Author Topic: 81 TA LS Swap exhaust  (Read 662 times)

TATurbo

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81 TA LS Swap exhaust
« on: June 11, 2018, 10:38:32 PM »
I'm working on an LS1 (1999 Firebird) into my '81 TA.   I intend on using the stock '99 exhaust manifolds, which fit with no clearance problems.
Anyone have experience or specific information  regarding using the stock exhaust manifolds and mating that up to a new exhaust sytem for the '81?
I was hoping for a bolt on solution, and the part that I'm concerned about is that initial 'down pipe'...Connecting the stock manifold flanges to a down pipe that I can build the rest of the exhaust system from.

Anyone tried using the mid 4th gen down pipes in this or a similar swap?  What are the odds that I could use all (or at least the top part with the matching flange) of the 99 down pipes to start the exhaust system?

Any insight would be appreciated.

Thanks!
-Tom
Tom
King of Prussia, PA

1981 Turbo Trans-Am
Build thread - http://transamcountry.com/community/index.php?topic=69897.0

jonathonar89

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Re: 81 TA LS Swap exhaust
« Reply #1 on: July 23, 2018, 08:28:34 PM »
I’m looking at doing this as well.  Once I get around to installing my headers/exhaust on my ‘98, I will have the stock ‘98 exhaust for my ‘79.  I’ll keep you posted as soon as I can.  Been a lot of money going into my ‘79 just to get it rolling again and simply setting in the LS engine.

scarebird

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Re: 81 TA LS Swap exhaust
« Reply #2 on: July 23, 2018, 08:46:12 PM »
AFAIK, there is no kit to do this.  I used a header back kit from Summit that had a transverse muffler. 

jonathonar89

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Re: 81 TA LS Swap exhaust
« Reply #3 on: July 24, 2018, 09:27:17 AM »
AFAIK, there is no kit to do this.  I used a header back kit from Summit that had a transverse muffler. 

I’ve been thinking I would be able to utilize the whole GM Y-pipe.  We’ll see what happens there soon.  It’d be nice if I can get a “free” exhaust out of my ‘98 once I do the headers.

TATurbo

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Re: 81 TA LS Swap exhaust
« Reply #4 on: August 03, 2018, 10:01:17 PM »
Thanks for the feedback everyone.
I'm still doing some research, The closest I found was this Dynomax 'off-road Y-Pipe' kit which has the down pipes with the flanges for the stock LSx exhaust manifolds.  The kits are intended for use on the late F-Body's which originally came with these LSx motors.  So, I'm not sure how the bend would match up with the firewall/floor pan of my '81.  Another issue (for me at least) is that it looks like the right side O2 bung is in the y-pipe portion.  I'd have no intention of using the Y-Pipe, so that doesn't directly address one of the problems I'm trying to solve.  Additionally, It's kinda pricey at > $200 bucks. So, I'm not inclined to buy one just to see if I can make it work.   
Here's a link to a diagram from Rock-Auto:
https://www.rockauto.com/en/moreinfo.php?pk=1523274&cc=1357095&jsn=8

I know there are several people who've done LS swaps in 2nd Gen's using the stock manifolds.   The only one I found directly mentioning it put in an X-Pipe set-up, leaving the last section (Manifold to X-Pipe) to be done at a shop.  They had the car towed to an exhaust shop to get that section of the exhaust hooked up.  By the time I pay for a tow and an hour or two of exhaust shop time, I might as well have tried that Dynomax kit. 

I'll post back, but if any of you guys who've done this happen to pass through...Please let us know your solution.

Thanks everyone!
Take care.
-tom
Tom
King of Prussia, PA

1981 Turbo Trans-Am
Build thread - http://transamcountry.com/community/index.php?topic=69897.0

Re: 81 TA LS Swap exhaust
« Reply #4 on: August 03, 2018, 10:01:17 PM »