Sunday San Diego

  Again, show up early to the Q and make some minor changes to the STR Miata after a promising practice event on Saturday.  Some used Hawk HPS brake pads come in handy and are quickly installed at the rear to replace the ultra grabby HP+.  Toe plates and a few wrenches bring to front toe measurement back to what I prefer, about 1/16" total toe in.

  Unfortunately, the sound meter placement on Saturday was beyond pathetic and as a result I did not get accurate sound readings for my minimalistic exhaust at the practice.  Sunday's meter location was decent and I was recorded between 90.2 db and 91.0 db on all four competition runs.  Acceptable per the region with a limit of 93 db @ 50 ft, but louder than I feel comfortable with.

STR class runs late morning in the second group with bright sunshine and warm temperatures, and the class was full of great talent in very well equipped cars.   My first run I find a down cone and get a rerun.  Get the water sprayer and hit the Toyos. My second run was my first official timed run and it was my fastest time of the day but plus one cone.  Water the Toyos again.  Second, third, and fourth runs were all consistent and clean, I think, but a tenth or two slower than my first.  Should have brought the Hankooks.





Final results put me in third place in STR, over a second behind first, with fourth through seventh places within a tenth. Official Results Here.

 With the brake and toe changes complete, the car was more predictable and easier to drive.  Balance is excellent, motor feels strong, and the Torsen LSD puts the power down smoothly.  Overall, I am happy that the car came together so quickly and that it performs well.

Planning to Plan

  The first autox event for my new STR Miata at California Speedway did not go as planned.  Simply stated, I missed the setup and the car was loose and slow, over 2 seconds back from the leaders in STR.  Slower than STS too.  Class results are HERE.  Briefly, a combination of wrong rear spring rates, poor ride height, limited camber, and uncertain front toe left me with an ill-handling machine. Aside from that the car felt great with good power and nothing broke or fell off the car.

  Following the problems the previous week at the CalClub autox, I showed up early for Saturday morning's autox practice at Qualcomm Stadium and installed softer 375# rear springs with new PES rear shock mounts and lowered the ride height approximately 1/2" at all four corners. Rear shock ziptie measurments from CalClub tell me I was running out of travel so the custom 20mm extended shock mounts should solve that issue.  Some old bumpstops are also installed.

   As a result of the spring change, the car was transformed and drove beautifully with a few minor quirks.  Previous owner installed Hawk HP+ rear brake pads which in my opinion caused too much corner entry rotation under braking.  Also, front toe out was causing me to literally hit every apex cone on course.  I can adapt to these issues and some would prefer a car setup this way, but I could feel the car working well beneath me without the alignment and brake bandaids. 

The 450# rear springs that I removed should be an ideal setup for grippier surfaces such as the concrete at El Toro or Lincoln Airpark.

Current ride height is near 4 1/8" front, 4 1/4" rear with 195 Toyos installed.

Maximworks

Maximworks header for any 1994-2005 1.8L Miata.  Currently has an EGR bung welded to the number three runner with a matching custom EGR tube, and the collector flange has been cut off in anticipation of mating it to my NB midpipe flange. 

I am thinking about selling it; make me an offer.

SOLD

Enthuza

   Jason from Enthzacar sent me a nice axle-back muffler that weighs less than 12 pounds, fits great, and has a good tone with minimal drone.  Although the previously installed catted midpipe has a decently sized resonator, I am not confident this full exhaust combination will meet out local sound regulations, 93db @ 50 ft.  San Diego is pretty strict about sound, so I am sure it won't take long to find out if I need to reinstall the larger, heavier, and quieter Roadstersport muffler.

Good-Win Racing's Roadstersport muffler waiting just in case the Enthuza XR is too loud.

Alignment

The front camber is maxed out.  I went a little conservative with rear camber, but then I have the easy adjustment upper control arms from AWR, and minimal rear camber should help me apply the power upon corner exit. 

Current ride height measured at the pinch weld (1/8 tank fuel and trunk empty) is 4" front, 4 3/16" rear, with a tire height of 22 5/8".  Both the R1R and RS3 have a new full tread height of 22 3/4". 

Shocking

Custom shock tops for the yellow Koni Sport and Race NA shocks, but specially designed to fit the NB chassis.  These tops are based on the original NB Miata top, and offer extended reach and a spherical bearing mount.  The shorter pair increase shock travel by about 20mm, the longer ones 35mm.  After my first autox and once the ride height, spring rates, and alignment are finalized, I will have a better idea of how much more bump travel may be needed, if any.  Regardless, the bearing mount design will make its way to all four corners eventually.
  

Send an email to Practical Engineering Solutions Inc. if you are interested in purchasing some of these mounts for you Miata.

Waiting

  The first autox of the year is January 22, hosted by CalClub at California Speedway in Fontana.  The weather is usually decent this time of year, although usually a bit windy, and there should be a good mix of participants in STR with well-prepped equipment and fast drivers. This will be the maiden voyage for my 99 STR Miata and I just plan to make sure the car stays together, get a general idea of the balance, and see if the exhaust meets the local decibel regulations.  The following weekend, January 28-29, is local San Diego Region practice / championship event at Qualcomm Stadium. 

   I plan to use the Toyos for the first several events of the year because both surfaces that we compete on are low to medium grip asphalt, and the weather this time of year is usually cool.  No setup changes needed when I switch over to the Hankooks; just a different feel and driving style.

 







15x7.5"+42 949Racing 6UL wheels with 195/50-15 Toyo R1R tires.

15x8"+40 949Racing 6UL wheels with 225/45-15 Hankook RS3 tires.

ECU

  Originally a California car, I tossed the stock ECU and picked up a federal BP4W unit and mailed it to Joe at Dynotronics.  Their tuning process involves replacing the code on the original chip without removal from the motherboard, which leaves all the idle and cold start features alone and just focuses on timing and fuel to extract more power and improve air/fuel ratio.  RPM limit can also be changed and I upped the limiter from a stock 7200 to 7700.  Unfortunately, the tune can only be modified or changed by Dynotronics, meaning that a time consuming and less than precise E-tune process will be needed to fully maximize the ECU's potential.  Also, only one tune can be stored at a time making it impossible to switch between multiple maps, different rpm limits, etc.

   A piggyback controller is now also legal for 2012 SCCA Solo competition in all of the ST* classes, but I chose to program the stock ECU because I believe it will be more stable and initially easier and cheaper to tune.  Eventually, I will probably want more personal control over the tuning and may step up to a Greddy Emanage Ultimate, Megasquirt, or similar device.

 












  Based on my first impressions while driving on the street, the low speed/low rpm throttle response is crisper and the off idle throttle response is smoother.  Horsepower feels the same and we will eventually let a dyno shop have a go with both ECUs to see the results.

Bling

Every good STR Miata needs some bling.  Steve from Panic Motorsports helped me with this used K&N intake designed for the NB Miata. Fits great, works well, looks good, and it is CARB approved.

  I plan to cut off the 45* on the right side after the MAF and shoot the filter element straight, moving it closer to the driver side headlight area where Mazda engineers designed factory cold air ducting.