Well, this is a good a story as any, and a nice capstone on the year’s time trials season.
I’ve been splitting my motorsports attention between autocross and time trials. My original plans at the beginning of the year were to go to all of the National Sports Car Club of America (SCCA) autocross events in the Midwest and tackle a few National SCCA Time Trials (TT) events at the tracks that I really wanted to run, but the pandemic had other ideas and flipped my schedule on its head. I ended up not being able to attend a single National autocross event — I even paid for the Pro Solo pass and never got to use it! — and instead went to a bunch of time trials events.
One of those time trials events was the SCCA TT at Road America, originally scheduled for the spring and to be run in conjunction with Global Time Attack (GTA). However, thanks to the pandemic, the event was binned and a rescheduled event was promised. Entry fee refunds were offered for those that wanted them, but I kept my entry in the books for the reschedule, which wouldn’t come to light until the month of October. Eventually, the date of the rescheduled TT was announced: it was to run alongside the American Road Race of Champions (ARRC) on the first weekend of November.
Troubleshooting the car
The Miata suffered from some sort of electrical malady on the last day of Time Trials Nationals (at NCM Motorsports Park), which caused the car the die twice on course — once at the hands of Matt Eddy, my codriver for the weekend, and again in my hands in my session after. The car kept blowing the Engine fuse in the fuse box, and a quick bit of Googling suggested that a possible culprit was shorting O2 sensor wiring.
The car also got really loud during the weekend, like there was some sort of massive exhaust leak somewhere. I looked all over the car, but couldn’t find anything. The muffler was still bolted on good and tight, I couldn’t find any leaking around the cat, and looking at the headers from above in the engine bay, everything seemed fine. I suspected that I had blown out the cat again, and made a mental note to fix the exhaust when I got home.
To fix the problem, I decided to replace the entire exhaust save for the rear muffler. My car had one of the early PPE headers (the 1.5″ primary version and not the later larger primary version) and it required its own unique midpipe. Having already replaced it before — and anticipating that I’d have to keep replacing it over and over again — I wanted a “standard” NC Miata midpipe that I could easily get my hands on, and so replaced the header and the midpipe together.
As the car was still primarily a street car, I thought I’d give Goodwin Racing’s Helmholtz resonator equipped midpipe a try to see if it would really quell the boominess of the exhaust. To go with that midpipe, I got his Max Power NC header too.
I sent the Miata to my shop, Shamrock Automotive, for the install. After resolving a minor parts mix-up — Goodwin Racing had accidentally shipped me the wrong midpipe, but they quickly sent me another one — the shop threw the new exhaust on the car. Along with the new exhaust, I had them install brand new O2 sensors and O2 sensor wiring.
Upon removing the old exhaust, they found out why the car was suddenly much louder: there was a 1″ hole on top of the header collector. There’s no flex joint in the NC exhaust, so years of hard driving must have fatigued the metal there. Alright then, add “header” to the list of things that will regularly need to be replaced (or repaired).
Now that the exhaust was redone, I decided now was the time to get the car dyno tuned. Fab9 Tuning is a local shop here that specializes in parts and tuning for turbo Miatas, especially NC Miatas. I brought the car to Fab9 the Friday before the last Gingerman Raceway Open Track Day (OTD) of the season and asked them to do their magic.
I had the car remote tuned back in 2011 when the car was first made into a Street Touring Roadster (STR) autocross car. Moto-East did the remote tune for me, and my former codriver Josh McDonough dynoed the car at around 135 wheel horsepower. (At the time of the dyno, Josh also tried the Open Flash Tablet, which was just getting off the ground, and tried his hand at tuning a car. He couldn’t do better than the Moto-East tune on the EcuTek, so we kept the EcuTek tune.) For a long time, I thought the car was fine, though there was an issue with the launch control that forced me to disable the feature in order to keep the car from killing the throttle; it was something that I was sure could be cured if the car could only make it on to Moto-East’s dyno and tuned there. When I sold the Miata to Shane, I recommended that he get the car dyno tuned, as he was now in Moto-East’s backyard. Shane never got around to doing it, and sold the car back to me on its original tune.
Bryan, the fellow at Fab9 that would be doing the tuning on my car, was amused that I had the old school EcuTek blow-molded case (the packaging now apparently is just a drawstring bag for the cable), and astonished at how old the EcuTek software version was on the car. Over the course of two hours, he found 15 more horsepower for a grand total of 150 wheel horsepower (on a Mustang dyno).
Wow. And this wasn’t just a improvement at the peak of the horsepower curve. Power improved across the entire rev range.
Suffice to say, this was the best $250 I’ve ever spent.
I wanted to shake the car down before I drove it all the way down to Road Atlanta, so I went to the Gingerman Raceway OTD to see if the car’s issue of stalling on track were finally resolved. (And also to see what having 11% more horsepower did, haha!) As it was the closing days of fall in Michigan, and my tire trailer was already packed for Road Atlanta, I decided to do the lazy thing and just run my street wheels and tires — 17×8″ Mustang Bullitt wheels wearing 215 width Continental ECS summer tires — for the track day.
The car ran brilliantly. There were few people there on Sunday, which meant tons of open track space, and the weather wasn’t bitterly cold. The car clicked off lap after lap, and it confirmed that the original issue of stalling out on track was due to melted O2 wiring. With narrow summer tires, I was able to put down a fastest lap of 1:48.61, which amazed me. My personal record with this car at this track is a 1:45.85, set back at the 2020 Gingerman Gridlife time attack, on 245 width Yoko A052s. Now I was regretting not bringing out my track tires to see what the car could really do.
But Road Atlanta was just around the corner. I took the car back home and readied it for the time trial event that I’d been waiting for the entire year.