Procharger Giving Me FITS!

[WELTERRACER]

O.K. here goes..

I had originally run a best time of 11.70 at 122mph with my camaro with 4.10 gears and only running 6psi of boost (procharger) I was running out of gear (had 4.10s) and was using 5th gear to get threw the traps..(no intercooler)

I then changed out to 3.73 gears, added a intercooler rated for 1000hp,bypass valve and added a much larger more effecient extreme velocity carb bonnet and went half an inch smaller on my procharger pulley (i should be running 12psi of boost.).

I am still only getting 5-6psi of boost and at the track my car slowed down to a 12.20-12.44 at 115-117mph and was falling on its face at 6000rpms in 4th gear..

Where did all my horsepower go?

I then bypassed my intercooler, thinking i was loosing boost threw the intercooler and tubing, but it made no difference and if anything made the car slower..


Could the gear change alone be whats killing my times? i lost a good .7ths of a second and 5mph

PLEASE HELP.. IM LOST

[PRONOVA]

You have a boost leak somewhere, you need to trace that down first. What's the pressure drop through the intercooler?

[camcojb]

sounds like belt slip to me. What blower, which tensioner? Do you have a brace for the blower? Have you checked under the top pulley to see if there's black belt dust on the blower snout?

Jody

[WELTERRACER]

ive got the PSC-1 with a 4.5inch pulley, no i dont have a brace.. I dont really have room for one, as it is a super tight fit in the car..(strut tower is in the way)

I see a very very small amount of black dust

It cant be a boost leak because ive checked all of that..

[oestek]

Is the carb getting sucked dry by the end of the track? With the added boost, you may be out of fuel in the bowls. Happens with carbed turbo apps alot.

[whytry]

I would look at belt slip, from what I have read before the P1SC bracket does leave a lot to be desired, and most have moved to the bracket from SD Concepts, or made a brace...

Are you sure you're not losing boost? How do you know that you should be running 12 psi?

[hotrodf1]

I don't mean to threadjack here, but can you (should you) hear belt slip as it happens?

This black dust - I see some black stuff on my intake pipe which is next to belt pulley - not sure what it is. Seems to be stuck on the pipe. And I also have a hard time making more then 5 psi, should be like 8.

I have a non self adjusting type adjuster so I could tighten up the tension.

But some guys have spoken about killing the front main bearing from the added stress on it - is this really an issue or not?

[WELTERRACER]

I was running 6psi with a 5inch pulley,, for every 1/4 of an inch in diameter smaller psi should go up 2-3psi,

I am running a 4.5 inch pulley.. THat should be good for 10-12psi easy..

I did add a pulley just below the supercharger to try and get more wrap on the supercharger pulley..

In the past i had heard the belt slipping, not something ive heard since i added the extra pulley

[WELTERRACER]

It definilty feels like the fuel shuts off on the top end.. It happens sometimes in 3rd gear too.. (but only at the track) could be vapor locking too..

Im not sure how i would go about fixing that problem either..

[shmoov69]

Put your old bonnet back on and see what happens. I bet the carb is doing goofy things since your change. Did you retune the carb for the EV hat? Supossidly you must retune it alot after using that hat. What fuel pump are you using? Is it possible that you increased the HP enough that you went out of range for the pump? I did on the last engine change.

[blown69nova]

Do you have a way to watch or datalog your boost? I would bet you have belt slip, since you said boost did not increase with the smaller pulley. Boost should go up the entire curve.
Even a little flex in your bracket will make the belt slip, especially if you are using 6 or 8 ribs.
Let us know how it goes.
Steve

[WELTERRACER]

What would you have to adjust just because of the different carb bonnet.. I would think it alone would make it run better, as it straitens out the air flow..

I will go back to the 5in pulley and see if i can make a bracket to support the supercharger better..

[GetMore]

Funny thing about carbs: If you make a change to something you need to readjust them.
If the hat changes the way the air flows over/into the carb it will throw off the mixture. You MUST retune it to compensate.

[shmoov69]

From what I have read about (NOT first hand experience!) is that you must take out about 5+ jet sizes! If you have modded the air bleeds or the PVCR passages to richen it up, than maybe more jet sizes. I would put the different hat on it to try, since it is by far the easiest mod! What pump are you running?

[whytry]

I agree with Jimmy in terms of trying to narrow down your problems. I still think its belt slip though, due to not getting any additional boost.. Are you getting to 5-6 psi any faster with the smaller pulley? You should be..... I bet the bracket is moving just a little and it is causing it to slip once you really start making more boost...

To check on fuel starvation at the top end, are you seeing your fuel pressure drop when you hit top of 3rd and then to the end of the track? If you have a starvation problem, I bet you are. You might be able to run the floats a little high to help compensate, if you can't afford getting a pump that can keep up.... Short term fix....

I do know you do have to adjust the carb when you go to the EV hat from the stock procharger one....

[WELTERRACER]

I contacted EV and they too said i might need to tune my carb..

But no one has told me for sure if i would need to go richer or leaner..

Car runs great on the street... I never have a problem..

I think everyone is right.. I think the belt must be slipping just enough to only allow me to get 5-6psi of boost

[whytry]

Do you have an AFR gauge in the car? It should tell you to which direction to go in....

[DeltaT]

I have never heard a thing when my Vortech belt was slipping like crazy. Just lots of rubber dust. Not always visible too - sometimes it is hiding farther back on the motor or brackets - getting blown back there from the wind. The tension needed on the blower belt shocked me - it's not like our normal serpentine belts - you want it to be HARD to turn the belt 90 degrees in the middle of its longest unsupported length. If it's still easy to flip 90 degrees, it's too loose.

Jim

[WELTERRACER]

Just when i thought it couldnt get any worse!!

I took off the 4.5inch pulley and when back to the 5inch pulley (which should give me less belt slippage right?

Now im only getting 2psi of boost?? What the hell..

Ive got the belt so tight you can barely get the belt to turn 90 degrees!

Im guessing the belt must be glazed at this point.. Whats a good way to deglaze the belt.. Or should i just replace the belt with some other brand?

P.S. i have a O2 sensor in my exhaust, but im using a autometer AFR and its pretty much useless as it bounces all over and i wouldnt trust it..

[shmoov69]

Replace the belt IMO.
Have you checked your pullies? Are you sure that you don't have a pressure leak?