i just put the 3.40" pulley on my d1sc down from a 4.13" i was only getting 7#'s of boost, and wanted more, and the supplied 3.40" belt is slipping xxx645 belt, anyhow i'm reading 7#'s max again, i've checked all the tubing for good connections and everything, something is not right, anyone have any ideas?

 

Well if the belt is slipping, it is hard to say how many rpm's (airflow/boost) you are losing.

Some things to try-
-I used some tire grip compound to try to fight belt slip
-Check the surge valve. We did it on a dyno, no easy way without one. We zip tied a rag to the end of the surge valve. At idle/cruise it flaps like crazy due to being open, but under boost it shouldn't move at all if the surge valve is closing completely.

Matt

 

I wish I had boost...
But It defenitly sounds like your belt is slipping. I've heard the tire grip compound works well, or just go turbo

 

the supplied belt just feels too loose with the tensioner all the way up, i'm going to get a new belt today and see what happens, i'll update later.

 

When I was running a serp set up, I had the best results with Gates brand belts, which also NAPA brand belts are made by Gates, so they always worked pretty good too. I never really had good luck with Dayco. I wanted to try Goodyear Gatorback belts but never got around to it.

Are you seeing belt dust on the front of the charger? That is a sure sign the belt is slipping.

With my vortech I was able to move the tensioner to the top side of the belt, it worked better that way; the engine runs clockwise so at high rpm, the belt's arc becomes bigger and runs above the pulley, so having the tensioner on the top side, it keeps the belt from running a high arc and keeps the belt on the pulley as it feeds the pulley. Well it worked for me anyway, but I still ended up with cogs.

 

cogs are the way to go

 

i had to order a napa belt, i got 2 that didnt fit, going to put it on right now, 87tpi i see you have an alky injection setup, i'm thinking of going that route also

 

Yea, Aquamist 2d system, its really nice but I got better results from the intercooler and they cost about the same.

 

the procharger intercooler?, anyhow i got the belt on and it's tight, the other belt i heard squeel but i still have some sort of problem, max boost is showing 6 psi from my autometer boost gauge, with the 3.40 pulley, i saw around 7psi max with the 4.13" pulley, i dont get it, i can hear from the surge valve at idle that its blowing a lot more air then before, under boost i hear it close. how is the boost supposed to "build" ? i have a 5 speed, i take off in 1st gear mash the pedal, the tires squeel and grab i come up to around 5k rpms and 6 psi is showing, i shift in to 2nd...same as first 6 psi again

 

Not a procharger intercooler, I mounted a universal intercooler and universal piping to it.

As far as building less boost with a smaller pulley, its been said that with a smaller pulley there is less belt wrap and contact area so slippage can be greater and hence less boost.

The one thing I don't like about serps is how tight the belt has to be, I cracked a stock balancer in about 100 miles, it worries me about how hard you pull on the front of the crankshaft, no matter what block you have, the front main is only two bolts. I could see a potential problem with my old setup being serp so I feel that the $725.00 for a cog has saved me from breaking my engine not to mention unsurpassed performance, oh and the cogs make a nice sort of whiirr at idle to ward off evil imports.

 

The only way to go with a serpentine belt is with a dynamic tensioner, if you’re trying to do it with some assembly that tightens an idler or something you need to get it much tighter to hold.

As far as this goes… do you have a bypass/bov? That would be my first thing to check, second would be some ducting that is moving when you hit 7psi, 3rd… a restriction in the blower inlet, even a tube that is crushing down under boost….

 

ok i've been talking with lonnie where i got the supercharger, he told me to put the 4.13" pulley back on and try a few things, has anyone ever heard of the bypass valve being installed backwards? i turned it around with the 3.40" pulley and no change, i put the 4.13 pulley back on and i tightened the belt a lot more then before and i'm able to pull 9#'s in 1st gear and it overall feels good all these rumors about crank snouts breaking off has me worrying about tightening the belt a lot.... i didnt see any black belt dust anywhere

 

Hmmm. I haven't heard of surge valve installed backwards. I know with my valve(the stock one that Procharger sends in the kit) I had to use a stiffer spring inside valve. The stock one would take forever to close almost to the point like it sticking on something. That helped quite a bit with low end boost. Before it would bleed off. MY belt ALWAYS slips at the Higher RPM's.. The most boost I can get is about 6 psi. Never been able to get more. That tightening deal that procharger designed just sucks. You have to run a super tight belt. I run a Napa/Gates belt as well. With mine I have to unbolt the blower to put the belt on. If I don't run it tight or it gets stretched out then I get the dreaded "clunk,clunk" when it's cold. Man I hate that sound. My next step is either a cog set up or a belt tensioner. I would actually like to get within 2 psi of what Procharger says I should get. Wonder how they really got that number?

 

What size pulley are you running and what mods do you have done to your engine and exhaust?

 

Right now I run the stock 4.25" pulley. I do have the 3.70", but since I have slipppage issues right now that one would just be worse. Only mods are the 1 3/4" slp headers and free flow cat and exhaust. I do have some 383 forged goodies waiting along with some AFR heads and a superram. That will be this winter's project. This is when I plan on doing some mod work to the Procharger set up for a better install.

 

4.25" is what ATI specs for a bone stock car to get 8psi, which was dead on for my car. Anything you do to make your engine combo flow better is going to decrease the amount of boost you'll see. If ATI didn't know about your headers and exhaust, then that's why they sent you the 4.25" pulley. I eventually went with a 3.85" pulley and never had any problems with belt slip. I had to find the smallest belt I could possibly fit on there, pull the pulley off the blower, put it inside the belt, slip the pulley back onto the shaft of the blower, then tighten the belt back up.

At one time, I had found a really stiff Gates tensioner at the parts store that was for a diesel truck. It looked like it would be pretty easy to mount, but I never got a chance to try it out before I sold the car.

 

Actually they did know about the exhaust. If you didn't have have belt slip issues then you must have been the only person here not to have it. Go through all of the old post and that's the #1 issue for all of the Procharger users here. Even by looking at the design of the pulley set up it is not designed well enough. I figured a 1-2 psi lost with the exhaust, but the techs at Procharger felt that it wouldn't effect the boost much. Trust me the belt is the smallest one I can put on. When you have to take the blower off to put on the belt ,that's getting tight. Plus you don't want it so tight that it reaps on the blower bearings. Talk about the double edged sword.

 

coldgta there are people on here running stock 305's with the 4.25" pulley and getting 10#'s, so you should see less with your 350, i assume were talking about the one in your specs, i'm using a 4.13" pulley on my 305 to get 9#'s, i think i'll move up to a 4.0" or 3.9", anyhow when my belt was slipping i would only get 5-7#'s, also the belts that procharger sent me with these pullies, i had to remove the blower to install them, if i can slip a belt on mine without removing the blower, i dont think the tensioner will come up high enough to tighten.

 

if youd like more boost id say run a nice big intercooler with bigger piping and a Ntercooler nitrous ring and ill bet youll get plenty more boost without having to actually inject nitrous into your motor

 

You guys with the slipping belts must be running a 8 rib setup, with my 12 rib 3.4" pulley i was able to get 17ibs of boost but I could never get a good belt tension since the belt would stretch and I would run out of room to tighten it more. Right now I just run the 4" pulley to get 10Ibs boost at 5500rpm and 12 if I rev to 6k.

 

I'd be worrying about the crank snout before I worried about the bearings in the blower. The blowers are pretty tuff, but the crank snout isn't.

 

How odd. The belt they sent with my kit was to big. Much to big. Yes I do run the stock 8 rib set up. I use a gates /Napa belt # 080653 wich is a 1- 1/8" x 65- 7/8" . It stretches over time and eventually it gets tightened to full adjustment. Anything elese I found locally was either to small or to big. This belt worked the best. The cog set up sound like the way to go to eliminate all questions.

 

When you're ready, call Larry @ ASSC for that. He'll get you all set up.

 

That I will do.

 

hmm i'm using the gates 653 belt with my 4.13" and i have room to tighten...