I_Need_Land

iTrader: (12)

my newly setup 355 lt1 has a d1sc with 7.65/3.4 pulley combo and is only making 9lbs at like 5500 and holding steady at that. any ideas on what to do about this? i think it should be making about 13-14 at 6500 but im not sure.. is my cam hurting me? its a custom blower cam

236/246 .624/.630 114

TurboAv

iTrader: (6)

How much HP are you making? What do you have for intake, headers, and exhaust?

I_Need_Land

iTrader: (12)

no idea, the dyno was not reading correctly the day i went... dynod 1568 hp lol.

355 lt1, ported stock casting lt1 heads, ported lt1 intake, twin 58mm throttle body, 1 3/4 hooker long tubes, true dual 3 " exhuast, 9.5:1 c/r, 2.02/1.6 valves, above stated cam..

anything else?

currently rev limiter is set to 6200 because of whatever is causing the boost to stop or drop off.

Fastbird93

iTrader: (10)

Any signs of belt slippage?

TurboAv

iTrader: (6)

That's a maxed out pulley combo. Meaning at 6700rpm your impellar speed is 61807rpm of a recommended max of 62000.

I think you may have some belt slip. Boost should keep building with rpm. You can try running the EPP crank pulley that's an inch bigger. That would let you run a 3.8 pulley to put you at 62000rpm at 6650rpm. Or try a 3.4 Reichard Racing pulley.

I_Need_Land

iTrader: (12)

honestly wanted to run the bigger crank pulley with my 3.4 blower pulley to max the blower at an even lower engine rpm (to help save it somewhat)...

i am going to look into adding another idler on the bracket to get some more belt wrap on the blower pulley.

EPP

iTrader: (22)

If you're like me, you're not use to LT1 guys posting in here, but he has an LT1, we don't have a crank pulley for the LT1's. Bob

TurboAv

iTrader: (6)

Doh.

Get a custom pulley made by ASP then. It's gonna be spendy though. Like $400 spendy.

EPP

iTrader: (22)

Several things to look for:

Make sure all intercooler clamps are tight.

Try making a run without the air filter installed to see if the filter is causing a lot of restriction. The supplied ProCharger air filter is good for about 12-14 psi on most applications before it gets too restrictive, but it is a good place to start. Just don't suck any debris in there!

Make sure the bypass valve only has a slight air gap when in the closed position. We had one several years ago that had too large of a gap when closed, and we picked up two psi when we swapped it out.

Check for belt dust on the blower to see if you can detect whether the blower belt is slipping. A new blower belt needs to be retightened after a half an hour, as they stretch out. If the belt isn't tightened and it slips, it then has a tendency to slip easier as it gets what I call "greasy".

You might need to remove the intercooler tubing from the blower and at the throttle body, and cap each end of the tubing. Install a schrader valve into one end and pressurize it to check for boost leaks. Caps can be purchased in the plumbing section of a hardware store. You can probably pick up the valve at a local auto store. Several years ago we had a GTO that wasn't making the boost we knew it should be, we found a pin hole in an intercooler weld.

Your valve springs could also be bleeding off boost if they are not strong enough. Hopefully you find the problem, it can be perplexing to say the least. Bob

moehorsepower

iTrader: (3)

Did your kit come with the flexible tube that connects to the rear of the supercharger on the inlet side? if so, look at that. Mine back in the day was doing the same thing and the tube was collapsing under boost, I removed it (and like Bob says, make sure there is no debris that can be sucked up), the boost shot up from like 7lbs to around 14 lbs, I made one out of steel but I think they sell them now.

I_Need_Land

iTrader: (12)

i replaced my air filter today, massive difference in feel of the car havent checked boost gauge yet but i suppose its up 1-2 lbs.

i have the epp hard inlet pipe for the d1sc. got rid of the orange stuff long time ago.

belt slip, oh yes. my pretty new engine was COVERED in dust after like 700 miles of driving. i cranked it down a bit since then and it felt better after doing that (THIS WAS LIKE LAST WEEK I DID THAT).

ANYWAYS, im running 2 6 rib gates belts, think that is hurting me any?

ill report back on boost levels on the way home from work tonight.

thanks guys.

CALL911

iTrader: (17)

I went from the hard plastic ATI inlet tube to a custom metal inlet tube, and put a large air filter from EPP on it and saw a difference from 9#'s to 14#'s of boost (and about 100 RWHP on the dyno). I didn't have belt slippage because I already had the ASP pulley, but if if you also where getting belt slippage that would just add to it.

Sounds like you have everything worked out, but I thought I'd thow in my .02 cents as I was in the same boat in my D1SC LT1.

I_Need_Land

iTrader: (12)

well damnit didnt think the hard inlet was that big of a restriction. that thing wasnt cheap either.

EPP

iTrader: (22)

Ben, did you do both the inlet and the filter at the same time? I would bet the filter was the major culprit. Bob

I_Need_Land

iTrader: (12)

my air filter is the round tapered 3.5 inlet one, its 5" at the base and 7 inches long and i wanna say 4 inches at the top of the taper. is it a restriction?

I_Need_Land

iTrader: (12)

WOW. new air filter = 14-16 lbs at 6000 rpm.

time to go make sure the tune is proper.

TurboAv

iTrader: (6)

What was the brand of the old filter? Or is the new one just bigger? What brand and size you go to?

I_Need_Land

iTrader: (12)

basically, i had the front bumper off, and the d1sc air filter setup is right in front of the drivers fender liner. well i drove back from shop (200 miles) with the front bumper off (trailored it there....) and uh.. now i have BIG holes in my fender liners where they rubbed the tires from the wind at 80mph. well ALL that crap caked my air filter.

so...

didnt know it would do THAT with the boost....



edit, k/n 3.5 inlet, 7" long, 5 inch to 4" taper.

CALL911

iTrader: (17)

I did both the filter and the inlet at the same time.

It depends. I am 100% sure that I gained a bit of that boost increase from just the difference in the large aftermarket inlet tube over the much smaller ATI hard plastic one. The larger air filter without a doubt helped as well though. Not sure the exact measurements but the filter is pretty stout.

Heres the inlet tube


Here's my air filter (best picture I got, but its still not very good)

SRZ

iTrader: (14)

Glad to see you got it worked out. Seems the 2 gates belt are good cheap alternative too as a 12 rib is a 100 bucks easy.