I ran my '06 Boxster S at it's first autocross yesterday and thought I would post some impressions.
My car has PASM, Sport Chrono, Sport Shifter, Adaptive Sport Seats, Sport Steering wheel, etc. Basically I have all the sport options except for PCCB brakes and wheel spacers. I recently obtained some new Cayman S wheels and put Nitto NT-01 R compound tires in 245/40-18 and 275/35-18. The tires were not even scrubbed in yet as my first drive on them (and 18" wheels) was to get to the autocross location.
First, in regards to 18" versus 19" wheels I have to qualify any comments because I was not on street tires on the 18's and ther rear tires are a lower profile than the street OE 18" size. The smaller wheels felt a little more fluid in transition and probably have a better ride in terms of comfort but I didn't feel any big difference. I believe the 987's look better with 19" wheels and that would be the biggest factor in me deciding on 18" or 19" for a 987 Boxster.
Unfortunately, it was raining moderately for my first practice runs and the tires were still slick from molding agents in the tires so the car was skating around quite a bit. I kept PASM/SC on sport with PSM on. It was a valuable experience to feel the car transition from neutral to oversteer and understeer in the rain. Off the line with little traction it was obvious that the car could have benefited from a LSD. Too aggressive acceleration out of the hold results in spin and then wheel hop.
Afternoon sessions (the ones that count for the competition) the course was much drier but still a little damp. The tires finally got some heat in them and felt much better with the lack of standing water (duh!). I generally had good traction coming out of the corners and didn't see a big need for an LSD though it probably would make the car faster in an autocross situation and would definitely help with the launch from the start box. My times were very competitive but I did find PSM in sport mode abruptly cutting the throttle in one section consistently and another if I was too aggressive with the throttle; PSM Sport did not like heavy power oversteer situations. I had heard from a couple of sources that the car is a handful without PSM so I was leary to switch it off for my competition runs as this was my first time autocrossing a mid-engined car.
We had time to run some timed fun runs shortly after I finished my competition session (same course conditions) and it was time to test without PSM. I was immediately over 1 second faster on a short 40 second course without PSM, got quicker on each of the three fun runs without PSM and the last run was about 1.5 seconds quicker than my best competition run. The sections were PSM was kicking in were not hairy at all; just some fun tail out power oversteer. My best run without PSM was within .2 of a second of the FTD for the event. Autocross often requires quickness and tossing the car around like you would never do on a road course. I think PSM sport would never be intrusive on the track driving smoothly but I will never use it in a dry autocross again.
I didn't get a chance to get the car aligned to maximize negative camber up front yet but I will before the next event. With the tires scrubbed in and car aligned this will be a very fast autocross car. I definitely feel that I am getting used to autocrossing this car even though it is very different than the other cars I have autocrossed (modded WRX and C32 AMG Mercedes).
Carl
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