Trust, Slip Angle, & One Inch

   The weekend of April 14-15 hosted the last El Toro championship autocross before the upcoming SCCA ProSolo event scheduled for the first weekend in May.  The weather was beautiful with sunny skies and mid 60* temperatures.  I bring my 225 Hankooks out to play and snag a co-driver to help heat them up.  STR runs first group and I have not driven the RS3 tires on this El Toro surface for a couple of years; 2010 SCCA ProSolo in my old 1995 STS car to be exact.

Co-driver warming the tires

 


   I take it easy on my first run but I do not fully trust the tires yet, especially under braking.  Lots of grip at this venue and the Hankooks are much sharper than the Toyos.  Without all the magic Toyo slip angle I am turning in too early and nipping apex cones with the back of the car.  Or it could be from the 1/2" wider wheels.  Or I am just not turning the steering wheel enough on this busy transitional course.

 












    Second run was relatively fast, but drifting the sweeper and getting behind at the finish did not help.  Neither did the three cones; two of which were at the start.  By my third run I was feeling really good about the tires and blown away by the grip and responsiveness, especially compared to the R1R, but I needed a clean run so I backed it down a little.  My 4th and final run was much faster mostly due to staying ahead of the course and from fully trusting the directness of the tires, but I am still a little tight to the cones as seen in the video and I knock down 4 cones (two again at the start).

    I can't complain about my times but I can complain about my driving as I am normally not that dirty.  First place finisher Max H. was on 300+ run Dunlops and I finished second in class.   RESULTS

 




  

Fail

   DP Tune has been a major fail as I have been waiting over 2 months for them to send me an LM2 rental to fine tune the ECU and also bump the limiter up to my requested 7700 rpm.  He keeps saying I am next on the list with a sympathetic email or phone call, but then nothing happens. Last email says it is in the mail and should be here today.  With 2 weeks to go until the San Diego Tour and El Toro ProSolo, I cannot rely on them to process the order fast enough and return it promptly so I will keep what I have and figure this stuff out later.  Besides, my coil pack went bad last weekend with symptoms being minor hesitation and surging under load.  Check engine light is on for low cat efficiency.  Not sure an LM2 tune would be beneficial at this time anyway with the current engine woes.  Coil and plug wires were ordered this morning from Mazdaspeed Motorsports.

  

   











   Some of the coil pack issues could stem from the previous weekend when I changed out the spark plugs and plug wires.  What was supposed to be a simple job turned into stress and frustration when two of the spark plugs threaded out hard the whole way and the number four plug wire ends were fused to the coil and plug. Leftover used NGK blue plug wires from my '95 STS Miata will serve as the replacments in the meantime.  The oil on plug three is from a bad cam cover gasket which will be replaced along with the coil pack.

Bell Engineering Group offers an ECU tuning service similar to what I have, but the cost is a little more and probably well worth it.  After the big California SCCA autocross events, I may seek a refund from DP Tune and explore the BEGI setup. 

One week later

Another Saturday practice and Sunday Championship March 24-25, with another forecast for rain which fortunately held off until Sunday evening. 

  Saturday was terrible for me and probably my worst day of driving in the last several years.  Over driving, coneage, and DNFs ruled the morning session, but I came back in the afternoon and put together 4 solid runs, about a half second behind another fast STR Honda.

  I lowered the rear of the car another turn (1/8" at the shock) and was on the 15x7.5 195 Toyo combination.  As usual, koni shocks full stiff front, full soft rear.

  Sunday's championship course was reverse from Saturday, but the designer modified a few corners which opened it up way too much in my opinion. Speed maintenance may help the smaller more nimble cars such as the NB Miata, but I would rather see a more diverse course. I finished second in class with a very fast first run again thanks to the Toyo tires. The Toyos now have about 72 runs and 700 street miles.







RESULTS


  It seems that when a front tire rubs the inner fender splash liner, it rips out the plastic clips.  The NA Miata did not have this problem.

 












  Not wanting to get protested,  I installed the air intake baffle in the stock location behind the driver side headlight.  Some will argue that this baffle needs to stay to be legal because it serves two purposes- one being a place to locate the AC and fog light relays.  Without air conditioning or fog lights on my Sport model Miata, the relays that mount to this panel are absent, but the electrical connectors remain.  Not a big deal until I decide to alter the intake with a custom cold air box.

It never rains in Southern California...

   March 18th championship event at El Toro did not go as planned.  Because of the forecast for rain, I initially was not going to make it until I got a call from K-Mo interested in co-driving in STR with me.  Even says I can use his brand new 195 Toyos/SSRs. Deal.  I figure this is a good way to get valuable insight about the car's handling and potential from a multi-time champ and see how the car stacks up against the other STR competitors on the grippy ET surface.

   STR runs after lunch but we decide to run out of class in the first morning heat because Ken had other commitments in the afternoon.  Rain, wind, and cold throughout the first heat and then it dries up completely before lunch.  Screwed again, but at least I won my class (CST).  I should have run time only runs in the STR heat.

Although in the dry, STR was 5 seconds faster than my time.

RESULTS

March 4th Autox

195 Toyos, 80*F weather in March, carne asada burrito from the roach coach, and third place in class.

Results

Car was more stable with the rear lowered 3/8" at the shock.  Could go lower but I am near the bumpstop limit with this particular spring and top mount combination. More testing needed.





Only 6 weeks untill the SCCA San Diego Solo National Tour comes to town.  Still waiting for Dynotronics to finish the ECU updates as I am currently limited to 7500rpm.

Car in grid with lower ride height and 15X8 wheels.

Camera mount.

Rear fender rolling is next on the to do list.

Next event is at El Toro March 18th with a much grippier surface than Qualcomm.  I plan to run the higher rear ride height and hope that the balance is good.  No spring or bar changes expected.




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March 3rd Practice

Tested 195 Toyos in the morning and 225 Hankooks in the afternoon.

Toyo R1R 28 psi on 7.5" wheels.

Hankook RS3 30psi F, 28 psi R on 8" wheels.

New camera mount works good.






Lowered the rear ride height 3/8" at the shock.

3.15* front camber, 2.9* rear camber.  3/16 total rear toe in.

Lift off oversteer.

Misc.

Front upper shock mounts with spherical bearings are installed today.

 

Thinking more about the Contour camera, I really do like how simple it is to operate and the price was excellent.  However, any changes to the recording settings such as volume or picture resolution must be done through computer software; not something that can easily be changed on the fly.  And as mentioned previously, the .mov file output is not my favorite.

To get the most out of the camera, I decided to fabricate a mount using some scrap aluminum.  I wanted the mount to be behind the driver and high enough to easily see the course.  Some 1/8" x 1" angle was modified to mount to the passenger side hardtop bolt location which is standard on all NA and NB Miatas.  It stands about 19" tall and gives a good view.

I was worried that it may vibrate or sway with all the weight up high, but a quick video test drive around the neighborhood delivers good results. Sound is not great, but at least it does not pick up a lot of wind noise.  There is no remote on/off switch so I will have to deal with that too.

Data

  A Torque Android datalog using a cheap Amazon OBDII reader shows that my car tops out second gear at 59.2 mph at 7506 rpm.  This is with my 'street' tires that are about 1/8" shorter than stock. Data capturing was set at 500ms.  I was expecting to see at least 7700 rpm as that is where I told Dynotronics to set the ecu rev limiter.  For a planned ECU revision, I will soon be logging data with an Innovate LM2 which should be more precise and verify the accuracy of the bluetooth device. 

Action Shots

Pics from http://lateapexphoto.com/ taken at the January San Diego SCCA autocross.

Event #2

   Another championship SCCA autox event at the Q with a fast course gives me more valuable seat time.  The 4.30:1 rear gearing feels great but limits my maximum second gear speed, thus I was riding the limiter on this particular course for more than I hoped.  For faster courses I will need to shift to 3rd or extend the rev limiter beyond my current 7700 rpm - expected, but not something I am thrilled about. Fortunately, I expect most SCCA Tour, Pro, and National courses to be a tick slower than today's offering.




Sorry about the video's sound quality; it seems that youtube doesn't work well with .mov files and the sound is borked and then dropped halfway through the run.  Although the Contour camera was cheap and is simple to operate, the QT format is not my preference and something I was not expecting.

Transitionally the car is loose, especially on corner entry, but with great feel in the sweepers.  A rear toe measurement after the event shows I have 1/4" total toe in, and my rake is nearly flat with 1/8" higher in the rear measured at the pinchweld.  The traditional fender to hub measurement reads just more than 3/8" higher in the rear.  To help settle the car I have a few options including lowering the rear ride height or installing the 1.25" Racing Bear front sway bar.  The next autox practice is scheduled for March 3rd.

Event Results
Don't read too much into the results, as we had some rain in San Diego and the course was wet early morning and mostly dry by noon. STR ran 4th group in the dry.  Once again, the Toyo magic gave me an effortlessly quick first run that turned out to be my best raw time, but plus 2 cones. 


The lightweight Enthuza XR muffler got replaced by the Enthuza Speeder which will easily pass the local sound restrictions and yet has a great note.