majormojo

Thanks for all the great info. Lots to think about and consider. For this season, I think I will continue with the RE-11 while I'm learning the car and then try the ZII next year. As pointed out, my mod options are very limited while staying in Street class. I really don't want to go back to *SP and the dedicated race tires, and the trailering, and etc, etc. I'm old and lazy and looking for a more "arrive and drive" experience for a least a couple years.

I'm learning that the H&R bars probably aren't what I want long-term, but they came with the car along with the OEM pieces, so that's what I have to play with for now. I'm looking to keep things simple this year while I learn the car. Will look at GT3 or maybe TPC front bar for next year to get some adjustability.

mopar bob, you mention "Go a little deeper and hard on the brakes get it turned and hard on the gas out of the turn." Sounds like the classic 911 approach and I suspect it's at least partly true for the 986/7 chassis as well. Time will tell as I practice more. Autox is hard to get good seat time... Last weekend I drove 4.5 hrs each way for 6 runs. Not very time-efficient, but at least I got to make the drive in a nice car.

douglap1, that's an intriguing idea to run rear-sized wheels on the front to get a square setup. I'll have to dig into the rules to see if that's legal. Rule book only says wheels "same width as standard", which is kind of vague, so it's possible there has been an SEB statement clarifying that. My instinct tells me if it were that simple, it would be a well-known tactic already.

The reading I've done so far has lead me to conclude that because of the +/- 1" diameter allowance in Street classes and the fact that the 987 could be ordered with 19x8.5 and 19x10 wheels, the OZ Alleggerita in 18x8.5 and 18x10 are legal in Street. So I was planning on those wheels with 255/35/18 and 275/35/18 tires for next year.

sjfehr

Are you running SCCA or PCA autocross? SCCA street class rules restrict the wheels you can use to OEM size (though as you noted, you can change diameter +/-1" from OEM this year for the first time) to run 18x8.5 & 18x10 wheels. HOWEVER, you can't really take advantage of that with current available tires, in that the best tires sizes you can get right now will also fit on the OEM 18" wheels. If you're buying track wheels anyhow, I'd get the 18x8.5/18x10. Mind the offset, though; not only do you need to be careful for SCCA legality purposes, the larger sizes can rub. I'm in the process of prepping my 2010 987.2S for national competition, and will be running 255/35-18 front & 275/35-18 rear on 8x18 & 9x18 OZ Alleggerita wheels.

Dunlop ZII is discontinued; the ZII star spec is coming out this fall. Will be interested to see how it drives.

majormojo

I'm running SCCA rules. I've joined the local PCA chapter, but they haven't been able to run autox for a couple years now (no local venue).

Is it your understanding that the 18x8.5 and 18x10 OZ's don't have legal offsets? Or do you have another reason for the 8 & 9 widths?

DOUGLAP1

You guys might want to look very carefully at those 275 tire specs. i believe the ZII 275 / 35 is a pretty large diameter that will not help your gearing for auto-x. These things are already geared a bit too tall for auto-x. The 285 / 30 works fine on a 10" wide wheel and results in better gearing. Caveat emptor...

mopar bob

Majormojo the guy that has been showing me drives a mid engine car also, a Lotus. Nice guy even if he kicks my butt every race, he wants a good SS class. With me we have a 3 car class with 4 drivers, one more would be good.
Off topic sorry That Lotus may have trouble at the nationals later this month with that 2010 GT3 that is also signed up

sjfehr

275/35-18 is a 3/8" drop from OEM, and pairs well with 255/35 in the front, which is a 1/8" drop; the circumference ratio between them is very close to OEM. 285/30-18, however, would be an almost 1" drop without any way to get similar drop in the front, which I was afraid would create ice mode/PSM shenanigans.

305/30-19 would probably be the best rear tire, as it's extremely close to OEM circumference and wide as all hell.

majormojo: the OZs I'm running are dead-on OEM offset. I just warn you to make sure to look at offset while you're shopping so you don't accidentally end up with a tire that rubs or isn't legal for SCCA street class. You can get spacers if you need, but they can get pricey. I'm running the 8x18 & 9x18" because I bought them about 4 years ago, before the +/-1" rule was created.

Audii-Dudii

The 18x8.5 ET53 and 18x10 ET40 OZ Alleggerita wheels have 2mm more offset than the equivalent Option XRR OEM wheels (ET55 and ET42, respectively) and as such are SCCA Street-class legal. On my '06 CS with an aggressive autocross alignment, they haven't rubbed anywhere with any tires I've tried on them.

(As it happens, my set is available for sale ... drop me a note if you're interested. I also have a set of 18x8.5 ET50 / 18x10 ET38 Champion RG-5 wheels available. They're also Street class legal, a bit lighter still, and IMO, much better looking, but YMMV.)

majormojo

Thanks again for the continued discussion and info. I did another autox event yesterday, ran pressures at ~37/39 F/R hot and didn't fuss with them much. Didn't log tire temp data. Instead I just focused on driving harder and figuring out how to work with PDK. I did OK, 1st in PAX in a field of 40 cars including a GT3RS also in SS class (beautiful, awesome machine). Weirdly, I started out fast in the AM and got slower during the day (brain fade?). I still feel like max grip will be at slightly higher pressures, maybe 42-44. I was seeing sustained 1.0+ G in the sweepers and hairpins and I think I can still brake later/harder than I am (7 yrs autox in a non-ABS car, need to re-train brain).

Audii-Dudii, I had been planning for new wheels next year, but will send PM about the Champions. I agree about the looks as well.

I've tried PDK in auto and manual modes. I think what's working best is to keep it in auto and manually select downshifts on occasion. Had a weird thing happen a couple times where it seemed to bog on the 1-2 upshift instead of the smooth linear power delivery that PDK usually delivers. Running with Sport Chrono in "sport plus" and PSM off, so I wouldn't think that it would be backing off due to PSM interference, but it certainly felt like throttle input was being modulated/restricted immediately after the shift. Felt kinda like a missed shift, had me wondering if it had gone 1-3 or something (nope). Surface was quite dirty and so modulating wheelspin was an issue generally.

sjfehr

I did my first autocross in my 2010 Boxster S yesterday, too; played with launch control and PSM and generally overdrove all the corners and felt I left a lot of time on course. I was logging ~1.15g peak sustained in the corners, which is a little higher than I saw in my 986S. I dropped the pressure in my ZIIs to 35/35 based on the 37/37 I found was optimal on my 986S, but I think I'll bump that to 36/36 next event. Definitely tough getting used to the extra power! I left it in D under the assumption the computer is smart enough to know what the lowest possible gear should be, but I noticed the car failing to downshift out of some corners where it sure seemed like I'd have been better off in 1st; will have to test manually downshifting on corner exit and see if that fixes it.

Has anyone done testing with launch control? Is it worth it? There's some tolerance/error in my data logging, but I was seeing virtually identical speeds at the 2nd gate whether I launched from 6800rpm or idle. I don't want to destroy my tires if the time gain is negligible.

majormojo

sjfehr, what are you using for data logging? I'm using CMS laptimer on an iPhone w/ Dual ext GPS @ 5Hz; as a previous MaxQData user, I'm used to how it does analysis. I've tried launch control just to try it, but have not done measured tests yet. Our local courses don't often lend themselves to drag starts like that, but I will test when I get the chance.

Tom Tweed

Your first statement about braking sounds like you were staying completely out of the ABS range, but if you did trigger ABS at some point, then PSM could have been responsible for the throttle modulation you felt, as it will re-initiate itself even if you have it switched off when ABS is triggered. Under Sport+, it takes BOTH front wheels sliding to do that, though, and it sounds like you were being careful about braking--did you ever feel the ABS pulse? With a dirty surface, the upshift from 1-2 could have caused some wheel spin that the PSM cut off throttle to fix, if it had indeed turned itself back on.

Sounds like you did very well even without having everything dialed in if you took top PAX. Good job!

TT

XPC5

We have had similar 1-2 shift behavior for several events in the '09 S. It was especially bad in manual mode, when using the kick down switch, or lever/paddle. We spent a test&tune event launching probably 20 times to figure out the pattern, no luck. Finally brought the car to the dealer, to get the latest update for the pdk controller, which also requires a recalibration, and also a clutch fluid change. At the next event a couple of weeks ago I think it's fixed now.

As for launch control, have used it in 2 pro solo's now. On a grippy surface it works really well. If the surface is bad, there is too much wheelspin and it starts chopping throttle, making for a lurch or two. We did find there is also a mini-launch control, if you do not engage the kick down switch, you get about 4k rpm to launch with, which can help traction.

majormojo

XPC5, thanks for sharing your experience. I will ask about the PDK upgrade, as I have a couple other issues the dealer needs to address w/ TPM and bogus brake pad sensor warnings. The car was just CPO and this stuff really should be working... but that's another thread.

When I experienced the shifting issue was immediately after a start w/o launch control, but with the throttle pinned at the time of the shift. Usually that shift is so fast and smooth (because PDK, duh!) that the bogging was really noticeable. Oddly, the bogging doesn't really show in my data logs, but I think I had a glitch in my GPS that day and was only getting 1Hz updates so the resolution can't show the drop in longitudinal G.

That particular course started with a 90 deg right hander, then a longish straight, so didn't seem suitable for LC. And of course, it's difficult to test LC on the street while remaining a responsible adult.

Tom, I was never into ABS that day. As I mentioned above, the bogging happened right after start and before the first turn so no braking at all on the run at that point. I don't really know yet what PSM intervention feels like on this car, but it definitely felt like a computer was dialing back the throttle even though I had the pedal to the floor (kickdown sw activated).

sjfehr

That's how PSM intervention felt on my 986S; you'd have your foot floored.... and nothing... nothing... nothing... then FINALLY, power. I haven't felt similar reaction yet in sport+ on my 2010, aside from PDK not necessarily always being in the most aggressive gear. I could feel it grabbing my back end in places during runs I left it turned on, but didn't notice any throttle retarding; it could be retarding throttle or modulating brake/throttle response (both things I my 986S PSM did), yet doing it subtly enough that we'd never notice outside of a full data acquisition suite.

If it's just doing good stuff in Sport+ (magic 1-wheel braking) without any of the bad (retarding throttle)... might it actually be faster to run with PSM on than off? Anyone did testing on this yet? I don't want to reinvent the wheel.

mopar bob

I picked up 1.5 seconds when I turned off PSM on my 07