Datawiz

Bill, when I run in full auto, that 3rd gear shift can and does happen, but even in full auto, the downshift still works.

Foosh

Not according to the pros at Spring Mt. who ran lap tests, found them equal for the first couple of laps and not significantly better on the skid pad either per GM. A 0.1g difference is not statistically significant. Driver skill way overcomes that, and a mediocre driver is not getting close to the g-limit.

The PS4S is only significantly better in long track sessions on a road course, once the tires get really hot.

Bill Baird

True, but then I might as well keep the thing in Manual mode, rather than be caught by surprise by the car making its choice.

sanddigger

I have run several autocross events in the past year since purchasing my 2022 Z51 and I have had the best times running in full track mode with traction control off completely. This past weekend I ended up third in my class getting edged out by a GT4 and GT3, I had just switched over to the Nankang CR1 tires and still working on getting the tire pressure figured out.

bhvrdr

Spring Mountain only uses ps4s (summers). I asked them if they used all seasons because I had heard that rumor on this board and they do not. I've been there multiple times multiple levels.


Autocross wins are often decided by hundredths of seconds...not tenths. A better tire is everything.

Datawiz

Again, for me it's course specific. If the gearing works for the course in full auto, then that's what I do. I still very much run manual mode too, but I find the auto mode is much more intelligent than I am. If I bog on 3rd gear on a given course, I typically switch to manual mode. For ProSolos, I depend on auto mode, as I need to launch control, and manual shifting in launch control is not as effective.

MattMD

I'd turn everything off. At Ron Fellows we did autocross in one of the PTM modes that still keeps ESC on. A couple times I triggered ESC which slows the car down. If it's just a big parking lot course where you're only gonna hit cones if you spin I feel like ESC is too conservative. We only did manual mode but aside from the initial 1-2 shift you do the whole thing in 2nd gear. I don't think I'd want to be on auto, rather be in control than unexpectedly be in 1st or 3rd.

Datawiz

I ran the Spring Mountain autox course in manual mode too. That course is WAY too tight for D. That course is NOT representative of a normal autocross course.

proeagles

I would submit that once auto shifted to 2, it would stay in second because you are using the car in a vigorous mode and it won't shift unless it needs to. Ron Fellows runs everything in manual mode last I checked just for the hell of it. Makes you more engaged with car for all the people that just need to shift something. Once again I can't say enough good about this car and the DCT. When it's compared favorably to what is arguably the best on the planet from Porsche, that says a lot about how good the system is.

Foosh

I've been to Spring Mt 4 times for owner's courses, as well as level 1 and level 2 from C6 to C8. Yes, obviously, they only use summer tires for the school cars for rather obvious reasons. They are on the track for more than 1-2 laps.

They also do a lot of testing for clients and sponsors including Michelin and GM. They tested the OEM UHP all season, and the summer tire, and that's the basis for what they told me about the two, in particular, that the AS tire produced almost equal lap times to the summer tire for the first couple of laps until tire heat comes into play.

Autocross runs are far shorter than any single road course lap, and unless you're running back-to-back-to-back runs, heat doesn't come into play nearly as much as on a long road course.

Think what you want to think, but the available data say they should be very comparable in autocross. The PS4S really doesn't come up to full grip until it gets very hot, just like racing slicks. That's why you see a lot of spins in racing coming out of the pits on new ("cold") tires.

That's certainly not true of the average AS tire, and it's a testament to how good, and how close, Michelin's UHP AS4 has gotten to summer tire performance. GM would not have put it on C8 if that were not the case, and it's the first time they've used an all season tire on Corvettes in many generations for that reason.

MattMD

Haha had a feeling that might be the case. Only other experience is from my older 6MT BMW on some parking lot courses, I had to rev and shift the **** out of it to get any power, C8 has a nice power curve for maintaining gears

jgorss

I'm getting ready to order new number decals, I used magnetic ones on my Miata. This is probably a dumb questions but will a magnetic decal stick to a C8 door?

sanddigger

Yep that is a dumb question........................static cling is the way to go. Stop by your local sign shop and see if they have the commercial grade static cling then spray a little soapy water on the cling and stick your numbers on the cling. Works great even if the car has ceramic coating.

dohabandit

Yeah, I was going to suggest the same. (I got first place in SM AutoCross, haha).
In Track mode with PTM set to Race 2 you have the nannies disengaged so you can break the rear end loose and get around some tighter corners.

SMOKN C8

100% this.

Poppa Wheelie

Some great advice in this thread! I am still experimenting but have been my fastest in track mode with all the nannies off and trans in auto. I have ran manual on a couple of runs, but for me there is already a lot going on and it took away from where my focus should be. For the last 2 years i have autocrossed a tesla model 3 performance. Nothing to think about there, just pin it out of every corner. The C8 is way more fun!