masonrx7

This may seem like a stupid question but does anyone know the differences between a stock12a and a stock 12a turbo (other than one being turbo of course)?

I'm interested in purchasing a jspec 12a turbo instead of doing a 13b turbo swap, and was wondering how much i would have to change on my stock 85 GSL... like would it just bolt right in or what? is the 12a Turbo fuel injected? etc, etc.. Any help is always greatly appreciated.

QuagmireMan

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QuagmireMan

the turbo is what japan got with the 12a (carbed) we got the se fuel injection 13b. i would go tII

hiboost7

12a turbo is fuel injected, turbo, and has lower compression rotors...no real changes to fit it into any non gsl-se first gen.

Alex-7

The 12At is Fuel injected, lower compression, turbo ect. blah blah blah


I think it'll bolt right in, but getting it to run is a differant story.

You'll need to track down an ecu for it (and all the neccecities that managed the fuel for it originally) or carb it, or get a standalone managment system like a Haltech or something.




--Alex

Directfreak

iTrader: (2)

And - it has tiny, tiny ports. Too small for any real power. You'l be hard pressed to make over 220 to the wheels with it, even with EFI etc..

mcnannay

yeah ports are tiny, and to make decent power you'll have to intercool the thing...so when you get into all of that fabrication you might as well just custom turbo you're current setup

the turbo is also quite small

good info on it here http://www.hitman.hm/12AT-hints.htm

masonrx7

Alright.... 13B seems smarter then... i was just wondering and all.. figured the 12a Turbo would be easier.... i found a site that sells low mileage ones in the states (imported from japan of course) for just under $1000 US for the engine...

//[T.0.P]//

So adding turbo to a 12A requires it to be Fuel injected? That would be more money to install a turbo, right? Because fuel injected is actually controlled by a computer, isn't it? .. Going carb I might do because there's no govener .. but then again there are computer for the FI to control that as well ...

Maybe even more mods to keep it carb .. probably the same price for a total turbo install?

hiboost7

fuel injection is not required for turbo setups. carbing a motor is alot simpler and cheaper, but will probably make less power. advantages of fuel injection to carb setups...better cold starting, smoother power band, and more power...down falls = more money, more confusing. if you want more power out of your FB and want to save money do a 13b,carbed, with a nice street port, bolt ons, and weight reduction...then suspension work and you have a quick little street car, thats alot of fun to drive, and is very reliable....if my 12a-T blows, i might just go with a setup like that.

//[T.0.P]//

I figured the real differences between the 12A and the 13B didn't have much difference, but I do know that there is more bhp in the 13B of course. Swapping to a 13B would probably require some heavier mods, like fabrication or something, wouldn't it?

hiboost7

nah, just a 12a front cover, SE tranny and driveshaft....i have never done a 13b swap though, so im no expert.

mortenf

If you go for the 4 port 13B (76-78) you dont have to change the tranny!

DAVID GRIMES

You think like I thunk.

masonrx7

alright seeing as how i started this thread with a question, lets go for another one... i'll probably get many answers telling me to use the search option but here goes... how can u carb a 13B if its supposed to fuel injected?.. and yes i'm a noob...

DAVID GRIMES

The 13B 4 port pre-dates the Rx-7. Cosmo, I think. It was carburated. Not until the '84 GSL-SE did the 13B get fuel injection.

mcnannay

racing beat makes intake manifolds for the fuel injected 13bs

you may want to talk to rob at rotary shack, he's had great success with turbo prepping weber carburators for use with the 2nd gen turbo 13b....going with a blowthrough setup.

http://www.rotaryshack.com/CustomPro...0gxl/85GXL.asp

thats probably one of the cheapest and simplest setups to go with if you don't like the idea of fabricating your own setup.

rotary emotions

You can carb a EFI engine, or put EFI on a formerly carbed engine, no prob.
You can also use a mechanical fuel injection (no computer)
The engines themselfes (blocks) don't need to be modified for all this, only the manifolds.

12at

The main difference between the 12a and the turbo version is the rotors. The 12at rotors are 8.5:1 compared to the 9.4:1 for the naturally aspirated versions. The 12at's also have better chrome on the housings, a 4 port oil metering pump instead of the 2 port and 2 oil injectors in the housings. And obviously a oil return for the turbo in the timing cover.

jasondawson

even newer newbie whats the difference between 12a and 13a. i just bought an 82 and know nothing about mazda just heard there fun to work on so me and my dad are giving his teen dream a whirl!

DAVID GRIMES

It's 12A and 13B. Difference is .1 liter.

nick1

.1 litre?

12a 1.1 litre

13b 1.3 litre

that's .2 liter difference

you suck

DAVID GRIMES

The different names (12A, 13B) come from the displacements. 12A has roughly 1.2 Liters of displacement (actually 1.145 but THEY ( the ******* MAKERS AND NAMERS rounded up ) and the 13b has 1.3.

There's no need to "suck". Just simply hold it in your mouth until the swelling goes down like your mother taught you, you mindless twit.

DAVID GRIMES

Actually 1.55 liter difference.

So how is the barrel-making business going there, sport ?

jasondawson

is there that big of a power difference then?