Modding a Pontiac Grand Prix

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Hi everybody, my name is Pat and I'm a 17 year old driving a 2002 Pontiac Grand Prix SE. I have about $2500 saved up, and I want to get to work on improving my car's performance. It has a 3.1L V-6 in it, with an automatic tranny, and everything is stock. I'd really like to boost my performance without resorted to N2O or anything like that.

I've done a decent amount of car work, and my Dad's done a lot,so I can probably do most of the standard modifications to my car that I want to.

I plan to:

1. Buy and install either a supercharger or turbocharger. I'm not sure which I'd rather have, because I have to pay for gas myself.
2. Stiffen the chassis
3. Bore the cylinders and install some larger piston heads.
4. Replace litttle things like air filters and stuff like that.
5. Eventually (way in the future), replace the auto transmission with a manual. It probably would be cheaper and less of a hassle to just leave it, but I like driving a stick and my dad says it would be good for my to get comfortable doing some major work.

My main question is, which should I start on first to improve my horspower, and if anybody else could recommend some other modifications.

Thanks a lot,

posted by  pquinny823

Well remember that with a super charger or a trubo... youll need to open up your heads too... along with boring your cylinders... you have to make sure the engine can take in the extra air... if you dont, you wont be getting the full power of your super charger and youll have basicly just waisted your money.

Plan your engine build around that super or turbo charger, that way you get full use of it...

posted by  TheFieroKid

Do you have any recommendations on any aftermarket supercharger I could drop in, preferably one that isnt too expensive, I want to do more work on the engine and I'm saving for college, too.

posted by  pquinny823

my first recommendation would be to get a 3.8 its one of the best v6's there is IMO they run strong forever. just from what ive seen, that 3.1 is junk if it gets hot it will crack the head. if it was me, id build the 3.8 and then switch it over. you can get a grand prix gtp motor that already has the turbo charger on it.

posted by  adamc44

Do you know any estimates on a price for a 3.8L? Also, I was sort of hoping to avoid an engine swap as I need this car to drive almost every day. Plus I want to sort of get my feet a litter bit more wet first before doing something that big.

Thanks a lot for the replies/advice.

posted by  pquinny823

i wouldnt have a clue on what they would run. you could prob call around to a few salvage yards that sell wrecked vehicles to fix up and they might be able to get you a price. to be perfectly honest with ya, i personally havent seen to many things to build up a 3,8 let alone a 3.1 of course im not out lookin for them in the first place. your just going to have to do some research on this. sorry im not of more help

posted by  adamc44

Hey Pat. Go to and click on "Club Garage". The Portland Grand Prix Club is based here in Portland, Oregon and a majority of the members own Grand Prix's. They are a good group of people and should be able to help you out.

posted by  76MonteMan

Thanks a ton for your responses, it looks like there isn't as much available for my car as I thought there'd be. Probably because its not one of those imports. Thanks a lot for that website 76Monteman, it looks like a good place to look for.

I might try a bigger engine swap from another GM car, I still need a little research to do on that, but I would probably just find salvaged one and rebuild it.

Thanks a lot.

posted by  pquinny823

just swap the motor out of a GTP thats already a supercharged 3.8 and have the heads ported and polished,a higher pressure pulley for the SC and get an open exhaust. I've talked to some pontiac guys that said with these mods they're close to or right at 300hp. Oh and don't forget about adding extra fuel when you up the boost on the SC also get it tuned. :2cents:

posted by  airmanUSN

How much would I be looking for as for actually buying the engine (i.e. how much should I pay a salvage yard for it). And while I am at it, would i just be worth it to swap in a new tranny as well, making my car a manual.
Thanks a lot,

posted by  pquinny823

swapping a tranny into a manual car cost a lot of money. You have to cut, weld, and fab some stuff in order to make it work. not to mention add a clutch pedal and hydraulics. Honestly it would be cheaper to trade your car in on a manual one. You could also rework your auto to shift harder and quicker if that's what you looking for. The engine would probably run you $500-800 depending on miles and availability

posted by  airmanUSN

The Ford 3.8L V6 is a great engine. Plus you could get one out of a Thunderbird Supercoupe with a supercharger already installed. A good engine will probably run you just above $1000.

But, if you want to keep it paired with a GM powerplant, get a Super Charged 3800 V6.

posted by  SlipKnoT

i didnt kno they still put the 3.1's in them, well the 3.8 is alot better maybe if u could swap'm u'd be doin good :2cents:

posted by  Tech_N9ne

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