Moonchopper

I have been trying to figure out what I need to convert my 12a to EFI and then turbo it, but I can't gather any definite information (Yes, I have searched this site).

Here's all that I know as of right now:
GSL-SE upper manifold
RB Lower Intake manifold
ECU (perhaps from 13b?)
Some kind of fuel delivery.

Please let me know what I need for at least the EFI conversion.

Or, if there's a kit somewhere (I doubt it), that'd be nice, too.

jayroc

Well, moonchopper, don`t take this the wrong way, but you`ve got some serious planning to do.
I too considered this seemingly bolt on method in the past, but I can tell you it won`t work out because the injector bungs are located on the GSL-SE 13b lower intake.. hmm, or was it the intermediate housing? Either way, it won`t work out by just using a RB lower intake (I am assuming you mean the lower part of the sidedraft mani) and GSL-SE upper stuffs unless you start custom modifying the manifolds. Which isn`t impossible...
There was a fellow who made an adaptable lower intake work with 13b s4 or s5 upper stuff awhile back, but I don`t think he finished a version to sell.
Me personally, I had a friend custom make a manifold to fit an IDF style throttle body and used Megasquirt. Unfortunately, I didn`t get to work out all the bugs before I had to leave for Japan, but it DID start and run. (Albeit, briefly)

You will want to check out www.msefi.com and www.megasquirt.info. My advice is to use Megasquirt as an ECU and, if you can, custom fab a manifold to match a throttle body of your choosing. I used two injectors from a s4 13b on a weber IDF throttlebody with a custom mani, with an autozone fuel pump from a F150 and a regulator from a nissan vg30e engine, custom made wiring harness, etcetc.
Even if you don`t use megasquirt, the info on their site is good. Learn the basics of what you will need and get as much as can from a junkyard. You shuold be able to do it all for under $800-1000 (and this is a high estimate) depending on how much usable stuff you can get from a junkyard.

Also, one last thing. After I get my setup up and going properly, I plan to follow zbrown`s method and put a m90 supercharger on it. It will be very easy to do, I think. Just bolt it up and you can keep the exhaust you have already.

Moonchopper

Well, as for that injector bung problem, I also read somewhere else that you can use a GSL-SE center plate to allow you to use the GSL-SE lower manifold. I'm going to be rebuilding the engine anyways, as the apex and side seals need to be replcaed (both blown). Would that make it less of a hassle for the injector bungs?

[edit] Also, thank you for the help

grantmac

Your on the right track it sounds like. I'm about to just head first into a 12A efi project myself. There have been quite a few done, info available on the www.msefi.com forum. Also look here: http://www.mazspeed.com/forum/thread...w4d34e8o61h883 My project is a little different in that I'm not going to run a turbo or Supercharger for at least a year because I want to get used to tuning the car with megasquirt without such a larger chance of destroying the motor. As for intake I'll be using a custom aluminum downdraft intake to mount a set of 4 GSXR throttlebodies, I'm working on a way of making them sequential so I can drive around on the primaries and only have the secondaries open at high throttle settings, sort of like a mechanical secondaries 4 barrel carb. I'm expecting that total costs including some freebies I've picked up will be in the $500-700 range. My set-up will look something like this when it's finished: http://www.mazdarotaryclub.com/forum...&threadid=6861 Well I hope that information can get you started, your not the first to get it to work, but it seems everyone has gone a different route to get there.
Grant

perfect_circle

just buy a 12at they are efi, and turbo.

grantmac

Too bad the EFI and stock turbo are crap, not even good for as much power as a streetport NA with good carb can put-out, at least this is what I've heard; 680rwhp would probably have a better take on it though. Why not build a custom log-style manifold? It would be pretty simple, I was gonna do it before I settled on my current set-up, and I may still if mine doesn't give me the type of power I want. You could then use some sort of Ford throttle-body from the junkyard and a set of Tii injectors and fuel pump. You could probably even use a shortened Tii or NA fuel-rail to keep costs down. There are many ways to attack this problem, and all will work rather well.
Grant

jayroc

Good luck finding a good 12at ECU and harness. They are a bit rare. And trust me, I`m in Japan.
grantmac, what are GSXR throttlebodies? Are those the single barrel motorcycle type? I also had the idea for split primaries and secondaries, except it would have looked like a dual carb setup and it wouldn`t be the traditional one carb per rotor, but one carb on the primary, one on the secondary. I think it would work real well with big port motors like bridges or large streetports. Especially after you set the throttle progression correctly.
I was just looking at that link you posted. Real nice setups. I am going to have to look into these motorcycle TBs some more...

grantmac

I'm going all out with them, although I'm going to go with a 38mm set-up non-progressive just for simplicity. Jayroc I'm gonna be modifying one of the first of those IDF manifolds for the project, it should be interesting. Although most carb set-ups say that I should be using 4 carbs with 32mm chokes, I think these won't be too large and should still have a decent bottom end. If I don't get the bottom end I want I'll just make the manifold into a wrap-around one and run them as sidedrafts, thats sort of the beauty of it; I can tune intake tract length by just clamping on different sections of tubing. Once I settle on what I want I'll get it all Tig'd togather.
Grant

Moonchopper

Yea, I've heard that stock 12aT parts are hard to find. But I would think that you could replace them with parts off of something else.

I think I'll stick with N/A for right now, and do blowthrough setup perhaps in the future. I'll just have to wait and see how everything turns out.

Thank you guys once again for helping me out.

wanner

are you going to get a big increase in mpg and power changing to fuel injection over carb? i mean more than 5mpg?

Manntis

Just go 13B Turbo

FD Racer

I can't give you any MPG info yet, but I can tell you that converting over to FI from a carb setup makes a noticable difference. My 13b FI motor with ~250 hp should have considerably better gas milage than my 170hp 12a with a carb.

Moonchopper

heh, the 13B TII will be a project for later days, even though I already want to do it badly.

shm21284

Buy a stand alone computer, and go to www.tweakit.net for throttle bodies with fuel injectors mounted in them. They make a weber style throttle body and a holley style throttle body, both of which you will need to buy the respective intake manifold. They come with 4 injector bungs and use american style (14mm o ring) injectors. Who said it cant be done?? Just gotta be creative and do research. CARBURETION IS A BITCH! a lot of people will hate me for saying that but its true, and it will never run as smooth as fuel injection.

grantmac

Tweakit is sooo much money, and ebay is soooo cheap. Go with motorcycle throttlebodies, it's been done before; although it's a bit more work.
Hey Jayroc, what size was your IDF throttlebody and where did you get it?
Grant

P.S. Full write-up will be made once system is running including all MS files.

Moonchopper

shm21284, is that for the 12aT? Or are we still on the topic of EFI conversions?

grantmac

Resurection!
The Honda CBR F4i throttlebodies have arrived! I'm gonna be starting in on the manifold mods this week and hopefully will have something sorta looking like an intake design done by next weekend or so. Now all I need is the fuel pump, ECU and swirl-pot!
Grant

web777

You would get more of a gain just putting a carb on a 12a. IMO I don't thing it's really worth it going efi on a stock 12a.

CarlRx7

mpg is based on tuning, and how heavy your foot is..

carl.

Moonchopper

Ahhhh...... ****. :P