thusly

Just spent five days running Sebring and COTA with an early production 2015 Z06 with Z07 package. Before running on the track, the car had 1,000 easy break-in miles and strictly adhered to the rpm limits.

We ran 3 days at Sebring - generally cool ambient temperatures - 55-70 degrees, and ran pretty hard (fastest time was 2.20). Total of 450 track only miles. Didn't experience any power down issues during those days. Ran the Track/Race settings for the entire time. Car worked flawlessly.

Later in the week, just finished 2 days at COTA - variably ambient temperatures - 55 +/- degrees for most of the time, and then got up to 65-70 for a portion of the second day. Ran both Track/Race setting combo, as well as Track/all systems off. Car was pushed pretty hard on the Track/all systems off runs. That said, on both the instructor's fastest laps, as well as some other (but not all) sessions, car powered down. According to the summary Cosworth Toolbox readout, oil temps hit a max 280 degrees; while oil temps were rising, water temps rose as well, and engine power was greatly reduced. These hot oil temps came after 2.75 laps (the out lap, and two hot laps). Pretty disappointing..... There were other Z06 owners at the same event who didn't have the same overheating/oil temperature issues. I also don't think they ran with all (traction, stability, etc.) systems off. Ran a total of 200 +/- track miles at COTA.

AIM data also attached. Instructor was driving and where we were marking the start/finish (just after T20) with an AIM Solo (see attached data sheets), best lap was a 2.24.7. At the official COTA start finish, the same lap was 2.25+. Front tires were just about toast when these laps were done. New rubber would certainly have been faster. Car was set up with more aggressive camber than stock.

Video from PDR is here - - - - - -
https://www.youtube.com/watch?v=Mo5F...ature=youtu.be

Pictures from the Cosworth Toolbox, which had been showing lap by lap data earlier in the day and the day before, but for whatever reason, didn’t when instructor turned it on. Pay particular attention to the max. oil and water temperatures, as the car powered down just after the 2 hot laps on the video.

For those track junkies that like data, I attached some charts from my AIM Solo. Based on my limited knowledge of AIM data, the attachments show:

- A chart of minimum and maximum speeds based on various lap times for the overall track: I included the instructor's 2.24, 2.25 and 2.26, as well as my best times at 2.31 and 2.32.
- A map with GPS speed overlays at various segments of the track. I believe the graph shows entry speeds. This graph shows maximum speed attained and minimum speed through a corner or segment. The data is for the flyer lap of 2.24.685.
- A graph showing differences in GPS speed for the various corners. The Red color is for the 2.24.685, the green is for the 2.25.085 lap, the purple depicts the 2.26.625 lap and the blue depicts my best at 2.31.816.

I had heard that there might be an update/recall for revising the cooling on early model Z06s. Has any one else had the problem/heard of the update/recall?

Otherwise, car is a lot of fun - ceramic brakes kept working despite some hard braking, particularly at COTA, tire wear was one set at Sebring, and another set at COTA. Need to replace the front brake pads after the 5 days as they are starting to crumble. I just wish the car didn't poop out so quickly at COTA and on the instructor’s fast laps....... or at all!

spz

that p1 is insane!!!!!!

Rob Willis

Whomever is driving in the video (you or instructor) seem to be very smooth!

JerriVette

You make mention of engine power Greatly reduced..

I'm curious what greatly reduced power output actually was....

Did the vehicle safeguard itself to what level? Not trying to be an @sshole......just wondering what hp drop we are discussing...

Thanks in advance...

Tnacdrmr

Nice vid. You can definitely see a reduction in top speed. Saw 148 on the out lap and only 140 with a good exit on the last, going off the vid.

Seadawg

I know you are talking about power issues, but do also mention the ceramic brakes crumbling.

Do you still like the ceramic brakes?? Every HDPE driver that I have asked does. They say they would not buy them outright and install on the vette, but they like them (this is ZR1 drivers, and also Z07 optioned Z06 drivers that I have personally met)

LFZ

I see this is going to be a pretty common issue with this car unfortunately.

Cyclone09Z06

Very nice, I believe that true track rats are going to have to add cooling, I am curious as to why the power loss with 280 oil temp?,..as most of us have been at 284 plus without issue. I was hoping to be able to wait until April before adding oil cooling as Bob with Xplosive is testing a nice setup on a ZR1.

Thanks for the write up, this is very helpful.

QUIKAG

Good info and as I already mentioned, 2:24-2:26 laptimes are SOLID for a stock Z06 at COTA. The car is being driven well and hard.

An 8mph drop-off of end of straight speeds is substantial. The programming does seem to be very conservative. I run similar coolant/oil temps at COTA with my '10 ZR1 in similar ambient temps and don't have nearly the drop-off. I'll see maybe a 3-4mph variance between beginning of session and end of session back straight speeds at COTA. I'm also hitting up to 162mph on the back straight, so that aero really slows down the Z06 compared to my stock (basically no aero) ZR1. It is making up speed elsewhere though as those lap times are strong.

BOBSZ06

"There were other Z06 owners at the same event who didn't have the same overheating/oil temperature issues. I also don't think they ran with all (traction, stability, etc.) systems off. Ran a total of 200 +/- track miles at COTA."


Outstanding!!

RC000E

Thanks for the in depth post OP...


Can you post over at the official track times thread please...a copy and paste of your post here over there would be great. I can then add it all to the times list. Thanks!!!!



https://www.corvetteforum.com/forums...post1588864194

FLATOUTVIPER

God I love driving that track. Watching your vid I can't wait to get my Viper back out there, so much fun! Excellent driving and very solid times, I can tell you're not new at this

As for the heat concern my biggest worry would be that it's still cold down here in Texas so I can't imagine what it's going to be like once we are in the 90's and triple digits.

BTW Z06 guys, if you bought one of these cars and don't take it on track you are missing so much of what your car is all about (That goes for Porsche, Viper, Vette, and any other track oriented car). So much fun.

sam90lx

Just stop Tadge. But please tell us the Ring times?

2K3Z06

wonder if the tires were getting hot??? and a little greasy.... that could be part of it.

amgman

Just watched the first two laps of that vid. I can believe the drop off in top speed on the back straight. Mine dipped into mid to high 140s, but also hit low 150s later in the session. I attributed the lower speeds to my exit of the turn. And yes, I hadnt been on a track in over ten years, new car, i ran with all the nannies

QUIKAG

Yep, if you drive a new C7 Z06 at 60% potential, you won't likely experience any overheating problems.

lawdogg149

To the OP:

I would be interest to see if you or the driver mistakenly did not use the Performance traction management. If you were in any of the modes they show up on the PDR video listed just above the rpm on the bottom of the screen. Or did you just turn everything off with just a single push of the traction control button. Since those are indeed fast laps would be interesting to see how much more faster they could of been in either sport 2 or race mode in performance traction management.

Thanks for clarifying.

I hope to see you out at Road Atlanta with chin. I will indeed be there.

MustOBeenYellow2015Z

Car was tight (understeer) in YouTube video. There is nothing wrong with your car!

With a tight car you will slow up because you will have to slow down more for car to turn & you will also have to wait for car to turn to get back on throttle.

Your front tires will give out (wear) before the rears

It will also raise the Oil temperature

On your next track day turn all the traction control systems off, go out & run hard like you did in YouTube video & try not to oversteer the car under throttle, come in & have your buddy take tire temperatures as soon as you come into pits & I'll bet you that the fronts will be hotter than the rears...

JMB

VERY disappointing......as you can see by the coolant timing table below at 230 degrees the ECM will pull 5 degrees of timing at WOT so instead of running 23-24 degrees of total timing you are only running 18-19 total timing which will destroy HP

WA 2 FST

IMHO, its good that timing gets pulled at these temps... so here is my issue. Design a cooling system for your "track car" that will keep it at/below 200^F. GM has the R&D budget to do it... so just do it.

Don't leave it up to the consumer to go re-engineer the system to make it up to task. Or, just make it clear to the consumer/racer, that "when ambient temps are 50^F, you'll get 3 good laps in", and "on race days that are 90^F, you'll get 1 good lap in."

This car has the capability of so much more than GM is allowing. And for all those that think the A8 is going to solve an engine cooling issue... phhhhtt.