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I had to double check after seeing the video you linked, but that's actually my old roommate's car and video. I don't remember all the details, but from what I remember it was an ex-Spec Miata car originally built by advance motorsports.
The wing that was originally on that car is actually the one that's on my car now.
Bonus photo of our old cat hanging out in the pedal box.
The swap was done when he bought the car, so I'm not sure how much he actually knows about the process. Somehow, I have a different friend who has been planning to do this swap, but that project is on hold for now since he's traveling.
I remember him liking the car, but he got burnt out on cars between that and his other NB which both had pretty major issues at the same time. He was directed to use a recovery road at ORP which resulted in a cracked oil pan and destroyed splitter on the J Swapped car, which was pretty expensive (I want to say like $700 just for the oil pan, but could be wrong). Thankfully the engine was fine. It took him a while to get that car put back together, but once it was he sold it before taking it back out.
I remember him liking the car when he had it though. Seems like a good swaption to me.
PS - if you go through with the swap and decide to name the car SwapTionXIII I want credit
While I'm waiting for other things to settle, I have tidied up the shell a bit and have it looking reasonably close to a normal car, other than the monster truck ride height. NB suspension plus no drivetrain will do that! I've been using this time to consider my options on everything. For now, I think I'll be doing the swap as cheaply as possible. Why? Well, it's a lot easier to spend money on a upgrading a running car than it is to spend it on a never ending garage/driveway ornament. From what I've watched the most expensive part of any swap is the kit and engine management.
I have a 1.6L 5 speed that should still be in decent shape in the wrecked car. If I keep the power down, I can get some decent use out of it before it goes KABOOM. That's free. On car-part dot com, J30's out of the 2003-2007 Accord an be had in running condition starting from $300. That gets me around 240hp and 210lb/ft of torque. A much lower mileage, better maintained JDM import J30 engine? $700. People have gotten standard Honda ECUs to run in swapped Miatas with some electrical trickery. That stays cheap. If I buy a 3.63 Torsen to go with the 5 speed, I'll have a pretty good gearing match for the engine. Sure, that's an added expense over whatever 1.8 diff I don't have to import, but it'll be easy to resell if I ever want to change.
From there, I can upgrade. Aftermarket engine management can be done at any time to let me play in the ECU. If I want a J35 that makes 240+ HP and lb/ft, they're basically the same price. Getting a higher rated factory engine is going to be cheaper and more reliable than any aftermarket hop up parts. That torque will definitely, eventually kill a tracked 5 speed, so I'll need either to accept that, or upgrade to a 6 speed, or a $3500 Walter Motorsports built 5 speed. I've read people say that 1st gear in a 5sp/4.3FDR with that much torque is nigh on useless, and a 6 speed with a 3.63 has basically the same shift points in 1-4 as a 5/4.3, so a 6 speed would be a better match to the aftermarket 3.3 final drive ratio. If I have to set up a diff gearset anyways, I'll probably want an OS Giken diff. You can see how the cost of a bit more power and torque snowballs quickly.
Now, why don't I want a Minitec kit? Here's what I was talking about. Apparently there have been multiple revisions of these parts and they are better now, but does that give you confidence in the thoroughness of their design? It doesn't for me.
Originally Posted by SimBa
He was directed to use a recovery road at ORP which resulted in a cracked oil pan and destroyed splitter on the J Swapped car, which was pretty expensive (I want to say like $700 just for the oil pan, but could be wrong).
Sounds like he had the Minitec kit. Here's a still from a Gopro video someone took from behind their front bumper, facing the rear of the car. Look how low the oilpan is and how close it comes to the ground leaving their driveway, with nothing in front of it.
This is a post from 2017 and their subframe design has likely been upgraded since then, but still - no bueno. It still moves the steering rack forward.
No. Thank. You.
Contrast that to the OZ kit. Here's some shots I've found on Facebook. They recently relocated their starter from the right hand side to the left hand side, which they say improves exhaust clearance. Because the starter faces rearwards instead of forwards like the Minitec kit, they can keep the standard Miata oil sump location nestled inside a stock subframe. They claim 5 quarts of oil capacity, which is more than the J30's stock 4.5 quarts. And no silly internal slave cylinder. Excellent!
Here's the fairly small mod to the bellhousing required to make it work.
And here's how it fits in the transmission tunnel, at least with their mockup bellhousing.
Lastly, here's a view of the oil pan from underneath so that you can see it's tucked up and behind the subframe. Also note the older, right hand side starter location that the exhaust has to snake around and requires you to cut out the stock slave cylinder mounting location.
Here's some posts from a guy on reddit that was sharing progress on his build. It's a shame people don't value the build thread anymore!
The only things I find concerning is OZs use of copper for the oil pickup and coolant manifolds. I'm not sure if that's the best material. For the coolant manifold, I'll probably go with a custom Tractuff unit. I suppose I could get my friend the machinist to remake the oil pickup in TIG'd steel if it bothers me too much.
Oh, and the final cool bit of the OZ kit? Apparently they can drill it for both generations of J series bellhousing pattern on the same adapter plate, so I would never have to worry about swapping between older and newer engines.
Originally Posted by SimBa
I remember him liking the car when he had it though. Seems like a good swaption to me.
PS - if you go through with the swap and decide to name the car SwapTionXIII I want credit
Haha, you got it!
Bit of a background story, the username is supposed to be a reference to F1. In 1994, Michael Schumacher and the Benetton team were likely using an illegal traction control system carried over from the previous year, before it was banned. In one menu of their ECU, there was a list of 10 options. But if you kept scrolling past all the empty lines, eventually you would find another menu item named Option 13 that contained a traction control program. They claimed it was easier to deactivate it and leave the code in place. Suuuuuureee. The FIA couldn't prove they ever actually used it, so there was no penalty or loss of points/victories.
Anyways, I'd been using Option13 as a handle for a while when on one website the name Option13 was taken. So, I went for the teenage edgelord roman numerals. And I've been using it ever since for all my car related activities.
Last edited by OptionXIII; Apr 4, 2025 at 03:35 PM.
Cats for the origin story. I was wondering where that came from, fun source!
That other swap kit looks way better. That oil pan clearance looks way better. The exhaust is close obviously, but I'd take that over cracking the oil pan just from driving around.
Damn! Good read man. I've never known much about the J swap option due to the lack of builds on here with them. Sometimes I forget that Reddit and Facebook are teeming with information (some bad, but some good) about these niche little projects we have. Seriously, I really am excited to see a potential J swap take place and follow along. This reminds me of thumbing through turbo NA/NB build threads when that whole scene was new to me (although I very much still enjoy reading said threads).
Also, in case the dead horse hasn't been beaten enough. Holy hell, that oil pan clearance on the Minitec kit!
Not much progress of late. I'm back in a place with a garage, which should accelerate progress. On the other hand, I'm looking at a few large expenses and projects in the near future and may need to re-evaluate my swap plans to save up for other, more important things. My NB is running rough lately. I am going to run some diagnostics, but I think at 195k miles and countless track days, it may just be getting tired. I need to get that engine fixed up before I put too much time and money into swapping an entirely different engine into this car. But, I do want my cars to be usable assets rather than just liabilities I tow around. So, I may be putting a 1.6 in after all.
For now, this car is still fun to play with as a tinkertoy that has no pressure to get it running.
Unfortunately, a few weeks ago I dropped the hood down and it latched shut. Pulling the cable release didn't release it, so I let it sit and focused on other things. After moving into the new place, I had a real garage workstation again.
Luckily I was able to sneak the car through the columns in the basement and free up the garage parking space. Now I'll be able to even more efficiently focus on two entirely different cars and get nothing done on either!
Boooooo. Just one more thing to fix.
Naturally, the old MC leaked and ate up all my pretty paintwork.
I spent last evening getting the new parts in place. The master cylinder is a 15/16" bore unit ordered for a 1991 Mazda MPV. It seems to mate to the booster just like stock, although the fluid port locations are different. I made one new line and modified two stock ones to mate to the factory NA brake lines. The Wilwood prop valve is something I picked up used and I am not sure it's in prime condition. The **** is much, much easier to turn than the one I have on my NB. Maybe this is something I should buy new. For now though, it's one less thing in the parts storage bins.
The only other thing I had to do to fit this was change the electrical connector for the fluid level sensor. Thankfully it was just a different housing and I was able to depin the connectors and swap over the Miata one.
Having decent tools makes running brake lines almost a fun puzzle instead of a terrible chore. This Titan flaring tool has made all the difference in the world compared to the typical split vise style I could never master. Even after a lot of practice, I'd get three test runs in a row perfect, but the final flare on the finished line always came out like crap. This flaring tool is virtually idiot proof in comparison.
Last edited by OptionXIII; May 2, 2025 at 10:01 AM.
New garage looks nice and roomy! That's gotta be so nice after working outside for an extended period of time haha.
Bummed to hear about the NB possibly pushing back the J swap project. Hopefully it just needs a tune up or some peripheral component replaced rather than a teardown, though you seem like you probably stay on top of that thing maintenance-wise.
Wow, what a journey! The nostalgia, the impulsive buys and life constantly interrupting the project really hit home. It’s great that you’re finally ready to turn those two piles of regret into one solid build. Maybe once it’s back together, consider adding some protective film or a subtle shade on the windows, it could help preserve the interior and give the car a cleaner look while keeping the classic vibe. Excited to see this one come to life!
Wait, when did we go from air conditioning ducting foam to V6 swap? F*ck it, I'm here for that!
Lol my thoughts exactly! Very cool with the J swap idea. I guess the reasoning choosing a J over an LFX is keeping a miata stock trans vs GM? I think ground clearance is a bit of an issue regardless as it's taller than the BP. A friend has a J swapped s2k and his ground clearance isn't great either. You probably know this but definitely get a new baffled oil pan since the OEM one designed for a transverse mounted engine ends up oil starving the engine. Not sure how well the OEM tranny will hold up to the increased power/torque of the J motor..
On the subject of the OZ Engineering J-series swap, some not-so-awesome news. Last year, the owner of OZ Engineering passed away and his family has opted to not continue his business. I know this because I was searching marketplace for Miata differentials and happened upon a listing from a friend of his whom had been tasked with selling off some of his accumulated Miata parts. It worked out for me - I ended up taking home a 3.63 differential - but that's a huge bummer for anyone in the Miata-verse who's looking for a J30 and is considering the same pros and cons of available swap kits like OP is.
The other thing I've learned recently is that Claire, the owner of CrapEngineering in the UK, is retiring very shortly. She made some comments about tax laws vs retirement status, but the takeaway is that she can probably continue to do local business under the table, but she does not seem willing to export anything due to tax implications. This includes her existing Mazda K V6 swap kits, as well as any Honda J swap parts (she has made a handful of these since 2022 that I've been able to hunt down on social media, but her online presence is non-existent and completely unknown to many of us in the US).
What this means for us - the current options for mounting a J-series in a Miata are now the minitec kit, or 100% DIY.
I heard the news as well. It's sort of **** to say in the context of someone else dying, but that's about in line with how 2025 went for me. If I hadn't had so much stuff go wrong last year, I may have taken the plunge in time to actually buy a kit before his passing and OZ closing up shop.
I did reach out to Gary Jr soon after his fathers passing. He seemed amenable at the time to sharing or selling me the design (for personal use... I'm not getting into owning a business), but I didn't push that topic any further. I wanted to be respectful of his space during that time, and I really did not have the capacity to take it on.
I'm close to buttoning up the engine rebuild on my 2001. Assuming all goes well, I'd like to restart this project in some capacity. I'm not sure what the end goal will be. I don't care for the Minitec kit. I still have the wrecked shell of my old 1990 that's been haunting a shed at my uncles house since 2015. I need to deal with that, and at this point I mostly want to limit the extra complication in my life. A plain jane rebuilt 1.6 is boring, but it would let me get a bit more crazy with my 2001 and still have a fun little go kart that's nice to drive around town.
Last edited by OptionXIII; Feb 13, 2026 at 10:55 AM.
There's nothing wrong with a plain-Jane 1.6 rebuild!
I know you've mentioned it already and have some concerns, but give the ecotec swap another look. It has been getting continued development over the last year or so after they change ownership and it's gaining some traction in my books.
It still has some quirks (no OTS solution for header or cross-under pipe), but:
unlike the K-swap, retains balance shafts
it now has a patch wiring harness and an available programable ECU
it works with a stock subframe or aftermarket
it has a revised oil pan design
it has a revised engine mount design
it has a revised flywheel/adapter situation
with an extra intake camshaft on the exhaust side, valve springs, ecotec's intake manifold, and a decent exhaust, the LE5 seems to make pretty decent power, ~185 or so with power all the way to 7500 rpm. LEA and LAF seem to make more power out of the box, but they have DI and that gives you less freedom on engine management for the moment.
a couple well-regarded porting shops exist for it because of its popularity in dirt track racing. Seems like there's 6-8% air flow improvement across the rev range to be found with porting.
Downside; it isn't ...uh... the sexiest exhaust note I've ever heard, but neither is the BP if we're being honest.
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