Changes to a GN 3.8 to fit in a F-body?

[Roc87]

What would I need to change in my '87 Iroc to make a 3.8 "complete motor" work? Right now the Iroc has a L98 from an '89 Vette w/ a painless wiring kit. I figure that I'll have to change the heads, get the exhast manifolds for a TTA, Change to a different fuel pump, run the complete wiring harness from '87 GN. Will I need to change the intercooler or are the the same from a GN to a T/A? How about the downpipe? Anybody else done this swap? How'd it go?

I'm really interested in doing this swap, I've spent way too much on my '87 IROC just to sell it and that's what I've thought about doing since Dumping all that $ and it's still slower than the GN!

 

[Hi-psi]

A stock GN motor will fit fine into a 3rd gen F-body. The only problem is you'll have to loose your A/C. There's no room for the compressor. That's why Pontiac changed the heads. So, if you can do without A/C, get a GN motor,....drop it in with the TH200R-4, and the only thing you'll have to work on is getting a custom down pipe. To keep your A/C, get either a TTA motor, or get a GN motor, put TTA heads on it, get TTA headers, and you can use a TTA down pipe. The only thing about putting the TTA heads on a GN shortblock is it will raise the compression ratio up a bit,...so you'll have to run a little less boost. BTW,...the TTA intercoolers are a little more efficient,...but either one will work. And yes,...you'll most likely need to swap the in tank pump to a Walbro 307 or 340.

 

[Roc87]

Losin' the A/C is no problem, already took everything off relating to a/c. Put on a heater box on the firewall from an '85 Camaro Berlinetta. So W/ out a/c, this thing will bolt right in using GN exhaust manifolds and crossoverpipe as long as I get a custom made downpipe?

 

[bruce]

You already got the engine info.,

for using a 200R4 takes a different tranny cross member, Spohn (?) Engineering makes the right one for putting a 200R4 in a FBod.

I think you have to do some driveshaft work.

 

[Hi-psi]

You can use the TH-700R4 with an adapter plate from TCI, or use the 200R-4, and like bruce said,...get a TTA cross member or the Spohn unit. I upgraded to the Spohn unit which is really nice and just recently sold my stock TTA crossmember to a guy doing a swap into an 85 Camaro. I'm not sure about the driveshaft length,...this isn't a real big issue. You'll have to fab up some motor mounts also. Seems like the big issues will be all the electronics, motor mounts, and down pipe. Everything else should be fairly easy.

 

[Roc87]

fabricate motor mounts? Could I buy some from a Pontiac dealership or are these just like everything else, Discontinued?

 

[Hi-psi]

Originally posted by roc87
Could I buy some from a Pontiac dealership or are these just like everything else, Discontinued?

Yupp,......you guessed it. There is a company I believe making some polyurethane mounts. These aren't out yet.

http://hometown.aol.com/HRpartsNstuff/myhomepage/auto.html

 

[Roc87]

Well, I found a totaled '86 T-type for a "steal", car has been sitting for over 2 years, checked the oil and tranny fluid, put a decent battery in it, cranked over 2-3 times and fired right up, even idles better than my '87 GN! So here in the next few months I'm going to see how this swap goes. Thanks for the suggestions!

 

[Roc87]

I forgot to address this problem. What do I do about the torque bar? Will the tailshaft from the 700R4 bolt to the 200R4? I know that I'll have to do something about the driveshaft length, so what happens to the mounting for the torque bar? I'm assuming this will have to be fabricated also? Thanks!

 

[TurboTA3.8]

no it wont bolt on it bolts to the trans crossmember in a tta


george

 

[GNVAIR]

Buy an after market torque arm such as the one offered by Spohn and you wont need the TTA crossmember. That way you could use the TH2004r

 

[Roc87]

Ok, So the torque bar bolts to crossmember. Spohn makes the crossmember and the torque bar? Is it possible to use my stock torque bar or crossmember? Or am I going to have to buy both from Spohn? Thanks guys!

 

[Roc87]

Nevermind, Just found spohns web site, I'm going to have to pay almost as much for the crossmember as I did for the '86 T-type!!

 

[TurboTA3.8]

well if u are a good welder weld one up

 

[Hi-psi]

Another option would be to use a TH700R-4 and just buy the adapter plate from TCI. This is usually what Steve Kaminski does. He says the 3.8L Turbo seems to like the little taller 1st gear that the 700 has. I'm not sure how much the adapter plate is,...I can't imagine it being more the the Spohn unit though. BTW,...if you do get the Spohn unit,...it is worth the money. It's a really nice unit, comes with an adjustable torque arm to change pinon angle. I have one on my TTA.

 

[1badTTA]

TTA engine

as far as the internals of the TTA engine goes, the only difference other than the heads and pistons (resulting C.R. of 9.0:1) is a hotter camshaft (higher lift, couldnt find the duration specs)
the TTA heads with GN pistons will result in 9.27:1 C.R. so a little less boost will be in order.

judging from what mine and several other TTA's have run compared to the GN/TR's all in nearly stock trim (stock engine, injectors, turbo, and exhaust) the added CR and better flowing heads/hotter camshaft makes a pretty big difference
even with the stock cars that the magazines tested brand new (TTA's and GN's) there was about a 1 second difference in 1/4 mile times

just my $.02 but i would change the cam and heads and then just get a TTA downpipe instead of having to have one custom made.

 

[webleyaz]

Re: TTA engine

Originally posted by 1badTTA
[Bjust my $.02 but i would change the cam and heads and then just get a TTA downpipe instead of having to have one custom made. [/B]

ditto.