Problems w/ Turboing a Grand Prix?

i know there are a lot of miss conceptions out there when it comes to turboing a grand prix. the main problem i have run across is that, no companys that make a kit for the grand prix list completely the specifications for their kits and this worries me a bit. basically the only two kits that i have come across are the cartuning performance turbo kit and the turbo kit that stattama offers. my question to all of you is how reliable are these kits? does anyone here actually have one? If you do, have you had any custom tuning done to the PCM or is the programming that either company does addiquate? have you come across any problems with the kit? also does anyone know what the difference between l67 ad l36 heads is or if there even is a difference? any advice other then "sell the gt and get a gtp to start" will be greatly appericated thanks

here is what i know:

-when adding a turbo kit and running 6 psi of boost it is possible to get in the 13's
-this added power will definately be enough to royally mess up my stock 4t65e tranny(i have a 2001 grand prix gt with only 30,000 miles) which i plan to rebuild with parts from intense racing
-a boost controller isnt necessary but it adds a factor of safety
-custom tuning is perfered in almost every application of aftermatket turbos

i offer this advice to you: read read read. ppl w/ the cartuning kit have run high 12's with it. Its proven pretty reliable. But Stattama's TT car runs 9.7. I'd trust zzp though. Stay away from intense trannys. Buy a 4t65e_HD tranny and go from there.. I am not totally sure but i think the heads are almost if not the same. The manufacturers probably dont list their parts for a reason.. so ppl like you dont copy their parts/design and make your kit for less (no offence) Alot of the extra cost is R&D so they can market a proven kit.. So IMO since you dont know the inner workings of a GP and pcm tuning (only a handful do) id stick with purchasing a kit

ialso does anyone know what the difference between l67 ad l36 heads is or if there even is a difference?


Good question and here is the answer:

Technically, L67 and L36 heads are different. The fuel injectors on a L67 are placed into the heads, while on a L36, they are placed into the intake manifold.

However, supercharged L67 heads and the L36 normally aspirated heads were identical in the 97-98 model years, except the injector bosses are not machined out to accept the injectors.

In '99 and newer models, the L36 heads went to a different casting, and these injector bosses no longer exist.


On the tranny:

ZZP has performed extensive testing on the RPO MN7 4T65E-HD tranny and it is typically good for mid 13 sec 1/4 mile times at a continuous duty cycle. I've done extensive testing and know for a fact it is good for low 13s. However, your standard RPO M15 tranny will be short lived with the turbo mods.

So I agree with GTP2K2 that you should go with at least the stock 4T65E-HD version. There are plenty of rebuilt 4T65E-HD trannies available for under $1K.

thanks for the advice guys, i really appericate it. i have another question though do you have any advice on where i can get an already rebuilt tranny for the price of under $1000? also, why are you against the intense racing differentials? what heavy duty LSD would you recommend? thanks for the info. on the heads, do you know anything about the flow of either of the heads?


to gtp2k2: what i meant by the specs on the turbo kits is just a basic break down of parts i know stattama lists what kind of turbo they use in their basic kit its a T3/T4 but the numbers that cartuning list seem to be only the specs for the exhaust side of the turbo. and they just day add on a boost controller it would be nice to what controller they sell. sorry for the confusion and thanks for the advice.

Another option is to go with ZZP's 4T65E-HD upgrade. Because all you really need is the beefier differential and passenger side half shaft unless you plan on modifying for 12 sec. ETs and staying there with any consistency and reliability.

http://www.zzperformance.com/grand_prix/products1.php?id=394

A company in Phoenix, AZ (Phoenix Retrans) has remanufactured 4T65E-HD trannies for $895.00 with warranty. They will ship but you will have a core charge until you get the tranny back to them and shipping charges. Last Spring I went with a friend who has a '99 GTP. It came out to $895 plus $400 direct replacement and labor at their shop. We had to do an overnighter and the car was ready the next day.

Also, check with Ed Morad at Morad Parts Company. He sells used trannies and periodically gets new pulled HD trannies from GPs and sells them for around $995.00. A lot of us have done business with Ed.

stock HD diffs outlast intense LSD's. All of ZZP's runs are with stock diff, both tires spin just fine.. and yes, ed morad is the man

hey bnaylor3400 do you know the casting numbers for the heads before and after the change?