S2000 drivetrain swap
 

It's been done before, so not a serious step by step blog, just some photos of problems solved to allow this great engine to join forces with the Miata chassis. The big issue is the different design in the oil pan, with the Mazda having the forward cutout oil pan that allows the engine to sit over the steering rack's rearward position, (compared to most cars), while the Honda's deepest section being the front. I didn't want to get involved with a pan swap, and all the changes needed to accomplish that, so moved the engine as far back into the chassis as I felt rational. I wanted to keep the wiper function, so that became the deciding point for stopping the metal cutting. I also wanted to create some more room to get a header downwind out of the engine bay, so a fairly big cut had to be made on the passenger side of the engine bay/ trans tunnel. Once that was done, I could see how much the steering rack had to move forward, to clear the oil pan. Not wanting to mess with the steering geometry any more than needed, I ended up using a V8R front sub frame, and cutting out the rack mount, and moving it 2 1/2 in. forward. I have found another guy's build, and the photo's looked like it was moved more like 5-6 in., and apparently the car could still be aligned to drive, so I think I'm OK there.
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Once the cutting was done, I welded up the new tunnel, and painted the engine bay, and while the weather stayed nice, the rest of the car. I sent out the subframe to be powder coated, along with the rest of the suspension, and am now waiting for 949 to have the next generation of their 863 suspension bushing kit available, so that can allow me to put the suspension back in. The shell got a new windshield installed, as the old one was cracked.

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Finally, yesterday was a long awaited re-installing of the drivetrain, which gets it off the garage floor, and let me make the trans mount, and start thinking about the header fabbing. Always great to put the engine in for keeps!
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Do yourself a favor and throw away all that fuse box/relay bullshit and buy a decent PDM. I do a shit ton of wiring, everything else looks great, but that made me cringe.

Looking good, can't wait to follow your progress.

What are you planning to use for tuning? Tuning options are terrible, but my '01 was running +14:1 at WOT with a testpipe and intake. This was a couple years ago, but I talked real sweet to Reverant, supplied him with a stock ECU, and he built me a megasquirt that's worked great for me.

I am using the stock ECU; it runs great and since I'm not shooting for mega power will suit me fine. I built a MG Midget project with this same drivetrain last year, but once it was finished needed something to work on, and ended up robbing the drivetrain, seats, gauges out of her to start this Miata project. For me, the package is a known quantity, and I'v done a LFX Miata, and an early NA turbo, so am pretty used to working on Miata's. I'm looking forward to all those rev's in a reasonably light car.

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Seconding Curly's comments, both on the build and the PDM.

I presume you are building it as a track car, and not shooting for rego?

Spridget looks good, how much did that weigh - must have been a rocketship!!

The Spridget was cool, thanks, and weighed about 1500 lbs. The Miata will be a street car, and will see some track duty as well. I was able to find a roller with a little rust in the rear rockers, but otherwise rust free. It had no top or drivetrain, but was a good shell to start with. I have retained the wipers, and all the factory lighting will work, and the engine controls, but that's it, so it will be a basic, simple ride. The engine set back dictated the loss of the HVAC items. On the wiring, I'v probably done 20 cars over the years, and understand circuits and relays, and have no issues with the finished product, so will follow that path, despite maybe getting beat up over it. Modern cars have so much wiring going on, that I have to gut the thing and start from scratch, rather than sift thru all the circuits and keep parts. Being red/green color blind doesn't help with that. I'v found a Torsen diff, and swapped that in, and the front brakes will get the Wilwood treatment. It will look pretty stock, and should be a little lighter than stock, 'tho the Honda drivetrain is around 40 lbs. heavier, if I remember right. A past project was a Seven clone with the 2.2 Honda, weighing just over 1000 lbs.; THAT was a rocket! Just wasn't as pretty as a NA.

Progress and a question
 

A little more progress, getting things off the floor, and back into the car. Diff brace made, and diff mounted. Rad installed, so now can make some shrouding around it. One question: are the parking brake cables crossed, as in the driver's side mounted crossing over to the pass. side, and vice versa, or do they stay on the same side as their location in the tunnel. Car came apart, so I have no notes on that, and can't find any online photos that show the instal.
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I don’t recall there being much slack in the cables, so they probably only fit one way. That said it shouldn’t matter since they’re pulled in tandem regardless.

What radiator is that? Looks ideal for my K swap setup…

Thanks for your info on the cables; finally got them sorted an hour ago. The rad is for an early VW Rabbit,1975-84 ish., Ebay aluminum version. Have used them on other projects, and they work well and are pretty cheap.

Nice build! Subbed for updates.

You made that custom firewall look easy, clearly you've got some fab experience!

Thanks! It's an addiction that's hard to shake, but is my favorite way to spend time. Probably spend more time dreaming and working on them than driving,( which shows a confused set of priorities.)

I hear you there, I always have a car project of some description on the go.
You have to have something to be passionate about in life!

I have a lot of admiration for folks like you who just can't stop building. I just want to ride/drive, not wrench! But if you love projects you'll never be bored.

I guess the downside is the $$ loss every time; I joke to my Wife that I should just ask someone if I can build their car, and give them $10K when it's done, as that's about how it works out. Still, it beats a gambling addiction, crack, etc. and I have a hard time not shooting right down to the garage as soon as I wake up. And these are great cars to work with! You are probably a lot smarter with the ride/drive approach!

Progress
 

Wiring now 100%, plumbing is also finished. Gave up waiting for the Supermiata suspension bushings to arrive, and ordered the Superpro kit so I could get the corners back on. It looks like a good design, so am happy with it. Bodywork back on, so finishing up the exhaust is next.
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Looks clean, I'd maybe wanna throw a heat shield between the relay bank and the manifold, and I'd also suggest some sort of intake tube. Filter right on the throttle body really kills power.

Any guidance the intake tube? I have a fair amount of room to 90 off the TB, but with the stock front bodywork (which I like, and don't want to mess with) don't have a good way to make a cold air box. What issues does the filter right at the TB cause? Thanks for pointing it out!

The filter directly on the TB gives super turbulent airflow, you ideally want enough length for the flow to straighten itself out and become more laminar. I was able to snake an intake tube across and down to behind the passenger side of the front bumper;
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pops out right here and Is anchored to the front timing cover, so it can move with the motor

Just do a cowl intake on the pax side, and skip the water ingestion/multiple bends/ size transition(?) ... cold air from a high(er) pressure source -> win!

Its 3” the entire length, and is ducted from the radiator bumper inlet so probably similar or higher pressure than the cowl. I live in southern California so water ingestion isn’t really a concern. The cowl area is pretty small in terms of fitting a decent sized filter in there.

Thanks for both replies. Problem with the PS cowl is that the header is tucked right below, so a fair amount of heat. I do have plenty of room to sweep some tubing across the engine front, so will take a look at that. Thanks for alerting me!

For the record, I had in mind the filter stays in the engine bay (you can do it the other way, but more trouble than it is worth IMHO) fed by pipe from cowl. Exhaust heat (radiant) easily fixed, after that the heating from hot engine bay air would also be fixable if it were troublesome.

Cowl intakes are pretty common on RHD cars, because they are easily doable (generally), not so much LHD. Swapping the hot and cold sides with an engine swap opens that possibility for LHD.

One downside, or upside for some, is induction noise ...

I don’t understand what you’re saying; it’s a LHD car, but it has had an engine swap that does flip intake and exhaust from the stock configuration. Are you saying it’s easier now that it has been swapped? Or it would be easier if it was RHD…?

You need the bulkhead to be clear of immoveable obstructions on the side opposite the intake (to avoid convoluted/constricted inlet tract), and LHD NA and NB put the brake stuff there. So RHD NA and NB8A (NB8B getting messy with ABS unit) avoid that. Then, LHD with intake/exhaust swapped opens up the bulkhead area in question (ie the Honda swap).

I ran one in my NB8A for about 15 years, pretty simple mod, still available out here.

Mounting your radiator at an angle may allow space between your core support and the top of the radiator for a filer setup like I have...

You can view my post about it here:
https://www.miataturbo.net/build-thr...0/#post1621184

With his bigly modded firewall and the motor pushed back I think he has plenty of room as is. But the V mount setup you did is rad. Def taking notes

The front sway bar is really the piece that gets most in the way (regardless of how far back your engine sits)

Some progress; exhaust system finished up, so she's a runner. The driveshaft finally got finished as well. New intake air tube swapped in, after it being brought to my attention here (thanks!). Had to face up to the new top install before I could make the roll bar. The car came topless, so I didn't have the old one to look at, and the junkyard one I found was missing parts, but finally figured it out. Only problem now is it is so F#$!ing tight I can't latch it. Even with me straining away, and my Wife helping, it will only do one side. Reading up on this, it sounds like hot sun might help, but that is four months away, so who knows. Have the roll bar 90% finished, then the car's pretty much done till I can get her out on the road.

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Glad to see it almost done!

Sorry to say, but that filter location still isn't great. If you have the ability to log IATs you'll see that the engine is sucking hot air right off the back of the rad.

On my E30 I could see the IATs come up and when idling in traffic things got hot enough that I had to start playing with the IAT correction tables to keep it running correctly.
Off the top of my head I recall 160F+ intake temperatures. Even when moving the intake temps were noticeably above ambient.

I agree with you on the hot rad air, probably something to keep working on. We get enough Summer rain I don't want a low to the ground source of air, and the engine bay doesn't offer too many good spots to make a cold air box, but once it's on the road I can keep thinking about the options.

Yeah, seconding that. Anywhere in the engine bay will be hot air.

Short option - cold air box taking outside air from headlight duct. Or take it from the front of the bonnet into said cold air box (front of bonnet is a low pressure area, so anything in that area is problematic pressure-wise)

Long option - either cowl intake on pax side, or taking cold air from in front of radiator. If you prefer, a rear-facing scoop inlet at the back of the bonnet would also work, but it is the windscreen driving the high pressure so you don't want to move the inlet any further away from it than you can avoid.

(cold=ambient)

All good ideas, but require the stock body be cut, or altered more than I care to do. I have a vintage formula car to race, so this baby is mostly a street project sleeper; I like an unobtrusive car that can surprise. If the cowl wasn't so non-existent due to the engine set back, that would be my path. For now I will leave alone, get some miles on her and keep thinking. Appreciate the ideas 'tho!