I have been racing with the 24 Hours of Lemons and sometimes Lucky Dog for 10+ years. For the last 7+ years I built and raced a 1985 Volvo 740 turbo wagon. At the end of 2024, I passed ownership of the wagon on to a team mate and decided to build a Miata. I had owned 1993 Miata, that I bought new, and wanted to have one for the track.

Plan is:
- fun car, that is easy on consumables and reliable
- 2.4L LE5 Ecotec, normally aspirated (sorry MiataTurbo)
- GM e67 ECU and standalone wiring harness
- Ecotec Miata flywheel, mounts, oil pan, DIY racer kit
- Supermiata 1.6 ceramic clutch/pressure plate
- DIY Bilstein coilovers, 700/400# springs
- Mishimoto radiator
- Supermiata small Wilwood kit in front, NB sport rear (already has NB rear subframe)
- Konig Dekagrams 15x9, RS4 225/45/15 tires

First race end of September 2025, 24HoL Buttonwillow.

My friend had a caged NA roller that had previously been a turbo Ecotec. It was well used, but it had a decent cage and a 24 gallon ATL fuel cell already installed.

It came with a few spares.





I cleaned it up, stripped the driver compartment, and set about figuring out what to do first.

I started painting the engine compartment, my previous racecar liked to leak oil, so I wanted a nice clean white so I could identify if this car was leaking.

Previous team seemed to like to make lots of holes in the firewall.



Some hack patches.


A little paint, good enuf. Previous team had also hacked the front clip, so I got another from a friend. Plan is for the front end to bolt on and off.

So we headed down to the junkyard to pull a 2.4L motor


Got it home, and it had jumped time and destroyed the rockers, and probably the valves. I had purchased the guarantee, so back to the junkyard it went.



Pulled a second motor, turns out it ate a ring.

After two attempts of pulling my own, bought one already pulled from a dismantler. Leakdown was good on three cylinders, wasnt able to get a good reading on #4, so decided to pull the head.



Dirty, but I did not see anything wrong. Some crosshatching still visible, so pulled the valves and lapped them by hand.



Pulled the pistons, bearings looked good enuf, so threw the pistons in the parts washed to free up the oil rings, and going to send it.

Next up is adding all the Ecotec Miata parts, timing chains, and tossing it in the car...

 

Wow that's a tough old bird. I've raced against it a number of times in LD, I think. Lots of Miatas out there, but I think I recognize that cut out in the trunk, it's a little unique.

We typically got our ecotecs from dismantlers like you did, maybe a bit pricier, but they were still in the $300-600 range. We went through a lot of teething issues with our swap, but ecotec Miata was always helpful, when you could get a hold of them. Sounds like they've changed hands and started fixing a few of the issues we've had, and are communicating better. Big thing was the billet flywheel, while you could use the adapter and the auto flex plate, it'll eventually crack and make a horrendous noise while it spins around in the bell housing. So get the billet one and a strong clutch, like you've planned. I think the new one is sized for 1.8 clutches? I'd highly recommend a 1.8 version if it's available. The 2.4 makes some great torque and you're planning on abusing it for 24 hours. Damn, just looked and they're only 1.6. Thought their new one was 1.8. Oh well.

Carry some extra engine mount bushings, they're a cheap energy suspension bushing that melts on the exhaust side. RTV the rear main in, it likes to pop out when you do the PCV mod, more crank case breathing would probably help, but it's a MAF car, so that's not as easy as said. Slather the bellhousing adapter plate bolts in loctite, and for the love of god start with a 6-speed or carry 4 extra 5-speeds. Then go enjoy your balance shafts! The 2.4 feels great in a Miata.

 

Yes, that car has been around LD for a while. Now they have a LS BMW. I read a lot of your other posts on other build threads. I went with the billet flywheel because of what you said. I plan on picking up a 6 speed when I find one, but I already accumulated three 5 speeds for next to nothing.

With regards to the PCV mod, do you mean covering the center hole on the intake? Other than the valve cover, not sure where else I can breath the crank case.

 

Any reason you're looking to go to the 6 speed? With no plans to turbo it I think the 5 speeds should be a lot cheaper and still reliable.

Interested to see where you go with it. I feel kinda bad seeing a car so haggard, but I suppose that's what you get going wheel to wheel.

 

Oh this is the Occupy Pit Lane Miata, I knew I recognized it. Aaron's great, his BMW is nuts now, so many buttons.

Yea just the center hole on the intake. We didn't have any issues beyond a few rear mains blowing out. Starting RTV'ing them, no real issues since.

The 2.4s make 180ft/lbs from pretty much any RPM you'll see on track. Equivalent to a 1.8 turbo. We went through quite a few 5-speeds. If you've got them, run them, but just know you'll start to have some failures, and they won't stop until you put in a 6-speed.

 

I have never used RTV on a rear main seal before. I did not know you could. I assume you just put it on the outside edge of the seal.

 

I'm really interested in this thread. I've been throwing around the idea of ecotec swapping my basket case NB2 seattime car. Curly always spoke highly of the swap, though I had read some questionable reviews from other sources, I love the idea of the ecotec motor in an endurance/seat time thrasher. Lots of torque, no need to rev the **** off of it, just short shift and the motors should last a long time. And a good power level for a miata, still keeping it a momentum car but closer to being on par with something like a 2.5 + cams NC.

Please continue to document this as much as possible!

 

A lot of the bad things I read were about response times and leaky oil pans. The new owner was very responsive, I got my kit in around the 8 weeks he promised, and there is a new oil pan design.

 

Engine has been put back together and Ecotec bits have been added.



I do want to change out the manifold outlet to a v-band.

 

Can't tell from the pic, but the lower alternator mount is usually a stud and a nut. Requires removing the stud to remove the alternator (or removing the engine), which sometimes comes out easy, sometimes doesn't. I'd suggest swapping that to another bolt if you haven't already.

 

Thanks. I removed all the studs that were hanging off the engine, with the exception of intake/exhaust. Only bolts on the alternator and I re-clocked it so the connectors wouldn't hit the frame.

The fit between the starter and engine mount is super tight, had to take the grinder to a couple bolts on the starter.

Keep the suggestions coming! I do need to figure out sway bar mounts. This chassis has the originals removed. I don't have any sways other that a stock in the rear. I was looking at the V8 roadster mounts and a solid RB front sway.

 

I thought I'd seen this car before as well! Super cool project, following along from here on out. Big fan of the ~180wtq level in one of these cars. What're you guys gonna rev this motor to?

 

I have no idea what the rev limiter is set to on the ECM. The guy I got my harness from put the tune on it, I think he got it from the team I got the shell from. From what I understand these engines have a pretty good torque curve, so probably set my shift light to low 6000s to start?

 

Got engine and transmission into the car over the weekend.

It made engine sounds with starter fluid. Somewhere in my garage the Corvette fuel filter/regulator got lost so I couldn't start it up with real fuel.

Also started installing the Brofab/Sadfab hubs I got from @sixshooter (thanks), plus Wilwoods with ducts I got from Supermiata.




Lower rear control arm bolt was bent to hell, took a sawzall and BFH to get it out.


This bearing is sub-optimal.


I wish I had access to a nearby shop press.

 

A press and a bearing puller probably isn't a bad thing to invest in. Helpful with anything from pilot bearings to suspension bushings to wheel bearings.

You can rev these to 7000, but you'll quickly realize there's little to no point past 6000. Shift at 6, 6500 if you want a barely faster lap, 7000 only rarely when you want to save a shift.

I've seen those corvette filter/regulators leak, make sure you know what you're doing. I'd recommend an aftermarket regulator with gauge or sensor mounted in the engine bay.

 

Now I am scared. Definitely going to put a pressure sensor near the rail. Filter/Regulator will be in the trunk next to the fuel cell.

 

Yeah I have no idea what the maintenance schedule of the car I inspected was. Just touched the hardline they had made and it leaked. ~2 weeks later I was doing 110mph a few feet off their bumper, so hopefully they fixed it?

 

It's been a while, haven't made the progress I wanted and missed the Buttonwillow race. Ended up "racing" a Daf 55 instead. Trying to make a track day on 11/8 or 9 at Buttonwillow. We will see. Next race is Sonoma Dec 12.



Front clip is back on. All bolts for easy removal.

Also hacked in a electronic throttle pedal



Working on the MK60e5 install. Used the Wingman method for the front rings, ended up buying rings from Brofab for the rear. Still trying to get them on, printed a tool I will try tonight. Printed a bracket engineered2win made.



Discovered I have a welded diff. Meh.



Did a little painting and cutting in the wrong order. Going to box the transmission tunnel in for more room for a Kirkey halo seat plus fill more holes.

This weekend will be finishing the side exhaust like Wingmans, final brake lines, and wiring. Maybe fit the seat if I have enough time.

 

I'll be at Buttonwillow on the 8th and 9th. Good luck with the car prep! Hope to see it there

 

Finished up the seat install, used Blackbirds mount in the race seat thread as inspiration. Try to ignore the messy welding on the trans tunnel. Since we have drivers from 5'2" 100 lbs to 6'+ 200+ lbs I added sliders. Kirkey 81, 16".