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Coddle my laziness. What is HP change with this swap? What other gains are here besides just that? Even better F/R weight ratio? Don't get me wrong; this thread has been technically interesting and entertaining.
More for emotional reasons. The op has had a history with RX7’s and wanted another rotary powered car. We had talked about a 2.5 swap, which would have been more practical. The way the rotary’s make power with a combustion event per rotor, per crank rotation like a two stroke allows them to make amazing midrange power and obviously with no con rod they are very smooth. They are just addicting. There are some future mods for this build, but I will leave that to the op.
Coddle my laziness. What is HP change with this swap? What other gains are here besides just that? Even better F/R weight ratio? Don't get me wrong; this thread has been technically interesting and entertaining.
Congratulations on the Smog Test pass.
DNM
the engine i have is from a 4 port auto usdm rx8, which a quick google says ~200 HP. i can tell you right now, this car does not have 200 HP, but it's certainly faster than a stock NC.
Andy's right, this swap is more because i think it's cool than anything else. I've always wanted to have a rotary miata, i've been scoping this project out for quite a long time. I had originally thought about doing it to an NA or NB, but i don't really think i'd like it as much. I think i know how i'd do it, i have plans for it but idk if i'll ever bother. It's something i'd love to help somebody else do.
The renesis swap is just something that "felt" right to me. The cars were both developed on the same platform, it was pretty easy to hack the two cars together, feels similar to what the subaru guys do with STI driveline into the other models. I still have a na6 miata and it's a really fun car, but i'm starting to get increasingly aware of all the "old car" **** about it. Manual windows, no power when the AC is on, crappy idle etc. i basically wanted to make sure the NC could still be a "modern" car, so that pretty much eliminates all of the past gen rotaries, renesis was just the right fit. Probably should have just 2.5 swapped it, but here we are.
aaaaanyway, I took the car for a pretty decently long drive the other day, ~50 miles of around town driving. I've been bouncing off the redline in first and second and it's a load of fun, but it's not particularly fast as is. Also once it got warmed up, it kinda lost all power. there's kinda too much stuff at play to go super into diagnosing it, so i'm wrapping up everything else before debugging further. first up was extending the ABS harness. Still needs to be tested than wrapped up, but all the codes are clear. EPAS also seems to be working, but i haven't tested it yet.
Getting ABS working involved a bit of wiring in the trunk, so i finished that up. the rx8 and NC abs connectors are the same, but i seem to remember thinking the actual sensors were different for some reason. ABS self test says they're fine, but i haven't driven yet. Will know for sure tomorrow.
Got some time to play with the NC this weekend, set out to "finish" the wiring modifications and get everything working as much as possible. I tried using the NC ABS sensors, but the instant that i started moving, the ABS light came back on the dash. EPAS still works thankfully, but lots of stuff is still not working right due to the lack of speedometer. I had a set of rx8 ABS sensors, so i figured that would be a pretty easy fix, but as it turns out the RX8 ABS sensors are way bigger than the NC ones. Luckily, the hubs are made of aluminum, so making the hole bigger wasn't too hard. Unfortunately even tho it was not that hard, i still somehow managed to eff it up. Forgot to grab a photo, but i took off a tooth on the tone wheel of the axle. The sensor itself fits, and when i check with a multi meter, it seems to behave how i would expect it too, but that missing tooth seems to be messing it up. I have a set of rx8 axles, knuckles and the rx8 diff, i just need to set some time aside to install it all. I was hoping not to bother until i busted the NC diff (which i think is inevitable) but i guess it'll be happening sooner rather than later now. :/
Other than that i did manage to finish up the other systems that didn't work. I now have a functioning (cheap) stereo with no less than both speakers working. While i was in there, i also fixed the HVAC panel and tidied up the dash wiring behind it all.
Spent pretty much all morning and afternoon driving the car around just getting a feel for it. I still haven't aligned it, the height is way and it kinda rides like crap, but the thing is an absolute riot to drive. I was mostly trying to "stress test" it in every day driving. it was pretty warm out for an October day, and i was not exactly being kind to it, and it didn't really even threaten to overheat on me which is a relief. I have learned of some things that need attention soon tho: i foolishly installed a used clutch and throwout bearing, so that definitely needs replacement. Once warmed up, that clutch cries the entire time and has a really hard time sticking. I've already purchased replacements for them, just haven't felt like dropping a transmission lately. I also need a real exhaust now that i've passed emissions tests. the 2 inch ID of the stock NC exhaust is super limiting. I managed to score a magnaflow high-flow cat specifically for Rx8 from someguy locally for $200. I'm hovering over the RacingBeat muffler "buy" button, so that should be solved pretty soon as well. Finally, there is a really annoying problem with the car as is, that it refuses to idle right because of my 8 pound flywheel. It'll hold at 1k RPM, then after about 5 seconds stumble down to ~500 and shoot back up to 1k again then repeat. Raising the idle up to 1000 RPM would fix this, which i assumed would be a pretty easy thing to fix but as it turns out, it's not something you can do without spending at least $250 on tuning software. Now i would have done that, however the license for the software is absolutely absurd and i refuse to support that type of business personally. I won't name any specific names, but all of the available tuning solutions for rx8 seem to be about the same deal - $$$$ for a piece of software that is limited to ONE COMPUTER, ONE VIN, and ONETactrix cable which i find unacceptable.
So anyway that brings me to now. I've set out to make a free tool for tuning Mazda RX8s if for no other reason than spite. So far i've managed to do the UDS handshake to get the ECU unlocked, and i've managed to dump the firmware out of the dang thing.
The code for this is open sourced, if you dig around on my GitHub profile, you can find it but i'm not going to officially post it anywhere just yet. The next goal will be writing a small kernel to allow re-writing the ROM as the default software on the ECU does not allow this by any means i've found so far. More to come soon hopefully
Been a while since an update. Progress has been made but not on the car itself. I got a little sucked into the rabbit hole of reverse engineering the RX8 ECU. Was surprising to me that there isn't a DIY option out there, so i had to do a bit of work to get this far. I've picked up 4 or 5 ECUs, and wrote a lot of code to download and upload the ROM for them.
Naturally, this process involved bricking an ECU, so i had to build myself a little debrickifier device to allow me to upload the original ROMs. This makes it pretty much impossible to permanently mess the ecu up.
Anyway, enough nerd **** for now. I started a thread back over on rx8club https://www.rx8club.com/series-i-eng...ration-274353/. Anyone interested might check that one out. Back to the regularly scheduled programming of rotary miatas soon
Found out that the RX8 actually came with a manual (5 speed) and a 4 port in other countries. This probably would have saved me some time before, but oh well. the more you know. Picked one up and threw it in the car. started right up perfectly after pairing it to my immobilizer. Dumped the firmware from it as well for good luck. I'm quite convinced i have the largest collection of rx8 ECUs at this point. I was hoping that i would have speedometer working after this but of course that was not the case. It seems like the speedometer is driven primarily by the rear wheels only. I get output from the front ones since they are the correct ABS sensors and hubs, but the rear ones still do not work right.
Other than that, i threw my RPF1s back on the car just in time for it to start getting cold and me to not want to have summer tires installed.
Figured out why my EPAS was so inconsistent. Peeled back some tape and found this lovely job. I can't for the life of me figure out WHY this was like this. My suspicion is that the donor vehicle i got all the parts from was in a junk yard, and someone grabbed the
EPAS controller and sliced the wires off just in case? idk. Anyway, i cut the oxidized, crappy solder job out and recrimped the connector back on.
I bought a manual 4 port ECU on Ebay and slapped it in and the car feels AMAZING in comparison to the auto ECU. Idles better as well. probably won't be doing much more to the car until the sun comes back out in the spring.
Major jobs remaining are
1) clutch + tob
2) swap in the rx8 diff
3) make brackets for the lose items in the engine bay. ECU + fuse box, fp resistor etc.
4) misc tidying up
subbed for more updates, I have a 2009 NC and a 2009 RX8 waiting to do the same. I was searching the web for someone that did this and besides a guy named Paul in England there's not much info anywhere else. So glad to see more info on this especially since its a street oriented build with working car bits and not just a stripped out race car.
I actually chat with Paul from time to time. He helped me with a few things along the way. Would love to help out where possible. I've documented most of the important steps along the way, so if you get stuck feel free to reach out. The working car bits were the most important part for me in this project.
No major updates, it's been too cold here in Denver to do any car touching. We had some nice weather recently and i took the NC out for a short drive in the snow. Only managed to get it stuck going up my driveway one time!
Still not much work on the NC. Pulled it out of the garage over the weekend and at least hosed it down. I left the battery without charging it over the winter and have to replace it. Not sure if i have a gremlin in the wiring or if that's expected on the rx8. Battery was brand new. It'll go on the trickle charger next year i guess.
Heading out to an autox with the NA next weekend which i'm hoping will motivate me into finishing the NC enough to take it to the next one. It's not far off from being ready, just a few crappy jobs to do.
Also a side project i've been working on over the winter. I was getting tired of the existing underglow controllers available on the market all being kinda crappy, so i designed my own. Currently waiting on the first (second actually but we're not gonna talk about that) prototype production run of them to be completed in China and delivered. I'll be installing on the NC as soon as they arrive. Here's a shot of how it looks on my NA so far.
nothing huge to report, NC has been on the backburner while i plan out a move. Pretty much just sits in or around my garage, waiting for me to finish it
10-07-2022, 08:28 AM
