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"Time for an LS swap"
LS is ******* boring and doesn't excite me whatsoever(sorry Padlock, nothing personal).
...I'm just here for the inappropriate humor at this point
Full disclosure.... By the time my car runs again, you'll have swapped whatever new engine you are considering in, completed seventy-hundred laps, blown it up due to failure modes only ever known by an alien species, and then have rebuilt it on a sidewalk with tools from a Texas Roadhouse kitchen to podium in unlimited class... and I'm here to find out whatever piece of that sentence is true
That said, absolutely gutted to see you deal with this K24 stuff. Saw the cracked turbo housing and just about threw my phone out my 2-story window for you. What a wild failure mode. To ice the cake with a cylinder 4 failure is just... demoralizing hot garbage... Your resilience to keep pushing on is both admirable and incredibly exhausting to watch from the sidelines, but I do think you are on the right path by finally tossing in the towel on the K24. Briggs has tossed multiple factors of dollars more at his turbo Kmiata and can't seem to catch a break either, so I'm beginning to believe it isn't coincidence that there are not many 500+hp RWD K24's seen on track (except for Kpower's cars that are always reliable with no issues). Look forward to whatever new engine this could be. As much as I'd like you to come to the dark side of basic b*%#$ LSx land with me, I am equally excited for you doing something different.
My guesses (all of which somehow can't be less reliable than your K24):
4.0L Audi Hot V Twin Turbo V8 (....because 2 hood dumps is way cooler than 1)
5.0L Jaguar S/C V8 with RWD 8HP
Kia Stinger 3.3L Twin Turbo V6 with RWD 8HP
2.5L Audi Daza 5cyl (....I'd actually genuinely love to see this)
A copy of Rob Dahm's turbo 4 rotor to stay true to the Japanese roadster path to mecca.... lol
That is all... I should probably go turn some wrenches in my garage instead of typing here
Full disclosure.... By the time my car runs again, you'll have swapped whatever new engine you are considering in, completed seventy-hundred laps, blown it up due to failure modes only ever known by an alien species, and then have rebuilt it on a sidewalk with tools from a Texas Roadhouse kitchen to podium in unlimited class... and I'm here to find out whatever piece of that sentence is true
In all seriousness, so sorry to see this... again. At the risk of being the party pooper voice of reason, you're so far beyond the design parameters of the car, engine and even swap kit at this point that failure of one form or another is almost inevitable. Even the Miata chassis parts are going to have an accelerated failure rate beyond 300hp with big Hoosiers. You had some amazing achievements, but at the performance level you're pushing nothing is designed for the kinds of stresses the car is seeing.
An LS may be 'boring', but as noted, it's the proven pathway to the kind of power you want with some reliability and naturally aspirated simplicity. Anything else is going to require forced induction on an engine that wasn't designed for it, and some choices will require rolling your own.
If 300hp would be enough (clearly not ) I think you're failure rate would be lower, and you'd have more choice in direction.
Damn man, that's a huge bummer, I can't blame you for taking a break after that, especially considering most people would've taken one after the first failure of the year.
Now, I assume this is a stupid idea considering they are still fairly new, likely hard to source, hard to control sensor/ecu wise, and would probably be topping out around the power levels you want, but what about the G16E-GTS out of the GR Corolla/Yaris?
The more I think of it, the more ridiculous and stupid it sounds, but I'm pretty sure people have made upwards of 500 WHP on stock internals. I'm not sure about reliability, sensibility or feasibility, but given who I'm talking, those seem like topics to be ignored.
I've been observing this thread for awhile, gonna jump in with my observations. There is a lot to take away here and it aligns with what I've learned going through a time attack build myself. It really sucks to spend $1000 for a weekend at Gridlife just to get like 5 minutes of seat time and a broken car. I'm sorry to hear it.
About the engine failure: since you observed the remains of the #4 rod bearing as "flakes and glitter" that made it into the oil filter, this would be due to the bearing grinding away over some time to make it through the oiling system like that. If the rod bolts alone let go on an otherwise good bearing, then the bearing would just be left in larger chunks/pieces in the pan. Also your #4 crank journal is discolored from heat. This looks like a classic spun bearing which you first heard with the noise and continued to race on until the secondary catastrophic failure. I too have spun a bearing on the track back when I had a K20 powered RSX. #1 rod bearings ground away until there were no bearings left, and the rod was just rattling around on the journal (rod and bolts remained intact). But I didn't break the rod because I pulled the car off track as soon as I heard the noises start and just tried to limp it home. In that engine, the remaining bearings on the other rods also looked fine with no play in the rod ends.
I think you picked some conflicting or unrealistic goals at the beginning of this build thread. If you want to have The Fastest Miata...ever or hold lap records, firstly you must throw out the idea that it can be done on any sort of reasonable budget. Those kinds of records are held by "he who is willing to spend the most money" and always will be. The same holds true in professional racing as well, even in "stock" car and formula racing with their rules. Even the best drivers will struggle if their teams are underfunded or the car isn't as well developed.
For the goal of having a reliable car that can run all season, can finish events and drive home; this is probably the best goal to have because its going to be the most rewarding. But the more power you make or the further you push the performance of a given car from stock, the price for this reliability will also skyrocket.
You could move to an LSx swap in your Miata and solve your engine reliability issues, but the rest of the car is still not up for it. You don't have enough brakes, the suspension parts (like control arms) are getting worn out fast, your shifter keeps breaking, electrical issues from a custom harness, broken axle and diff mount on that previous event; on top of that the couple times that car has gotten acquainted with a wall or guardrail. To handle this much power and cornering force, you may as well build a real tube chassis race car and just put a Miata silhouette body on it.
But what if I told you there was a lightweight RWD convertible with double wishbones at all four corners, big brakes, fantastic aero, is designed to hold up to the power of a V8, and it also left the factory with 16 valves just like a Miata?
Its the C5/C6 Corvette. If you must drive a 600 hp car around a racetrack and you want it as reliable as it gets for a relatively bargain price, then take the red pill and buy a Corvette.
I have to agree with Roda above; the Miata as a platform is in a happy place between 200-300 hp. If you choose to stick with the Miata time attack car and want a less-worries experience with reasonable costs, that's where I would advise sticking to.
And doing K24 swaps is just as basic as an LS swap.... Change My Mind! There's nothing original about another turbo Honda K in the world. Its just a worse way of making that big HP when you can have more displacement instead. Honestly you could have made similar numbers with a 4G63, Ecoboost 2.3, or any number of factory-turboed 4 cylinders that were built for boost. You get to a point where the turbo was the real engine with a just piston-stage in the middle, negating the need of Honda's secret sauce VTEC system. Even using the "base" low output K24 from the Accord/CRV/Element would have probably made the same numbers but with the benefit of a bit lower compression to help reduce the strain. Anyway...
Sorry to hear about your motor blowing up...again. I can relate and I know it sucks. I had my LFX swapped RX8 blow up on the first session of a two-day track weekend few weeks ago LOL.
I will selfishly vote for an LFX swap with 8HP trans and a single turbo....just because I want to do the same for my Miata and I want to follow your build thread. ;-)
LFX with Simple fuel mods, LF3 rods (those are OEM titanium and can be had for $800 a set) and LF3 pistons @ 10 psi will do 500WHP without a sweat. I got my spare LFX with 40k miles for $780.
Man, sorry to see this happen! I have followed your adventures over the years, having a soft spot for a quick hillclimb car. You are at the bleeding edge of extracting grunt, and pushing it on the track, and while it doesn't help - these things happen.
I look forward to your next step, engine-wise, I certainly hope it retains the Miata platform but you are putting it under a lot of stress.
LOL... These motors are stout. In my case, it was mostly a user error as I was messing with the tune and fuel system at the same time and did not pay enough attention to making sure all is nice and clean before putting it back together for a track weekend.
Since we're bench racing here... I do daydream of putting a big roots or screw-type supercharger on my LFX (or just starting with a LF3 since they're already built for boost). I agree the turbo route adds a lot of weight in plumbing, not to mention taking up space that isn't there. But there's plenty of room up and out of the hood . You'd need a custom intake manifold, injector rail, air to water intercooler, etc. Definitely not the simplest way to make power but having a big supercharger sticking out the hood does score more than a couple cool points.
Also, sorry about your motor Wingman. Like others have said, I'd have given up after the first motor blew up. Your dedication is admirable. I'm sure you'll be back with something even wilder.
13bREW or bust. While I am mostly joking, I'd bet money on it being more reliable than what you have been running. ****, I'd bet money on a built to the **** BP being more reliable.
LS is the way man. I know you are in the south and are tired of every-*******-thing being LS swapped, and yeah it's annoying, I hate it too. But for your use case it just makes sense to have an N/A v8 making the power you need. Almost anything else will need turbo(s) and you are gonna basically be back where you started with this and might as well keep banging your head against the wall trying to iron out the K. Plus if you build a higher RPM screamer of an LS i bet you will change your mind about it being not exciting.
And no offense, but K swaps aren't super exotic or cool either. They are pretty much right there with LS swaps for me, overdone and tired of every ******* 14 year old telling me to swap my car.
Whatever you do I'm here for it. Just hope you keep the NA chassis going!
About the engine failure: since you observed the remains of the #4 rod bearing as "flakes and glitter" that made it into the oil filter, this would be due to the bearing grinding away over some time to make it through the oiling system like that. If the rod bolts alone let go on an otherwise good bearing, then the bearing would just be left in larger chunks/pieces in the pan.
Good observations here. I guess that solidifies the rod bearing failure/spin over the less likely ARP bolt failure. The weird part of this is there was zero sign of this happening ahead of time- I'd just done an oil change before Pitt and there was no sign of metal in the oil or filter. Whatever caused it to come apart happened rapidly.
Originally Posted by Fireindc
13bREW or bust.
Lots of people voting for rotaries, but that's one I ruled out very quickly. I can't afford that high power rotary life, I'll leave that nonsense to Dahm 😆
Originally Posted by Fireindc
Whatever you do I'm here for it. Just hope you keep the NA chassis going!
This chassis is staying and I'll stick with it until something forces me to write the chassis off.
A replacement for the K has been selected.
It's not a V8 or turbo 4 cylinder, and it will not be backed by any 6 speed. I selected something that will give me ample engineering challenges to keep me occupied, and force me to kick my fabrication skills up a notch, as no kits or off the shelf parts exist for this motor in any Mazda chassis.
Things are in motion, but it's going to be a little time before anything postworthy happens. The *very ambitious* goal is to make season openers by April, but as stated... That's unlikely.
2
) I think you're failure rate would be lower, and you'd have more choice in direction.
. You'd need a custom intake manifold, injector rail, air to water intercooler, etc. Definitely not the simplest way to make power but having a big supercharger sticking out the hood does score more than a couple cool points.
