kdochert

Just did my third track session in my 2016 Z06/Z07 A8, this time it was just an afternoon consisting of 3 x 30 min sessions and ambient was 85 DegF.

Temperatures

To recap:

• First track event was at 95 - 100 DegF ambient and the car overheated (full limp mode) 10 minutes into each session.
• I then installed Dewitts 70mm HP radiator, reduced coolant ratio and bled my intercooler system.
• Second track event was at 70 DegF ambient, the car didn't overheat during the 20 minute sessions but coolant went to 260 DegF and Oil to 280 DegF.

In the third event @85 DegF I was pleasantly surprised that I could run for ~20 minutes before my oil temp was up to 280 - 290 and had to to to cooldown lap('s) to avoid limp mode. I'm ok with this for the time being and not ready to commit to the significant upgrades required to resolve all cooling issues.

Don't have an issue with trans temp yet, though as I'm increasing my pace a little with each session trans temps are climbing a little, 215 DegF is the highest yet.

Brakes

My front pads are now gone, ordered new pads ($750) but need to consider swapping out to Girodisc iron rotors if I'm going to continue tracking, will look for sales events? (are these things ever on sale?) Started getting more pedal travel in third event, brake fluid needs changing again.

Track Mode

Moved up to Sport 2 mode in PTM settings, this seems to be the right level of driver control invasion for where I'm at, but will be interested in trying more aggressive settings :-).

Questions:

1. Tire pressure - where should my tire pressures be once the tires are upto temp on the track? I have Conti Extreme Contact Sports on in stock sizes.
2. Brake Fluid - I was planning on just getting dealer to flush and bleed with AC Delco Dot 4 fluid, is this stuff good enough or should I bring some better fluid in for them to use?
3. One challenge I'm having is keeping the car in a straight line under max braking, the car becomes very darty and I have to micro adjust steering through the braking zone to keep it straight. I know these cars are prone to going a bit light on the rear end under braking, so I'm presuming this is stability control kicking in? Am I simply over braking and causing the system to correct too much? Is this a common challenge?

On a side note, I emptied my tank after 2 x 30 minute sessions!

Thanks,

Kevin

Bill Dearborn

Bill

kdochert

Thanks Bill.

Yeah my brake fluid now has a tinge of brown color, think the combination of the dealer putting in DOT 3 last time (despite me asking for DOT 4) and my pads getting thin and thus transferring more heat has overheated the fluid, some of the pedal travel is sponginess for sure, indicating some air in the system. Good brake fluid is cheap in the overall scheme of things so I'll probably just buy some good stuff and flush / bleed the brakes myself tbh. As for the weaving under braking, stability control was probably the wrong explanation, like you said it's turned off in Sport 2 and tbh the sensation has been identical in all modes on the track so far, I'm guessing it's my driver input being poor including not braking in a straight line and relying on ABS too much.

Looking at the PDR data it looks like my tire pressures are in the right range once warmed up on track, I can maybe edge down one or two more psi.

Throttle control is still one of my weaknesses, so having that nanny in Sport 2 is needed right now, I need to learn to trust the car more when getting on the gas exiting corners.

Supercharger boost data/inlet manifold pressure is a curious one that I'm not fully understanding yet, I'l probably post separately on that topic as I have questions, or if you have links to any good threads explaining this one I can probably figure out.

The biggest question I still need to answer myself is how many track days to do each year, I either go all in, swap out the brakes and do something with the cooling, or I limit it to the two half day sessions with have with the local Vette club and leave the car as is? Only I can answer this one!

Torque Obsessed

As another 2016 Z06 A8 owner, I'll throw in a few tidbits in case it's helpful. (Bill may need to correct me if I get the details wrong.)

• Did you use a Cooler Bleeder? If not, you're likely still running with air pockets in the S/C coolant. I wouldn't track a Z06 without using one.
• Next steps for cooling upgrades could be:
  • The LG kit, which everyone seems happy with after they get past the price. This moves the intercooler to the sides, making the radiator's job easier to keep coolant and oil temps down. I did the 70mm DeWitts radiator first and then this.
  • Different S/C lid and cooling bricks, or different S/C entirely. I picked up a used 2300 mostly for this purpose (not installed yet), but the 2650 has even more cooling capacity. This cools the intake air better after it leaves the supercharger, and eliminates the OEM cooling brick shortcomings which can cause detonation on the back cylinders.
• My car's braking is amazingly steady, for example coming out of the esses at Road Atlanta I couldn't believe how hard I could stomp the pedal and just lock the car down. At the time I was on well worn Cup 2's, which really dampen steering feel and reduce the car's agility for direction changes. (My point is, maybe consider different tires if this remains a problem.) I'll be on PSSs (front) and Contis (rear) next time, so it'll be interesting to see if the car behaves differently.
• I also haven't seen high transmission temps, but I'm not running the car hard enough yet. My main problem, being an A8, is breaking loose on upshifts. The short middle section at AMP does it every time - the transmission shifts, the rears break free, the electronics shut it all down, things get settled, and then the power comes back. I really need to teach myself to shift with the paddles, but it just feels so strange to do. (I drove manuals for decades, and to me, an auto should just be an auto.)
• I don't remember the details, but some members have wrapped a section of the exhaust (or other components?) toward the rear of the car to prevent fires. This is still on my to-do list.
• There's a front undertray piece that I think can be removed for track sessions to keep the power steering cool? I just leave it off year round. Others have built ducting to send air to it. (If this is inaccurate, I'm sorry, it's from memory.)

Bill Dearborn

If you mix tires, ensure the best handling tire is on the rear or you can have a severe oversteer issue.

Here is the TSB for the power steering cooling duct.




Bill

kdochert

Kevin

Brad Larsen

You are headed down the right roads and there is excellent advice above. I also track a 2016 C7Z A8. I'm not willing to cut the front bumpers to look like crap (LG solution). I have replaced the radiator, removed the factory reservoir in lieu of a G-Speed high-mount reservoir that reverses the coolant flow for the SC circuit. That has completely eliminated any issues with the SC coolant pump shutting off due to lack of head pressure. I have a 160-degree thermostat as well. With these changes, my coolant temps at 100-deg ambient are still okay. The bigger issue for me was oil temps. With the factory oil cooler being too small and placed between the catalytic converter and engine, keeping oil temps down wasn't possible at max pace for very many laps. I had Cordes replace it with a Setrab cooler mounted in the left brake duct channel. Now my oil temp isn't an issue. Finally, I did wrap the exhaust near and around the transmission to reduce radiant heat as much as possible. I haven't had issues, but also don't want any.

On brakes, I went to GiroDisc and kept the factory CCB calipers. The only meaningful upgrade was AP, and I didn't want to spring for them. I run Ferodo pads, but there are several good options.

Finally, I struggled with alignment on track due to a lack of negative camber capability and the mushy stock suspension (despite it being an FE7/Z07 car). So I changed the camber bushings to Borg delrin; installed LG bars and an AMT camber kit. Now I finally have the alignment I need and the car is super stable in all situations.

kdochert

Cheers,

Kevin