how to turn the boost up

[99' Z-28]

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" .

Your going to lose Horse Power if you increase the piping to 3inches or even 2.5. The reason being is that V-6 will lose and gain backpressure more than V-8's. If you have Too big of piping you will not have enough.

What in the world is a "t" pipe?

Its the pipe that makes your Y-Pipe a Y-Pipe.

[ChaosStarter]

I would agree with that statement as far as teh 3" piping goes unless you are pushing SERIOUS hp. However, every catback system out there for the GTPs increases piping size to 2.5".

[99' Z-28]

every catback system out there for the GTPs increases piping size to 2.5".

Yes, 2.5'' is fine. No bigger though.

[navyblue 00gtp]

You want as little back pressure as possible with a supercharged motor. You re not going to lose hp with 3" pipe, you may lose some low end power/torque but pick it back up on the top end and hp actually increases. Which with the torque of the L67 and front wheel drive, this is a good thing. The MSP cat back is 3" so not every catback offered is 2.5". I agree 3" maybe overkill but it can be and is being done everyday.

The y pipe is a y pipe, not a t. Not being picky but it simply doesnt form a T.

The biggest restriction in the exhaust system is the downpipe. Its 2 1/4 on the outside but it is double walled. So actually, its a little over 2".

Do you have any basis for your arguements or are you arguing for the sake of arguing?

Brad

[The_Pope]

Originally posted by 99' Z-28
Oh yeah, i almost forgot...I'm a I don't know shit about Grand Prix's

Not much shit anyway.

Smaller pulleys and other mods don't 'hurt' your car, they improve it. All the power adding mods I've done have improved my gas mileage. Now if you push your car too much you can hurt it, but you can do that to an unmodded Grand Prix too. I have a Thrasher CAI for intake.

My car could easily use a 3" exhaust system. Instead, I open a cutout before the Y pipe to eliminate the Borla mufflers for track racing. I have a cam, intercooler, TOG headers, 3" downpipe and a carsound high flow cat.

To handle the added power I have just rebuilt my transmission. I installed a hardened input shaft, 3.29 heavy gears and single heavy drive chain, Raybestos High Energy clutches for input, 2nd, 3rd, and 4th clutch packs, a Quaife torque biasing differential (posi), and a Pro Torque 245 mm TCC 300 torque converter. This transmission can probably handle 1000 HP safely. By the time I'm through modding and adding a ported blower, ported heads and an LS1 throttle body bored out to 82 mm, I'l be pushing close to 550 HP, so the transmission should be able to handle it easily.

[ChaosStarter]

Although I like you plans for future mods The_Pope, but I really don't think, even with that many mods and future mods, that you won't be close to 550hp. I could see in the area of 350-400 (maybe), but remember, we lose a lot of hp to the ground with these trannies...

[scrubin63125]

Wont the tranny re-build help gain back some of that lost horsepower or does it just reinforce and nothing else?



Oh and Z you being new doesnt matter, you not owning a Grand Prix does.

[ChaosStarter]

It just reinforces it. The only way to gain back lost HP is to put a manual tranny in there, and as pretty much anyone with a modified GTP knows, no FWD manual tranny will be able to hold up to the power that we will/do make...

[GTP Racer]

The fastest way i found to add power to my 2000 GTP was to..

-K&N Cold Air Intake
-Magnuson Nose Drive
-Pulley Boys 3.75" Pulley
-Borla Cat-Back Exhaust
-Borla Headers

although this isn't cheap my GTP is running at 350+hp.. ( i have yet to dyno it)

[Ripn12s]

Dyno that thing, because I doubt you are over 230hp if even.

[GTP Racer]

230hp tops?? haha wow buddy.. r u drunk.. u must have a SE 3100 Series Grand Prix

I have a GTP! with 240hp STOCK!, i had it dyno'd before any serious mods, only a K&N air filter and it had 244hp..

trust me with the money i spent i would drive my car into the atlantic if it decreased the horsepower

[Ripn12s]

deleted.

crank hp vs. at wheel hp

usually when people refer to dyno numbers they give the hp at the wheels

good luck

['00' GTP]

I am throwing the BS flag on this one. first off these cars push 200-210 bone stock at the wheels. you only have a CAI not a FWI you are only looking at a 10 hp gain, prob 7 (I am being generous) at the wheels.

3.75 pully are you kidding me? that is like a 10 HP if that..

Exhaust I will give you no more than 15 HP ahh what the hell I will double the actule HP gain, and say that you are not loosing anything from crank to wheels so 30 HP

47 HP that will make it 257 HP..... unless you have a magic car, There is no way that you are any higher than that. and before you say it, yes I have a 2000 GTP 3.8 liter, I have a 3.4 pully, FWI, and a few other things... have you touched your boost controller, or the throtle body screen???????

[halcyon026]

First off dont listen to that guy about exhuast size. GTPs have a SC, forced induction cars are totally different than N/A cars. 3' is fine on a GTP even more so if you do CAI, ubend, 3.4 pulley.
Second some of the GTP owners are a bit off on some things...
someone said youd get max 10hp from a CAI on the GTP, read here
http://easyperformance.com/CAI/Head_to_Head_Content.htm this shows about 17hp gained over another CAI, NOT OVER STOCK over another CAI over stock would be even more... gm intake is very restrictive, mind you that GTP was slightly modded making for better gains of more air. that car had a PCM, exhuast 3.25 pulley, getting 262hp at the wheels with no IC.
anyone with a GTP needs to goto this site and do some research, http://www.zzperformance.com/ They are simply the best Ive found when it comes to GTPs, they have people getting 12s with no IC and no KR.

Heres what i would do with your GTP, get the wizard CAI if you have the money other wise build your own with a 9" K&N and only goto a *3.4 pulley for now cause smaller will give you almost no gain without certain other mods like CAMs/rockerarms.

remove u-bend: $ exhuast shop can do this <8hp
180-160 thermostat:$12 < 1 or 2 hp
throttle body spacer: $50 <shown 30 degrees cooler inlet temps
3.4 pulley* use gatorback belts <25hp
cooler plugs like NGK TR6
For safty but dont need a tranny cooler from ZZP $220. and fuel cooler.

From there if you have the money and want more power
Mini-AFC 2.0: $150
VS CAMs: $300 from ZZP <40-50hp

from there you could also do plug wires and heat wrap. by the time you do cams it may be about time for an Intercooler. But only if youre getting Knock and want to go to really small pulleys like 3.0 and smaller.
You can get the 1st gen IC from ZZP for $1200 or there new 2nd gen for about $1600. With this you can take youre pulley sizes way down and start thinking 12's-11's in the 1/4 mile no BS!!! read up on it on ZZP. This might also be time to get high flowing injectors and new fuel pump. $300 for matched and balanced injectors. Im leaving my GTP stock looking on the outside and removing the GTP badge then once the IC in ordered and Im hauling ass people wont know what hit em! MUAHAHAA! BTW the numbers i quoted here are actually shown and tested on a dyno other wise i wouldnt put them up and wouldnt buy the parts myself for my car.

If you really have the money and want more ZZP has headers showing a huge 18hp gain over stock at the wheels thats about $730 though of course with all those other mods it would only help replease more HP. ZZP also has tons of porting mods to do to the SC and Intake monifolds and throttle body. These mods arent cheap but the more you mod the more these will add to the gains and should help reduce Knock if you dont have money for an IC. Oh you can also get a shift kit to get firmer shifts from pfyc.com and something to raise line pressure.

[halcyon026]

BTW i when talking about the exhuast when i said "even more" when saying 3" was fine i didnt mean even bigger i meant its even more ok to have 3" if you have mods....

When youre at ZZP check out the members cars, some dont have even as much done as i say to do and get very good 1/4 miles.

heres a list in order that I am purchasing my Mods for a 99 GTP, if you have 98 or older add a ported 99 throttle body from ZZP.
http://www.boisepcrepair.com/GTP%20Mods.txt

I also think exhuast is about the last thing to buy on the GTP but it wouldnt hurt of course, getting the modded headers for $250 from ZZP and heat wrapping them or getting the coated ones would be about as much as I would do on the GTP other than u-bend removal. I mean 18 HP for over $700?!?! Not when this is all just for fun having exhuast isnt a bragging right its saying you cant find things that cost less than half as much for the same gains... I mean get cams and rocker arms and some head work for the same price and get twice the HP, come on people!
hehe thats all sorry if i seemed rude, i was just trying to inform a fellow GTP driver what his car can really do. I think the GTP is the cheapest car to buy then put the least amount of money into to be the fastest, cause you can get a 98 for 9k and put 4k into it and get 12s-11s and have a totally street rideable car still in stock trim. Maybe not the only car you can do this too much one of the better looking and Newer cars at least. Later guys hope I helped out. I just ordered a Gtech Pro competition so maybe Ill post my numbers soon! weeee