First track day with the '19 Z06 / Z07 / A8. Only mods are Halltech intake, Soler TB and Corsa X pipe. Running on 19" Forgeline and R888R's. The day was sunny around 75 deg at CTMP in Toronto. I have a fair bit of experience at the track and spent the first 3 sessions running in Sport mode learning the car. 20 min sessions with 40 min breaks.

When I switched to Track Sport 1 in the afternoon the car began to 'bog' or hesitate on corner exit. Misfire? Fuel starvation? After hard braking to set corner speed I tend to feather the throttle, feeding throttle in on corner exit, try to work on the edge of adhesion. G meter would touch 1.2 in some corners. RPM generally 4500 to 5000 on corner exit. Problem was most noticeable in the turn 8 /9 / 10 complex, basically an S, before the front straight. These turns are 70 to 90mph before WOT.

I let trans do what it likes and it runs the track in 4th 5th and get to 6th at end of straight into turn 8/9/10...around 150 mph before brake to 90ish. Not using the paddles. The A8 for me works very well in auto and I think does a better job than I could at this point with the car.

I run 94 fuel. Tried the 98 at the track when I burned through a full tank of 94. Same experience with both fuels. BTW I didn't feel any difference in performance using the 98...lol wasn't worth the $304 to fill the tank

Next step is to grab an OBD scanner to check for codes. No CEL's or dash warnings during the day.

Any suggestions or similar experiences?

 

that's your traction control kicking in and pulling timing on the engine. You either have to adjust your line or you are pushing the car too much for what the tires can handle.

 

Very well could be what was happening.

From the 2019 OM Description of PTM and how to use:
To experience the performance benefit of this system, after entering a curve and at the point where normal acceleration occurs, fully push the accelerator pedal. The PTM system will modify the level of engine power for a smooth and consistent corner exit.

OP could you hear the exhaust blatting as you powered off the corners? When Performance Traction Management is working the system will limit power to the rear wheels to the grip level available. It will also route power to the rear tire that has the most grip through the eLSD . When you are in Track Mode PTM is on in all the sub modes including RACE. It takes some cajones to start using it because it is counter intuitive to what you have learned over the years. There are a few turns at VIR where I can get it to cut in as I power off the turn. Turn 1 it starts activating before I get to wide open and the back end has stepped out if I tried to add any more throttle. Turn 12 Oak Tree I can go wide open with ease with the exhaust blatting away and the rear tires slipping, gripping causing a vibration in the car as I power off the turn.

If it seems like it is activating sooner than you think it should that may mean you need tires with more grip.

Make sure you read and memorize the section of the OM that tells you about the various track modes and what they do.

Bill

 

Thank you so much! The explanations, especially with the 'blat' sound lead me to believe the TC is kicking in and glad to hear it's not something mechanically wrong. I hear the 888's hanging on for dear life in these corners lol. I'm running 325's on the rear so will try the 345's next set since Toyo doesn't make a 335 and a switch to slicks isn't possible for me.

Again, still learning the car so pretty glad the nannies were there to save me from myself lol. Have to say I absolutely love the Z! Last track car was a well prepped Factory Five Cobra on Hoosiers...less power but zero nannies. Still fun but now my old bald head doesn't get a sunburn

Thanks all and stay safe

 

If you switch to 345s in the rear, be sure to balance them with a 295 or 305 in the front.

What PTM mode where you running in? Dry or Sport 1 or ? There's also "Race" which turns things off. Love the Factory Five Cobra btw

 

Running with a 295 in front now so should be good going to 245. I was running in Track Dry on Monday. I'll step up one mode after a couple of sessions next outing.

This was the FFR I built. 302 with only about 370hp and a 5 speed but 2500lbs with my butt in the car. Pretty light and nimble. Lol and the only power was the steering. Miss the quick ratio rack but the Z is responsive and smooth for a heavier car. Man I wish the Cobra had the Z07 brakes tho...damn they haul the car down quick. Pretty good modulation too and zero fade.

 

Cobra

I recommend you run Sport 1. You'll still feel it and it can reel you back in (within the laws of physics of course). Dry is obnoxiously intrusive as you found. I think it's great for a new driver but not so much for a person with experience.

 

I always tell Corvette novices to run the Track setting in Wet Mode for a few laps to become familiar with how PTM works. It is very aggressive in Wet Mode especially on a dry track but it activates at almost every turn exit and you can get a sense of how it sounds and feels. Once you know the beast then switch to Sport 1 or Sport 2. The difference between Sport 1 and Sport 2 is there is no stability control while there is still some throttle dampening and of course PTM. Race mode only has PTM with no throttle dampening. Throttle dampening just slows how fast the throttle opens or closes so softens some of the hard engine torque reaction you will get in Race mode.

Two years ago I put my car into the Turn 10 tire wall at VIR. I was at the point I wanted to apply power, maybe had too much steering angle and right at the point where the track curved downward and to the left. The car was in Race Mode, in 4th gear, on Pirelli Slicks, speed was right about 90 mph and when I hit the throttle the rear tires spun and I spun off the track. I had been through that turn hundreds of times over the previous 5 seasons with PDR videos of the last 3 seasons and I hit the throttle a few tenths of a second sooner than I had before, right at the wrong time. If I had been in Sport 2 the engine wouldn't have reacted quite so fast and maybe I wouldn't have spun.

Bill

 

Thanks Bill. I'll move to Sport 1 next outing next day out and see how that works out. The TC would kick in most often out of Turn 10 onto the front straight, especially when getting a wave to pass others. Have cut the corner exit a little tighter to get by them on the right instead of being able to use the natural race line.

One of the first things I did to the car was add a Soler TB to smooth out the throttle response instead of the on / off of the stock one. Made a world of difference. Gives me a lot more confidence in throttle control. There's a wall on both sides of the front straight and no somewhat forgiving tires lol