07/22/2026
Ooooh
A page dedicated to Sonic MX5 - a VQ35hr swapped Mazda MX5 Miata being developed for SCCA Solo Xtreme Street B.
Sonic is piloted by Michael Carpenter and Rusty Horlacher.
07/22/2026
Ooooh
07/21/2026
Well... What an awesome weekend!
I finished 3rd and I'm super happy with the results. This car has come so far in such few events.
This was my first National Event since Lincoln last year. Furthermore, this was my 2nd Autocross event of the year. So, yeah, I'm happy. Congrats to Andy McKee and Brandyn Marlow. I couldn't catch these guys as hard as I tried.
Rusty and I have made lots of changes to this car. Fortunately, it feels like all the changes keep making the car more consistent and faster.
I'm going to make some alignment adjustments for our next event (Top Gun in Helena, MT). It seems like this new Vitour tire wants a lot less camber than the original P1. All of our temp probing seems to show that we're not utilizing the whole surface of the tire.
07/19/2026
26' Packwood National Tour Day 1
Sitting a tad out of 2nd. Not as far out of 1st as I should be...
Sonic is having a difficult time putting power down. We attribute this to a combination of - Lack of Right Foot Finesse and Lack of grip at this site. It might also help if the car was willing to squat. I think I'm going to try a tad softer rear rate and maybe compensate with a stiffer rear sway so we can still get the rear to rotate.
This is the 2nd event on the Vitour P1 X compound tires. We probed outer/center/inner on tires and learned that we are absolutely cooking the inside of the front tires. Sonic only has 3.5 degrees front camber, so we landed on way to much caster. And... We can feel it. The front tires are just washing out in sweepers and we're waiting, waiting, waiting to get on throttle.
So, I'm going to officially eat some crow on these new Vitour tires. They're a lot better than I thought at heat management. The overheating that I ran into at the first event was a result of too much caster and way too much right hand turns that probably just boiled the compound of the inside front left tire. This tire is such a massive improvement over the original P1. Thank you Vitour for making a proper wide tire in a 15" size!
Rusty removed half of our caster (estimated) last night and we eyeballed camber and set toe. Let's see if this car can sweeper today.
First day on the Vitour X1 compound.
Initially, I thought it would be a weird day for testing. It is uncharacteristically cold here in Utah. Ambient temps were in the mid 60's and it was windy.
Oh well.
Ironically, today ended up being the perfect day to figure out this tires characteristics.
Rusty and I co-drove. I decided to drive first as I wanted to formulate my own opinion about how the tires activate with heat and at what temp they actually activate.
The lot we were on was tight, surrounded by k-rails, and postage stamp sized. The course designer really did a great job using all of the lot and really got creative. However, it ended up being all right hand turns and double looped on itself (so double the right hand turns).
In short, Vitour did deliver a tire that activates early and at a lot lower temperature than the P1. It is absolutely a better Autocross tire.
However, after just the little bit of initial testing (3 runs), I feel like it's almost too focused on early activation. The operating temp of this tire seems to be 70-105F. Furthermore, when they fall off, they fall off super hard.
Run 1: 38.7** Launched using launch control. Excessive wheel spin but modulated quickly to get the tires to hook. Grip came in very quick even for a colder day. Tire was predictable and delivered a very fast initial run. This was literally the first time even driving on the tires so I'm sure I was wearing through the mold release as well.. so maybe they could come in even faster.
Run 2: 38.2** +1 this was really the 3rd lap on the tires. For me this was the best the tires felt and laid down the fastest scratch time of the day but picked up a late cone somewhere.
Run 3: 38.4** Once again, I was the first driver, and on my 3rd run - I learned very quickly that the front left tire was absolutely cooked. The car that was pretty neutral all day was now experiencing terminal under steer everywhere. I feel like the tires probably peaked either my run 2 or Rusty's run 2. I can't really speak for him, but he had no complaints about how the car was handling after his 2nd run.
There is definitely more testing to come.
A couple caveats:
We realized that we should have sprayed the tires between runs. Definitely a hind sight is 20:20 thing. Lesson learned.. we honestly just never even thought of spraying with the P1... ever. It couldn't get hot enough.
Also, this course was especially punishing to the left side of the car. Especially the front left tire. All sweepers were right handers.
I would probably recommend that anyone getting the X1 get them shaved. Less tread depth = less squirm and less heat generated.
I'm still thinking these results over... I'm pretty shocked that I got these to fall off like I did. After all, Sonic MX5 is not a heavy car and I'm on 305's square.
P.S. Launch control is fixed! Yay.
06/25/2026
New Vitour 305/30/15 X1 Compound tires are mounted.
In my opinion, these seem to have a less stiff sidewall than the P1 tires. So, I was wondering if there would be a weight difference.
Turns out there is.
P1 is 26.80lbs
X1 is 26.58lbs.
I was a little bummed that my new KE Motorsport Gen 2 15x11 wheels are heavier than the listed weight on the website. .5lbs heavier in fact.
For anyone that cares like I do, the actual weight of the 15x11 Gen2 is 15.08 lbs NOT 14.6lbs.... bummer.
Total weight savings vs my last wheel/tire combo is still 1.4lbs / corner. Why do I care? Because I'm still 200lbs over the min weight for the class.
Sonic MX5 currently weighs in at 2276lbs.
06/15/2026
2026 Autocross Season Starts now!
06/11/2026
It's proving to be an interesting race season.
I gave up on the Vitour P1 for autocross and as a result, I've honestly had no interest in running the car at any National or local autocross events so far this year. The 305/15 tire just takes way too long to warm up on this light of car.
That being said, I still want to race. Luckily, Rusty Horlacher turned me on to Grand Junction Motor Speedway and the Red Rock Racers events. Then, shortly after learning about those events Rusty told me about the annual Flying Miata Summer Camp that also hosts track days at G.J. Motor Speedway.
I registered late and as a result, couldn't get a spot for the Thursday and Friday track days. However, Sonic was able to run Wednesday.
Rusty was with me this time and I was hoping he could help me pinpoint the random power cut issues I've been dealing with.
He did not disappoint. Before we even started racing the car started turning itself off while just idling. Rusty plugged in his laptop and noticed that the fuel pump thought it was getting too much voltage. He bumped the tolerance a bit and boom.
No issues whatsoever all day!
This was the very first event for Sonic with no mechanical issues.
Oil temps are good.
Oil pressure is good even after hot laps.
Coolant temps are good.
No random power cuts.
Finally, I could simply focus on just hitting my apexes and pushing this car.
Sonic delivered a 58.516 on 200tw Vitour P1's.
Supposedly, after numerous delays (the war), the X01 compound Vitours are shipping this week. I'm really excited to take this car autocrossing again.
Flying Miata Summer Camp 2026 Sonic MX5 58.516 Sonic MX5 HOT lap Flying Miata Summer Camp 2026
What a fun day of racing with Red Rock Racers @ Grand Junction Motor Speedway!
This was my first event at this site AND Sonic MX5's first event of the year.
New Springs, Ride Height, Alignment, etc.
While I am still chasing some random oil pressure and random unknown limp mode issues, I was still able to have quite a few laps without issue.
My fastest Counter Clockwise lap was a 59.8**. I was told, unofficially, that this is a 200TW track record. I did have two other laps that could* have been roughly 4/10th's faster, but ran into some brief limp mode issues on course that buggered those laps.
Sonic_MX5 was on the set of Vitour P1's that I took to Nationals last year (305/30/15 Square). It was painfully obvious on every out-lap that this compound needs heat and that a 305 P1 is probably too much tire for this car to ever heat up at autocross.
The car would understeer, then oversteer, then just four wheel slide. I honestly didn't have the courage to push this tire until hot lap 2 in each session. Keep in mind, all this tire sliding drama in 85 degree ambient weather. It was very evident when the grip turned on and the tire never fell off with heat. That being said, they never got super hot. My pyrometer clocked a max temp of 140 on the right side tires after warm up lap, 4 hot laps, and a cool down lap.
Anyway, it was a great day. Car held together, truck made it there and back, and I have an ice cold IPA to sip.
There are quite a few Red Rock Racer events remaining on the schedule for 2026, and I will be attending as many as possible.
https://youtu.be/1POZWw42cb4
05/06/2026
New tablet mount installed. Maybe, just maybe, I can get my Go Pro and Solo storm to work consistently.
05/01/2026
Sonic_MX5 is aligned and corner balanced.
This car is nose heavy. (55f/45r).
Things can be done to help correct that... But nothing cheap nor necessarily easy.
I probably should not have the word "cheap" in my vocabulary at all with this car...