Starfox07

I can't seem to find the answer to my question anywhere. What would happen if you stuck a renesis engine into something other than an RX8 and tried to run it on the factory ECU? I know the computer would technically be looking from all manner of inputs such as abs sensors and stuff like that, but wouldn't that only trigger a check engine light? Or would it put it into a limp mode or cease to run at all? I keep coming back to the renesis as a perfect engine swap for my S3. I wouldn't be interested in modifying it, just keeping the stock motor with the stock ecu.

j9fd3s

iTrader: (3)

ecu is looking for a TON of stuff, gauge cluster, climate controls, plus the OBDII stuff, etc etc

you might wanna contract racing beat or Cobb tuning to see if they can disable those features.

the evap stuff isn't too bad to hook up, but the CAN network things would be nice to not have to deal with

Starfox07

what are the can net work things?

Attila the Fun

iTrader: (1)

A possibility to explore: When the Renesis engines were first introduced, you could buy a crate motor (supposed to be for Formula Mazda cars) for $4500. I have been told that the motors came with a custom Wolf ecu. IF your state emission laws wouldn't get in the way of that and if the motors are still offered, it might be worth the price to bypass the stock ecu and all its connections, especially if the Wolf can be re-tuned from the factory settings.

Starfox07

Well we have a 25 year cut-off for emissions so that's not a problem. I'll have to look into that. I'm hoping those engines have come down from that price in recent years. Perhaps I can find an ex-race engine?

edit: Looks like the star mazda's use a motec m400 ecu.

edit 2: Brand new renesis engine for formula cars...15k http://www.starmazda.peachhost.com/ct_PR050-524s.htm

peejay

CAN = Controller Area Network.

Nothing is turned on by a switch anymore. It's all computer operated, using data signals.

To give a generic overview with SAE terminology, there is a master module (usually the body control module, sometimes it's the instrument cluster) that, when you turn the ignition key to "on", sends a wake-up signal to all of the other modules. Other modules in this case being the powertrain control module, air bag module, radio... basically, everything.

Note the first one on the list. PCM. You can give power to the PCM, but without the data signal going to it, the engine won't run, because it will never turn on. There's no "power up" wire. You wouldn't have a check engine light, though, since the PCM has to send a signal along the data bus to the instrument panel to pretty please turn the MIL on, kthx. And before it can do that, it first has to power up...

That's why the factory ECU swaps that I've seen included basically EVERYTHING from an RX-8 donor car, including the instrument cluster, heater controls, everything.

Chuck Norris FB

What an *** raping price for a N/A renesis...

Starfox07

Thanks for the explanation. My knowledge of EFI cars goes no further than OBD1. So apart from the Formula Mazda cars, does anyone have a stock(ish) renesis running on an aftermarket ECU with full functionality? (specifically the intake manifold)

I've been searching the web all morning. I keep ending up at dead links, outdated and failed attempts, speculation, and some really expensive solutions. It's like the holy grail.

j9fd3s

iTrader: (3)

i'm sure people have done it.

MOST of the engine is just like an 89-91 NA, the big difference actually is the 6 pi. the rx8 uses a stepper motor to run em.

so setting that up is kind of weird. i know the e11 haltech can do it, the metering pump is a stepper motor too (as is the fly by wire throttle, assume you'd convert that to cable) the e11 probably can't do BOTH stepper motors though.

the VDI is vacuum, injectors are injectors... the rx8 CAS pattern is weird but you can swap wheels like the star mazda, or maybe haltech has put the patten in by now (we sent it to them in 2003! and its the same as some subaru), coils are just coils

the rx8 engine would be almost perfect for a 1st gen, i think. compared to a PP engine its similar power, but you can put mufflers on it, and it'll pass smog...

Starfox07

Passing smog is no issue. But having nearly 10,000rpm out of an engine that can go 150k+ miles and making what most bridgeport 13b's make, not to mention better fuel economy is something I do want. I just got word that haltech is working on a plug and play rx8 ecu. I'm hoping its true.


These are obviously substantially more specific questions, but:

Does the renesis have the same input shaft spline and bellhousing patter as a regular 13b? (Basically, will it mount to a stock S3 trans without modification? Not interested in the six speed, want to keep the rest of the car as stock as possible)

Can I swap an S3 front cover on to mount it to the stock mounts?

Provided the answers to those questions are both yes, I imagine the swap would be fairly straightforward, mechanically at least. I wonder if the S3 oil cooler is up to the task?

Attila the Fun

iTrader: (1)

Right. "Wolf" was a brain fart, I guess.

Holy cr@p! Inflation done struck, again.

Starfox07

Good news is that it looks like used rennys only run about $1500.

j9fd3s

iTrader: (3)

the rx8 uses basically a t2 clutch, so if you want to run the stock trans, you need a lightweight flywheel for the FB, and the rx8 counterweight.

the 6 speed is really the secret weapon, it is basically the mazda race ratio's from the 80's with a granny 1st gear added on.

the early front covers will bolt on, but i don't think they work, as the irons are thicker on the Rx8, it makes the turn into the ports better, but they also shortened the front cover to compensate.

dunno about the oil line, its likely to be like the FD, so length is probably ok, but well oil lines are actually really easy to make

diabolical1

iTrader: (3)

the thought of a Renesis in a Gen I really, really appeals to me. however, i feel your pain. that's been my complaint with my Rx-8 since day one. the bloody thing is way more complex than it needs to be.

anyway, i believe Ken Schepper is performing this very transplant now and has encountered the same issues. maybe he'd be generous enough to help you out. i don't know, but he has a thread on rx8club (username: kens). it would be great if Haltech does come out with a unit that does the job. i'd jump on it in a heartbeat.

i'm excited to see someone finish this, so i wish you luck.

Starfox07

Looks like I found a solution:

http://www.lms-efi.com/haltech/PLATI...t_RE_Rev_A.pdf

Be interesting to see what happens with this ECU. If its (reasonably) affordable, I might just do it.