My third year of NB Miata ownership

It’s hard to believe that I’ve owned my NB Miata for three years already. For the first two years I wrote posts covering the previous year of ownership. This year I continue that format where I cover the year with a single photo and short description for that month of ownership. This particular post goes from March 2023 (where I left of last year’s post) through February 2024.

March 2023: Tire trailer upgrades

NB Miata tire trailer upgrades - March 2023

In 2022 I built a small tire trailer to bring additional tires and other supplies with me to track days. This year I made some upgrades to my trailer by adding a lower deck that goes down to just below the axle.

I also added a larger 15 gallon fuel jug (instead of two 5 gallon jugs), added a way to mount a spare splitter underneath the trailer, and installed a tube that allows me to bring along different sized wing gurney flaps. The photo was from September, which is why those additional decals disappear and then reappear in later photos.

April 2023: Splitter troubles

NB Miata damaged splitter - April 2023

After installing the Nine Lives Racing medium downforce kit over the winter I was excited to get back on track and feel the added aero. Unfortunately the first few events I went to with wing didn’t turn out as expected.

On my first push lap at my first track day of the year I went a little too fast into a high speed turn and overshot the exit, meaning I went straight off track. This ripped my splitter into pieces, bent my splitter mounts, and bent my radiator support.

I did finish the day and made it home without the splitter. That same weekend I had an autocross event (the track day was on a Friday and the autocross event was Saturday and Sunday). For the Saturday event I put back on my stock front end, and was able to put together a new splitter out of 1/4″ plywood for Sunday. Purchasing spare mounts came in handy.

I ended up making a few more spares, and attached one to the bottom of my tire trailer for future use. That future use came pretty quick as I ended up bottoming out and cracking a splitter on a pothole at the entrance of the next track day.

Eventually I settled on 1/2″ plywood with side supports which seems to hold up pretty well to the occasional scraping.

May 2023: Heartland Motorsports Park

NB Miata at Heartland Motorsports Park - May 2023


In May I drove my first SCCA Time Trials event of the year at Heartland Motorsports Park. This was only my second time at the track, so I was still getting up to speed.

This year I ran a set of 225/45R15 Falken RT660 tires on 15×9 wheels since I wanted something a little faster than the Hankook RS4 tires that I ran most of 2022.

Unfortunately this may end up being the last time I’ll ever be able to go to Heartland Motorsports Park. At the end of the 2023 season the track shut down since the owner was refusing to pay property taxes. All of the property was auctioned off separately, and there hasn’t been any announcement of new land owners reopening the track yet.

June 2023: No more soft top

NB Miata, the last picture with the soft top - June 2023

I did some testing and found that the rear wing really needs a hardtop to function properly. It still does generate downforce topless, but not nearly as much as it does with a top.

In an effort to save weight, and knowing that I’m pretty much always going to be running a hardtop with the wing, I ended up removing my soft top. The new top was installed in the car for about a year, but didn’t get used a whole lot.

One side benefit of no soft top is that there is a little more room in the back for things, and I can access the fuel pump without removing the hardtop.

July 2023: Ozarks International Raceway (plus some clutch issues)

NB Miata at Ozarks International Raceway, July 2023

In July I went to my first new track of the year, Ozarks International Raceway. But before that happened I noticed my clutch start to slip on the way to an autocross event. I was able to complete the event, but I knew the clutch needed replaced.

I wasn’t so sure if it was an issue with a leaky rear main seal previously, improper break in, or just too much racing on an organic clutch (even though it was a performance one).

Unfortunately I didn’t quite have enough time to source a new performance clutch since I had to be at Ozarks International Raceway the following weekend. So I sourced a generic cheap parts store organic clutch to install. I was able to install the clutch and break it in just in time for the track day.

Ozarks International Raceway is quite different from any track I had been to before. Heartland Motorsports Park has elevation, but not like this. There is always something going on here, you are always turning, changing elevation, or quite often both.

Every session I went out I was able to shave a ton of time off of my laps, and I know there is a ton of time left out there. With the barriers just a few feet from most of the track I didn’t really want to push too hard right away, especially with no way to trailer my car home.

I really look forward to returning here many times and working up the confidence to set great lap times. I know that my car with the aero should be able to be quite fast here.

August 2023: Motorsports Park Hastings

NB Miata at Motorsports Park Hastings, August 2023

I made it back to Motorsports Park Hastings several times this year. In March, June, and then again in August for SCCA Time Trials.

I was eventually able to set a lap time of 1:42.78 which feels pretty solid. A NASA Spec Miata lap record is 1:40.415 (and TT6/TT5 records are currently 1:39.625/1:34.110), so there is definitely more time for me out there. I think a lot of the time can be had at turn three, which is the high speed right hand turn that I lost my splitter at earlier in the year. I’m fairly confident that the car can take it without any braking, and probably even full throttle, but working up to that is a little tricky.

September 2023: Hallett Motor Racing Circuit (plus Cool Shirts are cool)

NB Miata at Hallett Motor Racing Circuit, September 2023

In September I attended Miatas at Hallett. This was my first time at Hallett and I enjoyed being able to spend a day driving the track in each direction. The track is fairly short as far as tracks go, but has a lot of nice turns and elevation changes.

It was kind of like Ozarks International Raceway, but much less scary because the elevation is nowhere near as extreme, there are some actual straights, and the walls aren’t right up next to the track. Being shorter also makes learning the track and getting a good lap much easier, since there are less turns to master.

Before coming to this event I also got a Cool Shirt system, which is basically a cooler that pumps cold ice water through tubes in your shirt. I had been wanting one of them for a long time and finally bought one, and I’ll say that it’s worth every penny. On really hot days it’s even hotter in the car, and a lot of times you can’t have any skin exposed for safety reasons. So being able to cool yourself off on track makes driving so much easier.

October 2023: Evaluating my two spare motors

NB Miata spare heads, October 2023

The engine that’s in my Miata is still the original unopened BP4W that came with the car from the factory. I’ve done a few things to make it more reliable and make as much power as possible (fresh seals/gaskets, Boundary Engineering oil pump, coolant reroute, upgraded valve springs, and Exhintake cam swap), but the motor isn’t perfect. It burns some oil at redline, and smokes quite a bit under engine braking deceleration when warm.

Over the past couple of years I’ve collected two spare motors, and another spare head. All in I have two BP4W motors, one BP6D motor, and an extra BP6D head.

The spare BP4W motor was what I got first. It was a known bad motor that I was told ran, but had bad compression. I confirmed the low compression and noticed major leakage from the valves. After taking it apart I discovered some of the exhaust valves had chunks missing. Pretty much all of the valves were very worn in and had negative valve clearance. The bottom end of the motor actually looked pretty good, so at a minimum this motor would just need a fresh head.

I got a good working BP6D motor in early 2023, but never ended up putting it in the car because I had just put all of the money into some upgrades for the original motor.  At a minimum the BP6D would need fresh seals, but the leakdown numbers on the vales weren’t the greatest, so I wanted to dig a little deeper. I ended up sending off the head to be rebuild. Originally I was going to leave the bottom end alone, but I ended up sending the block off for machine work (honing and decking).

I’m still waiting to get the block back, so I ended up just rebuilding the BP4W bottom end at home (honing and cleaning everything as best I could) with the rebuilt BP6D head and new BP6D pistons.

November 2023: Getting ready for winter

NB Miata cone mark, November 2023

November 12th was my last event of the year, an autocross event. Not long after I put away my car for the winter on Black Friday just like I did in 2022.

I attended quite a few autocross events this year, 15 days in total, a nice bump from 9 in 2022. All of the local Nebraska Region events, the Midwest Division event that was in Lincoln, and the spring Solo National Tour event in Lincoln.  The Bridgestone RE71-RS tires have held up really well, I’ve done 17 autocross events with them (about 70 runs) and they still have tread left. I’ll be going with Yokohama A052 next year just to see how much faster they are.

I also happened to attend 15 track days this year, a nice bump from the 10 I attended in 2022. For most events I used Falken RT660 tires, which have held up really well. They have about 8 and half hours on them, with 38 heat cycles, and still have tread and heat cycles left in them. I’ll be going with Nankang CRS v2 next year to see how much faster they are.

My old Hankook RS4 tires were also used for an event, and I sued a set of Continental ExtremeContact Sport tires for part of a day in the wet. What was interesting to me was that I was actually able to drive the ExtremeContact Sport tires at a similar pace to what I can get out of older Hankook RS4 tires.

December 2023: Dash removal and wiring cleanup

NB Miata with dashboard removed, December 2023

I didn’t have a whole lot of plans for the car over the winter. Time Trials events I attend have classes based on power to weight ratios, and I’m sort of in the middle of the class I drive in. So in order to be more competitive I would either need to gain power, or lose weight. If the BP6D motor makes enough power I might be fine as-is, but losing a little bit of weight isn’t a bad idea since weight can easily be added as a ballast.

So over the winter I put in some effort to lose some weight in my car. Things I did included:

  • Pulling the dash and removing all of the removable insulation from the firewall.
  • Removing a lot of unnecessary wiring. I also took out the airbag sensors.
  • Removing the radio, speakers, antenna, and power door locks.
  • Installed a quick release steering wheel.
  • Removed the charcoal canister from the back of the car.

All in I saved about 50 lbs of weight from the car. Not enough to put me in the top of the class, but still pretty good.

January 2024: Quick release steering wheel

NB Miata with new quick release steering wheel, February 2024

Over the winter I finally installed a quick release steering wheel. Part of me has been wanting to do it for a long time, but part of me also liked the idea of having the airbag. Since I plan on getting a truck and trailer I decided to get a quick release since it makes working in the driver footwell easier, and allows me to more easily get into and out of the car on track. Plus the quick release setup weighs slightly less than the stock setup.

I ended up choosing a flat 330mm OMP wheel that ends up in about the same position as stock, and is slightly smaller. So far I haven’t had any issues using it without power steering.

February 2024: Better Cool Shirt mounting

NB Miata trunk mounted Cool Shirt cooler, February 2024

When I bought my Cool Shirt I didn’t really have any place to mount it, so I had just been ratchet strapping it to the passenger seat. This worked well, until I had a passenger. I basically had to choose be cool, or have a passenger. Over the winter I made and installed a trunk mount bracket that allows me to secure the Cool Shirt cooler in my trunk.

I used some aluminum angle with some Alumaweld sticks, all bolted to the floor of the trunk. It’s lightweight, sturdy, and cost quite a bit less than the first party Cool Shirt bracket.


My NB Miata after three years of ownership

I still can’t believe I’ve had my NB Miata for three years already. I spent most of my time with the car this year driving it. Over the course of the calendar year of 2023 I spent 15 days on track, and spent 15 days doing autocross events. I drove at five tracks in five states, two of the tracks were new to me this year (Ozarks International Raceway and Hallett Motor Racing Circuit).

Unlike previous years I didn’t really modify my car a whole lot this year. I mostly just did small tweaks to make it even better on track. The car, and me as a driver, are in a pretty fast state at the moment, but there is always room for gradual improvement over time. One of these years I need to make the big leap and add some forced induction to my car to make it truly fast (not just fast in corners). Right now I’m actually pretty happy with the power level, but would really like a setup that’s closer to the top end of the power to weight ratio of my Time Trials class.

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