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-   -   Just your average K24/Drysump/Stocksubframe/S2000trans build for NASA/WRL (https://www.miataturbo.net/build-threads-57/just-your-average-k24-drysump-stocksubframe-s2000trans-build-nasa-wrl-96178/)

greddygalant 04-19-2018 01:07 AM

Any interest in making another set of your diff and trans mounts? I want to ditch our current setup with the ppf . Good luck at your enduro, our first ecotex swapped tace is this weekend.

jpreston 04-19-2018 10:16 AM

Sure. It will probably be another 2-3 weeks until I have the trans mount ready.

jpreston 04-20-2018 01:59 PM

Well I think I fucked up again by buying used ebay parts. I started playing with the 2011 equinox wiring harness last night and a few of the connectors are wrong for my 2017 motor, and some of the connectors are partially broken. So now I can either buy a new/correct harness for the 2017 motor, buy some new sensors and a new throttle body to match the 2011 harness, or buy connectors and pins and start cutting and splicing.

I put my engine's VIN into one of the gm parts websites and found this:
https://www.gmpartsdirect.com/auto-p...g-harness-scat

For $80 more I could have had a brand new engine wiring harness that's specific to my engine. Dammit. I'm going to play around with the 2011 harness a little more this weekend before making a decision, but I think I'm going to just order that 2017 harness.

jpreston 05-02-2018 11:04 PM

So I've had an NB2 ABS pump sitting in the garage for a while that I was too lazy to install on my old NA, and I decided I was finally going to use it on this car. I wouldn't complain about having it for street tire enduros. I bought a 929 master cylinder to go with it-- the one with only 1 port for front the front circuit. Now that I'm way behind schedule on this car and I really want to get on track, I've decided to skip the ABS for now and revisit it this winter. I still want to use the 929 master though, so I need a way to tee the front lines.

I really want to use this factory 929 fitting, but it looks like mazda discontinued it and it's NLA everywhere. I tried searching for used 929 masters on ebay hoping one might have the tee still attached, but no luck there either. Does anyone know of a source for it?

https://cimg9.ibsrv.net/gimg/www.mia...acd15e9599.jpg

jpreston 10-25-2018 09:24 PM

I've spent the last few months finishing up a huge project at work and then spending a ton of time living in hotels for the project install, and I haven't made any progress at all on the miata. While traveling alone and trying to kill boredom, I've been watching the ecotec miata facebook group and seeing more and more racers and track guys having problems with the swap. Most of the problems are relatively minor or could be avoided with a specific preventative maintenance and replacement schedule, but they still slowly killed all of my confidence in using this swap for an enduro car. At one point I convinced myself to ditch the oil pan from the swap kit and go to a dry sump. I even designed a dry sump pan that would fit around the stock subframe but I couldn't get excited enough to start machining it.

Then WRL released their 2019 rules, which now require dyno classing to get onto the podium. This kills the small loophole that my LEA engine fell into, which was my main source of excitement for the ecotec swap. With the old rules I was able to legally class the car at 182 factory rated hp while actually running at 200-210whp. New rules force me to class at the 200-210 number, which is a roughly 300lb difference in comp weight or a very heavy detune. Sucks.

So I decided fuck it, I'm selling all my ecotec stuff and switching to a standard Kmiata swap. It's more expensive than the ecotec swap, but seems to be much more proven and reliable, and the K series has limitless potential if I get tired of nasa/wrl in a couple years and want to build it into a crazy time attack car or whatever. Only downside is that it's not NASA ST4/5 legal and has to run ST3 with an unfavorable mod factor because of the aftermarket subframe, but whatever, I decided I didn't care.

Then, about 3 days after deciding to go Kswap and almost being ready to pull the trigger on a huge Kmiata shopping cart, NASA went and announced that 2019 Nationals is at Mid-Ohio. Mid-O is one of the 3 tracks closest to my house. It's possibly my favorite track that I've driven and I won TTE nationals there in 2012. There's no way I'm not going to have a car to race at Mid-O nationals.

The options I came up with:
1. Finish the ecotec swap. The smart choice that's already 95% paid for, but is the least exciting to me and still has potential reliability issues that need figuring out.
2. Go back to a BP setup and run ST5. Surprisingly expensive since I've already sold almost all of my BP stuff, and I would be starting from scratch then shooting for 160+whp.
3. Go back to a BP setup and run ST6. Too slow, and too close to the same car I've been driving for 5+ years now. Not interested.
4. Go back to a BP setup and run ST4 with a TSE turbo kit. Would be an awesome car that's 100% capable of winning Nats at mid-o, but again, would be really expensive since I'm starting back from the beginning with BP stuff. Also I still want to enduro the car a few times a year, and turbo fuel economy is a problem.

5. The nuclear option that I've been dreaming about for over a year but didn't have the balls to take a gamble on: dry sump K24 with stock subframe. The power potential of a TSE turbo miata but with n/a fuel economy for enduros. Lots of development work and potential reliability issues in the beginning, but not much worse than the ecotec and will be way more awesome once finished. Surprisingly, cost ends up about the same as the ST5 option and not much more than a standard K swap. I only need 200-220whp for ST4 so stock TSX engine with bolt-ons will be plenty.

I finally said fuck it and placed the order for the dry sump kit this morning. I'm still not 100% sure it's going to work, but I've studied a ton of build thread pictures and taken a bunch of measurements off my ecotec swap, and the only thing left to do is try it and see what happens. 3-5 week backorder for the dry sump kit, so plenty of time to start organizing parts. I'm nervous, but also really excited.


Tl;dr - Broke brain. Selling ecotec stuff and attempting a dry sump K24 swap with stock subframe.




jpreston 10-25-2018 09:29 PM

The Pace dry sump kit that I'll be attempting to use:


https://cimg3.ibsrv.net/gimg/www.mia...2bf6a5c53e.jpg
https://cimg4.ibsrv.net/gimg/www.mia...6cbe6bd39f.jpg

zellers88 10-25-2018 09:33 PM

This sounds pretty wicked. If you need a completed one to look over or take measurements from I'm up in Indy and head down that direction every so often.

jpreston 10-25-2018 10:16 PM

In an effort to make this even more complicated and dumb, I'm going to use an S2000 transmission. I can't stand the miata 6sp shifter, even with the MR short shifter, and the adapter plate and flywheel are already available for the K24 and S2000 trans combo. I was already planning to do a PPF delete and custom trans mount with the Ecotec, so trans mount is no big deal. The S2000 trans has the slave cylinder on the driver's side, which should help quite a bit with exhaust routing. Driveshaft is the only thing left to figure out. I was talking through this idea with a friend today and he had the realization that since the S2000 and miata ring and pinions are interchangeable, the pinion/driveshaft flange might be a straight swap into the miata housing. That would mean I can just use a shortened (or maybe even unmodified) S2000 driveshaft instead of starting from scratch with something custom. Rockauto says the S2000 and miata use the same pinion seal, so I'm pretty optimistic. Found a used S2000 pinion flange on ebay today for $37 shipped and jumped on it. Hoping to find a cheap 1.8 NA/NB flange that I can take measurements on and compare to before disassembling one of my miata diffs.

Biggest thing left to figure out is the header. I won't be able to run the exhaust under the engine like Kmiata does, so their headers won't work. David says the OEM TSX header should fit and easily reach my ST4 power goals, so that will likely be my starting point. The best option I've found for the future is to weld a K24 flange onto the big primary Good-win NC header, but I'm still not sure that one will fit. I'll probably buy a stock NC header to test fit this winter.

sixshooter 10-26-2018 07:31 AM

Nuclear option indeed!

I did a custom PPF solution when I switched to the BMW trans kit from KMiata. It's probably not what you want to do but it is holding up well. Check the end of my build thread.

Efini~FC3S 10-26-2018 09:18 AM

Ballin...

Maybe I'll see you in ST4 at Mid-O??

jpreston 10-26-2018 09:36 AM


Originally Posted by sixshooter (Post 1508377)
I did a custom PPF solution when I switched to the BMW trans kit from KMiata. It's probably not what you want to do but it is holding up well. Check the end of my build thread.

Go back to post 43 to see my diff mount solution. It's the same basic concept as yours, but I wanted to shorten the PPF as much as possible to give room to cross the exhaust over under the driveshaft. And I didn't need any rubber because racecar. Justin Lee has already been testing it on his J-swap enduro car this summer and it's been working great so far.

My trans mount will be very similar to what hingston did on his F20 swap, see below. Haven't decided yet if I'll do poly engine mounts with rubber mounts for the trans, or delrin engine mounts with a solid mounted trans.
https://www.miataturbo.net/build-thr...e2/#post512327

https://www.miataturbo.net/attachmen...n-p1010114.jpg

jpreston 10-26-2018 09:42 AM


Originally Posted by Efini~FC3S (Post 1508389)
Maybe I'll see you in ST4 at Mid-O??

That's the plan. WRL just released their 2019 schedule yesterday and Mid-O and NCM are both missing, so I'll be running very little WRL and mostly focusing on NASA next year. NASA Nats actually stole WRL's mid-o weekend according to facebook gossip.

curly 10-26-2018 09:53 AM

I got all excited when you said you were using the S2000 trans, missing the part where you switched to Honda power, doh!

In the long run, I think you'll appreciate that engine more.

flier129 10-26-2018 10:12 AM

This makes me so happy.

KMiata 10-26-2018 03:34 PM

I'll be following this, and helping wherever I can

jpreston 10-29-2018 02:25 PM

Lol, props to whoever made the thread title change.

Made some totally unexpected progress this weekend. I learned last week that a friend of a friend has also been working on a K24 swap with S2000 transmission and I spent some time talking to him about it on Friday. A recent job offer in a different city and the accompanying relocation meant that he’s putting the project on hold for a few months and was very interested in clearing out some of the big parts that will be easy to re-purchase later. So I now have a 2NRS adapter plate, good AP1 trans, damaged AP2 trans (was part of the package deal), AP1 driveshaft, and a blown K24 (with all of the steel internals removed so it weighs nothing) that I can use for mockup purposes. Shibby.


https://cimg2.ibsrv.net/gimg/www.mia...2235b167d8.jpg

Full_Tilt_Boogie 10-29-2018 03:03 PM

Awesome build so far. Cant wait to see moar!

jpreston 10-30-2018 04:01 PM

Received the S2000 pinion flange. I think it's safe to call it "confirmed" that it will be a straight swap into a miata diff housing. The critical diameters are identical and the critical lengths are within a tenth or two of a millimeter of each other.

https://cimg6.ibsrv.net/gimg/www.mia...3361275348.jpg
https://cimg8.ibsrv.net/gimg/www.mia...3311cc938c.jpg


The for sale ad wasn't labeled AP1 or AP2 but I got lucky and this pinion flange is from an AP1, which matches the driveshaft I have and the transmission that I prefer. The flange ("companion flange") is only around $120 new if you can't find a used one. The small amount of research that I've done says that the only difference between AP1 and AP2 is that AP1 uses M8 driveshaft bolts (front and rear) and AP2 uses M10 bolts. You can mix and match parts between the two generations by swapping trans/diff flanges or by swapping the ends on the driveshaft. The S2000 has an interesting driveshaft (propeller shaft in honda speak) design with CV joints on both ends instead of u-joints. The CVs are attached the usual way with splines and c-clips so it's super easy to disassemble. S2000s are known for problems with the axle CVs but I've seen very few reports of problems with the driveshafts, so fingers crossed.

Now the only question left is driveshaft length. I don't have an exact measurement yet, but so far it's looking like the S2000 shaft will be ~5" too short. Does anyone have experience getting a driveshaft lengthened? I'm guessing the original tube section will go in the trash and they'll just weld the old ends onto a new tube. Custom driveshafts are completely new to me, and I'm not close enough to purchase time to start calling around and bugging driveshaft shops.

https://www.s2ki.com/forums/s2000-un...KHdz6gZrpDkEyg

https://cimg9.ibsrv.net/gimg/www.mia...e88a0de6f7.png
https://cimg3.ibsrv.net/gimg/www.mia...2ec8cf4af7.png
https://cimg2.ibsrv.net/gimg/www.mia...5e8b5593f5.png

curly 10-31-2018 10:48 AM

I had a custom driveshaft made for a Ford 302 in a E30 with a....something something not a T-5 transmission. I provided the stock driveshaft and output yoke, but they used their own tube, and sourced a new rear U-joint.

No need to cross your fingers on the stock driveshaft, the axles break when S2000s are lowered without spacing the axles out. It spaces the CVs incorrectly to a point where it damages them and they go ka-boom. Hence no known issues with the CVs on the driveshafts, which is also a BMW thing.

jpreston 10-31-2018 11:30 AM

Sweet. I remember seeing all the little axle spacers for S2000s now that you mention it. Thanks Curly.


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