oregonarchaeologist

Helping my dad resto-mod his RX7, and we want to convert it to fuel injection. Its the 12A engine, and we were thinking of using a chevy tbi throttle body and fuel injection system, with a speedwino (sp?). Was wondering if anyone had any tips or tricks, or thoughts? Has anyone else had luck with different parts? Any help much appreciated!

t_g_farrell

iTrader: (1)

It would be easier to put an EFI 13B in from an FC or GSL-SE. The throttle bodies setups aren't so hot for rotaries. There have been threads on here about folks trying various ones out.

j9fd3s

iTrader: (3)

the TBI style setups are using a manifold with a plenum, and the rotary intakes are setup to be individual runner, so the TBI setups tend to not work very well out of the box. there are plenty of Weber style intakes and you can buy throttle bodies with injectors in them.

or you can rebuild the engine with an EFI center plate, like a GSL-SE or 12A turbo, but unless you had the stuff in front of you, you might as well build a 13B

LongDuck

Maybe a better question is; what does he want to get out of the car when he's done?

Most of us have modded out of necessity for reliability or because of parts that are no longer available. The typical route this takes is upgrade of parts when an OEM part fails so we don't have that weakness in the car anymore; case in point, the Moog Idler Arm. If your dad is simply looking to improve the reliability of an older rotary car, the Nikki carb is the last thing I'd touch, as these have been proven to run acceptably well as long as you don't try to rebuild the needle valves and seats, float them correctly, and don't overfeed fuel pressure. They perform well just as Mazda set them up, and know that removal of the Rats Nest can lead to idle issues for the sake of cleaning up the engine bay.

Your dad may be better served by opening up the exhaust with a Racing Beat header or one of their mufflers, and going from there. At this point in age, the car would perk up pretty well if he replaced the springs with RB lowering springs, put new shocks and strut cartridges in, and also replaced the suspension bushings, arms, and any rubber joints which are probably dust anyway. These simple improvements, along with a new radiator (I like KoyoRad), and other routine tuneup items would get the car working a lot better for the driver. TB EFI is throwing $$$ at a non-existent problem.

Give it some thought and reply back,

elwood

iTrader: (1)

My 12A is still carbureted, and I'll probably leave it like that. It has historical significance for me, and my other FB is injected, with a 13B-RE engine, so I know what EFI brings to the table. If you want to do EFI, start poking around. I went with a standalone aftermarket ECU on my injected 13B-RE car, but there may be other options for your 12A project.

When it comes to mechanical parts and pieces, I've bought from this outfit and been impressed with the quality: https://www.efihardware.com/products...t-tapered-bore

Let us know what you decide to do.

Mivroum

Carburetors are simple, carburetors are easy, carburetors don't need electricity.

mazdaverx713b

iTrader: (91)

I did a resto-mod type restore on my 85 GS. I put a GSL-SE engine in the car. Its fuel injected and I had to use the SE harness and ecu, make new fuel lines, make and engine mount, use an SE gas tank etc. Its a great runner and nearly everything was bolt in. Couldn't be happier with it. I didn't want anything crazy, just a fun reliable cruiser. Everything else is original to the car and looking at it, you'd think it was just a standard GS. Its just an idea.

sommmatt

iTrader: (2)

If you're planning on doing something with a speeduino then you already know pretty well everything has to be fully customized.

GM TBI on a 12a can work provided you do your homework about where fuel needs to be going in the 12a intake manifold.

Just remember even in 2008 Mazda had trouble flooding fuel injected rotaries.

I'm all for bad ideas and doing things the hard way, trust me I am, but I really think if you want to play with speeduinos and fuel injection conversions, a 12a is a pretty hard place to start.

Richard Miller

I knew that I wanted EFI this time for my 1980. While soul searching this is what I concluded. My car will see mainly excursion trips. Not likely any track time and even if it does see track time Im thing to build a balanced car. Example, from my undersrtanding ITB or Webers work really well for high rpm peak hp, but low end suffers. I wanted to have the staged intake for better road drivability.

As for the EFI, an observation was that options like Speediuno or mega squirt seemed to attract two main types. Electrical engineers who put together Heath Kits and hung out at Radio Shack,or people on a budget who lack the education needed to be successful. I chose to go with a Haltech 750 Elite. but the DYI autotune was in the lead for a while.

talk to these guys about speediuno:
https://speedyefi.com
Issac may be able to help you out.

tommyeflight89

iTrader: (4)

I don't see the benefit. A nicely restored OEM fuel system (dipped and coated fuel tank, new lines, order a pump/filter from Dealer..) and an original Nikki is hard to beat.

An OEM Nikki behaves and drives so well I am not sure why anyone would want to deviate. This was the setup that provided a perfectly reliable daily driver to original owners 35 to 40 years ago.