AD07 pressures for track use?

[Au111]

First lapping day scheduled for Thursday, and I'm starting to think about tire pressures. I'm heading out on the standard AD07s.

I'd normally take the pressures up a few pounds (5-7 psi), see how it feels, and go from there, but I'm wondering if anyone has already put alot of heat into these tires and has a better baseline than my guestimate to work from . . . .

Opinions?

I'll report back either way on results.

[thegit]

I'd do what you normally would up 4 psi.
If straightline stabilty is poor then come don in pressure.
If the handling is greasy you also have to drop pressure.
I'd keep front to rear pressures at the same ratio as street until you find optimum cold race pressures, then fiddle with the F/R ratio to adjust front end turn in bite .
Get a tyre pyrometer asap too.

The lighter the car, the less increase in pressure. In a 1300lb car, pressures for track usage would be the same as street, except you raise rear pressures slightly 1-2 psi for more front bite when carrying a passenger as a passenger tends to increase rear grip.
m.

[Au111]

Although I didn't see your post untill after I came back, 4 lbs was about right. Hot pressures were 34 f / 33 r. Cold is about 31 f / 30 r. The car was squirrly in the first session with more pressure. That, and I hadn't adapted to MR configuration yet. Oh, and I was anxious to get out there. Two spins later, I had my head and driving style sorted out.

I'll download more later, as I'm exhausted right now, but that was an absolute blast. With a little more tire than the AD07, this thing will be a giant killer.

[Au111]

Some random thoughts from yesterday:

• Keeping it on the cam requires hitting the rev limter occasionally. I hope Lotus doesn't mind.
• With a "neutral" approach to a 90', 2nd gear corner corner, the car understeers slightly. On a scale of 1-10, where a stock Audi S4 is a 10, a track-prepped S4 is a 5 and a SpecMiata is a 1.5, the standard suspension is a 2.
• Trail braking or aggressive throttle input can very easily get the car to rotate. The cam-step even does it for you, sometimes.
• The car will do what you tell it to, even if you tell it to do the wrong thing, so don't go out there (like I did) and think that you can man-handle the car around the track on your third lap. "Toss and Catch" is not the fastest way around in this car.
• At the limit of grip, the car gets very upset by bumps, rumble strips and abrupt slope transitions. It runs out of suspension travel very quickly, and can "hop" out on you, probably as a result of hitting the bump stops.
• The handling is very sensitive to tire pressure changes. I'm not sure that I have the pressures right, as we ran out of time and the batteries in the pyrometer were dead.
• Passengers make the car feel sluggish.
• For those familiar with NHIS in the chicane/chicane configuration, the car can carry as much speed through both infields as a SpecRacerFord/Spec Miata. Through turn 6, as well.
• The car has enough power to spin the inside rear wheel all the way up the hill out of turn three until the crest of turn 5.
• The driver's door will survive a full-opposite-lock slide directly into a pylon at 50 mph without cracking (but it sounds absolutely, horribly, gut-wrenchingly disasterous).
• Trail braking and trailing throttle tricks work really well to unsettle the car, and it's really communicative as it starts to come around.
• I can't position my feet to left-foot brake, but I probably shouldn't be doing that anyway . . .
• Don't follow formula vees around the track, they're likely to put oil down right in front of you.

The car is huge fun in base, stock form and is as-capable as many track-prepped cars right out of the box. It is also probably one of the best driver training platforms I've ever driven - it is just so communicative and easy to modulate at 9-10ths, and relatively forgiving at 11/10ths. A SpecMiata allows more room for error, but with the Elise, you never feel as if you're fighting the car. It has almost no handling vices that you have to drive around. It's a far better car than I am a driver, and it's a little humbling to realize that. I think this is the begining of a beautiful relationship.

[_JD_]

AU111-
thanks for the thoughts- interesting read.

[Au111]

And another thing:

The brakes.

The ABS is really non-intrusive. I only engaged it (that I noticed) once, and I attribute that to a relatively bumpy braking zone. On smooth surfaces, you can take the tires to the howling edge of lock-up without the ABS cutting in.

Although I was being a little conservative under braking for much of the day, lengthening the zone and not using the brakes' full power, I had no issues with them fading in 80+ track miles.

The 1" of useless brake pedal travel doesn't seem to bother me on the track, where I'm usually looking for a lot of engagement anyway.

I was able to lock up the tires when I had "both feet in" during my spin. I don't know if the ABS software is calibrated for that, or if the trajectory/physics of this particular "off" simply allowed it to happen, though.

The fuel mileage.

About 10 mpg. Apparently it doesn't exactly sip gas when on the cam!

[James A]

Nice write up, thank you !