Robert Nixon

Looked like some pretty fast spots there, so hopefully good practice for Lincoln.

Yon Visell

Very helpful, thank you. Regarding your codriver suggestions, I'm on top of most of that, including data, about which I agree. My co-driver, Jeff Stuart, is really talented. A couple weeks ago when driving my car was a cone away from 1st in STR on his last run at the Fontana tour event, even though the car is not fully prepared or set up yet. I realized that one drawback is that talented driver can often drive around issues. Nonetheless, Jeff's and others' feedback (Cal Club in Los Angeles, folks have been super helpful) has been invaluable. Mark, who developed the suspension before I got it, has also been incredibly helpful.

The car has 90k miles, and I've recently been attending to maintenance issues affecting the suspension. A prominent vibration mid-corner was noted by co-drivers (half the time I'm driving I can't hear that kind of thing - deer in headlights). Just replaced the rear hub bearings, but the mechanic noted issues with rear suspension joint decay. I may need to replace hub carriers and LCAs. Another observation was that my lower strut section is nearly touching the CV boot. I'll need to address.

Car is in the shop today for Fabspeed exhaust install. Re-aligning and testing this weekend. Sparco seats arriving on Friday. I am tentatively planning to swap to the '04 986 LE / 987 intake/airbox before DME tune. Might consult with another Porsche race shop or two before deciding how to proceed.

Have a name or link?

Question for All: How many of you have reflashed or tuned the DME/ECU? Have you considered raising rev limit? Currently, I'm running 4% larger diameter rear tire, raising top speed in 2nd to roughly 70. Avoids having to sit too long on rev limit, which happens out here in CA. It occurred to me that I could revert to 4% smaller rear diameter tire (Yok 255-35-18 vs 255-40-18) and raise the rev limit by ~300 to compensate, thus providing 4% more thrust across the rev range. Not sure what risk would be entailed.

sjfehr

I can't recommend it due to the temperature inaccuracies, but it's compact, turns of fast, and takes cool pictures. Just assume the temps are 10-15F low when you first turn it on. But for what I need it for in grid (measuring relative temp across the tire), it works pretty well. There are much better thermal cameras in the $400-500 range if you need accuracy. FLiR makes some very good ones, I have a FLiR C2 at work I like a lot.

There are a few in the ~$200 range that plug into a smartphone, too.

Link:

sobiloff

Are folks getting better results with thermals than pyrometers at autox? I've heard people say that the short runs in autox don't get heat down into the cords, so measuring the top layer of rubber with thermals gives more actionable information, but wasn't sure if that was true or not.

sjfehr

Friend of mine and I tested pyrometer vs IR thermometer in grid one event, and found they agreed within about 1 degree of each other. There's always going to be some gradient through the rubber between ambient air and inner carcass, we're not doing hard science here; ballpark is good enough. Any way you measure it is going to give good feedback.

sjfehr

We had a local autocross yesterday; I started at 31psi all around and dropped further to 29psi, so low TPMS was alarming about having four flat tires! Wasn't until I got home and measured tread wear than I discovered these pressures are still likely too high and need to drop even lower. This is foreign territory for me, I'm not used to running pressures so low for autocross. The wear rate decreased a little and extrapolates out to about 39 runs how; I'm hoping I'll have enough tire left after our SCCA regional in two weeks to get one more event out of them after that. The balance of the car changed as I dropped pressures, and felt quite a bit looser than before, so I'm also debating whether or not to tighten the front swaybar a hole. Hmmm, choices choices!

And I'm still unsure about camber. Thermography was inconsistent- temperatures were pretty close across the tread. I'm seeing very little indication that more camber will provide more grip. Nearly every thermal image I took shows the inside corner hotter than the rear - except for one, taken immediately after stopping the car just off course in the video below so I could get the best data. And only on one tire: front right. Which makes sense it would be on the right as the last element was a 180 degree left-hand sweeper, but I didn't see this on the first two runs.

Is there a way to change the TMPS alarm setpoint with Durametric?

I took FTD, yay! Lost top pax by 3 hundredths of a second, though.



Got fresh tires in for Bristol, too! Which, sadly, I'm probably going to need.

28 runs, and down to 2.0/32 in the middle of the tire. The two main water channels start at 6.7/32 fresh and have worn down much faster than the outer shoulders, which start 4.0-5.0/32.

edfishjr

Data point for you: Two of us in Street-class Corvettes (505hp and 345hp) both came to the same conclusion about Yoko. 70 runs best performance. Got to 90 runs for locals. Pressures in the 30/28 range. Outside edges wore first.