I'm going to convert my 12A carb, which isn't running well at all, to a fuel injected system. I'm comfortable wiring and programming stuff, but vaccuum lines running all over the place scare me. I've researched the hell out of the topic on these boards, and asked a local guy who's on these forums about it as well.

I have a friend who works for an injection and ecu manufacturer as an engineer, who is going to help with the conversion. We are planning on getting a throttle body injection system out of a late 80's early 90's GM car and making an adapter plate to the stock intake manifold. We'll use one of my friend's ecus as a stand alone. Then I'll use my stock air cleaner on top to fool the emissions guys.

However, the local rotary guy, who also frequents the forums mentioned something that caught my attention. He mentioned he had done several conversions using the intake system from the s4 and s5 models, including the tuned intake from the s5 which mildly increases power over a standard intake. I've been trying to track him down to ask about this in more detail, but he's been busy with work and hasn't had time to call me back. SO, i am asking here, because I haven't found anything specific about this conversion on the boards from searching. my 12A is a 4 port, but aren't the NA 2nd gens all 6 port? I am trying to grasp how this would work. I'll probably go with my original GM TB injection idea, but the s5 intake would be much cooler if it's not much more work.

I'm hoping to start the conversion this weekend or early next week and need to start rounding up the parts.

 

The 13Bs from 84+ are all 6 port, except the turbos which are the 4 ports. You can put a 6 port intake manifold on a 4 port engine with an adapter plate just as easy as your original plan. So, take the 6 port upper and lower intakes or however you want to mix and match and put them on a 4 port 12A block with an adapter plate, done.

~T.J.

 

thanks for the info. I haven't actually taken a manifold off of a 6 port to look at it yet, I may do that tomorrow at the junkyard and take some rubbings off of it. I'd like do this the slickest way possible, but if it's gonna be too much work and expense i'll stay with plain old TB injection. Those GM rochester things are cheap and plentiful and my ecu guy knows them.

The other thing to consider is I may have to go with a different set of injectors in the 13b manifold due to the lack of injectors in my center plate.

 

You would probably be best off using turbo manifolds, if you were going the S4/S5 route. That way you would have a 4 port intake to go to a 4 port engine. You would just have to get or make an adapter to bolt it on. One problem is that since you don't have injector holes in the center iron, you would just have the injectors on the intake. The injectors, though, are located on the secondary portion of the intake, so the is little to no air following though them at idle/low load situations. The fuel will still get to the engine, but won't be properly atomized, so gas mileage would probably suffer.

Another option is to go with the TB style injection. There are setups based on weber and holley designs just to name a couple. Get yourself a holley or weber manifold and the TBs to go with them, and you'll be set. Just need to add TPS, air temp sensor, coolant temp sensor, injectors, and wiring.

Here is Mike Robert's setup (pmrobert here on the forum). He is running a MegaSquirt ECU on his 12A.

http://smrmicro.com/v-web/gallery/album01

Kent

 

If your not against rebuilding your 12A, you can re-assemble the engine with a GSL-SE 13B center housing which contains 2 injector sockets.Then youll have superior,factory designed port injection, instead of throttle injection.SE fuel rail,injectors,regulator and pulsation damper will bolt right up and will make things simpler than converting GM or other brand parts to your Rotary.
With the SE center housing your potential intake manifold design/selection would be greatly simplified as you will only have to adress air delivery and throttle.
Also,I noticed your in CA.Are you in a smog check area?It wont be legal if you have to test it.