how to turn the boost up

['00 GTP]

is there any way to turn the boost up on a GTP? I know they run a max pressure of 7.5 psi. I was wantering if you could increase that some way......

thanks
-00-

[jon@af]

Ive heard ideas of changing the pully wheels around but Im not sure, Ill get a little more information on it and post back.

['00 GTP]

I know about the pullys, but is that the only way? I am thinking about putting a 3.0 pully on it. I have heard that it adds 40-50 hp to your car. I have also heard that you have to put a tranny cooler, and a cold air intake on it. do you all know how much that is going to cost me?

[jon@af]

Originally posted by '00 GTP
I know about the pullys, but is that the only way? I am thinking about putting a 3.0 pully on it. I have heard that it adds 40-50 hp to your car. I have also heard that you have to put a tranny cooler, and a cold air intake on it. do you all know how much that is going to cost me?

Well, you can put the pulleys on, but you have to make sure you dont add too much boost, because if you do you can burn pistons up and mess up gaskets and have all kinds of messes on your hands. But if you do do it, it would be a good idea to get the tranny cooler and the intake.

[Juggernaut]

There is NO way you can just bolt a new 3.0" pulley on your car without the supporting mods. All the mods in my sig were required in order for me to safely run a 3.25" pulley. BTW I'm seeing 12psi with this pulley.
I'll be hitting a local track on April 19th to see what my car will do modded. My best stock was 14.5 @ 93 mph with a 2.1 60' time. There are a few sites with really good information for GTP's and modding
They are.... www.oqcgp.com and www.clubgp.com. Check these sites if you are seriously considering modding your GP.
:sun:

[scrubin63125]

In order to run a 3.4in pulley you need; U-bend removed, CAI, 1-2 degree cooler spark plugs, HD spark plug wires, and tranny cooler. To do a 3.25 You will need everything above plus; Cat-back exhaust, either water injection(about $350) or an intercooler(about $1100), DHP pcm, RT downpipe and to get the full effect do rockers or a cam at the same time.

If you dont do these support mods the first major issue you will run into would be boost stacking wich leads to Knock Retard, this is when the pcm senses that your engine is knocking and it retards your timing. If you ignore the KR then that would lead to engine failure.

Also with the 3.25 and supporting mods you will probably also need a Bullet proof tranny rebuild,
Level 10 performance
and an LSD because these will could break with that amount of HP.
For questions ask Zoomer there is a ton of good info on his site.
It is possible to go smaller than a 3.25 but you will need to do serious bottom end work because the stock 3.8 cant handle it.

[ChaosStarter]

He doesn't necessarily need an I/C with a 3.25" pulley. I've seen people go to 2.8" pulley's without 'em. However, HEADERS, downpipe, O/R pipe (or high-flow cat), and catback will help.

Cam and rockers however should be done at this point though.





BTW, if you do rockers alone, go 1.9ratio, if you ever then had a cam, go with 1.75ratio.

[gtp 2000]

i wouldnt touch the boost on the car, you can really hurt the way the car runs and cause some major damage to the motor, i dont feel it is worth it

[99' Z-28]

i wouldnt touch the boost on the car, you can really hurt the way the car runs and cause some major damage to the motor, i dont feel it is worth it

I don't feel its worth it either. ChaosStarter, '00' GTP don't need headers in order to un that amount of boost. He is just going to need two new mufflers that flow about 300 cfm more than stock and a Ultra Flow Converter. He also don't have to have the U-Bend taken off although he will need to have his resonator removed.

[ChaosStarter]

Not necessarily. For the 97+ GTPs, when it comes to turning up the boost and running into Knock Retard, the headers, downpipe, cat, and u-bend are the more restrict parts of the exhaust system. Our catback actually flows very well, it's everything before that that is restricted. Many people still have teh stock mufflers on.

If you were to go onto ClubGP or any other GTP website, you'll see that headers are usually always done at the 3.25" pulley or so, because it's one of the most effective mods for reducing KR.

[99' Z-28]

If you were to go onto ClubGP or any other GTP website, you'll see that headers are usually always done at the 3.25" pulley or so, because it's one of the most effective mods for reducing KR.

Right, who is actually going to spend all that money on a set of headers?
The Cat-Back for the Grand Prix's 97+ is just basically getting rid of the U-bend and resonator and having a better ''T'' Pipe. People think the U-bend restricts alot of air and it really don't. The T pipe don't restrict exhaust flow much at all, but its not restricting enough to were you can't run 12 psi or even 15 psi of boost. A person can go out and buy 2 very good mufflers for about $80 and have resonator removed for $15 at a muffler shop.

[scrubin63125]

Do you own a car with an L67 or know anyone that has a highly modified L67? I just have a hard time taking advise from anyone who doesnt own the car especially from someone who owns a comaro with a V-8.

[ChaosStarter]

Listen, by the looks of you Camaro, you know what you're doing, for that car. However, this is a whole different type of car that responds to things much different than your Camaro.

The resonator is not a flow-restriction point on our exhaust. The U-Bend, manifolds, and downpipe ARE. If all you do is replace the stock mufflers with anything, all you're doing is sound, with maybe a slight gain in HP. The pipes are still the same size, and you're still causing a restriction.



BTW, you couldn't even run 15lbs out of the M90, and if you were to, all you'd be getting is a hair dryer and a side dish of boost stacking.

[navyblue 00gtp]

What in the world is a "t" pipe?

The downpipe is the most restrictive part of the exhaust, followed by the ubend. Replacing the ubend showed 6 hp on the dyno, so yes I would say thats a restriction. Removing the resonator doesnt really do alot, if you look at one, its simply a straight muffler used to reduce drone inside the car.

The cat back exhaust for the GP DO NOT replace the ubend. Its not simply replacing the ubend and resonator. Piping is increased to either 2.5 or 3" .

You can run a 3.4 pulley with few mods, as long as the car doesnt get any knock retard. I have a 3.4 with colder plugs, 160 thermo, cold air box, ubend and resonator removed. I have ZERO knock.

Like whats already been said, if you go below 3.4, you ll almost for sure need headers. And there are quite a few who run headers.

Going to a 3.0 pulley without the right mods will actually hurt hp bc of the amount of knock retard you ll get.

Changing the boost isnt going to cause any damage as long as you do it right. If you do it right it is well worth it.

Actually, you want to run less boost. Most of the guys who do headers, exhaust, smaller pulleys, rockers or cam have their boost drop. You run into heat problems or boost stacking if the exhaust isnt free flowing.

Just go to www.clubgp.com and do a search on pulleys.

Brad

[99' Z-28]

Oh yeah, i almost forgot...I'm a I don't know shit about Grand Prix's