sevoz78

After reading multiple posts regarding the overheating issue with Z06 cars on the track I would like to conduct a poll from those owners who have driven their car at the track:

1) Manual (M7) or Auto (A8) transmission
2) What model year is your car? 2015 or 2016 (include month of build if possible)
3) Has your car overheated at the track? If so, what was ambient temperature when it happened?

The reason I am asking these questions is because I am trying to find a common denominator if possible as to why this is happening. I know it is a real problem, but given that they have built almost 10,000 of these cars or more I would like to know how common it really is.

I own a 2008 Z06 which I track and am trying to decide if I should get a C7 Z51 vs. Grand Sport vs Z06 since I will be tracking the new car as well. After reading the overheating posts, I am thinking that most of the issues are with 2015 models with Auto transmissions and hot days. I am planning to get a M7 Z06 and track it in spring or fall and hoping that it won't be an issue for me.

Please don't reply unless you actually track your car. I am not interested in anecdotal stories about what you have heard or seen at your last track days. I drove at NCM and Barber in the last 2 months and it seems that the handful of C7 Z06's that were running had no issues.

ElCid79

Get m7 track it. If you have issues get the secondary radiator from GM.

Snorman

I'm not going to reply except to say search my posts. I'm pretty sure I've got more time on-track in an A8 Z06 than anybody here.
S.

Theo Harris

I track my Z all the time, never had a problem with the engine or the transmission, the Z07 is a must have for the track and one of only 2 models Z07 and C7R) with hand built engines in Kentucky

Bill Dearborn

I have done 6 track days so far with my 15 Z07 that was built in June 15. I have the GMPP Secondary Radiator installed and coolant temps have maxed in the 212 range and the oil temp in the 255 range. That is with an ambient temp in the low to mid 70s. So far no overheating issues. I really haven't had a hot day to run in so it is hard to say what it will be like with temps in the mid to upper 80s. Maybe all that means is 10 to 15 degrees gets added to the numbers I have seen. That would put coolant in the 222 to 232 range and oil temp in the 265 to 270 range. If it comes out to that then I will be happy since those numbers aren't bad. My C6Z would run somewhere around 220 coolant under those conditions with the oil temp pretty much staying right at 258 to 260.

Bill

Dabigsnake

What you seek is this:
My documented experience shows that All A8s driven fast (9/10) by a experienced, front of the pack, driver WILL overheat in most all ambient temps of 75 up. Some guys just will not admit that they are not a great/fast driver, and continue to say "mine never overheats" and yours may never overheat. I have yet to see a well documented total fix. Yes, there is help with aftermarket "I'm smarter than GM engineers" companies out there, and water wetter and 90% water, etc. but? Fact is, even if you never get to the DIC warning, you will get reduced power, and that just sux. Sure, you can do a tune and get past the reduced power part, but now you are on your own without warranty. Bottom line, it's just fine for 98% of the owners and it's easy to wax. Lol

sevoz78

Thanks to those who have replied with actual information so far. So Theo, do you think that the cars with hand built engines are less or not prone to overheating issues than those who aren't? And have you done any modifications to it so far?

For those who have added the GMPP secondary radiator, did you have the dealer do it? And did they give you any hassle regarding affecting the warranty?

Babaron

Very early build Z06/07 M7, no mods; track prep per manual. No overheating, but as mentioned above, I only drive mine about 7/10ths. Neither the skill nor the ***** to go higher...yet.

But, if you digest all the posts over the past 18 months, you may find, as I did, 2 conclusions:

1.) M7 better for road courses as far as heat dissipation.
2.) Z06's come in 2 varieties from the factory: Those that have zero heat issues on the track and those that have constant heat issues on the track.

There is a Nobel Prize in Vettes waiting for the one who figures out what the difference is.

Poor-sha

Search my posts as well as I'm pretty sure I have more track time in this car than anyone else on the forum although mine in an M7. I've also posted a lot of data including full session videos, PDR data, and Aim Solo data.

Bottom line is that after 6500 track miles and 30+ days mine has never overheated. That includes running in temps in the upper 90s. The first 5000 track miles/25 days were bone stock cooling but I added the GMPP secondary radiator over the Winter as some added headroom.

My car is not a Z07. A secondary issue is whether the Z07 package really is the best package for a mainly track car and that's it's own debate. What I can say is that brake cooling on this car is terrible and a number of folks that run the CCBs get them outside of their temp range and they start to oxidize the rotors. That gets expensive quick and I run the AP Racing setup instead.

Also, the FE6 (non-Z07) suspension is plenty capable although a bit soft on track. If you want to improve it then buy the DSC Sport shock controller and the Tractiv DDA shocks. You can buy the extra aero bits from a number of vendors.

I'm not aware of any correlation between overheating and whether the motor was hand built or not.

sevoz78

Poor-sha,
I was rather hesitant to get a Z06 until I read your detailed post with all of your track experience which led me to believe that as long as you get a manual transmission car and avoid hot hot days you are probably OK.

I am not a front of the pack driver and seldom push the car beyond 7-8/10's. I live in the South and have done track days in the summer before but have no problems just sticking to spring and fall events. Given all the current deals on the Z06 I am thinking that may be the way to go.

sevoz78

Babaron,

I like your comment: "Z06's come in 2 varieties from the factory: Those that have zero heat issues on the track and those that have constant heat issues on the track.

There is a Nobel Prize in Vettes waiting for the one who figures out what the difference is."

Perhaps there is some dude on the assembly line who keeps falling asleep and forgets to insert or tighten the magical cooling bolt onto the car ;-)

peterjank

I have a 2015 Z06 with automatic transmission which was built in March 2015. As documented in a prior post, I overheated my car after less than 15 minutes on track at the Autobahn Country Club in Joliet, IL with the ambient temp slightly below 80. After replacing the stock radiator with a Ron Davis radiator, I was able to get through a full 20 minute session in similar conditions without overheating the engine. (Please search for my post reporting the results with the Ron Davis radiator.) However, I did overheat the power steering near the end of that session. During the Winter, I installed the GM cooling duct for the power steering unit and also added the DEI cat blankets and the DEI oil line blanket. I have not had a hot enough day yet this year to gauge the impact of those mods, but will report back once I do.

davepl

A8, 2015, track it with no problems. Once got over 230 (DIC alarm isn't until 250 or something wild) so turned off AC and continued tracking it. That was when it was 88F out, and I has driving it hard in auto mode.

I've never had a problem while paddle shifting it.

If I were buying a car primarily for the track I would likely get an M7, unless I knew the A8 was bulletproof, which is has not been for some people.

davepl

Just going to take a second to repeat my unprovable theories of variances in intercooler tank fill at the factory contributing to the differences between cars, on the off chance it actually turns out to be that one day!

I also considered variances in the amount of oil blowby (oil causes serious detonation which retards timing which makes a lot of heat) but why that'd be different from one car to the next, I don't know. But a good separator and catch can would then solve the problem for those folks and I don't think that's been the case.

If it were all that easy, someone else would have solved it by now though!

spearfish25

Dave, none of those things should overheat the car. Lose power but not overheat. How does pulling timing which makes far less power lead to more heat?

davepl

Not sure I make the leap to bad paint, but give me the benefit of the doubt for a moment. I'm not talking about reduced power, I'm talking about heating.

Anything that causes a reduction/retarding of timing will cause increased heat (it's held in the chamber longer, basic reason why). So from there I ask "What could cause retarded timing", and the two culprits could be high IAT (post-blower) or detonation.

High IATs could be caused by bad intercooler fill. Under load at the track that could add up significantly. Same deal for the oil blowby - it causes major detonation (oil has an octane rating of about negative 100 or something) which will cause the computer to retard timing.

Driving around a track at WOT with retarded timing should, in my mind, really cause a heating problem. So I worked backwards from there based on reports of things, like improperly filled intercooler tanks, that we've seen.

Make sense?

Now if it were really the case I imagine someone with the Cosworth tools or other logging would have noticed high IATs or a lot of knock retard. I don't think anyone has said that yet (I stay out of the mega merge) so I'm not seriously advocating either of these very strongly, beyond "Just in case it turns out that way, mark me down for one of each".

spearfish25

LOL. Ok fair enough. I don't know enough about timing retard to have an opinion anyway.

I may just remove my hood for hot track days.

davepl

At the end of the day I imagine we will find out that the thing that varies the most from one car to the next is the driver, not the intercooler tank.

sevoz78

So, is it possible to have your intercooler "refilled" or "properly filled".
Maybe it's the guy on the assembly line at that station that keeps falling asleep on the job!

Bill Dearborn

That will always be true. Even among very good drivers. It depends on transmission gear chosen, carrying max speed through corners Vs braking and then accelerating to regain the speed. Some guys sledgehammer a car around a track and others just seem to glide along without any fuss and turn faster times.

At VIR my best time is a 2:10 and I have been running a fair number of 2:11s when traffic isn't making me slower. However, Poor-Sha has turned a 1:59 and probably runs a consistent 10 to 12 seconds faster than I do. I have watched his videos and I am never going to get near him although I think I can get into the 2:08s. If he isn't getting overheating then there is hope for the rest of us.

Bill