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

12at

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Old 03-29-03, 07:59 PM
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12at

I have a question about the 12AT. I am really considering swaping my engine (By the way, I have a 1985 RX-7 GS) for the 12AT one. Then I would add an intercooler to it. This seems like a neat setup and I was wondering if anyone could give me some advice on this. I was told to talk to 680rwhp about this process. Could anyone tell me where I can get a 'package deal', which includes the engine, computer, intake, ect. Finally, I have a Racing Beat Exhaust and I was wondering if any of it could be spared. Thanks for your time. If you want to e-mail me, that would be great. Thanks
Old 03-29-03, 08:16 PM
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you best bet would be to make a 12A into a turbo.. it is fairly easy just takes a bit of time.. it wouls be easyer then dealing with computers and geting the engine to you..

do a few searches for blow though setups.. i know we covered it in the GSL-SE swap up above on page 4 i think..

Tyler
Old 03-29-03, 08:35 PM
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the 12at motors arent worth the effort imo. you get the cool factor, but for the price you could easily turbo your car using a s4-5 turbo and manifold with rounded out mount holes, modified carb, and locked dizzy.
Old 03-29-03, 11:19 PM
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Yeah, I'll be going the route gamble described as soon as I can. If you decide to just add a turbo to your 12a, then I would defiantly talk to Robert, he's helped me out a bunch so far, and I havn't even ordered a single part from him yet.
Old 03-30-03, 09:49 PM
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First the 12AT, its a Japanese spec engine which produces about 138bhp. They are expensive to buy and most would need a rebuild. A specialist import house can obtain one for you. The ECU will need replacing with something more modern. The fuel system will need upgrading to a high pressure system, pump, lines, regulator.

Then four modification need to be undertaken to make the project worthwhile
1. upgrade the turbo say to one from a gen 2.
2. add a front mounted intercooler
3. upgrade the exhast system.
4. if you are rebuilding, then go for a street port

The outcome will be in the order of 250bhp and a performance of low 14 second 1/4 miles.

The second option,much cheaper is to add a turbo to a 12A. It is very difficult to add a turbo to a Nikki carb. The beat option is use a side draft like a Weber DCOE 45 with a front mounted intercooler. You will get about 160-180bhp. for this route read moremazda's description called 12A turbo write-up.

WARNING you are adding power to a 20 year old engine. Any boost above say 6lb could lead to an expensivebang. Rebuilding first is the best method of going for major power.

the third option is go 13BT turbo, a low mileage imort engine is easy to obtain and the transplant is very common and done by most rotary tuners. you will end up with about 190bhp in a reliable engine. If you want more power there is a route via bigger turbos and intercoolers to 500 bhp in a street car capable of a sub 11 second 1/4.

I suggest keeping away from the 12AT and going the 13BT route, it will be more reliable and possibly cheaper.

Last edited by PaulFitzwarryne; 03-30-03 at 09:55 PM.
Old 03-30-03, 10:19 PM
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Also remember the 12AT only has 2 injectors. For higher boost you will want to add 2 more, meaning more work and money...
Old 03-31-03, 06:26 AM
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You can get about 220bhp full cycle with the 2 12AT 800 injectors, then for further power you add 2 13BT injectors. At that stage you will be 300 plus hp and thinking of upgraded transmission. I have seen some really good Japanese RX-7 12AT engine bays which match the performance.

One option I have not mentioned is a hybred of mix and matching 12 and 13 parts while retaining the 12AT low compression rotors.
Old 03-31-03, 01:59 PM
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how much dose the 12at cost, i called some of the importers by me and they dont even get them in.
Old 03-31-03, 10:01 PM
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Rotaryshack's web site says they have used 12at's for $800 but I'm not quite sure what they all come with or if they still have one left?

You could always be like me and just get a 12a mannifold, carb hat, etc etc. and not have the money to go through with your project!
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