"Mr. Toad" at The Streets of Willow Springs (27 February 2021)"Mr. Toad" at The Streets of Willow Springs (27 February 2021)
 Miata, Mazdaspeed, and MINI Cooper meetup in Santa Nella |
 Reflecting on our numbers |
 In California's Central Valley, Mr. Toad turned into Dr. Bugvorkian |
 Los tres amigos |
So it begins |
 Lime and lemon Porsches |
 Taped-up Honda Fit |
 NOT my wheel weights! |
 Brothers? (Greg Epstein on left) |
 Greg's tires took a beating |
 Broken wheel from Big Willow (the driver cracked two ribs) |
 Snow above the desert |
 Packed up |
 A successful day! |
 Joshua tree sunset |
The facility is time-worn and could use some care. The paddock areas are full of debris which could probably be addressed via a simple pass with a street sweeper. Worse, the track pavement seems to break up alarmingly often. By late morning a brick-sized chunk had appeared just off my line (but possibly on the line for others) midway between turn 10 and turn 11. During the afternoon, a number of track turds cropped up just beyond turn 4 (going towards turn 3 since we were running "backwards"), avoidable for me but right on the line for one of my friends.
Beyond that, several locations desperately need run-off strips but just have a small cliff from the edge of the pavement dropping into the dirt. The one which bothers me the most is the exit of turn 2 but there are others.
Oh yes, this was also my birthday, one of those that ends in a zero, and not only did I get to spend it on the track but did so with friends: Greg Epstein with his 2014 MINI Cooper S and Ray Allustiarti with his 2016 Mazda Miata (ND).
Although these track days are not races, some friendly competition is always
fun. I had registered in the advanced group (in NorCal I go in intermediate
since advanced tends to have many insanely powerful cars) and Greg moved up
to it. Ray was in intermediate but the last morning session combined the
two groups so all three of us were on track together.
This was just Greg's ninth track day (it was my 52nd) but he's very good
and his MINI Cooper is nicely matched with my car. He pushed me to do
better!
 Best lap, first session (1:36.341) |
 Best lap, clockwise (1:34.218) |
A key goal for the day was to explore the benefits of recent upgrades, first and foremost a Big Brake Kit (BBK) but also new, wider, stickier tires, with a front track increased by 50 mm after factoring in the 20-mm spacers required to fit the stock wheels around the BBK. In addition, since my last time at this track, I had also added 10-15% to the car's horsepower with a package of engine upgrades. During my first (warmup) session my best lap time was within about 0.25 seconds of my best time last year, an encouraging start. Despite tire-pressure issues my second session knocked over two seconds off that time. Subsequent clockwise sesssions fell short due to traffic and other issues but I was still happy with the improvement.
With the stock power curve, peak horsepower (263 hp) is generated from 5500 RPM to 6250 RPM, falling off to 250 hp at about 6550 RPM. Shifting from 3rd to 4th gear (1.366:1 and 1.025:1 respectively) at that point drops to about 4900 RPM, at which point the engine is generating about 245 hp and climbing, so it made sense to shift there.
Now power is robust all the way to the 6700-RPM redline and beyond to the rev limiter at 7400 RPM. (Running the engine up to the rev limiter is not good for the engine's long-term health but I've now encountered it occasionally.) I don't have a power curve with my engine mods but it feels nearly flat to redline so it makes sense to use that headroom; when finally shifting to 4th gear more than 90% of peak horsepower should be on tap.
For the most part, my turn-by-turn comments from last year still apply. One big difference was Turn 13 (the skidpad, leading onto the front straight), where understeer and wheel spin had plagued me. This time I didn't notice any significant understeer and accelerating out of the turn onto the straight was much more controlled.
Only later did I remember that the second apex and exit of Turn 3 had also been a wrestling match with understeer. This time the car stayed exactly where I wanted it without fuss.
The upgraded rear swaybar and the wider, stickier tires clearly helped. The final test will be at Laguna Seca next month, where understeer on Turn 2 has been a huge problem, but at this point I'm confident that the problem has been banished.
Later, in the last morning session, passing the start/finish line at the end of the first lap, someone decided to release an open-wheel car in front of a line of traffic (led by me). It became clear within a few seconds that this was not a fast car. Coming up to Turn 3 I was looking for a point-by, didn't get it, and decided to pass anyway. I lapped him and was ready to pass again just as we got the checkered flag to start the cool-down lap, which I've started taking seriously.
Later in the day, I again experienced someone coming up to my to say
"your Mazdaspeed is impressively fast." Yes, yes, it is. I adore this car.
Session Best Lap Delta Fastest
(mph)5 1:41.389 - 103.1 6 1:37.422 -3.967 107.7 7 1:35.569 -1.853 105.6 8 1:34.781 -0.788 105.1
Turn 2 is especially important in this direction because it leads to a downhill, full-throttle run into the fastest portion of the track. (Turn 1 can be taken at full throttle.) This run on the front straight ends with heavy braking before the skidpad (Turn 13), which I had expected to be a challenge but turned out to be surprisingly easy, leading into a fun run through Turn 12 to Turn 10.
Turn 10 is another critical spot since it leads into the chicane and the back straight. Many drivers hit the apex early; my strategy was to stay as far left as possible, using a bit of access pavement to expand the turn further, until making a hard right and going to full throttle for a late apex and wide-open run all the way until braking for Turn 8.
I was wary of Turn 8 since in the reverse direction it is a decreasing radius turn. In the Zoom drivers meeting someone said one option is to treat it like a double-apex turn while another, favored by cars with lots of power, is to go wide and then dive in for a single, late apex. I followed the latter line and it worked reasonably well. I started off shifting just before that turn-in but doing so just before needing to steer in was too much disturbance so I ended up downshifting during heavy braking at the end of the back straight. I should have figured that out at the start but thought I'd carry more speed into the faster, banked beginning of the turn.
Accelerating further into the straights, then braking HARD, right at the limits of tire adhesion, significantly improved my lap times—without boiling brake fluid, roasting brake pads, or running off track. Curiously, after getting serious about braking, my top speed dropped a little. I'm not entirely sure why that was the case but a quicker lap is more important than top speed.
Tire pressure was a challenge as always. Running clockwise, the left front tire works hardest and the first session of the day saw that tire increase 9 PSI, from 34 PSI at the start to 43 PSI after that session. Assuming a start from the ambient temperature of 51°F (283.7 K) and ignoring the increase in tire volume due to the higher pressure causing bulging that implies a temperature increase to 186°F (358.8 K).
I reset the pressure to 35 PSI (hot) but during the 40-minute break the tires cooled enough (therefore losing pressure) to trigger a TPMS (Tire Pressure Monitoring System) warning for nearly half of the second session, and handling felt as sloppy as an early 1970s Buick. TPMS went away more quickly in the next session and did not reappear after that but that still meant a compromise in terms of running higher hot tire pressures than I would prefer. Fortunately, this did not result in the feeling of driving on ice skates, probably due to the stickier NT01 tires.
The following table summarizes tire pressures throughout the day:
Description Time Ambient LF RF RR LR Note hotel 0637 46°F 36.5 36 36 36.25 before session 1 0823 51°F 39.5 38 38 36.5 notes say 61°F (clearly wrong) 34 34 34 34 reset after session 1 0854 52°F 43 40.5 38 39.5 35 35 34 34 reset after session 2 0955 55°F 38 37 36 36 TPMS for 9 min before session 3 1023 55°F 31.5 32.5 32.5 32 after session 3 1056 57°F 38 37.5 36 36.5 TPMS for ~3 min before session 4 1136 57°F 31.5 32.5 32.5 32.5 after session 4 1205 61°F 38 37 36 37 no TPMS after session 5 1324 63°F 36.5 36.5 35.5 36 CCW, no TPMS after session 6 not recorded after session 7 1522 60°F 37.5 38 36 36.5 CCW, no TPMS after session 8 1633 57°F 37.5 38 36 36 CCW, no TPMS Chevron 1736 54°F 30 31 32 32 Rosamond 35 35 34 34 reset
Another option might be to spend a few minutes doing slaloms in the paddock to warm the tires before going back on track—isn't that what the sign at right means?
Once again driving this track was a workout, leaving me sore for several days afterward and occasionally breathing hard while on track. Greg felt the same way and we both realized that we spent a lot of effort just holding ourselves in place. A five-point harness would help considerably.
At first it seems strange that this track should be such a workout but it
is only 1.6 miles long yet contains 13 numbered
turns—several of which have two parts. For comparison,
Thunderhill East has 15 turns but is over twice as long while Laguna Seca
has just 11 turns in 2.238 miles.
There is a lot of action packed into the short span of
The Streets of Willow Springs!
This video (MPEG-4 version) is from session 4, the last morning session and last clockwise session before changing directions for the afternoon. It features some passing along with my fastest clockwise lap.
This video (MPEG-4 version) is from session 8, the last session of the day and my fastest counter-clockwise lap. I was finally starting to get comfortable with the new brakes and braking later at the ends of the straights.
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Copyright © 2021-2022 Karl L. Swartz. All rights reserved. |
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