Thanks for your input. I've been doing research about this subject. Very interesting.

I've watched your video several times too. You're right about the oversteer part. I think you must have counter-steered the car at almost every corner. You probably lost some time too because of that. It sounds like you haven't driven the car since that video was taken. I was curious to see how you tamed the oversteer (driver/car setup).

 

I wish I could recommend a book on tires for you, but almost all of my knowledge has come from physics class, engineering journal articles, and experience. Tune to Win by Carroll Smith has some good basic information on tires, but alot of it deals with bias-ply (not radial) tires IIRC.

Yea we definitely lost 1-2 seconds with that oversteer. Hell that last corner F up was 1 second alone...That was my first time in an S2000, and I didn't know much about the cars at the time (still don't, lol). But just from driving it that day, the biggest basic thing it needed was more front spring rate. The front was too soft relative to the rear, so that's where the over-rotation on corner entry came from. The only thing we adjusted that day was the front dampers; we went stiffer with bump & rebound, and that definitely helped me trail-brake deeper into corners. Looking back, we should've tried something else to give the rear more grip during trailbraking. I bet lowering the rear would've helped alot. Still, we beat Tim Kuo's time in a similarly-equipped S2000 from the year before, and I think he had roll center adjusters too. So we were happy.

But I digest. No, I haven't driven that car since then. It would want stiffer front springs mainly, and RCA's, a BSK, softtop delete, a front splitter, a turbo, etc etc would be nice too

 

Wow! I've seen web pages that state increasing pressure increases grip. This to me seemed odd. I would have thought you want to decrease pressure until you get to the point where you are showing abrasion right up to the tread pointers (often triangles) on the sidewalls. Max use of tread should be max traction for that given tire... right? Of course, if you are going beyond that tread pointers, increasing pressure should increase grip.

It is good to see that my common sense is confirmed by someone else, but with me not being a technical car person, I always question myself.

-Dave

 

One good visual aid that I've found in my search on this subject is to imagine a graph (with tire pressure on the X-axis and tire performance on the Y-axis). The graph looks like a bell curve with the left side representing underinflated tires (tires overheat from flexing too much). The right side of the bell curve represent overinflated tires (tires don't stay warm enough because it is not flexing as much and too stiff to provide mechanical grip). The optimum point is around the top of the bell curve where ideal pressure exists for a given driver and the conditions. I think I read this on the rennlist or evolution forum. Can't remember. I think the trick would be to find this ideal range of tire pressure where you're on the top of this bell curve.

 

[QUOTE=daverx7,Mar 18 2008, 07:51 AM] Wow!

 

I recommend a book called "The Racing & High-Performance Tire: Using Tires to Tune for Grip & Balance" by Paul Haney. The book is fairly complex but has all the great information about tires tuning such as inflation pressure, limit of adhesion,spring rates, swaybar rate, etc.

 

Thanks, I'll look that up. I need a book on tires.

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