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View Full Version : Need suggestions, repairing S13 firewall/trans tunnel

tb13
03-31-2019, 09:22 AM
I picked up an S13 from a friend of mine this weekend that was heavily modified to run an RB with custom mounts behind the front crossmember. This required a significant amount of the firewall to be cut out along with the trans tunnel to be hacked up. I have no interest in attempting to run a setup similar to that was intended, I am just looking to put a firewall/ trans tunnel back in the car.

How would you guys go about replacing what is missing? Chop an entire firewall/trans tunnel out of a donor car or just replace what is missing? Really want to get the car back in one piece and make something of it, let me know what you guys think!

https://i.imgur.com/PM0ucXSh.jpg
afishysilvia
03-31-2019, 09:56 AM
Drill spot welds out of donor car and swap in entire section would be correct way.
tb13
03-31-2019, 10:47 AM
Drill spot welds out of donor car and swap in entire section would be correct way.

That will work for the firewall and was the way I was leaning, but wanted to ask.

As far as the trans tunnel is concerned, that is part of the floor board which I can't replace due to the car having a cage. Cutting the same section from the donor car, slightly larger, then trimming to match the missing section should be the best method, right? Will tacking it back into place be sufficient or should it be fully welded into place?
afishysilvia
03-31-2019, 11:57 AM
Factory was spot welded and then body seamed. I was planning to just weld mine in completely then using sealer. I think that would be sufficient.
jedi03
04-01-2019, 09:36 AM
my uncle does that with his race cars and bolts in a piece of aluminum...he advises its significant weight reduction...but up to you!
Kingtal0n
04-01-2019, 03:49 PM
Um wow. I would use it the way it was intended- Put an RB in that sucker and run it.

What can any other engine do that would sound better? Or be any better?

Even if you got an extra 100 or 300 horses from some huge turbo V8 engine it still won't sound and handle better. It isn't worth the extra power at that level in that chassis.

If you were doing a daily driver, a NEO RB25 is affordable and would do 500-600rwhp iirc on a daily pump+meth setting

otherwise a forged RB @ 800-1kbhp E85 is the way to go with something like that in racing