Forced_GTA

Hi.. I just put a paxton SN2000 on my 305 TPI GTA. Besides the supercharger the engine is stock except for a ported plenum and air foil.

The problem I have is that when I put on the S/C originally, I i would get the car up to about 3500 rpm and up and their would be a squeeling coming from the engine. I drove it home and noticed that the plastic cover on the S/C pulley nut had worn down to the nut. I am guessing that the S/C was flexing forward and hitting something (all I could see was the radiator hose in the way though) causing that sqealing. I also thought that the car wasn't that much faster, so I ordered an autometer 2 1/16 phantom boost/vacuum guage from summit to see if I was getting any boost. When I put the guage on I noticed that I was getting about 3-4 lbs at full throttle at around 3500-4000 rpm (i'd then let off because of the squealing). The belt was pretty tight. The boost seems alright, but the car doesn't really _feel_ that much faster. I am going to the track soon so I will know then if it made it faster. Is there anything I need to do to it to help out? I was thinking of hooking a scan tool up to see if my computer was pulling timing or something, and buying an MSD 6BTM too. Maybe some bigger injectors (19 lbs now).

I also didn't re-locate the battery to the passenger side yet, so the intake piping is probably 5-6 ft long. Does anyone know how to crimp such large wire and where to get the supplies to do it?

When I bought the kit the piece that mounts to the intake manifold to brace the S/C was missing. So i didn't install it. I _think_ this is my problem. Does anyone know if I can just go to home depot or kragen or something and buy a part I can modify instead of ordering one from paxton? Do you think it might be something else? The kit looks really cool on my car, but it is kind of frustrating right now getting it working right.

Thanks.

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1989 GTA w/ 305

Stock TPI/LB9 w/ iron manifolds...
Paxton SN2000
N.O.S. Throttle Body Plate Kit
Bunch of Suspension Stuff

[This message has been edited by Forced_GTA (edited May 23, 2001).]

IROCKZ4me

Sounds like the drive belt is slipping. Perhaps from too much bracket flex. Any decent welder should be able to fabricate a brace for you, and that should be cheaper than a new brace from Paxton. After suring up the brackets, you might also want to make sure the belt and pulleys are clean. belt dressing or any oil, trannie fluid or grease will allow it to slip. I use Simple Green. It doesn't cause corrosion on bare aluminum like many cleaners will.

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Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro
"Cogito ergo zoom"

• 355 cid
• AFR heads
• Arizona Speed & Marine hydraulic roller cam w/ AFR hydra-rev kit
• modified SLP runners
• TRW forged pistons/ceramic coated
• fully balanced
• Edelbrock headers/ceramic coated
• SLP cat-back
• Paxton supercharger
• Nitrous Express nitrous oxide

EFI Performance Club on Yahoo

Forced_GTA

I fixed it.. just got a bracket from home depot and drilled two holes in it. Worked perfectly. Cost about $.50. I looked at your page and was wondering if there was anything you would recommend to keep the paxton running well and not needing a rebuild soon. From your dyno chart it shows you rev your engine to 6500 rpm.. any problem with the paxton at that speed? It seems as if that is past the s/c redline. Do you have any times for your car? It looks really nice and I was amazed at your HP numbers.

craiger

I have a 91 Z28 with a 350. I also have the Paxton sn2000 with the modified impeller. When i first put the supercharger on, my car did not seem to have much more power. It kind of petered out at about 3500rpm's. I hooked up a scan tool and noticed that i was running extremly lean above 3500-4000 rpms. I was not getting any detonation because of the cold water injection (i guess??). Anyhow, I purchased an auxillary fuel pump from vortech, created a bypass valve, hooked the ground on the aux. fuel pump to the hobbs switch so the pump would come on only under boost. Then i put in an fmu which really helped me fine tune my fuel psi. These two items made a world of difference. Now, my Z28 pulls until i need to shift! And to figure out the max rpm of the supercharger; dia of crankpulley/dia of s.c.pulley x 4.4 x rpm = supercharger rpm. I think i can rev mine up to 5800rpms but i never go that high.

good luck

Forced_GTA

I fixed the squeeling problem with a tighter belt and adding a brace, but now I am having a problem that my car feels a lot better up to about 3000 rpm and great at partial throttle, but kinda dies after 3K. I am seeing 5+ lbs of boost, so I know the blower is working. I am building the RS-232 cable interface right now so I can hook up my old 486 laptop as a scan tool w/ Craig's Software so I can see if I am running lean. I have the feeling that I am running lean as well at the top end and am going to be very dissapointed when I go to the track next saturday. I have LT1 24lb injectors coming in the mail very soon, so I hope that that will help. Right now I havn't even turned up the fuel psi and am running on 100,000 mile 19lb injectors.

The auxillary pump/hobbes switch sounds like a really good idea.. although kind of expensive. How much does the pump cost? Where do you plumb it into the fuel lines? Thanks for the help.

BLOWN85/TA

iTrader: (2)

theformula Shoot me a mail please, I tried the other address and it did not work.

GTA Sounds like it's running out of gas.

craiger

I will bet my next paycheck that it is running lean! Because my Z28 with the same supercharger was doing the EXACT same thing! The addition of the aux. fuel pump made a whole world of difference!!!! And the FMU helped me tune the car. With out the fmu, I ran a 13.2, with the fmu, 12.9. I added the ford svo 24lb injectors hoping that would cure the fuel problem but it did not! The stock fuel pump can't give you the fuel requirments you need for the supercharger. Get an inline from vortech! Mine cost me about 89bucks. An fmu is another essential in getting your supercharger and fuel dialed in correctly.

craiger

After i got my vortech aux. fuel pump, i went to the local Wiliams oil filter service shop, got two 90deg brass elbows and connected them to a T fitting on both ends of the aux. fuel pump. between the two fittings which was the bypass, i put a 1way check valve capable to withstand up to 100+ psi. Then i got a piece of flexable fuel line, hooked it up from the one way check valve to the fitting on the other side. If you want me to send you a pic..email me.

Forced_GTA

Well, I looked into aux. fuel pumps. It looks like used they run anywhere from $50-$100, and new they are $160 and up. So getting one won't be a problem.

I went onto vortech's site and on their tpi install, they just put the pump inline in the feed line and had it looks like they just gave power to it through an ignition source.. wouldn't that be better than using a bypass line and only using it only under boost?

craiger

NO!!! Superchargers require at least 92 octane fuel! Adding an additional fuel pump decreases the octane between 2-4.5 points depending upon where you live. It changes due to the altitude and specific gravity etc..... A bypass is easy, cheap (about 12 bucks) and you can add a small 12v light to your boost gauge which truns on when you are under boost. the light lets you know your fuel pump is working properly! My fuse went out on the aux. fuel pump and my car was not running right; i just looked at the light, and got to the problem! You could just hood the fp up to the ignition switch, but a bypass with a small light on the boost gauge looks good, works great allowing you full octane, and lets you know if every thing is working right! email me for a pic. It's easy and well worth the putting in the bypass!

Forced_GTA

Ok, I guess I'll do the bypass, cause fittings and line aren't that expensive, but why does vortech put the pump inline (as well as other S/C manufacturers) instead of by-passed then?

craiger

None of the companies who make the aftermarket aux. fuel pumps make a bypass. I had to fabricate mine from brass fittings from williams oil filter service. You may be able to get these parts at a plumbing contractors store or home depot? Anyhow, I can send you a pic, just email me. You could put a better intank fuel pump, but that can be a lot of work. I like the aux. fuel pump hooked up to a 30amp relay, grounded to a hobbs switch with the bypass. I think the light i have on my boost gauge is a 1/8 or a 1/16? I got the light at radio shack. I would send a pic of that but my dig camera went bad Anyhow, if you want a pic to give you something to go on, just email me!

Guido

Inline pumps work just fine. Vortech and Procharger both supply them with their kits. There are people with inline pumps with their stock ones running in the 10's.

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-86 IROC
S-Trim, Speed Pro, AFR
this years goal: 10.50 @ 130+ mph
-=ICON Motorsports=-