too much boost??

[fastGTP01]

i have an 01 GTP that has a smaller pulley on it, and according to my gauge(not factory gauge) it is boosting at about 11-12 psi at full throttle. is that too much for the motor with no lower end work? it has headers, cold air intake, and 1.6 roller rockers. and if so what size pulley is recommened, i do not kno the size of my current one. thanks.

[BNaylor]

The best thing to do is measure the SC pulley. The stock is 3.8".

The boost reading could be normal for the current pulley size.

Welcome to AF.

[fastGTP01]

right i understand that, but what im asking is, is 12 psi too much forced air for a basically stock internal motor, like is it gunna internally destroy it, if so i need to kno what pulley to get. this is my daily driver and i will occasionally race it. keep in mind i kno NOTHING about supercharged motors, my current race vehicle is an s10 with a smallblock and thats where my knowledge is. also what is the factory psi on a 3.8 inch pulley? thanks again

[BNaylor]

Originally Posted by fastGTP01

right i understand that, but what im asking is, is 12 psi too much forced air for a basically stock internal motor, like is it gunna internally destroy it, if so i need to kno what pulley to get. this is my daily driver and i will occasionally race it. keep in mind i kno NOTHING about supercharged motors, my current race vehicle is an s10 with a smallblock and thats where my knowledge is. also what is the factory psi on a 3.8 inch pulley? thanks again

You're welcome.

No 12 psi will not blow your engine. I ran 12 psi with a 3.25" SC pulley for a long time.

Now above 15 psi and you could have a ticking time bomb.

Stock 3.8" boost is around 7.5 - 8.0 psi.

The biggest issue is to minimize knock retard (KR) due to possible detonation with the smaller pulley sizes. Have you checked your KR?

[fastGTP01]

lol...umm how do i do that? see the reason im even asking is that i havent had the car very long and it already had an issue, either the wrist pin got loose and the piston hit the spark plug or the valve head popped off and hit my sparkplug. cuz i started to do a compression check when it started to make the loud pinging noise and not run right, and i took out the first plug and it was smashed so i am asking is it becuase off too much boost. its in the shop now, soo. how do u do the kr check? thanks very much, as u can c im new to boost.

[BNaylor]

Originally Posted by fastGTP01

lol...umm how do i do that? see the reason im even asking is that i havent had the car very long and it already had an issue, either the wrist pin got loose and the piston hit the spark plug or the valve head popped off and hit my sparkplug. cuz i started to do a compression check when it started to make the loud pinging noise and not run right, and i took out the first plug and it was smashed so i am asking is it becuase off too much boost. its in the shop now, soo. how do u do the kr check? thanks very much, as u can c im new to boost.

I really don't think it is because boost is too high but you could be getting detonation or it was just a mechanical malfunction. KR has always been an issue on any L67 Grand Prix such as the GTP when modded. A lot of us use either Autotap run on a laptop or gauges such as a Autoscanner type that reads out KR, otherwise it is just a guessing game and could lead to engine damage due to not monitoring KR.

I would recommend checking into it and maybe it will help when you get the car back. It is better safe than sorry. Good luck!

[fastGTP01]

thanks, now my next question is where cn i get gauge for that or have it chcked ona laptop? thanks much

[BNaylor]

Originally Posted by fastGTP01

thanks, now my next question is where cn i get gauge for that or have it chcked ona laptop? thanks much

Best places to get these items are the specialty performance sites for the Grand Prix like ZZPerformance, 3800Performance and PFYC.

Here is one link with Autotap and the Aeroforce scan gauge:

http://www.3800performance.com/Merch...tegory_Code=EB

[fastGTP01]

will the caspers electronic timing gauge work, or which specific one do u reommend? or is their any shop i cantake it to to have it chcked on?

[BNaylor]

Originally Posted by fastGTP01

will the caspers electronic timing gauge work, or which specific one do u reommend? or is their any shop i cantake it to to have it chcked on?

I really don't know. For tuning possibly but I would not use it for solely monitoring KR. I prefer re-programmed PCMs to handle timing and advance.

High end odb-ii scanners may have KR readout capability as does the GM Tech II diagnostics machine. Autotap is really good but you need a decent laptop computer to run the software.

I use the Aeroforce scanner gauge for constant monitoring. Expensive but worth it.

[MIKES3]

Originally Posted by fastGTP01

i have an 01 GTP that has a smaller pulley on it, and according to my gauge(not factory gauge) it is boosting at about 11-12 psi at full throttle. is that too much for the motor with no lower end work? it has headers, cold air intake, and 1.6 roller rockers. and if so what size pulley is recommended, i do not know the size of my current one. thanks.

I run 14-15 lbs of boost with my setup. Our bottom ends of out motor can handle mad power. I'm thinking at least 500-600 HP an I think that's being conservative. Guys were running in the low 10s with a stock bottom end. Now that doesn't mean it will hold up for a 100 passes on the track, but I motors are strong as long as you maintain it. I run a 3.2 pulley soon to be a 3.0. I venture to say I will be around 17lbs of boost with my GEN V blower. Did you mod your own car? It almost looks like you were set up for a CAM due to the fact you mentioned stock 1.6 rockers. Usually you don't mention stock rockers. I have the 1.8 Aluminum RRs. The best thing for you to do is scan your vehicle for knock. With you GEN III motor it sounds like your running either a 3.25" or a 3.2" pulley. The GEN Vs are a lot more efficient than the 97-03 GTPs thusly making more boost

You can run Autotap with a Palmpilot

Good Luck
Mike

[fastGTP01]

thanks for everyones help, but no my rockers arent stock, but they are stock ration. they are roller rockers. and do i have to buy something to check for KR or is their shops that can do it like, autozone or a dealership or sumtin. thanks.