pp13bnos

iTrader: (1)

Ok...couple weeks ago, i was helping my brouther street tune his blown mustang. He was running a SDS computer that directly plugs into the stock wiring harness. Uses the stock sensors, injectors (He runs bigger injectors of course) but gets rid of the mass air flow meter, and replaces it with a map sensor. So it would be realy easy to install. If you don't like it....just put the stock ecu back in. But anyways, I was thinking....do you think it would be possiable to use the stock computer to run the spark (SDS does'nt run spark on rotarys ) and the SDS ecu to run the fuel. I bet you could pickup atleast 20hp. Get rid of that mass air meter, probably 10-14hp right there...then be able to fine tune the top end. Good for anouther 10 or so hp. (These are just guesses)

I wanted to get some info together of the stock ecu, and how it works, before i asked Rob if he would be interested in putting his time and research into making a kit that would be a throw in kit, for the 2nd gen (mabye GSL-SE guys too.). Could the stock ecu, just control spark...without having a serious meltd down?

The reason i say SDS, because its extremely easy to use. And cheap. A halteck would be nicer, but then you have to install it, use a lap top etc. But the halteck would be more flexable in its abiltiy to dag log, and stuff.

So n/a guys.....give me some ideas!!

CJ

Or do you guys think this is just to far out there?

pp13bnos

iTrader: (1)

Sorry for the last post....i was just typing as fast as i could. It was'nt very clear.

When i looked at my brothers setup....i thought why could'nt the n/a guys have something like this?

CJ

peejay

I think it would be possible to run the SDS ignition setup for a four banger, and fire leading and trailing at the same time. Lots of guys do that anyway, apparently it's how you get max power but it's a little harder on the engine. I'd imagine that you wouldn't run nearly as much advance either... so say if you used to run 20L/10T you'd instead run 15 or so. I know there was a big discussion on leading/trailing split a while back in the single turbo section.

mazdaspeed7

Sounds like avery good idea to me. BTW, how much are the SDS fuel only computers? Its been a while since I looked.

Im curious as to which parts of the wiring harness you would need for the stock ECU to run ignition only. I

FPrep2ndGenRX7

The SDS unit can not control igntion. I've called them and confirmed they could not get there unit to work reliably and keep the price reasonable so they quit working on it about two years ago. The only way I know to use the SDS unit on a GSL-SE or any N/A 2nd gen is to install an electronic distributor off of a 81-85 12A engine. You can use the SDS with the factory intake and totally eliminate the factory harness(which is prone to porblems the older it gets). This setup will get you 140HP to the rear tires with a stock port 13B out of a series 4 car.

I think the only current unit that will work on a rotary engine is the EM-3 D. It cost about $760 and includes everything you need to install it on a factory intake(wiring harness, sensors, controller, etc..). Distributor and coils not included.

I'm going to run a setup similiar to this on my mildly ported 6-port 13B with the hopes of 170HP to the rear tires. I would be extremely happy with that.

www.sdsefi.com

pp13bnos

iTrader: (1)

I know that the SDS unit does'nt control spark. But i wanted a system that i could plug into my stock harness, with little cutting on it. I wanted the stock ecu to control ignition, oil metering pump, and the sds system to control fuel. I installed and owned a system on a peripheral port engine. And done some street tuning with a couple different cars. My old rotary truck is on there web page. I'm pretty shure i could install a system in less than two hours...but like i said, i would like something that is just a plug and play. With very limited cutting, CJ

FPrep2ndGenRX7

Thats your truck. Very nice. I would be very interested if you could figure out a way to control the ignition. I think you and I are the only ones on the forum that think the SDS unit is worth using. Everyone else is convinced the Haltech rules. It is very nice but way out of my price range. Easily two to three times more expensive than the SDS once you get everything you need.

mazdaspeed7

I really like the SDS, but I wish it could control spark. If it did, I would definately go for it, but Im leaning more towards a Wolf3d, because it controls spark and fuel, and it is easily swappable between 2 vehicles if they both have the harness.

j9fd3s

iTrader: (3)

you could use an f-con harness, it only uses the map sensor and injector wires. if you want to do haltech talk to paul at k2rd he has some plug and play harnesses. or you could wire in a power fc.

mike

peejay

Why can't you control spark? Sure you can't control leading and trailing individually, but if you treated the engine as a 4-cylinder and put one coil pack on one rotor (firing L&T simultaneously) and the other coil pack on the other rotor it should work.

I forget if it's Haltech or Autronic but one of the popular aftermarket ECUs in Australia has to be run this way and they don't have problems with it.

peejay

Here ya go:

https://www.rx7club.com/forum/showth...t=timing+split

Bambam7

I don't really want to think about it right now, cause I feel lazy, and I'm sure I'll think of something in a few minutes, but is there an easy way to fire the trailing/leading at the same time?
Can I just splice the igniter signal wires from the leading coil to the trailing coil? (disconnecting the trailing wires of course)

The stock ECU uses a few inputs to caluclate advance... I suppose you can leave the stock ECU intact, feeding all of the input to it, but also splice the inputs off to the SDS, and unhook the injector wires from the stock ECU, and hook them up to SDS. You will probably need to run a wire from the stock ECU injector outputs to ground, with an 8ohm resistor (or lower, depending on year of make), to prevent a code from the ECU, or it shutting off or something.

OK, that solved- next prob.
Without the AFM detected, the stock ECU will go into failsafe mode, which means basic fuel injection(but who cares if useing SDS) but also basic timing advance (loss of power...not good)
I suppose you could fake having the AFM there to the ECU, by putting a resitor across the pins of the AFM plug, but I'm not sure how it would affect timing not having the AFM there to gauge air input. It might trigger failsafe anyways since it won't be giving the "expected" signal most of the time.

I'm sure Six Rotors, ReTED, or Irv can voice how the ECU uses AFM input to modify timing.

This could definately work, but I'm a real hack.

Bambam7

How does the SDS (Who makes that anyways? I've never heard of SDS)
calculate fuel without the AFM?? Just TPS and RPM?
I love the ida of getting rid of the AFM....
How much are these computers??
I wouldn't need and S-AFC for my bigger injectors if I got this I'm assuming....

peejay

www.sdsefi.com

BTW go to the "Project Page" and click on "Rotary Truck" Yeah that MIGHT be enough power for a REPU... (dammit CJ you shoulda gave thet truck to me instead of selling it for, you know, MONEY )

pp13bnos

iTrader: (1)

To be honest....over 110mph that truck was realy scary! BTW, 110 was when i was shifting out of 3rd gear. It was fun...but it was time to move on. I wanted something with that much power...but quite. My 3rd gen is faster now, than my peripheral ever was. Not on the nitrous of course If you guys ever get a chance to ride in a peripheral car, you should. Nothing comes close to the feel of the motor come up the power band. Its like someone droping 75-100hp right in your lap. Lots of fun. CJ