RenNC rotary swap street build
 

This build has been in the process for about a year or so now, off and on between different projects. For anyone super interested in the live-tweet-style updates, here's the original thread. For anyone whose time isn't worthless, i'll try to do a quick up-to-speed in this post and layout the overall goals of this project.
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I bought this lovely car way back in 2016 or so. I loved it, but my previous car to this was an NA miata, and the only thing i really wanted from the rx8 was for it to be lighter. anyway after exactly one lengthy series of poor decisions, i bought the 06 NC GT, mostly because it was the only miata available for sale at the time.
https://cimg6.ibsrv.net/gimg/www.mia...135c6f3af9.jpg

And if i'm being honest, the NC is probably my favorite car i've ever owned. I got the cheapest one available, and it was HEAPS better than any of the NAs i had owned before this. Unfortunately my fate with the NC was not to keep it stock no matter how much i promised my friends that i wouldn't mod it.

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was out for a drive one morning and was greeted with the noise of neglect - a wavy rod trying to escape the crank case. I just sat on the car for a while after this. I got a new job, moved a few states over dragged the car with me. I pondered a bit about how i work from home and don't really need to own a car at all, let alone three of them. Ultimately decided the only logical thing to do was to take as much of an rx8 as i can and jam it into the NC.

The original plan was to buy just the engine and piece together the rest. This was a super huge mistake, but i didn't know that at the time. This will become a theme. I got so far as to install the engine and transmission in the NC. But ultimately stalled out here once the mechanical components were sorted.
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Now i know this is the million dollar question for anyone familiar with he NC and RX8 platform - Which components from which car were used?
The easiest way to answer this is to say "if in doubt, it's probably from the rx8". The original plan was to use:
0) rx8 subframe
1) rx8 engine (duh)
2) rx8 transmission
3) NC PPF and driveshaft
4) NC steering
5) NC ABS
6) NC radiator
7) NC wiring harness

The more "in the weeds" i got into this, the more i realized how unlikely that would be. The real winning combo turned out to be:
0) rx8 subframe
1) rx8 engine
2) rx8 transmission
3) NC PPF and driveshaft
4) rx8 steering
5) rx8 abs
6) rx8 radiator
7) rx8 diff
8) rx8 wiring harness
9) rx8 everything

This entire thing was based on the concept that the subframes were the same bolt layout and could be interchanged. This is very cool but kind of masks how much work the rest of this entire project would be. I was very much hoping to get out of this without having to invent a part, but alas that didn't turn out to be true. I spent a few weeks learning some basic cad and had a part machined for the swap. This part is the magic that lets me use the NC PPF which is super light, and more importantly already exists and doesn't need modification. First photo shows the problem. The top mount of the rx8 transmission doesn't line up with the bolt holes of the PPF. (i think the ppf is upside down in this photo, but the problem exists when mounted the correct direction) Second photo shows what i came up with to solve this problem.
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by the point i had this part made, i was already kind of losing motivation. I took a break from it for a handful months, then another month etc until i did enough mental gymnastics to convince myself to buy a different car.
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I bought this gem with no engine or transmission or wiring. Whipped it together over the winter and now it is in a perpetual state of "ran when parked".

Went and got married, moped around for a while etc and finally found a path forward on the NC. The solution was really simple. The little voice in the back of my head was telling me this the entire time. just buy a car that runs, idiot.
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One very cool 2004 Mazda Rx8 with the heaviest automatic transmission i've ever had the displeasure of dragging across my garage floor. Speedrunning one rx8 disassembly, I pulled the wiring then connected up the , and then the . once i had this running on the floor, it was basically "ready to go" just had to drop the harness into the stripped NC. it totally worked first try and didn't take 6 hours of work, but finally the first start happened
. Which is where it sits right this moment. My goal is to get it ready for a first drive this weekend. We'll see how likely that is.

Sounds like you work on your NC project at about the same rate as I do. A build thread can be a strong motivator, so good move starting one. Now that I'm interested in the progress its expected you'll be driving it around this weekend. Ha, don't mind me I am just projecting. :)

Much fun, love the rumble and linear power of Wankel engines.

as of yet, my biggest motivator has mostly been being made fun of for having a broken car in my garage

Yeah i've always loved the engines but whenever i have one, i just want it to feel like a miata as well. I'll never understand why Mazda didn't make a special edition rotary miata with any of the generations. oh well.


Haven't had as much time to work on the NC this week as i wanted, but i've done a few things in the time i have. Pretty much just picking things at random to tackle until i feel i have a reason to do otherwise. Replaced both headlights. I lost one of the parts too the headlight during disassembly some time last year which sort of sucks, but that's how it goes i guess. Also did a bit of scoping out the interior wiring. haven't fully decided how i want to tackle this yet, but it will likely involve throwing parts into the cabin until they all work. i went and repaired a few of the wires that needed it from the previous owner's handiwork.

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making progress at a snails pace. Realized that i haven't taken the hard top off one time since getting it, so i probably don't need to waste all the room on it. It's ripped to shreds anyway, so out it came. The NA or NB can be the top down cars if ever i decide i want that.
next i chased the harness about the rear of the cabin, and into the trunk. Some emissions component whose name escapes me is on the opposite side of the NC rear subframe, so i have to extend that. RX8 only has one door sensor (i think?), yet the NC has two. I haven't decided
if i care enough to fit the other door sensor. Fit up the Bose amp, the DSC gyro etc etc.

i didn't notice this at the time, but looking at these pictures made me notice that my drain holes are mega clogged. Yikes. Gonna try to finish up the trunk and rest of the interior tomorrow. high hopes i guess, feels like i'll never be done

https://cimg8.ibsrv.net/gimg/www.mia...262b46efda.jpg
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by the way, for anyone wondering why the interior is covered in dust absolutely everywhere... womp womp. Wondering if that's what clogged my drain holes. looks like the same sort of dirt.

https://cimg3.ibsrv.net/gimg/www.mia...d1e1afec1c.jpg

Nah, they were clogged before fitting the HT. There's no way that water gets to them with the HT on.

Would believe that too. Is the trombone cleaner still the best move for NC, or is there some other method?would like to clear em out even tho i won't be running the soft top, seems foolish leave a drain full of dirt lol

Was planning on accomplishing more today, but this took me way longer than i expected. Goal was to get the dash, and maybe interior trim back. Started by chasing down the door harnesses from the NC, and laying them over RX8 one. You can sort of see the driver's door connector from the RX8 harness ziptied out of the way in the first photo. There are 9 wires in total that must be joined to the Rx8 harness. Took me a few hours of flipping thru the FSM and Wiring Diagrams to match the circuits up. I don't currently have a stereo to install, so i won't be able to test the door speakers, but i am pretty sure i did it right.

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I must say, i expected this next part to go a lot faster than it did. it took me quite a few tries to get it right. i couldn't remember how either dashboard was routed originally, so that made fitting the rx8 one to the NC, and even harder to fit the NC HVAC on top of it.
In the end. Ultimately what i ended up doing was fitting the driver's side components first, and worked my way all the way over by bolting the ground terminals where they felt about right. once i got as much of the rx8 harness in place as i could, i draped the NC harness over it, and spliced it into the harness.
interestingly enough, pretty much everything in the rx8 harness "has a place". Even the Bose Audio microphone thing. The other really crappy thing about this was the previous owner of this rx8 really had his way with this darn harness. there were random cut wires and busted connectors everywhere, so of course i had to repair all of that. probably 5 or 6 wires total, but they were all broken in their own unique, head-ass way.

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I fit up all the components as i was able. It's about ready to go back in now. Harness is secured to the dash. Cluster even fits quite nicely. The auto cluster i have is in really awful condition, but i'd rather mess it up than my good one anyway. I think i'll probably try to make up a little cover for the exposed portion of the cluster face. I was really excited to see that the dash cover fit onto the gauges fine. I think this is the final fit of everything before going back into the car.

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This all feels like a lot of work right now, but hopefully tomorrow it'll be looking a little closer. I can't believe how heavy the stupid dash is compared to an NA or NB dash.

Another day spent working on the NC, another day wasted. Went in with the intent to put the interior together, figured i'd start the day out by repairing the wires in the engine bay. This wound up taking up my entire morning. i just kept finding more and more rubbed through wires. Pretty much all 8 wires on both headlight connectors were worn thru in different locations. i don't usually choose to post closeups of wiring for the same reason i don't post closeups of welds, but i don't have anything else interesting to share, so here's a couple.


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Also connected up the headlights, running lights and fog lights. Why, one might ask did i do this instead of the interior like i said? So i could pretend the car is complete again. Bumper is absolutely scuffed from getting kicked around the garage all year. i'm just not gonna think about it for now. The entire paint is a C+ at best, i've been considering a wrap some day. Guess i should get it driving before then. Hopefully back to the interior tomorrow.

https://cimg3.ibsrv.net/gimg/www.mia...1c51bbfc7c.jpg

Reinstalled most of the interior today. Had to start with connecting up the door harnesses. this was pretty easy, needed some keyless entry wires, the window switches and an ignition wire. Wrapped all that up, tied it back and then installed the dashboard. really starting to feel like a real car again.

https://cimg8.ibsrv.net/gimg/www.mia...1cd34dee6f.jpg
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Once everything was installed, i started testing each circuit. Headlights, tail lights, blinkers, windows, mirrors, etc. Almost everything worked first try. There are two things that don't work currently - the HVAC and the horn. The horn didn't work when i got the car. i thought i had fixed it by repairing a couple wires, but that didn't seem to do it unfortunately. the hvac not working is kind of annoying, it seems like it should be. I have a couple working theories on this, the top one being that i just killed the module a while back. Ran out of time to debug it, but there's also the possibility it's just the fuse. that would be lucky.

Last major job is replacing the ABS pump. this doens't seem that hard, but i'm not really looking forward to it anyway. will hopefully get it started tomorrow. once that's done, i think it's time for first drive.

I am impressed with your wiring perseverance. I am not intimidated by wiring, but I don't know if I could have gone that route.

I prefer velcro straps over zip ties since they can be undone to add in more wires as needed.

believe it or not, this has been the easiest way to handle the wiring so far. I've tried it 2 or 3 times up until this point and failed miserably each time.

This was my first attempt. I had planned on using the NC body harness, and was going to combine the rx8 engine harness into the NC harness + fusebox. After stripping both harnesses down and getting rid of that nasty gunk that goes on the grommets, i decided this was not going to be the move.

https://lh3.googleusercontent.com/63...-no?authuser=0

The next attempt was to just run the rx8 engine bay harness, and connect it up to the NC body harness. this would have worked on paper, but would have required a lot of work.

Ultimately, just running the entire RX8 harness has been very simple conceptually and easy to accomplish.

sometimes the hardest path ends up being the shortest. so good call on doing that.

Got started on the ABS swap today. Had to cut away a portion of the strut tower material to make room. took a few passes to get it all due to not wanting to cut shit that didn't need to be cut. Can also see from the pics where i cut away the old ABS pump mounting point.

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Once there was enough room, i just jammed the pump in the spot to see where it might fit. I tested each orientation and ultimately landed on this. i believe this is reverse of how it is on the rx8 originally, but all the ports lined up (after some light bending)

https://cimg2.ibsrv.net/gimg/www.mia...c74567ba98.jpg

The two lines that go from the MC to the pump are an M12x1.0 on the rx8, the NC lines are M10x1.0. I think i've read that later pumps use M10 on the rx8 as well, but both of the ones i have are the bigger ones.
The lines being on the top instead of the "back" of the pump also made it such that they didn't quite reach easily anyway, so a short extension helped here. I went to 3 or 4 different parts stores until i found a suitable set of fittings and adapters.
In the end, the combo was a short extension with M12x1.0 on one end, and 3/8 on the other plus a union from 3/8 to M10x1.0.

https://cimg6.ibsrv.net/gimg/www.mia...59b9c56547.jpg


I can't say i'm super happy with how it looks due to all my hand bending and adapters etc, but it seems functional for now. I was going to pressurize and bleed the system, but i forgot to pick up fluid while i was at any of the stores, so it'll have to wait until tomorrow. I'll also have a fair amount of cutting and grinding still until i have a bracket that actually locates the pump rather than just hanging it by the lines. There's a pretty good chance that i'll redo these lines some day, but for now, as long as it seals, i'm happy.

https://cimg5.ibsrv.net/gimg/www.mia...7a0dc86868.jpg

i was going to bend my own pipes but ended up using AN3 fittings, talk about a nightmare to find the stupid fitting and adapters etc!

def get yourself a pipe vender although those factory lines are made of solid steel! fucking things are hard to ebdn but you won't risk kinking. aline and fucking yourself over.

also, the doubleflare is not that difficult to do.
i bought these from the Forrest store

these people sell premade brake lines, PTFE in different lenghts

Thanks. yeah i have all these tools, i've just never had good results with them for whatever reason. Every flare i've made has leaked, and every time i use the bender, i end up kinking the line. I probably just need more practice with it, and maybe a better tool. I'm gonna run what i have for now, but once the car is running and driving these lines will probably be the first on my list of stuff to replace.
The lines that go to the rear of the car are terminated at a nice little block, so i can feasibly make just the lines for the front of the car at some point. it would look much nicer than what i have.
Will hopefully be finishing up the bracketry today for the pump. Went outside with the grinder and welder in hand but realized it's 9:30 in the morning and my neighbors probably wouldn't like that too much.

Went to work on the ABS pump today. spent about an hour cutting and grinding the frame rails and killed all 3 of my batteries. Will hopefully finish it up tomorrow, just need to fix the bracket to the car now. Haven't decided exactly how yet, it has three studs on the bottom where it was originally mounted to the rx8. there's no similar spot to fix them in the NC, but 2 of them are kind of close such that i could make it work. Might riv nut the third and use a bolt thru it instead of the exist stud. or i'll just weld it in so it can't be removed again. not my favorite solution but it'd work.

Still had some time to work on it after my batteries died, so i tossed em on the charger and started putting everything else in the bay that needs to be there. Surprisingly, everything seems to fit quite nicely. i'm probably not going to keep this wacky K&N cannon forever, but for now it's the easiest solution - the stock airbox is nowhere near fitting. Both the ECU box and fuse box are sort of just floating about in these photos, i'll have to come up with a way to fix them in place. The rx8 uses captive nuts inside the frame rail making me think i can probably use riv-nuts for this as well. The installed battery is also not the correct one. this is the original rx8 one. it does technically fit, but the NC battery box actually still fits, so i'll likely be using that with it's original battery instead. smaller and lighter.

Also sorted almost all of the coolant hoses. the only one that didn't fit was the heater core to water neck one on the passenger's side. It probably could have been stretched to fit, but there are a bunch of brake lines in the way now. i'll probably go get a joiner from the parts store and cobble something together.
Wont be long now. list of remaining tasks is quite small


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You're making great progress, following with interest, I wonder what this will do to the weight distribution.

i'm pretty interested in that too, i plan to weigh it when i'm done. it'll need an alignment anyway so that'll be a good time to throw it on some corner weights. Just a gut guess, but the front of the car seems like it'll be quite a bit lighter. the rotary engine sits back quite a bit farther than the original 2.0 did, and everything in front of the wheels is about the same. the weight difference between the two engines is negligible, between 20 and 50 pounds according to some light googling. as far as weight goes, all i've done is move the heaviest object lower and back towards the center of the car. the engine is still "behind" the steering, so i guess it may as well be about the same? guess only time will tell

Bit more misc progress today. ABS bracket is pretty much finished. Was able to get away with simply bolting it in via 2 or the 3 original mounting points. Gonna pull it back out one last time tomorrow to grind down any remaining sharp edges. I sliced the hell out of my finger feeling around for the heater core hose.
Should probably lay down a coat of paint on it as well for good luck.

https://cimg9.ibsrv.net/gimg/www.mia...fad5b75f93.jpg
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A similar treatment is still needed on the other side, if you look at the photos of the engine bay from yesterday, you can see the fusebox doesn't quite sit right either. All the batteries are chargin' again so maybe i'll finish that up next time. Really starting to wish i had a second angle grinder so i can have a cuttoff disc and the grinder wheel at the same time.

Otherwise, i just went about doing up misc stuff. Torqued all the subframe bolts, installed the PPF and driveshaft etc etc. I want to put it on the ground so bad, but it's not quite there yet. Soon tho.
I'm having a hard time deciding what to do about exhaust. i have the rx8 system that is too long, and the NC system that is too small. I'd prefer to be able to drive it a little bit before dropping it off at an exhaust shop to have one fabbed up from scratch, and i don't particularly want to drive around open header either. Currently, the best idea i have is to either cut the flange off the NC exhaust, and try to fit an rx8 flange to it. if i remember correctly the ID of the OEM NC exhaust is 2.5", compared to the ~3 of the RX8. The other idea i have is to take the rx8 exhaust, fit it up best i can, mark and cut it and chop about 1 foot out of it, then slap it back together. Maybe i'll just go grab a few sections of pipe and use the NC muffler. I'm having a hard time getting my hands on a cat for a prices i think is fair due to CARB laws. I'll probably try to snatch a used one when i get the chance.

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Other misc job i tackled was reinstalling the steering column and wheel. took a best guess on the wheel placement, will probably need to recenter it once it's back on the ground, but i just couldn't help it. Threw the seat in to remind myself what it feels like to be in what is almost a real car.

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Can you get a reducer sleeve/flexi joint to connect the rx8 to NC system?

Doesn't "need" a cat if it's only temporary? Also, does de-catting a rotary not induce flames anyway, win win!

flexi reducer sleeve thing is a good idea actually thanks for that! It doesn't need a cat for now, but i would like to run one in the long term anyway because it makes me feel a little better. car will almost certainly never be "legal" here, but i do try to do my part.

new parts time. I thought the rx8 pump would fit in the NC hanger, it seems really close in size, but it didn't quite for some reason. Ordered DW300 that showed up today. hopefully saves me any upgrades in the future anyway. Fuel pump assembly was actually quite interesting to assemble. this one just popped apart like a jack in the box when it came out for some reason, so i didn't quite pay enough attention how it came apart so took me about 20 minutes to put back together :vash:

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Also went and stopped by the parts store and grabbed a misc of exhaust parts, various adapters and joiners that may or may not work. kinda forgot to look at it before i went to the store. Threw up the old NC exhaust into the car. was sort of hoping that the cross would be more on the pipe itself and not against the cat like this. Might swap in the rx8 stuff and see if the story is any easier.
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hacked together an exhaust today. this is the first time i've used this cheesy little welder from Harbor Freight and i've gotta say, for what it costs this thing is amazing. it's not the best looking thing in the world that's for sure, but for around $150 for the welder + accessories it got the job done, pretty quickly. I think if i really needed to, i could build a full exhaust with this thing. i really half-assed the hell out of the cuts, and didn't take a ton of care on grinding or cleaning either part before stuffing the welder at it.
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I don't think i did any cleanup on this other than wire brushing it. pretty good for the cost and amount of work i put into it. it's all temporary anyway. I forgot (read: decided not) to grab a photo of what it looked like all cleaned up, but the exhaust is in the car.

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Just a handful of little crap tomorrow, then it'll go out for a shakedown. I ordered a fan for the oil cooler since right now it's not going to get any significant airflow, especially at lower speeds i feel. That should be in tomorrow. Bled the brakes this afternoon as well, but the clutch slave cyl wouldn't bleed for some reason, so i bought a new one. Once i get that in, all i need is to fill the trans and radiator and it's ready i think? hopefully good news tomorrow :party:

The first drive was a success! so was the second and third. Been taking it out on short drives all afternoon just to shake it down and see how it feels. It feels fast but moreso than that, it feels like it needs a serious alignment. I brought it up to redline in first quite a number of times, but didn't really push it outside of that.

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Took it to go get gas for the first time in a couple years and i've got to say that it felt amazing to get to this point.

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Here's a couple mediocre quality vids of the first or second drive around the block.




I'm genuinely so excited that i can almost look past all the shit i still have to do to make it into a car that's pleasant to be in. i'll probably take a bit of time to cleanup the garage and organize the mess of parts i have laying around now. it would be nice to get the entire interior at least back together such that it doesn't feel like half racecar. Anyway, updates to this thread will probably be a little bit more spaced out than they have been up until this point. i need to get a gameplan of sorts together for the remaining jobs. - ABS wires still need extending, HVAC still doesn't work etc etc. Hoping to return with a photo of the car with all the body panels attached next time

I have a 2.5 swapped NC right now that is mostly a track car. I think this thing would be so awesome on track. Possibly less weight up front, a 9k redline, smooooth power, and a unique sound.

my main goal is for this to primarily be a street car. i don't have the money to race a rotary car often :rofl:
I do plan on taking it to autox on occasion tho, and will be sure to report back how it feels when i do.

Took the car over to a friends house to show off a bit today. Bout a 20 minute drive each way. not quite the hottest part of the day, but it's pretty warm out. 85-90 today. Car is honestly doing great so far. I've found a few little things here and there that i wasn't already aware of, but nothing seems like a show-stopper.
The most annoying thing about it right now is that second gear wants to pop out when i clutch in due to the pressure applied at the shift boot being installed about 1 inch too far forward relative to the shifter. 4th, 6th and reverse do not have this problem fortunately but it is super annoying.

I've been ringing first and second all day. the most notable things about it is
1) (and i never thought i'd say this) 8 or 9k redline on the 4 port auto computer is too low.
2) i need the rx8 differential. the NC 4.10 is noticeably slower than the rx8 diff

I still very much need an alignment. i'm going to try to pick one up if the shop has time tomorrow.

I've been following this and love it. Can't wait for some good WOT thrashing videos.

I'd fix that shifter issue asap, pressure on the shifter while driving is bad for the transmission. For the same reason that resting your hand on the shifter while driving is a bad habit.

i've been giving it WOT ever drive. it feels pretty quick. haven't given it a real good thrashing yet, but im really excited to do so. Another issue i've found over the last few days is that my oil cooler is far too close to the driver's wheel. i can't get anywhere near full lock on a right-hand turn. i yanked the fan off getting the car into my driveway yesterday. Pretty much no other significant progress lately other than i gave it a quick hose-off in the driveway. looks alright for 2 years worth of dirt/dust getting washed off. Will be wheel shopping soon. I like the OEM wheels and all, but not really my style. I've been thinking about it for a few days and i think the next job i'll probably tackle is swapping back to NC brakes and stuff. the rx8 has too much rotor/caliper for my tastes, and the NC stuff is more than adequate. Still cleaning up the garage and organizing 2 years of chaos. More updates to come

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Really impressed with the progress, as far as niggles to sort out go, it doesn't sound like too much cause for concern!

Not much progress on the car, cleaned the garage up quite a bit today. i'm getting rid of unneeded parts and taking the first time i've had in a long while to clean up the space the NC was in.

One thing i did manage to accomplish on the car today however was pulling codes.


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https://cimg2.ibsrv.net/gimg/www.mia...dc298a588e.jpg

aaaaaaaaaaaaaaand fixed.

Put the interior back together this morning. was a bit of a chore, i had to cut out a bit of material from a few of the pieces. Took it out for a drive afterwards and it's sooooooo much better now. It's really quiet in the cabin, feels just like a stock NC if you don't look at the gauges. Even have the trim installed for the fusebox in the cabin, which i don't think has ever been installed since i've owned this car. Did a half-ass toe adjustment to get the the wheels pointed in the right direction, drives pretty good now. Still can't make hard right hand turns because of the oil cooler, but all in due time. Hoping to fix ABS wiring tomorrow morning. Would love to have a functioning speedometer and power steering.

https://cimg9.ibsrv.net/gimg/www.mia...0df39f33b7.jpg
https://cimg0.ibsrv.net/gimg/www.mia...764a584642.jpg
https://cimg8.ibsrv.net/gimg/www.mia...87cb4120c2.jpg

Super great progress. Nice to see the car being driven. I've got my project at least idling well and sounding good. The brakes are being really tricky to bleed. Pedal just does not stay stiff.

Anyway, hopefully I'll be on the street with ya soon. Keep at it!

If you don't have one, i HIGHLY suggest getting a power bleeder. They make an all day job of hydraulics bleeding a 12 minute job for miatas. Easily one of the best tools i've ever purchased.

I need to look into that power bleeder. If that tool means I can do it by myself, then maybe I will get it done.

Dragged the car down to the emissions station so i can register and plate the car. it failed, but they didn't arrest me for the swap so i guess that's good. Im guessing the NC cat i used isn't quite up to the task, so i bought the biggest aftermarket one i could find. Once it arrives in a few days, i'll try running it again and see how it goes.

https://cimg2.ibsrv.net/gimg/www.mia...124241e1e0.jpg
https://cimg4.ibsrv.net/gimg/www.mia...8f33ce69ca.jpg

Still waiting on the new cat and other parts. in the meantime, i spent a while with the cable stretcher so i can extend the ABS harness over to the other side of the car. This should hopefully repair my speedometer, get power steering and DSC working.
https://cimg4.ibsrv.net/gimg/www.mia...c6b9aae204.jpg
https://cimg6.ibsrv.net/gimg/www.mia...74833f7259.jpg

welded the new cat in this morning and ran down for another test. Passed super easy. Plate installed and registration in hand. Very happy with this, but there's still plenty to do. hopefully some time this weekend i'll get around to finishing the ABS wiring and maybe take it out for a proper drive finally.

https://cimg7.ibsrv.net/gimg/www.mia...d6e4e227fb.jpg
https://cimg0.ibsrv.net/gimg/www.mia...7c876b79cb.jpg
https://cimg9.ibsrv.net/gimg/www.mia...38763c3bf8.jpg
https://cimg8.ibsrv.net/gimg/www.mia...60abfa18c3.jpg

check engine light (un)delete
 

the astute may have noticed something weird about my gauge cluster (no, not the auto shift select) As it turns out for some wacky reason, the previous owner must have removed the LED. It was literally cut out as if with a pair of flush cutters or something. Dug around my spare parts bin until i found a similar LED and replaced it
https://cimg4.ibsrv.net/gimg/www.mia...66ad06aaf6.jpg
https://cimg5.ibsrv.net/gimg/www.mia...1340252eb1.jpg

https://cimg3.ibsrv.net/gimg/www.mia...4ae0fc40d7.jpg
https://cimg6.ibsrv.net/gimg/www.mia...f737fe03da.jpg

Took a couple tries to get the RPM needle back to the right place, for some reason it doesn't have a index location like the other needles, so i had to kinda guess until it worked right. Thankfully i didn't break it, they're quite fragile. Anyway, if anyone is looking for a cheeky check engine light disable, read this post in reverse

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. :likecat:

DNM

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.

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" shit 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.
https://cimg2.ibsrv.net/gimg/www.mia...7a8a118ba8.jpg
https://cimg3.ibsrv.net/gimg/www.mia...a5a4084e74.jpg
https://cimg4.ibsrv.net/gimg/www.mia...75e55e85bc.jpg

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.
https://cimg8.ibsrv.net/gimg/www.mia...ee71e36b35.jpg

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. :/

https://cimg2.ibsrv.net/gimg/www.mia...2c5b0a8bd3.jpg

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.

https://cimg3.ibsrv.net/gimg/www.mia...cd9939af85.jpg
https://cimg4.ibsrv.net/gimg/www.mia...2bfb292495.jpg

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 ONE Tactrix 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.
https://cimg6.ibsrv.net/gimg/www.mia...2dc358562f.jpg
https://cimg4.ibsrv.net/gimg/www.mia...822c28afb2.png


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.

https://cimg6.ibsrv.net/gimg/www.mia...53088be667.jpg
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.
https://cimg8.ibsrv.net/gimg/www.mia...01667d2b92.jpg

Anyway, enough nerd shit 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

The correct name for your device is D'Brickashaw Ferguson.

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.

https://cimg3.ibsrv.net/gimg/www.mia...c6eef471df.jpg

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. :vash:

https://cimg5.ibsrv.net/gimg/www.mia...a464f8bd3f.jpg

I definitely have a larger collection, including a quite unusual one.

https://cimg3.ibsrv.net/gimg/www.mia...54314cf713.jpg

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.
https://cimg6.ibsrv.net/gimg/www.mia...32830f0b49.jpg
https://cimg7.ibsrv.net/gimg/www.mia...7ceada2812.jpg
https://cimg8.ibsrv.net/gimg/www.mia...8703b0c1ce.jpg
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

https://cimg7.ibsrv.net/gimg/www.mia...3176141c9a.jpg
https://cimg8.ibsrv.net/gimg/www.mia...25988df98f.jpg

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!

https://lh3.googleusercontent.com/RS...-no?authuser=0

Silly thing still works but haven't given it much love lately. Snows meltin' tho, so should be doing some work soon..

https://cimg6.ibsrv.net/gimg/www.mia...e5fe481d74.jpg

https://cimg0.ibsrv.net/gimg/www.mia...a261ce9fab.jpg

https://lh3.googleusercontent.com/q0...-no?authuser=0

https://lh3.googleusercontent.com/p0...-no?authuser=0

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.

https://lh3.googleusercontent.com/vU...-no?authuser=0

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.


https://lh3.googleusercontent.com/ss...-no?authuser=0
https://lh3.googleusercontent.com/oj...-no?authuser=0


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.

https://cdn.discordapp.com/attachmen...48992907AA.png

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

https://cimg8.ibsrv.net/gimg/www.mia...3a6061ae46.jpg

Been another lazy few months. Been taking it out for a drive every once in a while but no huge progress updates as of late.

https://cimg4.ibsrv.net/gimg/www.mia...48a0f45c7b.jpg

Gonna finish this thing up one of these days? At least get the damn thing aligned, lol 😆. Sitting at the DMV killing time, so I went through this. Interesting build, and certainly something different from most others.

Yeah i haven't had a lot of time to do any car stuff lately. It's getting shipped to my new house in a week or two. After Miatas at The Gap in August, i'm planning on starting up some work on the NC again.