sizing a turbo

[omni spirit]

i know this is not a TD but people on this forum are much more turbo guru.i have a 89 turbo grand prix, i've always liked these cars and i found one for a good price and bought it. so naturally i want to make more power. the first thing is retune it, second bigger exhust , better intercooler then bigger turbo and retune again.
what i need is some to help me figure out what turbo is right for me the stocker is a garrett t25 that only suports about 6.5-7 pst boost at WOT at about 4600-5500 rpm the t25 spools instent.
people on turbo grand prix forums tell me a GT28 is ideal for it. BUT they are alot of money and i'm cheep, plus it still seems too small i could be wrong though.
basicley what i want to get out of it is 15ish psi boost and about 350 crank HP that seems to be the stock drive train limits. i've been tuning it with tuner cats RT and a EPROM emulator and a wideband O2.

for those of you that don't know what motor the TGP's come with they are a turbo 3.1 litre 2v per cyl. push rod. i just figured some of ya'll may have mest with other stuff such as v6 turbo stuff. i was thinking on a larger hybrid turbo like t3/t4 with may be something .63 or larger on exhust.
let me know what ya'll think
thanks Greg

[Rock Kustoms]

the first thing that you have to know about turbos is the size of the turbo has nothing to do with the amount of boost it makes, the t25 will make 15psi no problem, but it gets to the point where its inefficent. the big difference between turbo size is the AMOUNT of air thats flowing (CFM)

a 3.1 liter is a fairly large motor a t3/t4 would do nicely on it

[Gutfeeling]

You could do a GT3076, but it will be laggy and require some other supporting modifications in order to get rid of the excessive lag. To support that kind of turbo, you'll need a higher stall (if you're auto still) , injectors, cam MAYBE, and the other for mentioned parts you posted. Porting will be something I'd pass on due to the VERY restrictive plenum/LIM design. You COULD do a 3x00 top end swap, but I say go all the way IF you're going that far. The GenII will be your limiting factor for 350 reliable power IF you achieve that goal safely. The 282/284 (If you swapped) will not like that kind of power pushed through it, and those axles will snap like twigs if the Diff doesnt explode within the case. Dont half ass it, or you'll be kicking yourself in the end when parts start breaking or you end up doing it twice because the first time you decide to cut corners.
Dont forget to tighten up that suspension in that Wobble body!

[xrattiracer]

Call a turbo shop and ask them. or get a good book about turbos and figure it out yourself (i recommend this option; knowledge is power).
A holset HE351/HY35 would probably work well, if theres room for it.

[omni spirit]

Quote:

Originally Posted by xrattiracer Call a turbo shop and ask them. or get a good book about turbos and figure it out yourself (i recommend this option; knowledge is power). A holset HE351/HY35 would probably work well, if theres room for it.

you know a holset would probley work dandy for it. i may give it a shot, i am wanting to go cheap.

[Gutfeeling]

I will say the holset WILL need a custom crossover and downpipe. Depending on which holset you use, you'll need to fab in a wastegate or custom rig in an actuator due to the stock actuator pertaining a 18-20 spring rate. Also, dont forget a better IC. Due to the size of the holset, you'll probably just barely use the turbocharger in its 70-80% efficiently range. So that bigger/better IC will be able to cool that hot compressed air. I think the holset will be nice once you get the wrinkles ironed out to support it.

[omni spirit]

Quote:

Originally Posted by Gutfeeling I will say the holset WILL need a custom crossover and downpipe. Depending on which holset you use, you'll need to fab in a wastegate or custom rig in an actuator due to the stock actuator pertaining a 18-20 spring rate. Also, dont forget a better IC. Due to the size of the holset, you'll probably just barely use the turbocharger in its 70-80% efficiently range. So that bigger/better IC will be able to cool that hot compressed air. I think the holset will be nice once you get the wrinkles ironed out to support it.

yeah a better intercooler i a must. i am going to custom fab a x-over pipe consitering mine is leaking. i am starting to think this car is not worth the hassel. its going to be one of those cars that you sink a hell of a lot of money in to. it snow balls just to get what you want out of it.
i like GM cars but i thing Turbo Dodge is were its at for doing stuff like this.

[Gutfeeling]

Don't get me wrong, you can do a fair deal of modifications to those gen2s, but it's up to you if you see yourself holding on to it for a few year (4+) and maintaining it to keep it worthy of any resale. They only made those TGP's in 89 and the STE in 90. So don't trash it just yet. Look deep into the car to see if it's worth it. Hows the rust? If it's getting kinda wide spread, then yea winter beat it until the wheels literally fall off and move on. Just dont let the car develop rust and neglect it to the point where then it becomes a beater car.

[omni spirit]

well thats just the thing, my car is perfect. 100% rust free with 70K miles and its all orignal. i'd kinda hate to start moding it too much. if it's worth any thing it's worth it now. some or a lot of people frown apon modded cars.
i do like the car, but i almost think its too nice for some one like me to have. thats whati was saying about a TD it dosn't matter if you find the rarest TD like a CSX or somthing it's still not realy wrth anything so it don't matter if people mod it.
any way i'm just rambling

[stargazer7467]

Ah a fellow TGP owner, I have this and a GLH omni, the dodge will always be faster in my opinion. I love my 90 TGP but its too heavy for its own good.

[omni spirit]

Quote:

Originally Posted by stargazer7467 Ah a fellow TGP owner, I have this and a GLH omni, the dodge will always be faster in my opinion. I love my 90 TGP but its too heavy for its own good.

i have the same set up
i think your right of cores i have a srt-4 motor in my GLH and far from stock
hehe
i got all kinds of crap realy

[Gutfeeling]

If it is is great shape as you say it is in, I'd garage queen it and just wait for the right price to come along.

[stargazer7467]

unfortunatly resale sux on TGPs