Jan 9, 2006 update to the Mazda STS2 Miata project car

An Idea Takes Hold

There I was staring at the lonely CSP Miata sitting on jackstands in my garage acting as a storage bin for various automotive objects, contemplating my next move in getting it back in action. The motor had been removed and disassembled after the 2003 season in preparation for a full internal SP build (.047 overbore, balance & blueprint) yet I never seemed to get around to taking it to the machine shop. I had been consumed for two years by an STS Civic build-up and the excitement and cameraderie of the burgeoning STS class. But that car was nearing the end of its development cycle, and like any engineer, I was starting to run out of ideas and getting a little bored with it. So, what to do?

In addition to being a veteran Solo competitor, I also serve on the Solo Events Board and am one of two board liaisons to the Street Touring Advisory Committee. I was there when the idea of the STS2 class was hatched and played a key role in constructing its ruleset. At the time, I believed strongly that the target cars (CRX, early Miata, early MR2, early RX7) would all be contenders, with the Miata and CRX likely to have the most aspirational support from the autocross community. In short, those are cars people like to autocross and they are cheap to setup and race. Yet somehow, the CRX has shot way ahead of the Miata in terms of results and now performance expectations. This has turned STS2 into “yet another Honda class” and I believe is hurting participation. A strong rivalry would be better. How to change that?

A couple of other factors played a role in the decision that followed. I’ve personally always loved the way a Miata handles. I’m just “at home” in these cars and its one of the reasons I built mine in the first place. I first ran it in ES (nee CS) for two seasons with a number of national event wins, and a fourth place finish at the Solo II Nationals (fast time in class on one course!). But it was no match for the MR2 so I built it into a screaming fast CSP car. Oh my!! Two successful years of campaigning that car had brought it to the point of needing a bit more power to get to the front of the pack consistently. But my co-driver wife starting suffering from neck and back problems resulting from a car accident and the hard-charging Miata just beat the crap out of her while driving. The G forces that the CSP Miata would pull both laterally and accelerating/braking are simply astounding. So we toned it down a bit by building the STS Civic and running on street tires.

With all that running through my head, the idea hit me…why not combine all of that and built up an STS2 Miata? Mazda pays contingency for Tours and Pro Solos so potential funds would be there to help finance the effort. It would be a car that we could drive on the street again between events, and would be a wonderful touring vehicle for drives through the mountains and along the beach roads as we travel the country racing. Furthermore, by doing so “out in the open”, the entire Miata community could be engaged in the effort so as to share information and jumpstart the efforts of everyone (note: the Honda community is much better at this than the Miata folks are). With this case-study knowledge readily available and some excitement generated by the public development effort, it should help build STS2 participation in the hopes of gaining national recognition for the class. In short, we could do for STS2 what the early STS Civic pioneers (i.e. Jason Tipple and Chris Shenefield) did to finally kick up interest in that class. And my wife Ann could get what she wanted…damned car out of the garage!!


Any good development effort requires a plan, with updates done along the way as new information comes along. The goal is now pretty clear: Build a nationally competitive Miata for the STS2 class as an “out in the open” case-study, engaging the Miata community to increase participation in STS2 for national class recognition.

So who’s “we”? This kind of big job sounds like team effort. In order to provide the largest possible voice for the project, a quick call to our good friends at Grassroots Motorsports Magazine yielded their support via this forum and some potential print exposure. Ann & I have known Tim, Per and JG from way back in the early days of “AutoX” magazine and find that the publication has grown and adapted nicely to become a unique force in the motorsports community, especially among autocrossers.

Secondly, we’ll need to farm out certain areas of the car’s development that cannot be handled in-house. One of those is the motor. More on this later, but suffice it to say that there are few engine builders that I trust to build a fast and legal motor for solo, and Ed Gilfus at Applied Racing Technology is one of them. Ed has been part of the Austin-based racing crowd for many years, spending time chasing cones, driving in circles and a couple of stints in road racing. Like many, he has gotten caught up in the Spec Miata bandwagon and together with partner Karl Zimmerman formed a business around that opportunity. More info on their backgrounds, products and services can be found at www.appliedracingtechnology.com Oh yeah, did I mention that they have an in-house dyno?

Another key element once the car is actually built is alignment and tire service. I’ve yet to find anyone as meticulous and accommodating as Bill Kim at Soulspeed. They’ve been a sponsor of ours for the last year and have state of the art equipment for alignment and tire mounting. In short, I wouldn’t trust anyone else with my lightweight rims or to produce a repeatable and precise alignment. Bill can also do suspension installations and recommend racing or street performance setups. Check ‘em out.

And while they are not a specific partner in our project, Mazdaspeed Motorsports Development (www.mazdamotorsports.com) deserves mention since their support frees up funds and reduces costs through their contingency program and racer parts discounts. If you are racing a Mazda, “Mazda Comp” is your friend!

    Starting Point:

Since the ST rules inherit most of the suspension allowances from Street Prepared, we have no major development work there other than some potential retuning of spring/bar rates, and alignment to accommodate the switch from R-compounds to street tires. We also have two years’ worth of experience with street tire testing for the Civic that will apply directly to the Miata. In fact, the wheels/tires from that car will bolt right up!

Because ST has no update/backdate like SP does, the key “undo” will be the motor swap and engine management. In CSP trim, the car sported a ‘99 1.8 motor with a set of TWM independent throttle bodies and TEC3 engine management. That will all have to go. We’ll need to source a complete1.6 motor (the car is a ‘92 model) and get it freshened. We’ll also need to swap out the super-lightweight kart seats (SP-legal) and get some ST-legal (and infinitely more comfortable) racing seats. Seatbelts and steering wheel have to go back to original, as well. And finally, the clutch-diff rear end will have to go in favor of an OE viscous LSD. The latter are tricky to find in good condition and are no longer available from Mazda.

As far as unique performance parts, we’ll need a 1.6 header, some sort of intake, and an engine management solution. Some of these will require significant development efforts to maximize performance since there are not good off-the-shelf solutions as there are in the Honda world.


The stretch goal will be to have the car together and sorted enough to take it to California for the first Pro Solo in March. Much of that will depend on the engine rebuild timeline since this is the time of year when all the Spec Miata folks are having new motors built and ART is very busy. The rest of the car is very straightforward once it has been dug out of the garage. From there, we’ll do dyno work to optimize the power output and setup testing at some practice sessions. Car should be “done” by June. Of course, I thought my first Civic build would take a month and it took twelve.

And so it begins…

—Andy Hollis

PS: Better formatting and some pics to follow as I figure out this blog setup…

Future topics

  • Intake testing
  • Header testing
  • ECU development
  • Tire testing
  • Suspension tuning
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