Category: HyperMiata Build

The final thing I needed to get to the Racepak: RPM. The ECM has no tach signal output. Autometer tach signal adapter part number 9117 was the solution.

Pic here shows how it’s wired in, this was just temporary crimps to verify it worked before wiring it in properly…

The signal adapter gets wired in-line with the two main +12v supply wires that go to the coils, one wire to each bank. Follow the instructions included for an LS engine but your wire color is different. Pink/black is what you’re looking for in the LFX harness. Start at the coils and follow the light gauge pink/black wires up-stream until you find where they split out from a thicker gauge pink/black. That’s the wire to intercept. There are two of these wires, one for each bank. The autometer box outputs a lovely +12v square wave standard tach signal. The Racepak instantly reads it. Change the Racepak to V6 Even Fire (default seems to be V8) and voila.

Engine is in and fires up. Tying up loose ends right now.

Top of that list is some frustration with the Racepak stuff. Bottom line is it simply cannot read any PIDs from the 2012 ECU I have. Not with the OBDII adapter cable or with the CAN hi and low hardwired directly to the dash, despite the fact we can view live data streaming via that same diagnostic connector with either a scan tool or HP Tuners. Racepak themselves have no idea why it can’t read this ECU, and I’ve verified this particular dash will pull PIDs via the adapter cable to diagnostic connector on other cars such as an ND that was here in the shop.

SO… I’m bypassing the ‘read the ECU’ plan. Wired in a temp sensor for coolant and adding the Racepak GPS module for speed. RPM is a bit of a puzzle because these ECUs have no tach signal output, but I have an MSD signal converter on the way that should take signal from the coil wire and output something the dash can understand.

Only thing I’m stuck on at this point is my oil pressure sensor… using a second factory GM OP sensor to feed signal to the Racepak. Problem is in configuring the dash to read it. Configured for a standard 0-150 psi sensor (0.5v=0psi, 4.5v=150psi) the scaling is funky. Sensor is outputting 0.43v with engine off (0-psi) which would be -2psi. I can’t find any info for this sensor online or in the GM database to use for a custom calibration.

I want to be able to have complete confidence in the OP reading so the best approach is to test it personally and then manually calibrate the Racepak based on those results. I built a bench tester today, will get to play with it tomorrow.

Figured I’d take a little extra time to make something that could be useful in the future. NPT ports for all the common sensor sizes, two air valves so I can fill/bleed and monitor pressure without switching back and forth, portable enough that it can be placed in the engine bay so the sensor is operating on the vehicle wiring. Can be used to bench test temp sensors as well by standing it vertically, removing the end cap, filling with water and then heating the water and validating the temp with a thermometer.

With this new bench test contraption, I was able to confirm it’s a 0-130 psi sensor. I was able to calibrate the Racepack very accurately to the specific scaling of this sensor. Dash reads OP perfectly now.

So the engine didn’t just come back out a second time just so I could add some heat shielding…

With the car running I drove across the street for an alignment (sitting in the pic here waiting to go on the rack)…

On the drive back across the street to the shop, the rear tires locked. Fun times sliding into our parking lot. Motor was seized. Oil pressure was strong and everything was running right so best guess right now is that it was the thing I had feared in the back of my head from the beginning – this engine had come from a donor car that we discovered had been flipped, so if the engine had been running while it was upside down, the bearings were doomed from the start.

Not going to allow this to stop me, I gave myself one day to come to terms with things and began the hunt for a motor the next day. Made some calls and found that Cord Bauer of Catfish fame had a unicorn of a motor sitting around that he was willing to part with – this one from a 2013 with only ~500 miles on it (!!) Thanks Cord!

That engine is here already, and I’m about half way through transferring everything from old engine to new:

LFX’s are growing on trees around here! That’s the new motor on the right, with nearly everything swapped over:

A peek inside the pan from the old motor confirms that yeah those bearings are done! Thoroughly cleaning everything in the oil system before swapping over to the new engine (pan, pickup, adapter plate, lines, cooler, etc.)

Interesting discovery while swapping parts over from the old motor to new…

2012 valve covers – plastic, 3.45 lbs each

2013+ valve covers – aluminum, 6.40 lbs each

So the newer engines have 6 more pounds up high. The plastic valve covers are now on the new engine.

The engine’s out again. I’ll get to that update when I have it concluded.

While it was out of the way, I added heat shielding on the firewall behind where the engine resides:

I also added a second shield to the transmission tunnel (it already has a layer of adhesive backed insulation from the turbo days). I’m leaving the first layer in place and adding to that a modern-style thin aluminum layer with an air gap between it and the tunnel – very much like Moti did on Morpheus.

I started with a tunnel shield from an ND Miata. With the insulation layer removed (black part in the photo) it is a featherweight. Essentially no weight penalty for adding it.

Then I formed it to fit the NA tunnel:

Installed, with ~1/4″ air gap:

Time to get a hood on this thing!

The project began with a donor hood from a scrapped car. Bolted it to the hinges and set the hood down on the engine… and this is where it stopped. We’re going to need to get out the grinder!

Cut a big ol’ hole and now it closes.

That’s it! Hood’s done.

Ok, perhaps not quite. With the hood cut to clear we can see how much of the engine sits proud of the NA hood line:

Made a template for the contour needed in the hood:

Time to get the actual hood. I’ve had this one sitting in my garage waiting for this project. It’s a dry carbon piece with integrated headlight lids. Not the prettiest finish on it since it was a function-only part and I got it second-hand but it’s going to be covered in matching livery with the rest of the car when all is done. Transferred the template over to the carbon hood:

The “cut once, measure twice” point… or was it the other way around?

After many, many times of cutting, test fitting, cutting a bit more, etc. (also cut a slot for the tow hook):

Then installed the Aerocatch latches:

And it’s done! I’ll be adding louvers and a radiator exit duct later, but this gets the hood fitting the car and suitable for driving:

There will be more going on on the hood when it’s done too, so it’ll look less out of place than your typical blank hood with just a hole cut for something to stick through. With the big radiator exit duct just forward of where the intake manifold sticks through, and with the hood wrapped in matching tricolor livery I think it will look great. At least, I have it envisioned in my head and I like what I’m seeing…

Juuust about to go for the first test spin… turns out the clutch isn’t disengaging. Wonderful. Hydraulics checked out, so there was nothing left but to drop the transmission. Hey, on the bright side this was an opportunity to go through the whole engine removal process and take notes for next time 

Cooling assembly off:

Whole assembly out as a unit:

A view we don’t usually get of things:

Turns out…. the clutch disc was in backwards! The doofus who installed it (yes me) missed the small mark for which side was supposed to point to the flywheel.

Going back in today.

Got some work done yesterday after work. I had mentioned earlier that the coolant expansion tank that I had been using with the 1.6L turned out to be too small for the LFX. So I picked up a Moroso tank with just about double the capacity:

The larger tank needed a new home, so tank position is moving to go up against the right side firewall. Because the lines to/from this tank need to be easily accessible to disconnect if I’m pulling the front nose off, I broke the lines up into two lines each, joined by bulkhead fittings on a little plate I made:

Tank and lines installed:

The tank takes up the location on the firewall where the relays and fuses were living. Because those items stay attached to the engine if the engine is pulled, and the tank stays with the chassis, I move that stuff forwards of the tank via another bracket so that it’s still just one M6 bolt to remove to release that from the car. All this stuff is waterproof, but there’s a splash shield integrated into the bracket, just in case:

Another item not directly related to the swap but equally important. This was also one of the final things left before this thing is rolling.

V8R/Stoptech STR21 rear brake kit. This is a race only kit with no e-brake. 6 lbs lighter per side than my old rear brake setup.

Pads are Performance Friction 11’s to match the front.

With the bulk of the swap done and the thing even running (!!) it can be frustrating at times to still have many little details that come with a fresh build that need going through. Half of them don’t even have to do with the LFX swap itself. Tonight I’m making the rear brake/turn/marker lights sub harness. In the mean time, reposting this pic because it just gets me so excited for what this car is becoming!

As sometimes happens with long term projects, personal life stuff has kept me from the car for a little while. Getting back into it now, but there were still a few updates from the past few weeks:

Got a fresh windshield! Should be able to see things again which will be a nice change.

Made some shock reservoir brackets and had those powdercoated:

Front reservoirs are now cozy:

Also treated the car to a new seat! The Cobra Evolution is probably my all-time favorite seat, been wanting one for a long time:

Every time I put a seat in a Miata I am reminded just how much work it is to get a seat fitting just right. This seat is replacing an old Sparco Circuit and just because every seat has its own dimensions, layback, etc. fitting the Cobra took some cutting and welding to tweak things for this new setup. Finally happy with it after three days of after-work time spent, it’s super low, reclined a bit more than the old seat, and pushed as far back up against the cage as possible – you can barely slide a piece of paper between the seat and main hoop. I’ll be adding a steering wheel spacer to adjust for this seat being further back than the one it replaced:

With the engine running now I get to find all the little details that need to be sorted out.

One of the things I was spinning my wheels on for a while was a power steering leak. Turned out it was the pump itself leaking. Got a new pump, tapped for fittings, ready to go back in:

The next thing I’m working on solving is with the Racepack. Currently not getting any PIDs through the OBDII plug, not sure if it’s stuck looking for the other rental Camaro I tested this dash on or what, but right now it tries to pull the PIDs and says there are none. We can plug in a scan tool and communicate just fine, so not sure what the issue is yet.

Second dash related thing going on at the moment is reading the oil pressure gauge. Wiring is all good and I’m getting voltage input from the signal wire and that’s fluctuating appropriately with changes in RPMs but I cannot figure out what the voltage scaling is for this factory GM sensor. All research so far says it should be approximately 0.5V=0psi and 4.5V=120psi but that must be off because with that scaling it’s only outputting 3psi at idle while a mechanical gauge confirms it’s idling at 10-15 psi.