hello all,

i ran into a guy that is having issues with a procharger kit that was installed by a local import shop. it is a p1sc on a 2000 trans am. he thinks it does not run much better than stock and he says it reaches 3psi at 4500 and is barely making 5psi by the time he shifts at 6000rpm. is this normal with a kit pullied to 5psi? i saw an article in GMHTP where they installed a waste gate and decreased the pulley size to bring the system into boost sooner. i think this would be easy to do. the motor has like 190,000 miles on it so i dont think he needs any more than this until he builds a new motor, but i think with the large pulley for low boost this is all he can expect without using something like the waste gates mentioned from the tech article.

i dont think he has any leaks because it is reaching the 5psi it is pullied for, but i have not really inspected it yet. i will be building him a motor shortly and im curious as to what boost level/pulley size is safe for a p1sc.

thanks for any help or suggestions.

mason

 

It is important to note that the cars in the story used D-1SC head units, not P-1SC, which have a different efficiency range (the wastegate helped bring them into their efficiency range at a lower boost level). With a 190,000 miles he could very well have plenty of blow-by, as I'm sure you know. We've made 7.5psi before on a project car with a P-1SC, but there are plenty of others out there that have made 9-10psi (stock heads/bottom-end), which can equate to over 600-rwhp with a cam and methanol injection (or race gas) in a stick car. Good gas and a good intercooler are key.

http://www.gmhightechperformance.com...all/index.html

 

Sounds like he has a 4" pulley or bigger which this will be normal.He just needs a smaller pulley. We always run boost 8-10lbs on stock cars, but we always upgrade the P1's to use the 8 rib pulley setup.

 

It's tempting to take a swipe at the "import shop" as the cause of the problem , but that's probably not the case. 5 psi is common on a P1SC with conservative pulley sizes.

He could install a smaller pulley on the head unit to raise the boost, but before doing anything check the entire system for boost leaks.
Also if it has a 6-rib pulley system, promptly throw them away and install 8-rib pulleys. He could be losing boost due to belt slippage. However, getting back to my first statement, the system may be leak and belt slippage free and still only generate 5 psi if the pulley sizes are conservative.

No need to get crazy with trying to put a wastegate on the car as Scott pointed out. And I agree, a 190K mile stock motor may not deliver the best results.

 

If the engine has good even comp on all cyl, then it should still make good power regardless of the mileage. I did a comp check when my Vortech was installed at 172k and the results were 130-131 on all 8. It has lived comfortably on 9lbs for roughly 16k miles being a dd car. Good tune and dont beat the **** outta it at every light you come to is the best advice I can give ya...

 

i appreciate all of the responses.
is it common for this kit to make the 5psi that high in the rpm band?
what is the smallest pulley i can put on here once i get his new engine
finished and not overspeed the blower or run into IAT issues?

 

JRENIGAR
how much boost are you running?
i know what your saying about the good tune and not beating on it,
but as of right now it has a none dyno tune and he will be beating on it.
i dont know how they tuned it but i think that is the majority of his problem
right now.

 

Back in 2002 we installed a 6 rib D-1SC kit on my '99 Z28, back then they did not have the 8 rib kits out yet. With 110,000 miles on the engine, it ran great with 7 psi and we never had belt slippage with it. The 6 rib blower belt does need to be kept extremely tight, but I wouldn't expect belt slippage at 8 psi and below. One thing that should be done after a new belt is installed to prevent belt slippage is to take it easy on it for an hour. Then tighten the belt back down before going wide open throttle.
For now I'd go with a smaller pulley to up the boost and you'll have to either get another mail order tune for it or get it dyno tuned. 7-8 psi will make a huge difference, it will come in much sooner.


Yes it is common with this kit. Once you get the new engine built I'd send in the blower to have ProCharger turn it into a D-1SC and I would upgrade it to the eight rib kit. This kit most likely has the smaller 3.5" twin intercoolers. I wouldn't push them past 12 psi of boost, adding methanol injection will greatly decrease the inlet air temps.

How much boost the blower can produce depends on many variables.
* Cubic inch. The larger the engine the less boost it will make with a supercharger.
* Headers and exhaust. A better flowing system will produce less boost, requires a smaller pulley to regain the loss in boost. Ultimately though, more power will be gained.
* Camshaft and heads. A camshaft with some overlap will leak out some boost through the valves. Better flowing heads react a lot like a better flowing exhaust system.
* Altitude. Elevation plays a big part in how much boost is produced. Those people living in the higher elevations have to spin the blower harder to see boost.
* Condition of engine. An engine with real good sealing rings will ultimately produce more boost than one with worn rings.
* Rpm. An engine that is spun up higher in the rpm range will normally produce more boost.


More than likely they installed the complete 1GJ213-SCI kit that comes complete from Procharger with a tune. Bob

 

What are the current crank and head unit pulley sizes?

 

i'm going to get him to get a dyno tune and see what is really going on. for all i know he could have a bad 02 over/under fueling.

once again thanks for all the input i will update this thread in case anyone is interested.
after the tune is checked out and i see what kind of power it is actually making.

 

TWS i only briefly looked at the car last night. im going to put it on my lift and thoroughly check it out.

 

The six rib comes with a 6.0" crank pulley and the pulley on the head unit will have a number stamped on the side of it. Bob

 

Im running the Vortech 8 rib, intercooled kit with 9lbs @ 6000RPM. My tuner set the timming @ 12 deg and the AFR between 11.3 and 11.5. Im running the Racetronix kit and flow matched 60lb/hr inj. The tune is really safe, the engine has no KR on 91 octane gas, the #'s in my sig are with an unlocked stock converter, and no methanol inj. Not bad for what it is.

 

i made 5.5-5.7 psi.... was only making 4 psi on my D1 then i tightened the belt up and it raised almost 2 psi....so check everything out like stated. Im running the 7.65 CP and a 4.38" BP. But thats on a D1 also.... numbers in sig..

 

i've been thinking about it today, and i think i'm gonna order him a set of longtubes, an ORY, and i think a 3.70" pulley and belt. then he can head to the dyno and get a tune.

thoughts?

 

the main thing to pay attention too. is your only running 5psi. the blower is barely getting started. the pulley will help, but may not be necessary since you havent had it checked for boost leak. my pulley is a 4.13. im hoping it will make 8-10psi.

 

yeah, the guys who installed it told him 5psi was all that was safe for his stock motor.
i kinda figured the blower wasnt spinning fast enough to make any boost down low. he
also has 4.10's that i dont think are helping.

 

I was also unhappy with my low boost p1sc, It did run better than stock though

 

My "stock" 6 rib kit made the proper 8 psi it was supposed to make. This was with longtubes too, which can lower boost slightly. These are probably the same size pulleys that the OP has. My kit back then was exactly as sent from Procharger. It put down 479/450 to the wheels.

I upgraded to dual 4.5" intercoolers (over the 3.5" ones), got the Procharger billet bypass valve, and upgraded to 8 rib pulleys. Once I stepped up the injectors and fuel pump it put down 546/506.

With a 7.65 crank pulley and 4.50 head unit pulley I am hitting 10 psi by 5800 or a little before. They boost gauge on the Dyna-pack wasn't working that day so we could not record boost vs. RPM.

 

If the P-1SC kit came complete with a tune from ProCharger, they only have two boost options for it, 5 & 7 psi. My guess is they ordered this kit with the tune and opted for the 5 psi version, meaning this kit came with a large pulley on the blower. Bob