StocRoc

iTrader: (1)

I had my car dynoed w/ the ATI P1SC that I just got and it only made 5#s of boost. The kit was supossed to be for 9#s. If the kit was ordered for a stock TPI, is it possible that w/ my mods it would only make 5#s? The belt doesn't seem to be slipping, there are no rubber particles anywhere and it seems pretty tight. I'm thinking that since my engine "flows" much better than stock, I need a smaller pulley to make 9#s of boost. What do you guys think?

thanks

Willie

iTrader: (1)

I agree totally with your conclusion. Boost is only resistance to flow. The freer your intake system, the less boost you'll produce.

My D1SC kit with 4.00" blower pulley is "supposed" to make ~10 pounds of boost on a stock 350. Maniacc has confirmed this. However, I have a modded 305 so ATI had to "guess" on pulley size. If my engine was a stock 305, the 4.00" pulley should make more than 10 pounds of boost, based on the fact that it makes 10 pounds on a 350, so the question became how much of a decrease in boost would my mods yield? In addition, engine shift point rpm is a variable too. The result: My modded 305 produced "only" 8 pounds of boost, less than a stock 350 with the same pulley. I now use the smallest pulley 12-rib pulley (3.45") that ATI has. I produce 14 pounds at 6,000 rpm.

StocRoc

iTrader: (1)

thanks for the help man. That's one problem down and a few more to go.

KS91Z28

I'm surprised Mark and Chris didn't tell you that. What kind of numbers did you produce?

StocRoc

iTrader: (1)

Hey whats up man? Ya Mark kind of mentioned it, but he thought it was the belt more than anything. I don't remember exactly, but hp was about 293 and tq was around 340 or 350. That was w/ 5#s and no tuning. What's up w/ your car??

KS91Z28

I didn't have the vacuum for the FMU hooked up in the best spot, so I wasn't getting as much fuel as I needed, and I busted the ring lands on my pistons. I've been rebuilding my engine for the last month and a half. I just got it back on the road last week. I took the opportunity to put in forged pistons, have the lower end balanced, and put in 24# injectors.

nebulous

Yeah I have the 4" pulley with the P1SC and peak out at 4 to maybe 5 psi. I also don't see any rubber in the engine compartment and the belt couldnt really get any tighter. I have an LO5 penut cammed 350 with SLP 1.75" pipes going to a stockish cat into a flowmaster catback. Is that enough to lower my boost so much?

If so, where can I order a new smaller pulley without paying millions?
how do I install it without damaging the supercharger bearings?

Also, it took a week of making shims and moving them around to keep the belt from walking off the bottom pulley one way or another. If I raise the boost am I going to have to do that all over again?

Treys_IROC

well, i can answer one of your questions, new pulleys can be made by black mountain precision, www.blackmountainprecision.com for a reasonable rate, and from what i hear they do good work, i'm getting ready to order one myself.

Trey

ColdGTA

You know my motor is bone stock except for the SLP 1 3/4" headers and free flow exhaust. The most I get with my P1SC is about 4psi. I think it slips some though. I'm almost 95% sure. I ordered a smaller pulley from ATI a few weeks ago. The guy asked what boost level I was reaching as of now and I told him. He said I should be seeing atleast 8psi . Told him I still wanted the smaller pulley and he got a little pissy saying that it wouldn't give me any more boost unless I tighten the belt. He was sure it is slipping. Anyway I really wish I was seeing atleast 7psi with the stock pulley, but somehow I think that will never happen. Only getting HALF of the advertised boost is a little disappointing. That poor belt can only get so much tighter.

nebulous

I'm not sure my belt isn't slipping, but if its anything like the belt on my old Paxton I would be able to hear it.

My original order for the supercharger kit was completely wrong. I got the 2 core intercooler when I ordered the 3 and the P1sc when I ordered the D.

It is I think for this reason that the belt they sent me is so short the only way I can get it over the pulleys is by taking the charger off the bracket.

Yet I still have to crank the tensioner all the way to the top to keep the belt from walking off the crank pulley. Seems like a belt that short cranked all the way tight surely is not slipping.

Could this problem be caused by tube leaks? Seems like a small gap in the pressurized side wouldn't be able to flow enough to really hurt a lot, but the ATI kit was not exactly "precision fit" to my TA. Had to do some cutting and bending.

Speaking of which am I the only one who has to kink up the first rubber tube from the charger to get it into the driver side fenderwell?

BigL350

Maybe you're leaking boost somewhere? The local dyno shop made up some boost leak checking tools out of PVC and some air hose fittings. Just regulate your air compressor down to your desired boost level and connect it to the PVC adapter, with the adapter connected to the blower inlet, and listen for leaks.

Steve89GTA

If they advertise 9, that guage better read at least 8.5 after spending that much money on something. I would be callin steady

88 350 tpi formula

iTrader: (9)

it's not kinked but, does bend sharper then you think it should.

nebulous

kink is a strong word I suppose, but it is bent more when installed than when sitting on a bench. I'm going to check for leaks and get myself another pulley. If I do, how can I change it without damaging the charger itself?

KS91Z28

If you buy a pulley from ATI, it'll come with directions. Basically, just remove the bolt holding the pulley on and if the pulley doesn't slide off easily, heat the center of the pulley up with a small propane torch and it'll slide right off.