TTA Heads and 87 GN Swaps

[EricN]

Alright, I was under the impression that if I decided to stick with the 87 GN heads I have now that I would lose my A/C but I talked to John from Johnsperformance today and he said I am gonna have a hell of a time trying to route my exhaust if I use the 87 GN Heads instead of the TTA heads. I am using the H&R Poly Mounts so I know that will give me a lot of clearance with my downpipe but does anyone know anything about the clearance issues with TTA Heads vs. 87 Iron Heads? I have no problem losing my A/C (it doesn't work anyways). Just need some more personal experience opinions here. I can have custom headers and other pipes made but I just have to make sure I am not gonna be sawing away at my engine bay or frame to get stuff to fit. Thanks

BTW: This is going in a 1991 Pontiac Firebird

[Vyse]

From what I've read, the TTA used FWD heads, because they flowed the same and gave them the clearance they needed. That's all that I know.

[gnx7]

do a search first.....

.....but I've heard that you can put in a GN engine.... but the a/c compressor won't clear the strut tower. A 3" downpipe as long as you run a TTA style elbow and fabricate the rest should work.

There are a few guys on here with '86-92 style Fbodys and the GN setup.

TTA89 knows someone directly I believe. His name is Randy if memory serves me right.

-Mark

[Nashty]

If you can, or know someone who can reasonably, make a new passenger side header, you can move that turbo to exactly where the best position is. Consider not using a Huston type pipe, get an external wastegate, put it on the crossover and you'll have a lot more freedom with downpipe position.

Mine is like an ATR in design but the driver's side comes up underneath instead of beside the other pipes. The turbo is also lower and closer to the center of the car with this header.

It's a 3.5" DP and the hood closes with no humps or scoops either.

The temptation when you're faced with a difficult hurdle is to try to make the inadequate readily available part work. It's often easier (by the time you're done) to bite the bullet and do it the hard way.

[Nashty]

This might help...

[Nashty]

Another

[EricN]

Thats a 86-87 GN engine in ur fbody?

[Nashty]

F ??

No baby, it's a G-thang.

[EricN]

I have seen pics of your car before. Very cool.

[UR50SLO]

You will be able to use every part of the stock GN engine.
I would also buy the "begining" of the Terry Houston 3" DP for the GN instead of the TTA. We've used both and the TTA is more restrictive and does not fit as well.
You won't have any problems with the strut towers even if you run the A/C pump. I'm sure the A/C fitting problem could be solved with a little fabrication but you said yours does not work anyway. I'm in the process of buying the 86 Camaro I built with one of my customers. I've got alot of experience with this body and suspention to make it work.

E-Mail me any time for help.

Might be able to help you get yours going if your not too far from Indiana. I'm in Elkhart. (close to South Bend)

~Scott

[EricN]

Originally posted by UR50SLO
You will be able to use every part of the stock GN engine.
I would also buy the "begining" of the Terry Houston 3" DP for the GN instead of the TTA. We've used both and the TTA is more restrictive and does not fit as well.
You won't have any problems with the strut towers even if you run the A/C pump. I'm sure the A/C fitting problem could be solved with a little fabrication but you said yours does not work anyway. I'm in the process of buying the 86 Camaro I built with one of my customers. I've got alot of experience with this body and suspention to make it work.

E-Mail me any time for help.

Might be able to help you get yours going if your not too far from Indiana. I'm in Elkhart. (close to South Bend)

~Scott

I am a friend in south bend and I am located in Michigan so its not to far at all. Did u happen to run those H&R poly mounts? they say that you get more clearance with them on the downpipe. I bought them so I guess I will find out. So the stock 87 GN headers work fine and the "beginning?" part of the terry houston GN downpipe? How do I order just the beginning part and do I have to fab up the rest of it or am I missing something?
Oh and I am running the 700r4 tranny, I just bought a TCI adaptar plate so the buick engine will bolt up to a chevy trans.

[UR50SLO]

You'll want to cut the "ears" off the transmission for mor clearance with the 200 or 700R.
You can order the first 10" or so of the THDP directly from Terry Houston. Call a few people you'll get his direct number and he will sell to you. It's not 300.00 eather! From the start of that down pipe you'll be able to purchase a few bends proably 2 90's and 2 45's along with a little section of 3" and have a excellent fit for the DP. I can fabricate it with little problem. All the stock GN headers will work out fine along with the HR Parts motor mounts. Good choice

Wiring is faily simple. I know all the damn wires by hart now that I've done 2 GN swaps into F-bodys along with LT1 into S-10s ect.
Let me know if I can help,

Scott

[UR50SLO]

The above pic is of the exhaust,(9" with south side bars and no lower controll arms. (Can't see the coil overs)
Below is the drivers side motor mount with stock GN frame pad welded in place and the HR motor mount.

[UR50SLO]

This is Paul's engine in the car (customer I'm buying car from) Note the Front mount IC before the core support. That's what it will look like when all finished. Keep your head up it's worth the wait and effort!
~Scott

[EricN]

Originally posted by UR50SLO
This is Paul's engine in the car (customer I'm buying car from) Note the Front mount IC before the core support. That's what it will look like when all finished. Keep your head up it's worth the wait and effort!
~Scott

Dang that looks so good. I can't wait to get this all done. Thanks a TON for giving me an idea on how things are gonna go. If you don't mind, I will deffiently be contacting you in the future to ask some more questions probably for my swap. I am sure it will go by 10x faster if u can help me out with a few things since you have done more then your fair share of GN swaps in fbodies and other hybrids. Thanks for the pictures. Anything else I should know? This is the current setup I have.

87 GN engine, bored .020, ported polished heads, port matched intake, diamond forged pistons, thermal coated combustion chambers and tops of pistons, 208/208 cam, full rebuilt engine from the bearings to the valve springs, accufab 65mm plenum/tb w/ rjc powerplate, cas v2 fmic, te45-a turbo, 73lb injectors, reds chip, lt1 maf w/ translator +, etc. etc...