Friday, August 24, 2012

Another Month, Another Plan

So all of that stuff last month about building dedicated cars for each track?  Eh... Still sorta on the table, but it kind of limits what I can do with my stable of (potentially rentable) racing Miatas.

Last weekend was NASA Mid-Atlantic's Summer Breeze at Summit Point. It was far and away my best overall weekend of the season, with the best weather, turn-out, and camaraderie. Winning 4 tires didn't hurt, either.

I went to Summit Point with a plan. That plan was a bit hamstrung by the age of my tires (this was the 5th event on a single set of Hoosiers), but that kind of played into my hands just a bit.  Lemme 'splain...

The wing, as previously mentioned, is an anchor at VIR, taking a full 1-second improvement on the front half of the course and throwing it away in 4000' on the back straight. My plan was to switch back to last year's configuration, balance the car perfectly, and see if I could make an overall improvement at Summit Point just by driving better.  I was, after all, getting key data inputs like throttle-position and brake-actuation.

What I quickly found, though, was that even though we scaled and balanced the car to knife-edge perfection, there was just no grip in the rear.  New sticky Hoosiers can mask a lot of deficiencies in a suspension, but old ones cannot. The Spec Miata sway bars that used to feel so good and solid at preventing body-roll also place excessive duty on the tires. Again, that's fine when they're new, but at roughly 30 heat-cycles, not so much.

I tried to put down any sort of decent lap over two sessions and came out putting high 1:28.x laps. That's awful considering I'd done several high 1:26.x laps in April.

I also very carefully documented tire temps and pressures after each session, and the rears just weren't doing what I had hoped for.  Fortunately, I'd brought the wing and stock sway bars to experiment.

I switched back to that configuration, re-filed my class sheet, and hit the track again, immediately taking off almost a full second and keeping the car firmly planted in the rear.  The next morning, over the course of two more sessions I took off another full second, ending my weekend with a 1:26.862 lap, within 0.3 seconds of my personal best and on tires that had no duty-cycle left. And the crazy thing is, there was plenty more performance to be had.

So now I have a new quandary!  The wing is a proven benefit at Summit Point, to the point where I believe I have a reasonable chance at setting the lap record for TTE.  But it is also a proven boondoggle at VIR.

My plan for October had been to switch back to the beefy sway bars and just hope for the best in comp school, but then i realized that I'm taking exactly 7 points for aero.  What if I ran another dyno reclass for TTE/PTE with one star? That one star could represent a bump in horsepower or a significant drop in weight (I have about 70lbs of ballast in the car right now), or both.  No aero, compliant suspension, more horsepower, and less weight. Could that be the ticket, or will the car be too unstable at high speeds?

I must find out!