... the bigger pulley will help the snout go bad faster and in stock form these things last well beyond 200,000 miles. if your intent is to slow it down then just get a Honda or Toyota.
I do want less blower rpm. I guess a 1:1 jackshaft pulley wouldn't be terribly hard to make....
I very much enjoyed beating up on my friends with SC's with relatively tame turbo cars and would be "putting my money where my mouth is" if I quickly got the SC I picked up to be in the same league.
I'd like to try a bit more engine rpm.... Appropriate cam, tune for E85 full time, and a ~75-100hp wet shot when it needs to "go." I know the stock M90 can only move so much air and I'd like to skip past where most start to run out of steam.
Although if I wanted to try something silly like a rear mount turbo I would be asking the same question...
Are you looking to Underdrive, or reduce the overdrive?
If you build an engine capable of going higher rpm you will find underdriving the blower is going to starve the motor. Are you building a bottom end with good rods and pistons that will hold together at higher RPMs?
What size injectors are you looking to go to? E85 and nitrous, remote turbos, pretty heavy stuff are you going to build an engine with supporting mods to handle these plans or are you just dreaming. Your talking a lot of money and problems that even some of the big dogs here havent worked out.
Ken
I'm not planning to spin it to the moon.... but I've never seen a stock heaton no matter what the overdrive do anything but fall flat at 5000-6000rpm VS say a turbo split port motor, still pulling strong at 6000. Long term I see going to a turbo split port motor or 302. This good running SC somewhat fell into my lap or I wouldn't be in this situation.
I have 55, 72, 90, and 120lb injectors. The 55's are fresh and since I "only" have 6 of that set, I think a bit of blower underdrive and E85 full time could make nearly the same amount of power as stock since the E85 should let me run plenty of timing, without high intake temperatures at ~5500-6000rpm. 250 flywheel HP shouldn't be a problem on E85 and 6x55's.
I don't see a problem spinning a stock SC shortblock 5500-6000 and making 350-375whp with good tuning on a wet nitrous shot, E85, and a mild cam.
yet I already have fuel pumps, injectors, turbos, a moates J3 chip adapter and programmer, extra megasquirt, etc.
If I've built EFI harnesses from scratch and installed and tuned standalones and turbocharged non turbo engines in the past, does this "underdrive my blower and run E85 and wet nitrous" project still seem like "pretty heavy stuff" ?
Well Im glad you got it all worked out. If you had provided all this information in your first post, I likely would posted a diffrent reply that would fit your question. But since you know what you are going to do anyway and got it figured out I will refrain from offering you any advice
Ken
I very much appreciate all of the input.... and respect that the responses were written with sincerity and the desire to help out.
Still can't say that I have it all worked out, I just thought there would be some easy ways to drive the blower a bit slower than stock. Like in the case of belt slip, where if you were to get the jackshaft to blower speed up say 30% from stock and run a bigger blower pulley to get it back down to stock or a bit faster, the increased belt wrap I'd think would help with the slip. Or all of the different big blowers that folks upgrade to, I'd also think there would be some common need to drive some of them slower. I'd love a big screw to play with and if I came across a deal on one....