1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

12at swap info

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Old Feb 17, 2003 | 05:22 PM
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12at swap info

Im looking into getting a jspec 12a turbo since my motor is shot and the new motor is cheaper than me rebuilding my old one (bad rotor houseing)

what needs to be done to accomidate the 12at
I know the mounts are the same and my tranny will bolt fine.

just makeing sure i dont forget anything

im sure youll know 680rwhp

BTW its a base model 82


EDIT: I might not be back to read this today,
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Old Feb 17, 2003 | 05:25 PM
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Re: 12at swap info

Originally posted by wwilliam54

I know the mounts are the same and my tranny will bolt fine.
Your list seems kinda short.
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Old Feb 17, 2003 | 05:27 PM
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From: Raleigh,MS
oh well

mostly im just worried about the fuel system
it the turbo EFI or blow through
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Old Feb 17, 2003 | 05:39 PM
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The turbo engine is EFI. Youll have to try and get the computer as well, or get an aftermarket computer. You could also slap a carb on it, then make it blow through, but from what I hear, its not really worth it. The ports are smaller and the turbo is kinda undersized. If you dont really care about that stuff, the engine is still good for I think like 160 fwhp.

~T.J.
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Old Feb 17, 2003 | 05:49 PM
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From: Raleigh,MS
thanks for the info

the ports are small I know
but thats what die grinders are for

since most of my engine is trash
if wosrse come to worse i can use my rotors,intake, exuast and just use it for cheap houseings

BTW im useing corksport
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Old Feb 17, 2003 | 05:51 PM
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nice sig
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Old Feb 17, 2003 | 06:53 PM
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FWHP = your horse power at the flywheel...
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Old Feb 17, 2003 | 07:02 PM
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Originally posted by wwilliam54
thanks for the info

the ports are small I know
but thats what die grinders are for

since most of my engine is trash
if wosrse come to worse i can use my rotors,intake, exuast and just use it for cheap houseings

BTW im useing corksport
Ok, so if you crack it open to port it, then youre gonna need to rebuild it. Why not just rebuild the 12A you have and save the cost of the 12AT engine?

If thats really the way you wanna go, why would you use your rotors, intake, exhaust etc and then pay $800-$1000 just for USED housings from the 12AT? NEW Mazda housings are like $350 each...So for $700 you could have two brand new 12A housings.

If you just want to have a "true" 12AT engine, I personally would buy one from somewhere, get an aftermarket computer (or stock computer), and make it work. No rebuild. Theyre low mileage anyway, and usually run.

If you want the 12AT engine for the low compression rotors and the dizzy, this is what I would do. Strip it down to the block, get a bigger turbo, front mount IC, intake (carb or EFI, depends on how much money you have), and call it good.

If you wanted true hardcore ish under your hood, tear the thing apart, port it, rebuild it like new, throw it together with a bigger turbo, FMIC, EFI, aftermarket computer, coil packs, etc. Have it all tuned from your laptop, and have fun .

~T.J.

Last edited by RotorMotorDriver; Feb 17, 2003 at 07:04 PM.
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Old Feb 17, 2003 | 10:45 PM
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In stockform the 12at produces about 135-140 hp at the flywheel, about equal to the stock 13b.

Very, very few are low mileage, most available are from 1983 a twenty year old engine. Any attempt to get serious power will result in a blow-up. Remember boost is only 6lbs.

Assuming a perfect engine them a new fuel system is needed to get the higher presser of an efi input, plus a new ecu, and upgraded turbo. The boost will be much higer but so will be the input temperature. The only solution is adding a new intercooler and manifold. The exhast system now becomes a bottleneck so a 'turbo' set-up is necessary. With the higher boost you can get away with the stock porting until about 200 hp at the flywheel. Increasing the port size and power may require a dif overhaul to handle it. By then an electric fan to handle the extra heat is desireable.
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Old Feb 17, 2003 | 11:08 PM
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79+80_rx-7, your sig screams
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Old Feb 17, 2003 | 11:11 PM
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Basically, it seems that it would be more cost efficient to just rebuild your 12A if youre trying to save money .

~T.J.
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Old Feb 17, 2003 | 11:12 PM
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Originally posted by onepointone
79+80_rx-7, your sig screams


Ditto.

~T.J.
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Old Feb 18, 2003 | 08:42 AM
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From: Raleigh,MS
Originally posted by RotorMotorDriver
Basically, it seems that it would be more cost efficient to just rebuild your 12A if youre trying to save money .

~T.J.
heh my intermediate, front and back houseing are shot too

ill take your advice
ill make a dynamic chamber for my carb and get a new fuel pump and regualtor
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Old Feb 18, 2003 | 09:36 AM
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I just swapped my 12a for a 12at. I pulled all the EFI crap and stuck a modified Nikki carb on there (curtosy of Rotary Shack). Blow thorugh Nikkis are easier to set up, and in my opionion are better then a EFi set up, not to mention cheaper. I'll get some pics as soon as it is up and running. Youl also need a Malory fuel presure regulator, and a new fuel pump. Other then that, nothing else is needed.

Peace
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Old Feb 18, 2003 | 10:01 AM
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Originally posted by Turbo12A
I just swapped my 12a for a 12at. I pulled all the EFI crap and stuck a modified Nikki carb on there (curtosy of Rotary Shack). Blow thorugh Nikkis are easier to set up, and in my opionion are better then a EFi set up, not to mention cheaper. I'll get some pics as soon as it is up and running. Youl also need a Malory fuel presure regulator, and a new fuel pump. Other then that, nothing else is needed.

Peace
that sounds like a pretty good budget set up. Is it IC'd? What kinda power are you making?

PS. Nice Sig 70+ 80!
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Old Feb 18, 2003 | 02:37 PM
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Well the engine is still in the works, just bolted it to the tranny on Sat. I'm planning on using a TII IC, so well see what happens. I'm going to dyno it as soon as its running. hopefully I'll be pushing 180hp. If youre thinking about doing a 12at swap talk to 680rwhp. I got my 12at from him and he did a excellent job on it.

Peace
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Old Feb 18, 2003 | 03:39 PM
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Holy ****'n *****! That is a huge fricken sig.

-Error
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Old Feb 18, 2003 | 05:06 PM
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Turbo 12a- how will you add an IC to a blow thru carb system?
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Old Feb 18, 2003 | 05:53 PM
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Originally posted by Paul Fitzwarryne
Turbo 12a- how will you add an IC to a blow thru carb system?
It's no different to how you would on an EFI setup.
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Old Feb 18, 2003 | 06:58 PM
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Instead having the pipe from the turbo go directly into the carb, it is first routed from the turbo through the IC, then from the IC, the cooled air is then pushed into the carb. Get it?
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Old Feb 19, 2003 | 01:21 AM
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From: Raleigh,MS
ill just keep it without IC and run it at stock 6psi boost
I have school coming up in the fall and I want It to stay somewhat relible
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Old Feb 19, 2003 | 06:53 AM
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Turbo 12a- thanks for the info on the IC set-up. I take it the turbo out put is forward to the righthand side of a IC, exiting on the leftside[looking forward] then curving over the engine to the top of the carb

Revhed- I was having difficulty visualising the necessary plumbing for a front mounted IC. You communicated with 680rwhp some weeks ago on the possibility of adding a turbo to your 48IDA, have you any further thoughts?
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Old Feb 19, 2003 | 09:35 AM
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You got it!
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