Well la-dee-da, look at Mr Bigshot with his bags of 4P money and fancy tools. Doesn’t want a hunk of steel taking up space in his “I’ll use these bolts one day, promise” bin. I bet he’s too fancy to even have one of those, probably just buys new bolts every time.

(I really shouldn’t make jokes before my coffee kicks in, but I’m breaking that rule anyhow)

 

 

Just as a non-k outsider here, it seems that an inordinate number of track driven k-swaps are failing. Not talking about fitment or peripheral issues, but rather things that require engine disassembly and/or replacement. This is not a criticism but an observation.

 

At this point I would hope this is obvious to anyone who's paying attention. (this is not a dig at you personally, this is a broad statement) It's not just that the KPower parts are garbage, but it's also that the K24 probably isn't well-suited to the sustained high-RPM, high-load use that they're seeing as race engines. I didn't realize until too late just how much the extra stroke of the K24 vs K20 strains the engine (https://www.miataturbo.net/engine-pe...y-k24z3-110699)

I think for the NA/NB Miata, given the steering rack location and the height of the K24, there are too many changes required to the stock motors to achieve "Honda reliability" using stock components.

I wish there was another light, normally-aspirated engine out there that started at 200hp and fit in the Miata engine bay. The Ecotec may be an option, but it's not an out-of-the-box 200hp and it doesn't have the depth of experience we've built with the K24.

 

I wish more people would try the Ecotec. Don't turbo it, drop it in, tune it, and you've got 170-180hp and ft/lbs. Factory tunable ECU. The exhaust melts the driver side motor mount, but it's a cheap Energy Suspension part. Retains balance shafts. Engines are cheaper. DBW, which gets rid of annoying sticky throttles. Doesn't kill throttle bodies. Retains factory subframe. Requires internal slave for decent exhaust routing, but so do some K builds. "Only" revs to 7000, but apparently so should K24.

I'm not saying they're perfect, but recent upgrades to the Ecotec swap kit (oil pan and flywheel) are making it more and more impressive for the daily/track/enduro car. So far I've seen exactly 0 K motor builds that can do that. I've put dozens of hours on a enduro build, they feel exactly like a BP except a bit smoother, they eat 5-speeds once a weekend, and you pull on B6/BP powered Miatas like a freight train.

Sadly, they don't take well to boost.




Jk they take great to boost.

 

I was about to say... It's literally in the name. EcoBOOST 😆
I honestly think the four/six cylinder Ecotech/boost family would have been waaaay more popular if they had been just a year earlier to market, and debuted with an oil pan design that didn't suck(original versions required pan removal to change the serpentine belt). But KMiata went live ~2016ish with all the hype of the K's and the the Ecotech was looked down on as the inferior choice, "only" doing ~180whp when the K's were being toted as a $5k swap for a 260whp stock block invincible junkyard motor.
I've been very impressed with the Miata and non-Miata Ecotech/boost swaps I've seen in the last few years and I think they are starting to make a comeback. A decade late, but a comeback non the less.

 

Uh, Ecotec is GM, EcoBoost is Ford. Not related.

Yeah, if I decided on an engine swap today, I’d consider Ecotec. But I’m in deep on the Honda. Another motor goes and I may change my mind.

God I hope I don’t blow another mofor.

 

Huh. Well TIL ecoboost motors aren't just ecotecs with a means of FI added.

 

Lots of good updates Roda! I like your measured and meticulous approach to things which I can relate to. I'm sure the tapping of the pan on the steering rack probably contributed to the oil pan gasket eventually leaking. What a PITA to fix.

I do agree and wonder if the newer OEM turbocharged engines would be better swap candidates rather than everyone just using K's. It's taking some time as they don't have the upper limit power potential of the K's and the allure of the K, but out of the box with a turbo they should be quite peppy and reliable. I think they will be the next "wave" of swaps after people realize they're a solid option.

I'm not sure what it is about "engine builders" but I think it's a tough business. There's zero margin of error during the engine building process and takes a lot of time, which makes it rife for problems when you try and "streamline" the process. Too easy to screw something up unless it's all done by one person and they're very meticulous. Jeremy Allen is local to me and has a good reputation, but I've heard of so many issues over the years from "engine builders."

Ford Capri is very cool! Older cars are nice but performance wise they don't do it for me because of all the improvements with modern cars. I'm just gonna keep my low power turbo BP and drive it. Cool to follow you guys with your cool swaps though.

 

Welcome to 2026!!

K failures... Failures are definitely happening, but I do think the data set is a little too chaotic to draw solid conclusions as of yet, but we can call out some trends. IMHO, the main contributor to failures is the removal of the balance shafts (required for NA/NB swaps) and running the engine regularly over 7500 rpm. Some discussion here: 7800 rpm might be too much for the Mighty K I also think that 'big power' builds are much more prone to failure, though increasing stress on everything and ... higher revs. I also think there's a higher percentage of K24Z failures, but I don't really have any data to support that, it's just a perception of trends from posts here and elsewhere.

I've said it before, and I'll repeat it... IMHO the sweet spot for the K swap is a stock engine in a race Miata...~215-230hp @ 2200-2400lbs, and keep it to 7500rpm. If you're looking for big power there are better options.

Engine builders... You pay your $$$$$, and take your chances. Lots of failures of built Honda engines. A regular on here had a stockish naturally aspirated BP from a well known and well regarded BP race engine builder fail in less than one season of racing. That story pushed me over the edge into swapping rather than building a BP for turbo. I just decided my chances were always going to be better with a used OEM assembled engine.

I hope that as long as I can be satisfied with ~10:1 lbs/hp, the K24A will continue to work for me. And I will be keeping it to 7500rpm. If I were doing things today, with what I know now, I would probably do something different, though I'm not sure what at this point.

As always, YMMV...

 

'Shipping' is just robbery these days...





KPower is supposed to be sending me an invoice for the washers with a reasonable shipping price... their website software is apparently incapable. But when I can ship a shoebox sized box at 3lbs across the country for under $10 UPS, these prices seem a bit excessive...

 

 

I was actually surprised they answered the phone today...

 

Answering the phone has never been a problem.

Answering an email is hit or miss.

But to be fair, their failure to answer the last email I sent them caused me to have a nutty, spend less money with them, and buy a superior product from EcotecMiata...

So their lack of action cuts both ways I guess...

 

How many events do you have on your K now, Roda? It's been almost two years since you installed and dyno'd it now, right? Seems to be working solid for you so far.

I'm also kind of in the camp of leaning towards unopened used engines if possible for your goals. Maybe not for the reasons described above, though. I just want to be able to get back up and running cheaper and easier if a failure does happen. When the timing belt on my built BP blew and resulted in P2V contact (and some nice dents on the cyl 3 piston crowns), half of my frustration was knowing that teardown and machine shop wait times would be involved. Having another semi-disposable engine sitting on the rack ready to swap in is really reassuring, as opposed to knowing the car's gonna be down for weeks and weeks if the engine blows.

Of course this only applies if your target is under a certain power level. Obviously you gotta pay to play if you want proper big power out of any 4-cylinder motor.

On the coattails of that, though, unopened Ecotecs seem to handle boost really well as Curly mentioned. We've got a guy out here who's been running track events for years in a 350whp boosted Ecotec NB with minimal issue. Dude even drives his car to events and back.

YMMV for sure...

 

It will be two years in May 2026. I just sent of some oil for analysis, and I estimated the time since I installed the engine at ~25 hours. The engine (JDM) was reported to have ~55k miles when pulled. Other than the initial crank sensor issues, it's been almost perfectly reliable. I did have the throttle body cable quadrant come loose due to NVH, but that was fixable at the track, and I've had less NVH related issues than the Z engines seem to.

I agree that using basically 'unopened' stock engines, and having easy/cheapish engine replacements was a big part of my reasoning for using the K swap. If you want big power, you're definitely going to pay to play.

 

Magic KPower washers showed up today. Won't be getting to these for a bit. Still need to order some Honda gaskets before opening the engine up.

 

I do still own this car, even though it's been neglected for months, and the engine is still out.

The other day I tackled a small project that I've been putting off literally for years: a brake master cylinder brace... I had an FM brace on the car, but when I upgraded the brakes and changed to a Wilwood master it no longer fit. Dead simple project, just never got to it.

I started with my usual CAD (cardboard aided design) modeling...





I cut the parts out of some 3/16" flat stock I had laying around, and used the threaded rod/pad from the FM brace.





All done

 

I was thinking that I hadn’t seen any updates on this thread in a while. Glad to see progress!

Does the brake master brace make a difference? I loved the feel of the unboosted BRZ brakes at DirtFish; I’m not about to undertake a project to de-boost my existing, very good MK60 system, but I’d take steps if they’re small like this.

Throw those KPower mounts out and get the AWR ones, especially since they’re already available for your motor. I’m a huge fan of what the Z3 prototypes have done for my car.

 

Thanks... I've definitely been neglecting it while other stuff was going on.

The brace made a noticeable difference with the stock brakes... there's a LOT of flex in a Miata firewall. The Wilwoods are so much better than the stock brakes that I got lazy and never got around to making a brace. I expect that it will help, but probably not to the extent it did with the stock brakes.

I seriously considered the AWR mounts, but I already have zero hood clearance and they reportedly raise the engine by enough to be a problem for me. I didn't want this to cascade into a whole new series of problems... new hood, paint, etc. I also think that they are waaay overpriced at $500. Since I haven't had any issues with the KPower mounts to this point, I decided to stick with them (and add the position locking washers) for now. The AWR mounts are definitely on my radar if problems persist...