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Did my 2nd autocross day up at Lime Rock Park this past weekend, this sport is quite addicting. For those unfamiliar, the Lime Rock autocross is set up in a lapping format (5 or so minute 'sessions' on a very short track, nothing over 2nd gear). The course consists primarily of right hand turns with a small chicane on the straights to keep speeds low.
The feeling of the car was very different, not sure which of the variables (different ambient temps, different tires, different traction setting) was the primary cause or if they all just aggregated to a feeling of less grip on day 2 (e.g. when braking it seemed to slide first with anything more than moderate pressure and when changing directions it didn't feel as solid on turn in as the first day).
Based on the tire temperature (really the only objective data I have) I would say it probably came down to overdriving, or driving beyond my ability. Not unsurprisingly, the overdriving didn't actually equate to any faster times in the one portion where they monitor track times.
Day 1:
Temperature: 60* @ 9am, 72* @ noon
Tires: Michelin Pilot Super Sport, 255/35/19 front 275/35/19 rear
Cold tire pressure: 33f 35r (both left and right)
Hot tire pressure: 38f 40r (both left and right)
MDM traction setting
Day 2:
Temperature: 41* @ 9am, 55* @ noon
Tires: Michelin Pilot Sport PS2, 265/35/18 front, 295/30/18 rear
Cold tire pressure: 36f 36 r (both left and right)
Hot tire pressure: 46front left 42 front right 42 rear left 41 rear right
DSC Off
Both hot tire pressures were after the 4th session, not a before/after of a single session.
Overall it was still a ton of fun and I felt much more comfortable despite the lower grip level. Outright speed wasn't really the objective so I didn't play with pressures too much, but I did drop them back down to 40 all around where they seemed to stabilize for the most part thereafter.
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