I new here I posted a couple time inquiring about a gn swap into a 3rd gen...but now I have some new questions I just bought a gta and I wanna know what modss I should start out with its an auto and it has a 350tpi...also what rear end comes with them? I know its posi .....but have know idea what gears...I was thinking maybe a 3.23 or a 3.42 but not too sure?

 

Howdy

I have an 1989 GTA and it came with the 3.27 gears. From the experience with my car I would say do the exhaust system first. The biggest gains I got with the seat of the pants dyno were from my exhaust system mods. Allen

 

Also what intake do you guys use? Has anyone done the "speed density conversion?"ok so I'll get a set of 3.73 gears and a header back exhaust! Any input on what exhaust to get? Also when I start the sometime it struggles to start...then I smell fuel.....then it smokes a little and some times idels rought.....Also when I get on the gas it sputters and then I smell gas...leaky injector?

 

Hi Again

Looks like I'am the only responder so far. Sounds good on the exhaust system. I'am runing SLP exhaust myself. Hooker has a good reputation.

I'am running a highly modified TPI injection system. I have the Edelbrock intake that has been extude honed and port matched to my Trick Flow 23 degree heads. I'm using SLP runners that have been modified. I'am also using the stock plenum with all the modifications.

I have the 52mm throttle body but in your situation I would stick with the stock 48mm until you have good flowing heads and a bigger cam along with the exhaust and intake mods.

Regarding the 3.70 gears. I would stick with the 3.27's with your TPI until I had the above mods or a different intake system. You need a motor that will pull to 5500 plus rpm's before you get the 3.70 gears. A very good compromise is the 3.45 gears.

Regarding speed density versus your current MAF system. I personally have retained the MAF on my car. I'm currently breaking in my rebuild and it should dyno around 400 horsepower at the flywheel with my mods. Again if for some reason you decide to switch I would save this change until last.

Good luck with your car. Allen

 

as for the struggling to start, next time, press the gas pedal a bit, see if that makes things start a bit better. If so, you are on the right track with leaky injector(s).

Determine the color of the smoke. Either black from running rich, or possibly aslo a tint of light blue, which would not suprise me.

 

1989GTATransAm,

Do you have a Ford rearend in your car? The 3.27 gear is a Ford gear if I am not mistaking...if you still have the stock rearend and stock gears, I think you have 3.23 gears. My 91 has the stock rearend and gears which are 3.23.

Calico,

I would stick with your stock gears or get a set of 3.42's which really won't do much over the 3.23's. As far as exhaust goes...I have a set of Hedman LT's, no cats, and true duals with an x-pipe into a pair of Bullet Race mufflers that are dumped before the axle. I have been very pleased with my exhaust thus far. Only problem I will run into is when I get a set of SFC's, I may have to re-route my exhaust at which point I may either bolt the mufflers directly to the headers or get a y-pipe and put the muffler directly off of it and keep it dumped.

 

There were no 10 bolt rear axles offered in 88 GTA's. If you have the L98/700R4 combo in 1988 you have a 9 bolt 3.27 ratio Borg Warner rear axle. HTH

 

Thanks for that info...I was unaware of that

 

Ita all good...check out:

www.gtasourcepage.com


Go into RPO Option Code Figures and select the desired year. Lots of good info. And before anyone asks, there has never been anyone on these boards that has actually had the Y11 Dana rear end in 1988 AFAIK. It appears to be a misprint. If he checks his RPO's he should have GW6 which is 3.27 gears.

 

Yeah when i press the gas it helps the car start better! And it is a tint of light blue...and the car seems really weak as if it were fin to die on me (which it has shut off)

I have a question I originally bought the gta to swap in a Grand Nat engine and tranny...it seems like a faster engine and is lighter....how much do you think I could sell my tpi for?

 

Yup, leaky injector. Bad valve stem seals make for the puff of blue at startup.

 

The light blue smoke is oil past your leaky valve seals, just like mine and everyone elses (unless they replaced them).

I'd say get the car running good first before anything else. Get those injectors looked at.

The gn swap into a thirdgen should not be a problem. 1989 25th aniversary GTA's had gn turbo v6's in them. Just get the parts to do the swap. You need to make this decision before spending money on headers for a V8 that you might not be keeping.

For prices on a TPI, check out ebay. See what other people have sold them for. If you sell everything - wiring and ecm and all, I'd say you might get $2K to $2500 - depending on how many miles are on it.

 

Don where do you see used stock TPI setups for 2K? Even with wiring ECM, manifold, runners, plenum and TB the nicest sets are $800 and less. I have often seen them for around $400 and less. Hell I'll tear my entire modded, ported and polished TPI system apart and sell it if anyone wants to spend $2K -$2500 on a TPI.

 

intially I wanted to mod the tpi...The gn's are expensive drivetrains but its worth it cause they run a stock 13.5...and it will cost alot of $$$ to make my tpi run with a stock gn! what do you guys think?

 

The GN V6 turbo motors are not cheap. It is a neat conversion though. It really depends on what you want you could build your 350 to run mid to low 13's alot cheaper than buying a V6 turbo. So if money is an issue the built 350 is a better way to go.

 

Swapping to the non GN heads would be the biggest part of the deal.

 

I'm quoting the entire engine. He wouldn't need the V-8 if he swapped out to a GN V-6.

 

ahh I'll work with the sbc for now