It's been cold out. Too cold to lay down serious amounts of paint in my smaller garage. So I've been trying to find other stuff to do.



I measured about 18" of 5/16" fuel line needed, but they only sell it by the foot.

I put in bolts in to secure the big parcel shelf tin. In shifting it over, I pulled it towards me and my finger slipped and sliced it bad. No pics.



New foam for the HVAC clamps - I measured 1" x 1/4". I could only find 3/4" wide in the one store I went to, so that's what it got.



Oh, look what I caught sight of. I'm going to try to find a way to address these two gaps - between the two case halves, and between the warped part of the case and the flap.



I find it fascinating that the cheapest pedal pads I could find shipped to my door were apparently Genuine Mazda.



I'm going all over the car trying to find things that can be assembled without needing to be removed for later painting/seam sealing. Things are getting put back in place even if just loosely, fuse boxes bolted down, carpet going back in, etc. I need to clean up piles of spare parts and toss the ones I don't have use for.

I usually take good reference pictures. I definitely didn't on the engine bay wiring harness layout. I'm trolling the internet for stock engine bay pictures and service manuals to find the best guidance on how to lay out the harness like factory.



I did end up grabbing the cheapest possible combo for a Miata clutch dom and sub cylinder (I try to keep with the times, heard someone complain about the... traditional terms), and MPV brake dom cylinder. All for less than the cheapest non-ABS Miata MC.

 

Hell yes! This might be the first time I've provided inspiration for anybody on here haha.

In for the MC results. Stoked to see if that MPV unit works out for you.

 

I'm pretty sure you got more than one person thinking about getting into an NC!

I love it when what other people do lines up with what you need to learn. For todays example, I've been overanalyzing how to get a bead rolled onto the heater core hose. Well, @crxguy52 got inspiration from another build thread and shared what he did. I'd seen this before but wasn't sure how well it would work on the smaller heater core pipe compared to the larger intercooler piping most people do bead rolling for. After seeing his post I scratched "throw heater core pipe in car when you get home" off my to do list, and instead just went directly to HF to pick up the crimp pliers on my way home.

crxguy52's NB LFX build - Miata Turbo Forum - Boost cars, acquire cats.


Marking out the cut I'll make with the angle grinder.


Once cut down, it was able to fit inside the heater core pipe.

Important to note, but difficult to see - make sure you give the inside jaw a rounded profile! Otherwise every squeeze of the jaw will deform the circular cross section of the pipe.


The result isn't perfect, but I don't think it's at risk of popping loose.

Now here's hoping the corrosion on the bottom of this heater core isn't from a massive leak!

 

Kludge to the Max, Val would be proud! I am going to keep that one up my sleeve for IC piping.

But, how old is that core? How much fun is pulling it out? You may have simplified the job, but I would be looking for not having to pull it out again, especially as there is some evidence of leaking. And if you don't know, and plan to roll the dice, get it pressure tested at your local radiator repair shop.

 

Looks pretty good to me! If you hadn't pointed out that it was DIY I don't think I would've thought twice about the barbs.

 

Glad that trick helped you out, your beads came out great. I read that a while back and made a mental note since it was so handy. I'll probably steal your idea to rebuild the HVAC boxes while they're out, my car is new...er than yours, but I'm sure the foam is like half intact.

Looks like we're pretty geographically close to each other, if you ever need something welded I'm happy to help. I've got MIG and TIG machines. I won't pretend that I'm good at either, but nothing I've welded has broken... yet.

 

I may someday have to take you up on that! I always like getting to know the local enthusiasts.

So... I've got a bit of a dilemma. A 2003 LS just showed up in my local yard. I went ahead and pulled the ladder brace since I know I'd like to have one on this build. But... Should I grab more? The Sport brakes? The 5 speed that can handle more torque than the 1.6 unit? Maybe the Tochigi Fuji diff (not sure the ratio on this year)? The heater core?

 

Would grab brakes, servo and MC (they will not fit over 14" wheels though), heater core (aluminum), diff (if your car has the smaller unit, the fuji diff itself is not great but at least you get the bigger housing and gears for free). I was not aware the gearboxes were any different internally. Maybe also the front subframe/steering rack (I like how NB mounts the rack way better than the NA, but depends on the cost).

 

For me, I'd skip the brakes. Better pad options on the standard 1.8 brakes. I didn't know about the trans being stronger, just that it shifted nicer, but maybe that explains my luck with my nb 5 speed.

Front subframe as mentioned is a minor geometry upgrade, id like to get one for my NA at some point.

 

Well, I'm proud of me. I went there to take another look at the two Miatas and left with barely anything at all - a 1.6 crossover pipe that wasn't cracked, a 1.6 oil pressure sender, and every single screw I thought was worth keeping. I may go back for the booster and master off the NB... but it's $50 for the pair and I just picked up a 15/16 master - the MPV part.

And the front NB subframe swap is already done!

 

Been a long time since the last update on this. Life has been... interesting. I've had to make a rather sudden move to a new house. I've done some pecking away at this project but it's up in the air as to if I will even keep it. Regardless, I'm going to get it to one single pile of parts in good condition before deciding if it stays with me as a project, goes into storage for a bit, or gets sold.

I put the dash back in loosely to consolidate things. While I was doing that, I noticed some damage on the drivers side with broken mounts and such. So I whipped up a quick repair.


This area of damage at the bottom left corner of the dash, by the drivers feet, would be hard to reach with it installed. Hmmm... how to repair this?


Whip out the CAD, print, test fit, and iterate the design until your're happy.


I used some epoxy to bond the final version in place.

The heater core grommets were trashed. New ones would be something like $30.



Two PCV grommets for an SBC or 4.3 fit well and will certainly seal better than these old things. I got the idea from this m.net thread.

Now, as for the biggest piece of work that's been slowing me down - dealing with the surface rust.


I put down a layer of 2k epoxy primer.


And followed up with 2k epoxy gloss black. I couldn't find a cheap satin black unfortunately.

Also note the plug on the bottom that I popped out to unlock the trunk without a key or internal release - it's now glued in with seam sealer.


I sprayed a few other areas of the chassis as well. I didn't grab a picture, but I also scuffed this area after paint and applied seam sealer just like the factory did.


Last night I got the bumper back in.

Since I'm now working outside, the goal is to finish robbing the crashed automatic shell ASAP and get my new house to not look like a junkyard.

 

Dang, unexpected twist there. Hope all's well in your world man.

The recent progress you made looks good. Regardless of what you decide, good car karma's coming your way for breathing life back into her.

 

Hope all is well man. Cars are just a fun distraction in this short life.

 

Thanks for the kind words guys! This will be a change for the better, I am sure of it. Just a little hiccup on my planned path. At this point I am pretty confident I'll be keeping the car. As per the title... it's well into the sunk cost fallacy. For the price I have in it, I could have just bought a better condition NA from the get go. But where's the fun in that?

I got the subframes swapped over. This one from the automatic, while clearly in better condition, may have been a junkyard replacement item as part of the repairs from the crash(es?) the car was in. It has "22" written on the underside in junkyard-esque pen. The uprights don't match - the left one has no ABS boss, the right one does. I measured the distance between alignment eccentrics front and rear, and all appears to be okay. It got the usual cleanup and splash of paint.



I threw in my MSM coilovers as well. For some reason I didn't do that prior to installing the subframe and had to loosen a few control arm bolts to get enough flex in the suspension to slip them in.



Now we're on to the detail items... I am swapping anything I find to be in better condition on the donor automatic, onto the keeper car. Even the fuel filter hanger and e-brake cables.



The donor automatic is a '93, the keeper is a '91. Apparently at some point along the way, Mazda started using these rubber isolaters in the fuel filter mounting. Finding no other differences in any of the related parts, I went ahead and swapped them over as well.



She's finally back on the ground. There's still plenty of little details do to have this be ready for an engine to drop in.



Speaking of, I might as well spill the beans on my plans. There's no way I'm putting a 1.6 in this car. I've considered a lot of options and I'm pretty set on one that is not exactly a standard or popular choice. I've ruled out most of the popular options.

• 1.8 swap - too much work for too little power. I've already got an NB2 anyways.
• Ecotec swap - Reviews just aren't that great, and it's a pretty modest power bump for most versions of the engine.
• Turbo 1.8 - Too much heat management concerns. It's a well proven path, but not what I really want.
• K swap - Too much vibration from a balance shaft deleted K24, too many people saying they don't want to deal with KPower. Go with a K20 and you're looking at a seriously expensive kit and engine for a pretty modest power level.
• Rocketeer Jaguar V6 - This looks like an awesome swap. But it'd be more difficult than I'd like to source an engine, and I don't trust the maintenance on heavily depreciated European luxury cars.
• LFX - too expensive for what you get, a complete drivetrain tear up, and V8R customer service has me concerned considering most people consider the kit a starting point from what I've read.
• LS - Same as above plus, IMO it's honestly just too much power. Not what I want from a Miata. At that point I'd just buy a Corvette.

So, what do I think I'll go with? Well... I really like how this thing sounds.


The most well known Honda JV6 swap kit out there is the Minitec. It just sort of seems... hacked together. I think their setup is a lot of the reason this engine has been mostly written off in the Miata community.

There's a newer entry into the market - OZ Engineering. It's a small family operation with limited online presence, but they seem to have put together a good swap kit. Facebook groups are unfortunately where all the activity is for these swaps, and in my reading I've seen a lot of happy customers as well as active support from OZ. Their kit seems to correct a lot of the issues that the Minitec has.

• Keeps the stock subframe.
• Oil pan is above and behind the subframe - the minitec kit has the main sump in front of the subframe and dangerously low. Lots of cracked oil pans out there.
• Retains the standard Miata hydraulic clutch release and throwout bearing.

The main problem I see with the J is that it's pretty much right at the torque/power limit of the 5 speed, the 6 speed seems to be hit or miss on shift quality, and there's not currently a better transmission option that fits in the Miata well. Track J swap guys seem to always end up breaking the 5, but on the street they seem to hold up okay. This thing isn't going right to the track though. As of now I'm trying to lay out all my possible options for the specific variant of engine (lower torque J30 for durability? Full beef, 300hp J35A8?), which transmission to use (5 speed? 6? Built 5 speed?), and my options for engine management (Haltech? Megasquirt? Stock Honda ECU? Hondata flashable modification?)

Once the shell is ready, I'll probably back off for a bit and focus on other things. But I did just get a preview of my annual bonus at work and it's looking pretty darn good... Hopefully more to come soon!

 

Wait, when did we go from air conditioning ducting foam to V6 swap? F*ck it, I'm here for that!

Cool to hear there's a new player in the game for that engine swap. Never heard of OZ engineering, but would be stoked to follow along and learn something new as you put it together.

Don't have much worthwhile input myself, but a 6 speed seems like a no brainer at that power level. Have you driven one before? With a proper shifter, I never had a complaint on the shift quality. Stock shifter felt fine to me on the street as well, although 4th gear seemed impossible to find on track for some reason. I did a mild amount of modification to make an eBay 5 speed short shifter fit my 6 speed, added a 2" shift lever extension, and never dealt with a misshift after that. Was really happy with that setup actually.

 

If a 5 speed is marginal, a 6 speed should be safe, right? Careful bushings/mounts/shifter choices improve the shifter noticeably, and if the 6 speed is marginal the circlip mod is the next step. After that you are into transmission swap territory and personally I would not be going there with this platform. Maybe Santa Claus is real and the mooted replacement gearsets will eventuate, but I am not holding my breath.

On the numbers you quote for the J35 the 6 speed is at the upper end of its capacity, maybe on the limit depending on the torque number, so a circlip modded 6 speed would be my choice.

Looking forward to updates!

 

The upgraded transmission \ drivetrains is why I opted to go LFX over J-swap. That, and I wanted a project that required some fab (which I got).

If you can make a stock transmission work it would save you a lot of headache - once you swap transmissions you need a PPF delete, to add a transmission mount, custom driveshaft, etc. etc. Once you're in that deep you might as well do a diff and axles as well. If you're not looking for a huge project (and a lot more $$$) sticking with a Miata transmission would be my choice.

I want to build a tube frame car after my Miata is done, and a lot of the time I just end up asking myself, am I just building a worse Corvette? 😂

 

I dig the J swap idea. I'd keep it on a miata 6 speed, I honestly think it would hold up just fine with that powerband. Sure, it's torquey compared to a NA 1.8, but nothing like a 300+wtq at 3600 EFR setup. The N/A V6 is actually pretty linear and should be reasonably soft on the trans all things considered.

And personally when looking at engine swaps (and to be honest NA/NB in general) I try to build around the limits of the stock drivetrain. Even my current turbo choice is to keep things soft for my 5 speed.

Ecootec looked awesome for a dirt cheap endurance racer, but not very exciting or good sounding. And like you mentioned I've found the reviews to be pretty bad on that swap.

 

I've got some thoughts on "recipes" for the J swap at a few different price points I'll share when I have time to write it all out. The funny thing about engine swaps is that the engine is usually among the cheaper items you need!

Any thoughts on the last items I should grab off of this automatic? Pretty much the only thing left is the engine and transmission. I've grabbed pretty much all the hardware I could find. I think these things have value?

• 1.6 Automatic Throttle body/position sensor
• Oil pressure sender
• CAS
• Coil pack

Thankfully I never titled it in NC and don't have to deal with the stupid Notary BS that can make selling a car here such a pain.

 

@OptionXIII Sorry to hear about the unexpected house stuff. Hope all ends up well. Seems like you're making very good progress on this project though.

I dig the J swap idea and very interested to see where this goes for you. As far as ECUs, Link or Haltech for me.