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Old 09-20-2018, 06:19 PM   #4721
Turbo
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Join Date: Jul 2012
Drives: FR-S Turbo
Location: Grand Bend
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Could I ask for help reading my tire temps/pressure data?

I'm relatively new to tracking, but I've driven this particular track 4 times now, logging over 400 miles on it at speed.

I would characterize my car as having corner entry understeer, although now that I think about it, I remember it being more pronounced in left turns. If you watch video of me on track, it does appear that my steering input is leading turn-in by a good bit. At least to me. Mid-corner I would say understeer-to-neutral, and pretty neutral at exit (unless I get on it hard).


Questions:
1) are my hot pressures to high in the later runs? How about my tire temps? I'm running and was told they like to be at 35psi hot and I'm way passed that up front - but the inside-to-outside temp measurements seem to say they're not overfilled?

2) any tips to reduce the corner entry understeer? I think because of this feeling there are a few corners I turn into too slow (as the car doesn't feel like it's reacting). I think I start on a tighter line than I could otherwise take if it would turn-in faster.

3) I wouldn't mind a bit MORE looseness in the back. There is a rather tight S bend on the front straightaway and I could definitely take a better line there if the rear end came around a bit more. Anything I can do to make that happen?

4) the rear temps seem to say I'm running too much camber, but I'm not running that much. Thoughts?



Car details & setup:

- 2013 FR-S. 250.8 RWHP boosted;
- HKS Hipermax SP coilovers ~26mm drop;
- Camber -3.0 LF & RF with 0 toe; -1.6 LR & -2.6 RR with 1/32 total toe-in;
- 255/40R17 RS4 tires on 720 Form 9" wheels;


Data notes:
- temps listed in order of measurement. All presented as outside/middle/inside;
- "shock" is Ft/Rr HKS 'click' setting with 30 being full hard;
- any changes to tire pressures listed after temp data with a ---> in front;
- data from my first 5 sessions of the day. Approx 72 deg F that day;
- obviously session one is just tires coming up to temp;
- track data from racechrono;
- A former national FF champion runs 1 min 3 seconds in his Radical SR3 w/Hayabusa. My best is 1:15.82


Run 1/
1:18 fastest lap
shock: 23/18
LF 125/123/129 34.1 psi
RF 123/117/110 34.3 psi
RR 115/126/134 33.1 psi
LR 110/123/127 32.3 psi

15 min brk

Run 2/
1:17.29 fastest / 1:16.43 optimal
shock: 23/18
LF 139/141/143 37.1 psi
RF 121/126/135 36.7 psi
RR 124/135/144 33.6 psi
LR 129/140/144 33.9 psi

15 min brk

Run 3/
1:17.09 fastest / 1:15.70 optimal
shock: 25/20
LF 147/153/152 38.3 psi
RF 140/132/124 37.5 psi
RR 127/143/147 35.4 psi
LR 136/143/145 34.6 psi

--> increased RF tire pressure by 0.8 hot psi
--> decreased RR tire pressure 0.7 hot psi


15 min brk

Run 4/
1:16.07 fastest / 1:14.98 optimal
shock: 25/20
LF 156/159/155 39.5 psi
RF 129/134/151 39.2 psi
RR 128/145/153 34.9 psi
LR 137/148/151 34.8 psi

15 min brk

Run 5/
1:15.82 fastest / 1:14.30 optimal
shock: 25/21
LF 154/156/160 39.6 psi
RF 130/140/151 39.2 psi
RR 124/139/142 34.7 psi
LR 132/139/140 34.7 psi



I have video o Run #5 if that's of value.

Last edited by Turbo; 09-20-2018 at 06:30 PM.
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