12a Turbo
 

Well, just bought a 12a turbo from Japan2La. I don't know much about the engines so I am looking on advice from someone who has worked with them.
I am thinking about going with a Megasquirt II EFI kit.

Anything I need to know so I can have my car ready to install it when it gets here?

I've got a totally stock '85 GS.

Thanks,
Dylan

G/L with it post pics up when you have time, Japan2LA is a good seller.



Trini

Thanks, I will definitely get pics up as I progress. Going to be working in the winter, luckily I have a heated garage.



Planning on bolting it onto my 12A transmission, will it take the turbo?

12a trans will not take the abuse if you hook up.

A TII Trans would work right?

Yes, a TII transmission will work for what you want to do. It will take some minor modifications to get it in there but it will work. Do a search in the 1st Gen forum on TII Transmission and you will pull up at least one thread on how to get it done. Good luck!

You can blow any transmission with stock 12a power. The question is how hard you are on it.

Bad 83 ran a turbo'd 12a with 15psi on the stock trans. Never blew out.

Thats what I was looking for ;) Right now I just need a running car, not looking to do any major upgrades until summer comes along.

the stock 12A-T ecu is similar to the gsl-se, except it has TWO ecu's. one emissions control box like the us spec 12a, and one ecu like the gsl-se.

megasquirt would probably be easier than hooking up the 12AT ecu's provided you get them. next would be a gsl-se ecu/harness...

Yep, it isn't coming with the ECU's I believe, so my first choice was megasquirt. Need a harness though.

12a turbo
 

i just installed 12a jdm turbo in my racecar.i changed the efi and is running a 600 holley blow thur set up. make sure it come with the dist.

The easiest way to do this, is to run a TII CAS, and let the Megasquirt handle both ignition and fuel. I have one of these engines myself, running a stock 12AT tranny, and it handles 500 RWHP no problem. If the tranny does not come with the engine, run a TII, it will handle way more than the stock 12AT.

Also, if you are planning on running more boost than stock, get a front mount intercooler..

I have a volvo FMIC at the moment. An OEM 12A transmission won't work? Because I don't have a 12at tranny

12a turbo
 

would a measquirt ms122-c w/pcb2.2 work. for fuel or both fuel and ignition. you can email me at sonnytalfred@yahoo.com

So I could use the ecu and harness from a gsl-se?

it plugs into the engine BUT its not going to "see" boost, so you need to be careful

Would a harness from a turbo 13b work? Just trying to find out something that I could buy instead of a 12AT harness, because no one seems to have one :P

I think FI would technically work best, but it sounds like you are going for simple easy and effective... In that case, I think a nice boost prepped carb and rising rate fuel pressure regulator would work nicely.

no. the 12A-T and GSL-SE share most of their (weird) sensors.

if you had to run some other stock ecu, you'd have to swap out a bunch of stuff on the engine

Just get a microtech lt8 :nod:

Yeah looking that way. I was just trying to see if there was anything I could get quickly. Thanks guys, I'll be posting some pics soon.

If anyone could point me in the direction of a site with 12AT harnesses please PM me. lol

When you get the 12a Turbo can you post lots of pictures of it from different angles? It's a rare engine... I've seen more 20B's than 12a T's

I wouldn't recommend a Megasquirt unless you already have experience with wiring and tuning standalones. It has less support than the other options.

I'll take pictures of whatever you guys ask. Rx7club has helped me enough, I think I should return the favor :P

I'm not sure if you were planning on pulling most of the stuff off the motor for cleaning/inspection, but I would love to see good quality shots the stuff in this area:

https://www.rx7club.com/attachment.p...1&d=1260803696

I like to study OEM designs, I think they teach you a lot about cars. I've been studying the Turbo II and the FD a lot. I am VERY curious about this 12a T because I think it can teach us a lot about the evolution of the rotary since Mazda built on these designs. It's just like how you can see a lot of the GSL-SE designs in the Rx-8 today.

I've got a gazillion questions in my head that I don't expect to be fully answered. Things I'm interested in on your motor:

The thing in red I'm guessing is the intake manifold. I'd live to see the inlet and outlet of this piece. The engine is not intercooled. What does the LIM look like? How is oil and coolant routed for the turbo, do they connect to the front cover? Is the turbo even water cooled?

This is a fuel injected car right? What does the fuel rail look like... are the injectors really the same as the light blue Greddy 720cc's ? I heard a rumor that Greddy resells 12aT injectors, they are 720cc low impedence. I have those 720's in the primary position of my T2 right now.

What does the exhaust manifold look like? Mazda changed the exhaust manifold in the Turbo II's, series 4 and series 5 differ.

Are there any markings on the turbo that would indicate the model number? The Turbo II used an HT18, the Cosmo 13B-RE used twin HT10's, the FD REW used twin HT12's, the Cosmo 20B used one HT15 and one HT10. What are the sizes of the wheels on the turbo, both inducer and exducer on compressor and turbine wheels? What does the wastegate look like and what size

Where is the throttlebody positioned... It looks like it's downdraft style? Does it have a large primary throttle plate and then two secondary throttle plates, just like the EFI 13B throttlebodies? Does this car have a GSL-SE style BAC valve (vacuum orifice thingie) or an actual solenoid valve like the later cars?

I would LOVE to see detailed pics of a lot of the components, but even some clear pics of the longblock would be nice.

Yeah I don't know much about that area either lol. I'm definitely going to take off some of the peripherals and such to explore a bit before installation :P

awesome! I'm glad you picked this up, it's so rare

the 12at is neat, ive owned some stuff from them and have seen pics...

1. the LIM basically looks like the carbed 12a intake, although it might be a bit taller? think of a t2 intake with a 4 barrel carb flange on top, and you're close

2. no coolant for that turbo, oil inlet i dunno, outlet goes into the front cover. in the US we got the casting boss for it

3. not sure about the injectors, i had heard they were green? rail SHOULD look like the gsl-se

4. hard to describe the manifold, it looks like a manifold... its like the size of the s5, but non divided

5. http://cp_www.tripod.com/rotary/pg18.htm there were two turbos, both ht18 variants, i guess the FC turbos are larger and a bolt in

6. the throttle body looks just like the gsl-se throttle mounted on a downdraft carb intake (don't the nikki carb and the gsl-se TB share the bolt pattern?)

7. not sure about the idle control, in the evolutionary chain the 12at is BEFORE the gsl-se engine, but it would seem they did them right after the other, so the electronics are really similar, with the 12at being slightly more primitive, with its emissions control box AND ecu, something that was integrated for the -SE

anyways pics would still be much cool... wait until you see the ports

technically the red piece is before the throttle plates so I guess it's not an upper intake manifold, just a cast elbow piece connecting the compressor outlet to the throttle body. I think I see an IAT sensor in that cast piece. The TPS looks exactly like the other TPS sensors from the era. It seems like the basic TB design begun with the 12a T continued for 20 years, all the way until the series 8 FD left production in '02. Rx-8 is a single butterfly drive-by-wire TB. The secondary ports are opened by vacuum (secondary shutter valve and vacuum chamber/solenoid) and the auxiliary ports are controlled by a motor.

I can see that the 12aT doesn't have much of a plenum really, unlike the GSL-SE and later 6 ports. Later on the s4 Turbo II had a plenum after the sidedraft style TB, with slight modifications in the s5. FD 13B-REW has long runners and a small plenum, Cosmo 13B-RE had a much larger plenum volume. Both had bigger throttlebodies.

Solenoid rack and ACV look familiar.

My Greddy 720's clearly say "Denso" on them. They are a light blue but that could look greenish if they were old enough I bet. They are the exact style as the early series 4, same impedence and exact same early Bosch style connector. I think it was Keith from KGParts (which makes a lot of FD fuel kits) who said that the Greddy 720's are GSL-SE injectors. It wouldn't surprise me given that the GSL-SE's are 680's.

I don't know if you've seen the s4 manifold. The s4 turbo is actually divided but the manifold isn't. The manifold has a flapper that closes one of the turbine housing passages (the larger passage) in low rpm operation. The FD exhaust manifold is similar--it has a big flapper that closes when only the 1st turbo is running (the Turbo Control Valve). It also has a small flapper that opens in mid rpms as the secondary turbo is just starting to spin up ("precontrol valve"). That's controlled like a wastegate. FD has dual boost control solenoids.

Interesting. I wonder which turbo the OP has? That's a good site btw. The FC turbos may not bolt in. The series 4 and series 5 have different flanges, so one of them won't work for sure.

I'm guessing the emissions box is for the ACV etc like on the 12A. The fuel injection on 12A T and GSL-SE is really crude. Two batch fired injectors is very imprecise, especially compared to the duty cycle-based injector staging of the series 6 and later RX cars.

For spark control, I know the GSL-SE just modified the vacuum signal to the distributor some. I presume the 12A T is the same?

1. it would not surprise me if the greddy's were the same part as the 12at, the greddy injectors must have come from SOMEWHERE. gsl-se injectors are orange, ive had new ones, used ones several of the cars, 100% they are orange. its like a carrot color. oddly we had 4 of em cleaned and flowed, and they came out at 700cc... it'll be interesting to see what the 12at has

2. ive had s4/s5/fd's and the 12at looks like the s5 but the turbo is more centered, and its undivided. it does not have the twin scroll or anything like that either. it looks like a t3 flange too, but i bet its not. ive read you can use the FC turbo as an upgrade, i do not know if its just the wheels, compressor or what. if you do a little searching on ausrotary you'll get a bunch of hits on it. boost control is like s4, its just the wastegate spring

3. i actually had the ecu's and one box looked just like the gsl-se ecu, the other box looked just like the US spec 12a emission control box. i found a wiring diagram and it appeared (it was japanese) that this is exactly what they are. they are piggy backed together too, some things like rpm, are shared by BOTH boxes, its really funky.

4. yep, all of the rotaries have a solenoid between the vacuum source and the vacuum advance. so they can turn it on and off. i have never checked a gsl-se, but i did check a 12a, and its very simple, vacuum advance is OFF at zero throttle. the 12at has different vacuum advances that allow retard as well as advance.

one would presume the 12at uses the same strategy, but i don't actually know.

I have all the parts for the 12AT in my basement, and i can tell you this much:

- The injectors are actually light green and sized 850!
- The dizzy is unique, and very much sought after down under..
- Turbo is a Hitachi HT18 unit, two different versions were available.
- It has a very primitive knock control system, never really looked into it
- Centre plate ports are tiny! Secondary ports are the same as other 83-85 12A
- Rotor housings are also unique to the 12AT. It has provision for oil lubrication on top, like the 13B

If there is interest, i could find a camera and take some pictures?

Please and thank you :)

When will you be needing these parts? I have an 85 GSL-SE running and I am going to make a NASA ITS out of it. So I will be ridding it of the ECU and harnesses. I don't know what it is really worth other than Ebay prices.

gd

The tricky thing about injector flow ratings is that it depends on what fuel pressure they are tested at.

Here are the Greddy 720's:

http://i2.frsimg.com/images/detailed...3500072N_5.jpg

They probably aren't the same thing. Unless Mazda put two different sets of injectors on the 12a T? If they had two different turbos I suppose it's possible.

Any 12a T pictures you could post would be awesome. Clear closeups of specific parts or specific areas of the engine bay would be nice... I think we've all seen full engine bay shots.

found a thread on 12aT injectors: https://www.rx7club.com/1st-generation-specific-1979-1985-18/12at-800cc-shouldnt-660cc-212285/

I can't find any consensus on this issue.

It would be awesome if someone could find a part number on their 12aT injectors and post a pic.

Found mine, made a thread!

Any more pics on the 12A turbo I am very interested

Ask what you need and I'll take a pic.

Haven't updated this much.

Things I have done so far...


Street ported the engine a little, and painted.
Had a buddy make a custom T4 turbo manifold for the 12a.
Just put the engine into it's final resting place. Going to start making stuff happen in the next month or so.

First picture is just a joke.. I was excited to finally get the engine in so I threw some pipes on it.

https://www.rx7club.com/picture.php?...ictureid=30057
https://www.rx7club.com/picture.php?...ictureid=29893
https://www.rx7club.com/picture.php?...ictureid=29892


Still need to get some fittings for my fuel rails, a TII starter, coils, modify my driveshaft, set of gauges, BOV, etc. But it's finally starting to come along.

So how did you get the TII manifold to line up? Does the lower part of the 12at manifold bolt directly onto the top part of a TII? If so, couldn't you have put a 3rd gen manifold on it?

Did you tear it apart and port it? 2nd gen CAS?

What ecu setup did you end up with?

Thanks, sorry for all the questions

For the intake I used an adapter plate like this one,
http://www.tweakit.net/shop/images/1...anifold_fr.gif
You can find them at tweakit. I don't think it can use the 3rd gen's LIM, but I could have modified a S5 LIM to bolt to a 3rd gen UIM.
I am probably going to weld the adaptor plate to the TII LIM because the extra inch between the block and the LIM is causing some clearance issues that wouldn't be there otherwise.

Me and a buddy took it apart and replaced seals and ported it.

I'm using a 2nd gen cas.

Going to run a wolf3d ecu.

Looks as though the work done on it was really good, and that makes me happy. Since you're replacing pretty much everything with the engine, however, I have to ask why you didn't just start with a normal 12A and make all the same adaptations? Either way, it will put down some good power with that gt35r. Prior to my selling my FB I was going to use a gt30r, and hope for around 250-300 horsepower. I was also going to run a blow through setup, though, rather than going EFI. I had everything ready for it but had to move, so I had to sell the car that didn't run.

Enjoy the car. :)

I don't know why lol.. I bought the 12AT and was going to keep it stock but things took a change, and the 12A I had had almost 200k miles on it so I decided to just use the 12AT.