PCA Time Trial #4, Thunderhill Raceway Park

Friday

Open testing. Best lap time 2:23.18

I arrived at Thunderhill at about 1 PM to do a half-day open testing. There were quite a few cars there for the test day. I got in about an hour of track time, and just kind of tested my fresh rotors, pads, and brake fluid. Everything seemed fine and my best lap time was right around my personal best.

I checked my Kumhos for wear at the end of the day, and they seemed to be pretty well worn on the outer edges, so I figured I ought to see about getting the tires flipped to put the good tread on the outside. This seems to be how the Kumhos work with the maximum negative camber on the factory suspension -- about 6 or so days, then flip them for another 6 or so days of life. You just can't get enough camber to really get even tire wear on the track.

Behram said that Les Schwab was the nearest place and had done tire work for him before. They're in Orland, about 20 minutes north of Willows. I called ahead and they said they still had time to do it before closing. When I got there they put the car up on a lift and pulled the wheels off and went to work. A few minutes later, however, the guy called me over to the work area and said there was a problem. The bead on one of the tires was torn, and he said it couldn't be remounted because it would never hold air and be safe. Now, there are only three possible causes of this that I can think of: 1) when the tire was mounted at Big O Tires they mangled it with no ill effect; 2) when I spun off track 8 weeks and several track days ago, it somehow did it with no ill effect; 3) the guy at Les Schwab did it right there. Mind you, this is a 3-inch tear of the outer rubber layer, along the edge of the bead that is completely inside the rim. My money is on #3.

In any case, I now lacked a set of tires for the weekend time trial! AAARRRRGGHHH! At first I was afraid my weekend was toast. Then I realized that I at least had my spare tire, and could drive on that back to Willows, and that I had my street tires there. So I could do the time trial on my street tires. Then I got a bright idea. I could call Michael Saal and Doug DeVetter to see if they had any spare Kumhos and could bring them up. I left a message with Doug and after several frantic attempts got a ring at Michael's. And wouldn't you know it, Michael had an extra set of my exact Boxster 17" factory wheels with partially worn Kumhos sitting in his garage. He threw one of them in the van before leaving, so I was set. It turned out that Doug also was bringing up a new set of the same, to put on his car at the track Sunday in place of his more worn set already on the car. He called me back and said he had me covered in one way or another. These guys are life savers!

In the meantime, that night I was able to get this top-secret spy photo of the most awesome red painted race wheel on an Arena Red Boxster parked in front of my hotel room.

Saturday

DE sessions. Best lap time 2:20.29

I think I found three places on the Thunderhill 3.0 mile course where I made up a lot of time this weekend. Considering that by the end of the weekend I had lowered my personal best at Thunderhill from 2:23 to 2:17, it was a huge improvement. I can see how each of these three things could have been worth two seconds.

(Note that all speed measurements below are read from my '98 Boxster inaccurate speedometer, which is something like 5MPH or more high.)

Turn 1

The first place was Turn 1. Turn one is scary until you build up confidence -- in my car I approach it at over 100 MPH, previously up to 107 MPH when I really nail the corner leading onto the main straight. I think this weekend I finally got confident. Previously, when I crossed the pit exit line, I would start braking, and because of the high speed and lack of confidence, I'd sneak a peek at the speedometer, waiting until the speed dropped into the 80's before easing off the brake and transitioning to the throttle for turn-in. Then I would roll the throttle on through the corner, heading for Turn 2. I would usually opt to stay at redline in 3rd gear rather than shifting into 4th and immediately back to 3rd for entry to Turn 2. Given where 3rd gear redline is, the means I was probably taking Turn 1 good enough for a maximum exit speed (prior to braking for Turn 2) of 90 MPH.

But through this weekend I incremented each aspect of my execution of Turn 1. First, I extended the straightaway by finding a later braking point -- ultimately I ended up moving my braking point from the pit exit line to the first brake marker ("3"). This alone increased my maximum straightaway speed from 107 MPH to 112 MPH. Next, I shortened my braking zone and stopped looking at the speedometer, other than to peek at my maximum straightaway speed at the braking point. Instead of watching the speedometer fall, I simply developed a feel for how long to brake, almost like a short count 1-2-off in my head. Together, I was able to carry much more speed through the turn, and by working up these improvements in small increments, I never went near the limit and so it felt fine. I was able to easily measure the improvement by peeking at my maximum exit speed as I braked for Turn 2. From the prior speed of 90 MPH, I was able to consistently see mid-90's, up to 96 MPH as I braked for Turn 2.

Turn 8

The second place was Turn 8. This is another scary turn simply because the speed is high as you approach -- about 90 MPH for me -- and you just know that if your car can handle it and you can do it properly, you can probably go full throttle all the way. Yeah right -- at first you find yourself braking, and possibly downshifting. But although the turn has a little dip at the apex which worries you at first because it gives the car a little jolt, the jolt doesn't really do much to upset the suspension, and since the turn is into an uphill section, gravity squeezes the suspension to the ground and gives you lots of grip to take the corner faster. I would measure the speed by peeking at the speedometer as I passed the end of the exit curbing. Previously I would see a number in the high 80's.

I had by now gotten over the Turn 8 braking instinct, and was simply lifting off the throttle and moving my foot over above the brake pedal like a safety blanket. However, I was experimenting from one session to the next with whether or not I should downshift to 3rd gear in order to have more power up the hill; it didn't really seem to matter. But this weekend I improved further and didn't move my foot over to the brake. I simply stayed in 4th gear and lifted a little off the throttle, just for a moment prior to squeezing back on full throttle through turn-in. The result was still a comfortable line with sufficient track to drift out on, and a checkpoint speed of up to 95 MPH instead of 90 MPH. Going all the way up the hill to Turn 9, with your foot to the floor, this extra 5 MPH makes a big difference.

Turn 11

The third place was Turn 11. I felt pretty good about Turn 11 before, but I've started to learn and practice heel-and-toe shifting for the first time, and it is really, really helpful on Turn 11. It's a tight, hard left turn after heavy braking and downshifting from 4th to 2nd gear. It starts flat but the apex is actually on a slight, short uphill, and then it levels out. I've always found myself catching everybody under braking into 11. But the key to coming out of 11 fast is how soon you can get back on the throttle and start accelerating into the esses. Previously, I would find myself braking and putting the clutch in at the same time, then turning into the apex while blipping the throttle and preparing to declutch in 2nd gear. So I'd essentially be half-coasting across the apex while I started to disengage the clutch. By heel-and-toeing down into 2nd gear while doing the braking, I was able to get on the throttle in 2nd gear as I turned in, and was really well under throttle control across the apex curb. This meant that I was accelerating from that point all the way down to the hard braking at Turn 14. That's a long segment at full throttle, and so carrying just a small advantage at the start accumulates into a measurable time improvement across the turn 12-to-14 segment.

Sunday

DE sessions, followed by two timed laps. My best lap time of the weekend, 2:17.251, was one of my timed laps! Behram in the souped up S beat me with a 2:14.429, but I beat Doug's 2:20.261 and Michael's S with a 2:18.150.

Here are some photos I took while people were gridding for the time trial sessions: