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Another great PGP track day. Lots of run time. Well organized. Great people.
I was running about a half second off pace from the July 7th event due to weather (hot! - track temp was 140F+) and end-of-life tires.
1st Session: Car/track was very loose, big slides every lap (wish I had turned on my Video Cam), all laps were in the 1:11's with best lap of 1:11.069.
2nd Session: Grip changed from oversteer to understeer, lap times were about the same with a best of 1:10.9998. Required a bit more trail braking to rotate into turns.
3rd Session: Made some damper adjustments which improved turn-in. Times were still in the 1:11's with a best of 1:11.031.
4th Session: Drove with about 250 lbs. of ballast which induced a lot more understeer. Had to be much more aggressive with trail braking to rotate car. Times were in the 1:13's with a best time of high 1:12.
5th - 8th Sessions: Times remained in the 1:12's and 1:13's due to high temperatures and tires delaminating and cording. I had to end the day one session early as steel belts were visible on the tires.
Some Data:
Data logs aren't that useful as a static picture but...
Fast lap of day 1:10.9998 NOTE: Max Speed = 73.81, Min Speed = 26.23,
Session #1 Data:
Lap 3 graphed. NOTE: Lateral G's ~1.8, Theoretical Fast Lap = 1:06.388!!!
A few notes:
1. After reviewing the data, I can see running in the 1:09's. The theoretical fast lap of 1:06 seems very unlikely with the current set-up and conditions. This track is very much like an auto-x where a smooth car is a fast car but a smooth car does not mean slow hands. One needs to be pretty aggressive with the wheel especially on some of the transitions like T13-T14 and T7-T8. Notice the lateral accel plots and how they are at max accel in one direction and quickly transition to max accel in the other.
2. After a few scary slides at T8 and T11-T12 during the 1st session, I stopped pitching it into these corners and used a more constant radius line. I think this slowed me down a bit but I thought my luck would run out eventually doing it the other way.
3. I was trail braking into T1 pretty aggressively and down shifting mid-corner after the drama and sometimes using it to kick out the back end when the front started to push.
4. In the videos and in the graphs you can hear/see some inside tire lift which causes tire spin and some bouncing around. This was costing some time and was generally frustrating. Damper adjustments improved the situation but further tweaks are required.
The crushed rock around the perimeter of the track makes a huge mess when cars clip the corners. It puts large rocks on the track. This happens a lot.
Interesting that a SM driver mentioned that as the Miata guys seem to be the biggest culprits - gotta do what you gotta do when driving a momentum car I suppose.
Thanks for sharing Jared. I hope to make it out to the next one. You're only shifting to 3rd on the straight approaching S/F correct? The rest seems to be all 2nd gear. I had the sound pretty low so I may be wrong.
08-01-2009, 12:05 PM
PGP Track Day Review July 21 2009
