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lawdogg149 asked:
Could you describe what occurred to the car that the media ran at road atlanta back in November 2014. It seems several magazines have quoted having the over heating issue but no one clarified if it was the trans or the engine oil. I know from my personal experience that my car did get pretty warm on a cold 40 degree day there a few weeks back. I and many people are concerned we will see issues come this summer without mods.
Tadge answered:
There are lots of interesting back stories behind recent media tests, but the question asks about Road Atlanta so for the purposes of this thread I will focus on our long lead media event last November. We spent a week there with journalists from around the world. We had pro drivers Tommy Milner, Randy Pobst, and Andy Pilgrim behind the wheel along with many other very capable drivers. They were permitted to run consecutive laps with minimal or no traffic, so essentially "qualifying laps". Over the course of the week we had 2 cars come into the pits with a hot warning messages. The first was due to the loss of an accessory drive belt. We had a pre-production tensioner on that car which failed, throwing the belt and we lost the water pump. We have had no issues with production tensioners. The second car was an automatic. I believe it was being driven by Randy on the hottest day there which was right around our design performance target of 86 degrees (more on that below). After multiple laps at speed he came in with a hot warning message. Although the car had been out on track all week, that was the first and only incident. In Corvette's 60 year history, we have never put automatics on track for media and never encouraged people interested in track usage to buy automatics. The new 8 speed automatic gives us a chance to put more automatic transmission customers on the track. Since there is some lack of clarity around the true capability of each of the transmissions, this question gives us the opportunity to publish some guidelines:
The Z06 Manual is designed to keep engine oil, coolant, transmission and differential fluids below the hot warning targets when driven by a professional on a 30C day (86F) on a "typical" racetrack for an indefinite period of time (effectively the time to burn through a full tank of fuel). Our team validates the durability of the Z06 cooling systems with a 24hr accumulated track test to simulate the most aggressive track-day usage by our customers.
We designate our track: the Milford Road Course, as the "typical" standard, but recognize that there are tracks around the world which are easier on a cooling system and some which are harder on a cooling system. Generally speaking, tighter tracks with lower average speed and higher sustained RPM, will drive higher fluid system temperatures.
Higher temperature ambient conditions affects all car's abilities to run sustained laps at ten-tenths.
The Z06 Automatic transmission put in "Drive" selects the lowest possible gear ratio for best acceleration, and because it has 8 closely-spaced ratios typically runs higher average RPM than the manual. This optimizes lap time performance, but also taxes the engine oil and coolant more for any given track. So the automatic has the capability to run faster laps than the manual, but thermal limitations are reached more quickly. Customers who are planning to run extended track-day sessions at 'professional' speeds, are advised to go with the manual transmission, or to paddle shift the automatic and select higher gears when conditions warrant it.
Any time the maximum recommended temperatures are reached in any condition, the DIC will give warnings at the appropriate time for coolant, oil, or transmission fluid. A cool-down lap or two will bring operating temperatures back to a reasonable level and aggressive track driving can be resumed.
Some may wonder why don't we design to higher temperatures, say 110 degrees, to accommodate southern tracks in the Summer. We have used the "pro driver at 86 degrees" criteria for generations of Corvettes and for the vast majority of customers, it has resulted in excellent performance for their usage. If we designed to higher temperature criteria, we would have to add a lot of cooling hardware which drives mass up and perhaps more importantly, you have to feed the system with more air which has a huge impact on appearance and aerodynamic drag. Like most aspects of car design, the challenge is in finding the best balance of conflicting requirements.
Good for me as a couple of HPDE events now and then are all mine will see. As long as no overheating on a hot day in traffic I should be good. TPW of 3/2 and an A8 so we'll see what happens.
I plan on getting the Auto for 1/4 mile times. Seems like to me in Vegas summer you road race guys better stay off the track. We temps well over 105*.
I know even the GTR's back in 09 were overheating in spring mountain after 20 min sessions. Of course after market oil coolers helped A lot later on. I think GM should sell after market parts for the extreme road race guys.
Glad we got that question in front of him. Did he clarify if it was trans or engine oil that over heated on Randy's car though.
I agree with 98% of tadge's response. But I have to say this. Maybe the standard of the 86 degree day was good for the past generations he referenced but for GM to stay on top they should be looking very hard at raising that to maybe 95 degree criteria. Better to have more than less. Also with cars producing more power and we drivers getting faster and faster we will be looking to a car we can flog on the weekends with no worries.
Also hasn't anyone heard of the global warming we are having. Sure the boston folks can tell us all about it this winter. LOL
Maybe offer a GM performance parts cooling package for us track rats. That would make the most since. Then they could escape the EPA and label it as off road use only.
Thanks also for all of you that came out and voted for my question. We still have the big question what will these cars do this summer. I will be tracking march 9 at rd atl hope to have more good news once I get done. So far no overheating for me. My fastest lap last time out was my last lap # 14.
I have a MT and drove the car for around 30 laps total off and on in about 1.5 hours in 60F. It was a technical course with lower speeds and lots of turns and brakes. I ran mostly in 2nd and 3rd gear. A few laps I ran 90% in 2nd gear. I never saw any heat warnings or experienced any degradation in performance of any kind. My left knee is still bruised from sustained G-force pushing against the door on tight right hand hairpins.
I am happy with his explanation and very happy with the car.
I have a MT and drove the car for around 30 laps total off and on in about 1.5 hours in 60F. It was a technical course with lower speeds and lots of turns and brakes. I ran mostly in 2nd and 3rd gear. A few laps I ran 90% in 2nd gear. I never saw any heat warnings or experienced any degradation in performance of any kind. My left knee is still bruised from sustained G-force pushing against the door on tight right hand hairpins.
I am happy with his explanation and very happy with the car.
Did you have the PDR? If so could you post a thread in the Zo6 section and show your screen shots of temps. Helps some of us try to understand what is occurring here. Also yea that dam door piece where the leather meets the trim is a B---ch. I had a bruise for days after my two days on tracks. I will be having a pad for it before my next event.
Thanks Tadge, your answers make me more comfortable with the M7 transmission I ordered for my Z07. Although in California, we too have many days where average temperatures will easily be above 86 degrees.
I think there would be a large group of us in the West/South who would pay for an optional high-temp track package (Z07+HiTemp) with upsized oil cooler, transmission cooler and larger/race grade radiator.
Thanks again for your answer!!!
Last edited by Along4theRide; 02-22-2015 at 08:14 PM.
Reason: typo
Hard to think that my C7 Z51 with manual transmission running at 150 C (300 F) temp shown in picture is a good design condition (was about 80 degree F day at track), plus AFM valve actuators failing with one day on track, plus rear brake pads worn out in one day, front tires to cords on one day. And as I was driving it harder near the end of the day, water temps really started climbing on track to add to the very, very high transmission temps which were in the red zone every session in the afternoon.
We will see how others fare this summer with their more powerful Z06's.
Did you have the PDR? If so could you post a thread in the Zo6 section and show your screen shots of temps. Helps some of us try to understand what is occurring here. Also yea that dam door piece where the leather meets the trim is a B---ch. I had a bruise for days after my two days on tracks. I will be having a pad for it before my next event.
Thanks Tadge! It's about compromise and building a car the way most of the owners will drive it. 90% of these cars will never see a track so do you spend the extra $ and change the design just for the 10%? Or build a car that gets you 90% of the way there and then for those who do want to race it on the track can alter/modify the car to handle the grueling track conditions.
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Excellent answer. Can't wait for his response on how to keep my s/o from leaving death grip finger prints in the upholstery or flailing her arms around when we're on the Dragon's Tail. Very distracting to say the least.
Excellent answer. Can't wait for his response on how to keep my s/o from leaving death grip finger prints in the upholstery or flailing her arms around when we're on the Dragon's Tail. Very distracting to say the least.
Don't take her is probably the only answer. Mine grabs the seat etc. too.
"Customers who are planning to run extended track-day sessions at 'professional' speeds, are advised to go with the manual transmission."
Good that he spoke about the issue. Although, I'm not sure this day and age 30C is high enough of a target temperature. Most tracks are in the South and for a large portion of the year are hotter than 30C.
I pick my A8 up at the museum on 3/6 and it is being purchased to be a track car.
It would had been really nice to know that the M7 was the recommended track choice. Maybe I missed it but everything I read from Chevy is that the A8 was the faster car. No one said just for one or two hot laps.
Don't bash me. I am still excited but worried I wil need to mod the car which will void the warranty to run in the 95degree heat this summer.
02-22-2015, 11:50 AM
[ANSWERED] Car overheating issues on track
Very distracting to say the least. 
