1992 Mazda Miata V6 Swap- Build Thread

badfrogg wrote: Titus, I've had the idea for year about making a J motor RWD. Back than i couldn't find a single example of anyone else doing it. Now I've seen this kit and I've seen some S2000s done one off. Two concerns are the starter location and the gearing. I suppose the gearing can be fixed with a taller rear end and/or taller tires. (a good reason for going to 16x8 / 225/50s) So what do you think about the starter? does it become the lowest point on the engine. Do you think it could be moved to the top or side. i know the tunnel would need to be cleared but other than that?

The starter is a low point. Given the width of the engine, it is the only engine side location it will work. There are some other swaps that use a transmission side starter. To pull this off, I believe they do more significant cutting/welding to the bell housing to get the start in a position that contacts the flywheel and clears the tunnel.

I will probably come up with a plate to protect it. With that said, it is a super cheap starter that should take 5 minutes to swap out on jack stands.

Sorry for the less than intelligent question... What's up with the motor, strong,durable,??? My only experience is driving a Odyssey once or twice.

Thanks Ross

Ross413 wrote: Sorry for the less than intelligent question... What's up with the motor, strong,durable,??? My only experience is driving a Odyssey once or twice. Thanks Ross

Stong, durable, and found at every junk yard in the country for dirt cheap.

Yeah and some have forged stuff inside and its compact and supposedly light weight, relatively. I discovered this engine when i had my Odyssey. That thing had 200k + miles and the engine bay was almost spotless. Not even a hint of leaks. and it had a nice sound and good torque. The only maintenance i had to do was replacing ignition coils.

the reason that these things litter the scrap yards is because the auto transmissions that their bolted to are known to go. An Odyssey engine - $500 , An Odyssey trans - $2500

Ross413 wrote: Sorry for the less than intelligent question... What's up with the motor, strong,durable,??? My only experience is driving a Odyssey once or twice. Thanks Ross

And stock they make pretty decent power numbers and boatloads of torque.

badfrogg wrote: Yeah and some have forged stuff inside and its compact and supposedly light weight, relatively. I discovered this engine when i had my Odyssey. That thing had 200k + miles and the engine bay was almost spotless. Not even a hint of leaks. and it had a nice sound and good torque. The only maintenance i had to do was replacing ignition coils. the reason that these things litter the scrap yards is because the auto transmissions that their bolted to are known to go. An Odyssey engine - $500 , An Odyssey trans - $2500

Yep... I payed $650 for TWO J32A2 engines, both under 75k miles, including tax, core charge, and delivery to my driveway.

Crimper arrived. Looks like it will be perfect.

The Water Passage. This is going to be a long post.... On the back of the J series motor, there is a coolant manifold that Honda refers to as the water passage. Water coming out from the water pump passes through one middle of the water passage, through the thermostat, and out to the radiator, and then it comes back in to another section of the manifold from the radiator return where it is routed in to the back of each head. It also contains EGR passages that run from the head to Intake, the EGR valve mounts to it, The Air-Assist valve is mounted to it, it holds a temp sensor, and it has misc coolant input/output connections for Heater core, transmission cooler, and IAC valve.

This is what a stock one looks like off the motor (not mine)

While not really mandatory, there are several things that I am changing about my water passage. First was the replacement of the EGR valve with a blockoff plate. (This was shown back near the beginning, but here it is again to show all related things together:

The second change relates to the big coolant return pipe seen in the top right of the stock part photo. It is pointed back toward the firewall. While there is clearance between the firewall and pipe itself, it doesn't really leave the room needed to get a hose on there. Given that the Minitech kit is budget minded, the instructions call for you to "massage" the firewall with a body hammer to create needed room. This didn't sit well with me, so I picked up a new pipe. Speedway motors had what looked to be exactly what it needed, so I ordered it:

It was exactly what I was looking for. Given my welding is limited to ugly steel welds with my Harbor Freight flux wire welder, I took it to a welder near me with aluminum TIG experience. a Day later and the wallet a little lighter, The old pipe was removed and my new one was cut to size and welded on:

Once it was back, I did a quick test fit. The bend of the pipe is more than 1/2" off the firewall, and now there is plenty of room to easily get a hose on there.

Next up was deleting the air assist valve. It is mounted to the top of the water passage and is designed to let extra air in around the fuel injectors when cold to improve emissions during warm-up. Not needed. Prank parts makes a nice blockoff plate for it.

Here it is alongside the factory part:

And here it is installed.

Now I need to cap off unneeded coolant nipples. I got some silicon blanking caps and some Gates Powergrip shrink to fit hose clamps and capped them all off.

While I was at it, I capped off the line intended for the transmission cooler that comes off the water pipe between the pump and passage.

Also of note since I brought up the Gates Powergrips, I picked up enough to do all of the radiator and heater hoses too, and a bunch extra for on hand spares. Zoro.com is really the place to get them, as they charge about half what autoparts stores and places like jegs charge, plus free shipping when you spend $49.

Last up is dealing with the Temp gauge sensor. Honda has a temperature sensor that feeds the ECU, and then the ECU feeds the gauge, but that doesn't work for the Miata gauge. An easy fix is simply bringing over the Miata gauge sensor and finding a good place to install it.

The water passage has a nice spot for it that is tapped on some J series engines, but not mine.

The Miata sensor is 1/8" BSP tapered thread, so I picked up a tap and went to town. A few minutes later, we had this:

Also done but not photographed was the addition of a new thermostat and gasket. You may have noticed from a prior pic that the thermostat housing bolts were making contact with the water passage. The long bolts are made to work with the OEM thermostat cover, but are just way to long for the Minitech one. I turned to my bin of old Miata nuts and bolts and found some shorter ones that worked perfectly. *Side note- I have come to the conclusion that the biggest benefit to parting out a Miata is the wonderful supply of metric hardware it gives you. It saves me from a trip to the store and a regular basis.

I need to go back and add some PTFE tape to the sensor threads, but other than that, the water passage is ready to be reinstalled on the engine.

All done!

"I need to go back and add some PTFE tape to the sensor threads ..."
Some would consider PTFE tape to be a mistake.

Not in this application. Although you could also use PFTE paste. Those threads will definitely seal better with some sort of sealant on them.

I have been wondering about this area since I learned about the swap. I work with these engines daily and knew this would be an area of concern.
Would like to see it all plumbed up with the heater core and all. I have been visualizing fixes in my mind since seeing this as well as a way to support the front of the engine with the passenger side mount boss that is now in front.

erohslc wrote: "I need to go back and add some PTFE tape to the sensor threads ..." Some would consider PTFE tape to be a mistake.

Straight or tapered threads, yes, everything else, no. Basically, tape/dope on any fastener that seals on the threads. I laugh every time I see tape/dope on compression or flare fittings.

In reply to Keith Tanner:
Not questioning the need for sealant on tapered threads, but rather the habit of Teflon tape shedding bits of itself into whatever medium it's sealing and fouling things up downstream.
Careful placement of tape can help prevent this, but I prefer to use paste myself, I think it gives better control.
YMMV

It's not so much of a concern in the cooling system. Nice big tolerances there, a couple of shards of tape wouldn't do anything. Now, if we were talking about an NPT fitting being screwed into a brake caliper, I'd feel very differently.

Keith Tanner wrote: It's not so much of a concern in the cooling system. Nice big tolerances there, a couple of shards of tape wouldn't do anything. Now, if we were talking about an NPT fitting being screwed into a brake caliper, I'd feel very differently.

Or the lubrication system, or fuel system, or power steering system ...
Anyway, I'm not fanatical about it, just careful.

Yep... This particular sensor used tapered threads and needs some form of sealant. I actually was going to use some Blue Monster paste I had, but it was too badly separated in the can and I can't see buying another $10 knowing it would probably go bad again before I used it a second time.

Hi Titus, I have been following your build from the beginning with interest. I have a 93' LE that I'm willing to butcher and do this swap including the wide body kit. I have a couple of questions. What size rims/offset plates/tires are you using? They look to fit your car nicely. I'm from Nova Scotia and we do not see the crazy Texas heat. More likely cool Fall & Spring temperatures, so in my case would you recommend keeping the air assist system?

thanks, Bruce

racer025 wrote: Hi Titus, I have been following your build from the beginning with interest. I have a 93' LE that I'm willing to butcher and do this swap including the wide body kit. I have a couple of questions. What size rims/offset plates/tires are you using? They look to fit your car nicely. I'm from Nova Scotia and we do not see the crazy Texas heat. More likely cool Fall & Spring temperatures, so in my case would you recommend keeping the air assist system? thanks, Bruce

The wheels are 15×9 zero offset with 225/45 tires, but I believe there is wiggle room. My body guy had me bring him,the wheels with tires, so he could trim and adjust the fender position to work with the wheel/tire combo.

It is my understanding that the air assist improves emissions when the car is first, warming up but isn't needed for smooth running regardless of weather. The IAC on the other hand is something you would want to maintain in colder climates.

Titus wrote:

racer025 wrote: Hi Titus, I have been following your build from the beginning with interest. I have a 93' LE that I'm willing to butcher and do this swap including the wide body kit. I have a couple of questions. What size rims/offset plates/tires are you using? They look to fit your car nicely. I'm from Nova Scotia and we do not see the crazy Texas heat. More likely cool Fall & Spring temperatures, so in my case would you recommend keeping the air assist system? thanks, Bruce

The wheels are 15×9 zero offset with 225/45 tires, but I believe there is wiggle room. My body guy had me bring him,the wheels with tires, so he could trim and adjust the fender position to work with the wheel/tire combo. It is my understanding that the air assist improves emissions when the car is first, warming up but isn't needed for smooth running regardless of weather. The IAC on the other hand is something you would want to maintain in colder climates.

Hi Titus,

I'm new here but have been following your build for some time.

Are there any updates coming? I hope so as I'm planning the same. I already have the J32A2, just trying to decide on this kit.

Gary

1973elanst wrote: Hi Titus, I'm new here but have been following your build for some time. Are there any updates coming? I hope so as I'm planning the same. I already have the J32A2, just trying to decide on this kit. Gary

Yeah... it has been a long time since I posted an update, mostly because I didn't have much to post about. Life got in the way so not much got done, but I have been working on it some lately. Hopefully in the next few weeks I will put together a few updates for those still watching.

Oh, lots of us are still watching.

Just not lots of us have lots to say when things are headed in the right direction.

Keep it up; we're all interested.

I've got a Miata in the garage with a dead motor. I'm still weighing my options, so build threads like this one are right on target.

.. and I've got an Exocet in my garage with a ~ 125k old 1.6L - I also am weighing options! Build on, sir (in other words) !!!

Great thread! It's nice to see this swap being well documented. There's a few running now, but not a whole lot of info or photos yet.

Great work so far, looking forward to watching your progress!