I think this swap or a V8 swap would make me get back into an NA or NB Miata.
I think this swap or a V8 swap would make me get back into an NA or NB Miata.
OK, It is time to get this thread caught up.
Crimping
Not long after I posted about my soldering of connector pins, It was pointed out that I really should be crimping them with a proper crimper. I picked up this Eclipse Tools 300-005 Ratcheted Crimper from Amazon.
It handles 10-20 gauge pins and does a double crimp. Here is what the teeth look like up close.
It does a really great job. All of the pins I had soldered were cut off and replaced with properly crimped pins.
Clutch work
I went to install the Clutch, pressure plate, throwout bearing, and pilot bearing next. This lead to an immediate issue, as it turns out that the pilot bearing installs from the back of the flywheel. The Flywheel was removed, pilot bearing was installed, flywheel was reinstalled, clutch disk was installed, and pressure plate was installed. The clutch disk is for a 1.8 Miata, while the flywheel and pressure plate are Honda B Series.
Next the new throwout bearing was installed. I believe it is also from a Honda B Series. The tabs need to be bent in a little to work with the Miata transmission.
Prior transmission test fits were done without the water manifold in place. Now that it is installed, I needed to trim the top of the Miata transmission to clear the bottom of the thermostat housing.
The Clutch slave install in the stock location on the transmission, but you need to use 2 spacer provided with the kit to clear the engine. I had to also pick up a pair of longer bolts (not included with kit) to get it to bolt on.
The Clutch and brake masters were reinstalled and the clutch system was bled.
The Intake Manifold has been a crazy journey.
First, I intended to flip the manifold and have the throttle body mount modified to clear the hood, as was done in one of the prototypes. I sent the stock manifold off to Minitec, and they modifying it and shipped it back to me.
It was a few months before I actually tried the hood on the car, and found that even with the modification, it was not even close to clearing the hood.
Another person was also experiencing the same issue. It was discussed at length, and many pictures and measurements were taken. We could never figure out why it worked on Minitecs prototype car and not others. The idea was eventually scrapped, and I shipped it back to them again. The TB neck was removed, a plate was welded in its place, and a fancy new aluminum piece was shipped to me to replace the driver's side plenum.
The inside of the ports were even ported to match the mini horns of the stock piece that was removed.
Once on, it looked great.
It seemed to fit perfectly, but I found out otherwise once I went to install wiring on the car. While it clears the COP coils without the harness installed, it did not clear the bulky plugs. What to do?
A torch, the end of a broom handle, a mallet, and 5 minutes later, and we were good to go.
Starter and Alternator
The Mazda starter and Alternator cables do not reach the Honda start and alternator. I really didn't like the idea of cutting and extending these wires, but I saw a clever alternative on Andy Hollis's K-Miata build and had my plan.
First I picked up these.
They are 3ft 6 gauge cable wiring with ring terminals preinstalled, designed for an inverter. I choose these because they were on clearance from amazon for $8, but there are many similar options out there. One will be for the starter and one for the Alternator. I didn't want a big red wire in the engine bay, so I took a long black heat shrink tube and covered the red up.
I grabbed the first cable and bolted one end to the Alternator.
For the other end, I bolted the ring of the new cable to the stock Miata Alternator ring. I wrapped it in electrical tape for now but when I do wire cleanup and final routing, I will put some heat shrink over the connection.
The starter is a similar situation, but the Miata terminal is not a ring. It is bent into an L shape and has a pointy side. First, I bent it flat.
Then I hit the pointy end with the grinder before bolting it to my new extension cable.
The second wire for the starer is also too short. This is a lighter gauge wire, so I felt better about extending it. It also has a plastic connector on it that prevents it from working on the Honda starter. The spade inside the connector is perfect, you just need to remove it from the plastic connector case.
Finally, the 2 wires are connected to the Starter.
As you may recall, I wired in an 8 pin connector to the Honda Harness. It contained wires for the following:
-Permanent 12v for the ECU -12v on/start power for the coils -12v on/start power for the Injectors -12v on/start power signal to the Alternator -Alternator dash indicator -Radiator Fan Switch A -Radiator Fan Switch B -Radiator Fan control from ECU
First for Permanent 12V. If you take the cover off of the engine bay fuse box, you find that the 80A main fuse is bolted in. A ring connector can easily be bolted in there and get the direct power needed.
I didn't like the idea of 80A of power available to the ECU, so I added an inline fuse.
Second, I needed 12v on/start power for the coils, Injectors and signal to the Alternator. Looking at the Acura wiring diagram, they are originally 15A fused. I found that the Blue wire running to the Mazda coil pack was 30A fused, heavy gauge, and 12v on/start. You have to strip some tape off of it to really see, but it goes from about 10g to 16g a few inched from the plug. Clip the smaller wire off the end and it is just what I wanted.
I wanted to fuse them at 15A like shown in the wiring diagram, so I picked up a 6-way fuse box off of Amazon. The Mazda coil wire provides power for all of the fuses. I have connected the power wires for the coils and Injectors and the signal to the Alternator each to their own 15A fuse, and I have 3 more 12v slots sitting ready in case I ever need them.
For the alternator dash indicator wire, I don't have a picture of it but I simply took the equivalent wire from the Mazda alternator plug and ran it to my custom 8 pin connector.
As for the 3 fan signal wires, I added wires to the 8-pin connector for them, but I haven't actually connected them to the Mazda fan relay. It isn't needed for a engine start test, so it can wait until later.
Here are the 8pin connectors all wired up and connected.
The Honda harness needs to make its way into the cabin. I originally thought that I would use the existing hole that the Mazda harness goes through, but I have since realized that even after I remove every unneeded wire from the Mazda harness (a future project), I still will need another hole.
I picked my spot, put some painters tape over it to prevent paint chipping, grabbed a hole saw, and started drilling.
Unfortunately I didn't realize immediately that the hole saw I grabbed was made for wood. It made it about halfway through before its teeth were worthless. A quick trip to the hardware store for a hole saw rated for metal, and I was in. The Honda harness came with a nice big grommet and mounting ring already on it. I put it in temporarily to drill the mounting holes, and then pulled it back off. Next I added some black touch-up paint to the bare metal edges to prevent rusting. Finally, it was permanently mounted.
Looks awesome. Those touches (the grommet) really make it!
jfryjfry wrote: Looks awesome. Those touches (the grommet) really make it!
Thanks!
WARNING- This post has way too much painful details and gave me a headache just writing it. Casual followers may want to skip it.
I previously covered several connections between the Honda Harness and the car via an 8 pin connector I added in the engine bay, but that is only half the connections. Here is what is wasn't included in that: -Fuel pump relay -Engine speed pulse -Starter switch signal -AC Input -Oil pressure sender -MIATA TEMP SENSOR -Wide band #1 signal -Wide band #2 signal
Each of these connections take place in the cabin of the car, or are independent of the Honda harness. This entry will cover the first 3 that have been completed, along with the plans for the others. NOTE- Several of these connections are via the ECU's A Plug. The A Plug did not come with the harness, as it is part of the dash harness on the Acura. I previously posted about purchasing one new.
Fuel Pump Relay- The AEM is set up with a pin on the A Plug that goes to ground to trigger a fuel pump relay. For the 1.6 Miata, there is a LT GRN wire at the fuel pump relay under that triggers the relay when it goes to ground. It typically finds it's way to ground via the AFM or the diagnostic port. I tapped in to this wire with a new green wire and ran it over near the ECU (more on this in a minute). I chose to tap instead of replace because I wanted to maintain the ability to trigger the pump via the diagnostic port.
Engine speed pulse- The AEM has an output for engine speed pulse on the A Plug. I'm hoping that I will be able to adjust that signal in the AEM to allow it to properly drive the Miata Tach, but I will figure that out later. To get the signal to the tach, you don't actually need to get near the instrument cluster. It's signal comes in to the dash harness via a YEL/BLU wire at the a plug under the passenger side of the dash to the right of the glove box. I was able to remove the pin from the car side of the plug. I actually had a YEL/BLU wire with pin on it that had been removed from the Honda harness that I was able to snap right in to the Miata plug. By going this way, I am able to connect to the tach without adding a new connector between the dash and car. That will be useful when the dash is removed in the future.
Here you can see the connector referenced, with the old YEL/BLU wire taped off and the new one in place.
For connecting the Fuel pump and tach wires discussed above to the the A Plug, I wanted to have the ability to disconnect them. Below is the plug I used. On the left, you can see the GRN and YEL/BLU wires coming it, and the right side they are run to the A Plug.
NOTE- I bought a bag full of these plugs online, I am not happy with them, and will probably replace them eventually, but they will do for now.
Starter switch signal- The AEM needs to get a starter switch signal through the A Plug. For the 1.6 Miata, I found that the violet wire at 1C of the Miata ECU can cover this.
A/C- For the 1.6 Miata, you can bypass the ECU by connecting the wires at 1Q (LT GRN/BLK) and 1J (BLU/BLK). I have done this, but I also eventually want the ECU to know when AC is on so it can adjust idle. The AEM has an A/C Input pin on the A Plug, but I don't yet fully understand how it works and if I can simply connect it to where 1Q and 1J are connected. Just in case it is that easy, I have taped off wires right next to each other and ready for a butt connector.
Below you can see another 2 pin connector in use. The violet wire for the starter switch signal goes to the A plug through here, and you can also see the taped off A/C wires that come through it.
The ones left to do:
Oil pressure sender- This will be simple once the Miata Oil Pressure sender is installed on the V6. I will just need to run a single wire from the sender and connect it to the YEL/RED wire that was originally used in the Miata harness to carry this signal to the instrument cluster. This connection will be done in the engine bay.
MIATA TEMP SENSOR- Another simple one. I will run a single wire from the the sensor to BLK/BLU wire in the Mazda harness that originally carried this signal to the instrument cluster. Again, this connection will be done in the engine bay.
Wide band #1 signal- This is an input via the A Plug. I ran a wire/pin into the A Plug for it, so I am ready when I install the Wide band.
-Wide band #2 signal- The AEM has a pin ready for a second wide band. I don't know if I will run 2 for use, but it would improve tuning if I had one off each header. I ran a wire/pin into the A Plug for it, so I am ready If I install a second one.
The Fuel Pressure regulator is normally mounted to the back of the passenger side head, right above where the the heater hoses will need to run. I decided I wanted to relocate it so I had more room back there. The hoses have been temporarily connected in preparation for the first start, but it is just hanging in mid-air there. You will also notice the hoses are currently much longer than needed. That allows me to play around with different mounting location ideas. Once it finds its final home, the hoses will be shortened.
Those hot bolted connections worry me. I'd much rather see a properly insulated splice or a new wire.
Keith Tanner wrote: Those hot bolted connections worry me. I'd much rather see a properly insulated splice or a new wire.
It is not perfect, but it will be well insulated/protected. In the end, I am confident it will be more secure than any splice I could do with the tools I have on hand right now. Before finding Andy Hollis's build that had done it this way, I was shopping for a heavy duty crimper and sick over the idea of spending good money on a tool that would get used once ever. 
Titus wrote:Keith Tanner wrote: Those hot bolted connections worry me. I'd much rather see a properly insulated splice or a new wire.It is not perfect, but it will be well insulated/protected. In the end, I am confident it will be more secure than any splice I could do with the tools I have on hand right now. Before finding Andy Hollis's build that had done it this way, I was shopping for a heavy duty crimper and sick over the idea of spending good money on a tool that would get used once ever.
I picked up one of these when I redid the battery cables on my project car. Relatively short money compared to what else is on the market. Results were great and i've used it several times and loaned to a few friends.
http://www.harborfreight.com/hydraulic-wire-crimping-tool-66150.html
Hey Titus, this is Nick from the piata build: https://www.facebook.com/Piata-445868985595890/
Can you provide the part # for the aluminum tube you used to modify the coolant manifold? I would like to replicate what you've done.
If you're not a member, you should join the j series miata group on facebook: https://www.facebook.com/groups/JSeriesMiata
HondaNick wrote: Hey Titus, this is Nick from the piata build: https://www.facebook.com/Piata-445868985595890/ Can you provide the part # for the aluminum tube you used to modify the coolant manifold? I would like to replicate what you've done. If you're not a member, you should join the j series miata group on facebook: https://www.facebook.com/groups/JSeriesMiata
Speedway Motors, Part # 9171003-1.25
I actually started that Facebook group. 
Now that you're waist deep into this swap, how feasible would you consider a J Series swap as a completely DIY project? As in, saving much of that kit cost by fabbing the trans plate and modding/fabbing a subframe myself?
nderwater wrote: Now that you're waist deep into this swap, how feasible would you consider a J Series swap as a completely DIY project? As in, saving much of that kit cost by fabbing the trans plate and modding/fabbing a subframe myself?
That would really depend on the fabrication skills and tools you have at your disposal. For me, it is a non-starter. 
this is looking like it is almost as complicated as a V8 swap...
He's just being honest about what it takes to blend multiple vehicles. Other than the fact that he gets to keep the stock trans and rear, there's nothing magically easier about a V6 vs a V8 - especially from an electrical standpoint. In fact the tach might be a challenge with the V6 while it isn't with the V8.
In reply to Keith Tanner:
This is brilliant!
Any swap beyond 1.6 to 1.8 is going to be complicated, and the desire for a clean install can up the complication significantly.
The MAP, TPS, and IAC all get moved about 18 inches with the relocation of the throttle body. Each of these wires needed to be extended. I hate tracing issues with wires that change colors, so I wanted to find exact matches for,each wire getting extended. First, I dug through the box of wires that had been removed from the harness and found matches for all but 3 wires. Then I turned to EFIConnection.com. They are the best source I have found for short lengths of automotive TXL wire in various color combos. With the right wire, I spliced in extensions using uninsulated butt connectors and 2 layers of shrink tubing.
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