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Not much progress on my Miata other than driving this month due to other projects (kitchen remodel).
We ended up with 4th/5 at CMP this month in NASA TT4. The Miata has a misfire that has been getting progressively worse the last couple events, this time it ended up being down 5-10mph on straights, maybe 1-2mph of that was due to strong winds, and about 2 seconds off my previous PB, despite being down on time in some corners.
Still working through the list of items to check off. Replaced spark plugs before this event, then tried to replace wires at the event, but the new wires are about 5mm shorter, and despite hearing the click, wires on cylinders 2&3 would not stay connected on track, so the old wires went back on.
After the event, checked spark plugs, as I had been leaving them gapped at ~0.035 for the last couple years, was going to reduce that, and noticed that the cylinder 2 plug looked a bit different than the others, so I'm hoping this starts to isolate where the problem is.
Also managed to break a few plastic bits (fender liner, tire spats) that got disconnected/scraped and rubbed on the 15x10 wheels, so those will also get replaced before we're back on track again next month for a test day before swapping back to an N/A Miata for LuckyDog!
With all that said, the weekend was still a blast, and the cherry on top was getting to instruct a friend in his Porsche GT4, then getting to turn a few laps in it... Just slightly more capable than the Miata! Looking forward to finishing up the MK60 ABS install as well as swapping ECUs for some better electronics after that.
Didn't get to fit the grille insert due to not wanting to disassemble the SpecMiata anymore, but at least confirmed fitment of the bumper, and ready to finish assembly and prep for the mold!
Oy, I hope I’m not too late, but I just noticed you plan to put the MK60e5 in your TT4 build. Note that only the MK60 and MK60e1 are allowed in ST/TT4, there is no allowance for the MK60e5.
I think the e5 is a much more capable unit, if I recall my ABS facts correctly.
Damn, the car looks so good. Glad to hear it was a good weekend despite the misfire. Is it isolated to any certain scenario? What's your power level and ignition setup?
Oy, I hope I’m not too late, but I just noticed you plan to put the MK60e5 in your TT4 build. Note that only the MK60 and MK60e1 are allowed in ST/TT4, there is no allowance for the MK60e5.
I think the e5 is a much more capable unit, if I recall my ABS facts correctly.
Hope this isn’t an issue for you, love the build!
I wasn't aware that the e5 was much more capable, but it was much more available/cheaper when I was initially looking last year. Plan was to set it up first with the e5 to know that it was working, then swap over to a legal unit. The parts have just been sitting on the work bench for almost a year now until I drill and tap for the speed sensor mounting.
Damn, the car looks so good. Glad to hear it was a good weekend despite the misfire. Is it isolated to any certain scenario? What's your power level and ignition setup?
NB bumper looks damn good too mounted up.
Seems to be getting progressively worse, on power/under load, initially it was only really noticeable at the top end of 4th, by the end of the weekend it was noticeable throughout the midrange while accelerating through 4th. In the data you can see an old lap with similar cool conditions, a Saturday lap, then the Sunday lap. Noticeable stumbles in the GPS speed graphs at the top, and on Sunday, the slope is even less steep down in 3rd, but I did get on power less during that corner exit before, so it's also shifted over some. ~240whp, FlowForce LS Coils.
My flowforce LS kit ate a plug wire less than a year into running the kit. Really threw me for a loop because the wires were brand new looking still, and had like ~10k miles on them.
When the issue happened I traced my entire ign harness, and even re-wired it for seq spark while I was in there, and finally in the end figured out it was the dang wire. The wires are pretty specific, so I didn't swap one out earlier. I did end up rigging up a miata NGK wire with zip ties holding it onto the coil to test, which is how I discovered my issue was def with the wires.
My flowforce LS kit ate a plug wire less than a year into running the kit. Really threw me for a loop because the wires were brand new looking still, and had like ~10k miles on them.
When the issue happened I traced my entire ign harness, and even re-wired it for seq spark while I was in there, and finally in the end figured out it was the dang wire. The wires are pretty specific, so I didn't swap one out earlier. I did end up rigging up a miata NGK wire with zip ties holding it onto the coil to test, which is how I discovered my issue was def with the wires.
Was your issue sporadic/intermittent? Or just not firing on that cylinder at all?
Was your issue sporadic/intermittent? Or just not firing on that cylinder at all?
Somewhat. It started as only high boost misfire, I could run lower boost levels fine. drivability was fine before it build > 160kpa, then eventually got worse.
A little re-cap on the bumper/air dam with other larger 3D printed bits to catch things up-to-date going forward.
Modeled all the bits in Fusion360, and scanned the existing components, mounting surfaces, etc with Revopoint scanners. Ducting goes back to the intercooler, then traditional plastic sheet construction between the intercooler and radiator still for now. TDR oil cooler mounts on the sides for engine oil and the Rotrex oil. These are 3" sized ducts that can easily be used for brake ducting if not using the side coolers. Hood vents using the Spiked vent shape, but were redesigned and color matched. Wing was an upgrade over the used APR air foil using an MSHD foil shape and sized to somewhat fit between NASA and SCCA rulesets. All parts to date are generally printed in ASA, assembled, epoxied, and prepped for paint. In the future, the plan for the air dam and some other parts is to make a mold and swap to fiberglass/composites.
Hey, I’m interested in purchasing your front bumper… or if you’re not selling, could I purchase your file and I’ll have it printed locally… did you just use the printed bumper or did you mold off it and do a true fiberglass bumper?
It's been a minute with not as much activity as we'd like, but that's the way it goes sometimes!
Figured out the misfire, it's always the simple thing you overlook. Ended up just being a loose ground that I thought I had checked multiple times. Then had some MS3Pro "fun" reading the crank signal as the final fix.
First MK60E5 pump turned out to be defective at the test day, but last weekend was a success on the first attempt at pump #2! Braking went from ~0.8-0.9gs to ~1.1-1.2gs and much more consistent. Looking forward to finally getting some real confidence out of the car in brake zones!
Progress has mostly halted on the NB bumper for now due to shifting IRL priority/availability, but hopefully not the end of it.
Projects continue on the NA though:
Patch harness made for Link G5 Voodoo
Initial sketches for ND air intake/panel filter box
Initial sketches for turn signal -> DRL light fixture
Hey, I’m interested in purchasing your front bumper… or if you’re not selling, could I purchase your file and I’ll have it printed locally… did you just use the printed bumper or did you mold off it and do a true fiberglass bumper?
Appreciate it! Just running the ASA printed bumper. Not interested in selling the files at this time, but still hopeful to make some fiberglass or printed copies in the future!
Finished up my first full NASA-SE TT Season - Second place overall, with a new PBs at each of our SE tracks.
MK60 still working great, as are all the 3D printed aero bits, including some new tire spats/canards. For 2026, we're finally going to swap over to the Link G5 ECU, add DBW and traction control, as well as try and find another 30-50whp in the midrange, which likely means e85.
How do you get more midrange with a centrifugal supercharger? Bigger blower, but add a restrictor for the top end?
Given the E85 comment I think probably just more timing in areas of the map that are knock-limited on his current fuel. But also maybe a pulley change, not sure how close he is to maximum blower rpm up top though.
Last edited by themonkeyman; Dec 15, 2025 at 10:12 AM.
Given the E85 comment I think probably just more timing in areas of the map that are knock-limited on his current fuel. But also maybe a pulley change, not sure how close he is to maximum blower rpm up top though.
Yeah, timing first, but pulley and VVT swaps both seem like they can be options as well. Figured I'd just start with E85 as it seems like the best bang for the buck and easiest if the logistics work out given that it can be a little more difficult to find around some tracks down here.
Yeah, timing first, but pulley and VVT swaps both seem like they can be options as well. Figured I'd just start with E85 as it seems like the best bang for the buck and easiest if the logistics work out given that it can be a little more difficult to find around some tracks down here.
E85 is magical with boost. Looking forward to following along!
Not a whole lot of updates on the chassis this month. Picked up a new PB and one of my 2026 goals of a 1:17.X laptime at RRR. Looking forward to a 1:16 next time we have good weather! Still progressing through the design of a new v2 bumper/airdam to keep the side pod coolers from dumping air into the wheel wells, as well as a v2 of the wing to have a spare, but also a few improvements. Lastly made some progress on the DBW mounting bracket for the NC Miata pedal. Should be completely swapped over to the LinkG5 ECU and DBW setup sometime this spring.
February 2024
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