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2016 Z06 Z07 A8 overheating

 
Old 06-12-2019, 08:00 PM
  #81  
BrunoTheMellow
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Originally Posted by bbbvettes.com View Post
An automatic only has 2 HX cooling the engine, 3 if you count the tiny brick under the motor next to the cat (and it does not cool anything down, it simply pegs the engine coolant temps to the engine oil temps, as it exhanges their heats to each other).

You would like the world to believe, that cutting flow to one of the 2 HX that cool an automatic's engine, is not going to cause it to go from 255 degree coolant, to past 265?

You and I don't see the universe or laws of physics the same at all if thats the case. Its at least 1/3 of the heat extraction to the z06 auto's engine, and you think disabling it for 3 min at a time does not cause a car to gain 15 degrees when it is at 255 coolant during those 3 min of blower coolant pump shutdown on a track?

Thats 1.5 laps at VIR, with half the amount of HX active. ... and you think it makes NO difference

Goodluck, find better things to pick arguments with people on. I promise you are wrong on this one.
No data. Just words. We all know how you work.

Now that the blower hex isn't flowing, it's no longer exhausting hot air into the radiator. Colder air into the radiator allows it to work better. This seems to counteract the extra heating caused by the hotter intake charge. Per the data..there's a bunch of other graphs in that thread showing the same. Coolant temps. Not iat. I know iat is through the roof.
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Old 06-12-2019, 08:07 PM
  #82  
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the data is people who have solved their issue... and its data that you refuse to believe is real.

The data is right there, you just think since we dont have a pretty graph for you that you can call us all liars.

Give Rune a call or PM. Take me out of the discussion, since I'm well aware whatever I say, you want to argue with it...

including the idea that removing 1 of 2 EQUALLY SIZED HX from cooling an engine, does not cause it to pick up 10+ degrees during 1.5 laps at VIR.

You need data to believe that huh? Go create your own data, I don't have time to go get graphs to prove what common sense screams is true.

If you don't understand it, your problem. The OP will see the results soon enough for himself once the problem is resolved on his car.

We will see if he paints you a graph, or if maybe you learn to believe people instead when they say it has an impact.

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Old 06-12-2019, 09:23 PM
  #83  
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What is being disabled for 3 minutes and why?

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Old 06-12-2019, 09:36 PM
  #84  
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when there is air in the blower coolant circut, that air gets trapped around the pumps impeller blade and causes cavitation. The pump is "smart" and knows when it has air inside, and it shuts off for 3 min to allow the air to work its way out of the impeller blade of the pump.

You may as well throw your blower coolant heat exchanger on the side of the road when that pump is shut off.

An automatic trans c7, only has this blower coolant HX and the main radiator, to cool its engine.

Thus, removing this HX from the equation causes a swing of 10 degrees easily when the car is on the track and 10 degrees away from overheating to begin with when it had both HX in use, prior to the 3 min shutdown.

The proof is in the OP's video... he was not going THAT fast around the track and it was not THAT hot outside, and he still overheated. This is why a few of us are 99% positive it is the air in his blower res causing the shutdown.

Driving the same "speed/rpm" at that track as he is in the video, and same ambient temps, his car should never overheat again, once the air is purged from his blower fluid system.

As he becomes a faster driver, and as it gets hotter out, he will have more issues, but there is no reason NOT to get the air out of his system. To say it will have minimal impacts, is just not true in my observations on these vehicles.

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Old 06-13-2019, 05:02 PM
  #85  
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Originally Posted by Pluggzz View Post
So I just found stats from that day where the max oil temp reached 289, coolant 262 and trans 205. Is that normal to cause faults? Figured would have seen higher.
Water is much too high
200-205 is perfect
If you see higher numbers you lose a lot of power
and your wear is much higher

Cölestin
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Old 06-13-2019, 05:20 PM
  #86  
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right, the hotter the engine gets, the more pre-detonation occurs, which is knock, and then the knock sensors sense it and the ECU pulls timing and TB blade angle... its a black spin down from there, until you hit overheat thresholds, and the car goes into limp mode to protect itself.
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Old 06-13-2019, 05:27 PM
  #87  
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Originally Posted by Lasco001 View Post
Water is much too high
200-205 is perfect
If you see higher numbers you lose a lot of power
and your wear is much higher

Cölestin
Hmm ok...well i ordered the Dewitts cooler combo and largest radiator, so that should help for sure. Among the other stuff I'll do as suggested.
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Old 06-13-2019, 10:16 PM
  #88  
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Originally Posted by bbbvettes.com View Post
when there is air in the blower coolant circut, that air gets trapped around the pumps impeller blade and causes cavitation. The pump is "smart" and knows when it has air inside, and it shuts off for 3 min to allow the air to work its way out of the impeller blade of the pump.
.


Thanks.
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Old 06-14-2019, 08:12 PM
  #89  
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I had my first ride in an C7 A8 car at the Glen on Tuesday. The car was a GS and the driver was pushing it hard with the trans in Auto Mode. I saw how it was holding the engine in the higher rpm ranges with RPMs being held between 5K and 6.5K most of the time with a lot of time spent above 5.5K. Not sure how the A8 would drive the LT4 rpms but it was obvious comparing my laps at the Glen in an LT4 powered car, an LS7 powered car and a LS6 powered car with manual transmissions that I never used that constantly high rpm range.

Look at the videos of M7 Z06s on the track and the first thing you see is the lack of shifting to the lower gears. At the Glen I use 3rd and 4th and a sampling of 5th (although that doesn't get me much speed improvement on the back straight). I don't down shift to 3rd for the bus stop as 4th works just fine while permitting smoother cornering while avoiding a shift to 4th while running the carousel. My complaint with the GS in auto mode was it was downshifting when it didn't need to and was just buzzing the engine and making a lot of noise to little good. I run 3rd and 4th at VIR (with some use of 2nd odd Oak Tree) although I do use 5th on the back straight there since I can get a little more speed there due to running down hill when I shift. I don't short shift when I use these gears, I let the rpms go right up to red line and then shift.

My impression between the M7 and the A8 is the M7 3rd gear is somewhat equivalent of 4th gear in the A8 and the M7 4th gear is somewhat equivalent of 5th gear in the A8 with 5th being somewhat equivalent to 6th in the A8. I wonder what the results would be if A8 drivers drove like M7 drivers. Put the trans in manual mode and use 4th and 5th for most of the track and in cases where you need longer legs go to 6th. Don't short shift go to red line and shift. The car might run cooler without all of the low gear high rpm buzzing. Sure the lap time might drop by a few tenths of a second but you could still be damned fast.

I told the driver of the GS that my ears hurt after the 40 minute ride. As for his driving he pretty much followed my line and I only noted one or two places where he might try a slightly different line.

My car is loud at wide open throttle and high rpm but that GS had the LT1 wound so tight it was screaming through the whole session. Time wise the driver's quick time is in the range that good C7 Z06, C6 Z06 and C5 Z06 drivers can do around the Glen, I think he could have equaled it by manually shifting, reducing the number of gears used and taking it easier on both of our ears.

Bill
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Old 06-14-2019, 08:49 PM
  #90  
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Originally Posted by Bill Dearborn View Post
I had my first ride in an C7 A8 car at the Glen on Tuesday. The car was a GS and the driver was pushing it hard with the trans in Auto Mode. I saw how it was holding the engine in the higher rpm ranges with RPMs being held between 5K and 6.5K most of the time with a lot of time spent above 5.5K. Not sure how the A8 would drive the LT4 rpms but it was obvious comparing my laps at the Glen in an LT4 powered car, an LS7 powered car and a LS6 powered car with manual transmissions that I never used that constantly high rpm range.

Look at the videos of M7 Z06s on the track and the first thing you see is the lack of shifting to the lower gears. At the Glen I use 3rd and 4th and a sampling of 5th (although that doesn't get me much speed improvement on the back straight). I don't down shift to 3rd for the bus stop as 4th works just fine while permitting smoother cornering while avoiding a shift to 4th while running the carousel. My complaint with the GS in auto mode was it was downshifting when it didn't need to and was just buzzing the engine and making a lot of noise to little good. I run 3rd and 4th at VIR (with some use of 2nd odd Oak Tree) although I do use 5th on the back straight there since I can get a little more speed there due to running down hill when I shift. I don't short shift when I use these gears, I let the rpms go right up to red line and then shift.

My impression between the M7 and the A8 is the M7 3rd gear is somewhat equivalent of 4th gear in the A8 and the M7 4th gear is somewhat equivalent of 5th gear in the A8 with 5th being somewhat equivalent to 6th in the A8. I wonder what the results would be if A8 drivers drove like M7 drivers. Put the trans in manual mode and use 4th and 5th for most of the track and in cases where you need longer legs go to 6th. Don't short shift go to red line and shift. The car might run cooler without all of the low gear high rpm buzzing. Sure the lap time might drop by a few tenths of a second but you could still be damned fast.

I told the driver of the GS that my ears hurt after the 40 minute ride. As for his driving he pretty much followed my line and I only noted one or two places where he might try a slightly different line.

My car is loud at wide open throttle and high rpm but that GS had the LT1 wound so tight it was screaming through the whole session. Time wise the driver's quick time is in the range that good C7 Z06, C6 Z06 and C5 Z06 drivers can do around the Glen, I think he could have equaled it by manually shifting, reducing the number of gears used and taking it easier on both of our ears.

Bill
Bill, you are correct, the cars run cooler when short shifting is done. The problem is, the short shifts are awkward.

This was brought up to Jim Mero in his "7:04 ringtime" thread. He agrees that the car is cumbersome when the manual paddles are used on the A8 as they are overly delayed shifts,

And it is my observation that they can be very rough in transitions when done manually, which can throw a car out of control because the driver has no control of the "clutch/shift" impact of the actual gear change. Inversely, they are extremely smooth shifts when done in full auto mode, especially in high-speed curves

Mero agreed that the car's TCU is great at choosing when to shift on its own accord, if top lap times are the goal.... this is how he drives the car. He does not touch the paddles I believe he stated. He also agrees that the auto is faster than the manual.

I believe that to get-by on a track day without overheating, this short shifting at lower RPM technique will be a good alternative, but once someone really gets great at driving and starts pushing the limits, the TCU is far superior at shifting than the driver can be with the delayed paddles.

This is why we are working on affordable simple cooling solutions to the A8 vehicles. They are the faster cars compared to the manuals, the A8 cars just need extra cooling. The A8 is a great car. I plan to get another new 18 or 19 soon, just waiting until after the reveal so that I can plan long term strategies.

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Old 06-14-2019, 09:07 PM
  #91  
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I have an 2016 Z06 A8 and drive it like a manual at my local track. (Autobahn country club). I'm in the intermediate run group on HPDE events, not super fast but not slow either. I only need 3rd 4th and 5th gear. The car has so much torque I don't need it screaming all the time. I usually shift around 6k rpm. It runs hot but doesn't overheat on 90+ deg days. 240 ish water temperatures and 270 ish oil temps is the hottest it gets. I do have the 100 octane tune and run 98 octane at the track.

I also prefer manual mode because I don't like the car downshifting on it's own mid corner. I'd prefer a manual trans but this seems to work pretty well, and I already have the car. I'm hoping Tom's new trans and engine oil cooler will be all I need for this track.

I have seen other guys with A8 Z06'S go into limp mode there. I believe in auto mode. One guy was asking if my car was overheating. I told him to try manual mode and later I saw him pull off about halfway through the session. He was faster than me, but might have had other mechanical issues too.
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Old 06-14-2019, 09:11 PM
  #92  
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Thanks for the feedback Edster75. How do you do the 98 octane, an octane booster or is that level of octane sold at or near the track?

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Old 06-15-2019, 12:28 AM
  #93  
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They sell Sunoco 260 GTX 98 octane unleaded at the track. They also sell 260 GT Plus 104.

https://www.sunocoracefuels.com/fuel/260-gtx

https://www.sunocoracefuels.com/fuel/260-gt-plus

I've tried them both, the car seems to run fine with each one. I'm not sure which is better the GTX has no ethanol. The GT Plus is oxygenated. I'm not sure if that means it has ethanol or something else, or if the stock tune can even take advantage of that. There about fifty cents different in price.

The Z is definitely thirsty. I ran six 30min sessions at the Autobahn full track a couple weeks ago and burned approximately 30 gallons of fuel.
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Old 06-15-2019, 12:37 AM
  #94  
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especially with GM factory Tunes with COT activated, they drink a lot of fuel.

On a normal car, the oxygenated fuel would be dangerous I suppose, as you may run lean. That fuel has 13% ethanol content.

As rich as our cars run, the oxygenated fuel might bring you back to a better AFR.

The ethanol does provide cooling and knock protection.

If it were me, I would run half and half of the 2 each fillup... then you will be in the clear, but also save yourself a bit of money each fill-up.

Your car should run better with a bit of ethanol in the mix. It's also better for keeping your engine clean on the inside.
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Old 06-16-2019, 12:54 AM
  #95  
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Originally Posted by bbbvettes.com View Post
Bill, you are correct, the cars run cooler when short shifting is done. The problem is, the short shifts are awkward.

This was brought up to Jim Mero in his "7:04 ringtime" thread. He agrees that the car is cumbersome when the manual paddles are used on the A8 as they are overly delayed shifts,

And it is my observation that they can be very rough in transitions when done manually, which can throw a car out of control because the driver has no control of the "clutch/shift" impact of the actual gear change. Inversely, they are extremely smooth shifts when done in full auto mode, especially in high-speed curves

Mero agreed that the car's TCU is great at choosing when to shift on its own accord, if top lap times are the goal.... this is how he drives the car. He does not touch the paddles I believe he stated. He also agrees that the auto is faster than the manual.

I believe that to get-by on a track day without overheating, this short shifting at lower RPM technique will be a good alternative, but once someone really gets great at driving and starts pushing the limits, the TCU is far superior at shifting than the driver can be with the delayed paddles.

This is why we are working on affordable simple cooling solutions to the A8 vehicles. They are the faster cars compared to the manuals, the A8 cars just need extra cooling. The A8 is a great car. I plan to get another new 18 or 19 soon, just waiting until after the reveal so that I can plan long term strategies.
Just to clarify terms a little what I call short shifting is not running the car all the way to the rev limit. I am not saying to do that. I am just saying to limit the number of gears chosen just as an M7 driver would do. I run mine to the rev limiter most of the time just in two gears though. That means the car is traveling much faster when the rpms are the highest so it is also getting max cooling air flow. At the lower speeds and rpms there isn't as much frictional heat generated so have a better chance to avoid over heating. Limiting the gears makes the A8 more like a 15 or 16 M7 without the secondary radiator.

Bill

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Old 06-16-2019, 01:09 AM
  #96  
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I agree.

I also think a great add on (especially for GM who is having overheating issues) would be different trans tunes that can be selected in race mode. It changes where in the RPM range the trans likes to hover when it is holding gears, 3 different options a driver can select from.

If they sold such an update to the c7's at service departments for 500 dollars with a few reviews saying it solved the cars from overheating at the track, there would be a long line of A8 buyers at GM service departments, who all "think" they need it for their next track day...

which would also be their first track day....

which will also never actually end up happening ...

but the 500 dollar credit card swipe and 10 minute download would

They could also write a program that allows the driver to touch the paddles, but the paddle does not cause the car to shift instantly... instead, it is a "word of advice" for the car that you would prefer it to shift up when it gets a chance to smoothly do so...

or you wish for it to hold the gear its in until you push the paddle the other way to release it..

or you wish for it to shift down when it geats a chance. Kind of complicated to explain... but basically taking advantage of the A8s ability to shift smooth at high lateral G.

So on a roadcourse, a person would memorize where to push what paddles, and really start to get the hang of it...

but they aren't actually telling the car when to make each shift.

2 paddles, 2 directions, 4 inputs... or just add an input device on the shift ****, or add 2 paddles to each side of the wheel

The younger video game playing generation would have no issues learning how to use it.

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Old 06-16-2019, 09:50 AM
  #97  
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WHAT!!! I just cant believe I'm reading this crap. It's the drivers fault?? GM should now train drivers by virtual shift points so not to overheat a track capable corvette Z06 on sale for 6 years now??? @##%$##@
I for one do not blame GM. Yes they should have added extra heat exchangers in 2016. But as a track guy I know any manufactured street car will need upgrades for tracking.
So you guys are saying not to upgrade with AP Brakes, just learn how to brake properly without overheating pads??? CRAZZY

This is crazy short shift talk.
OP, Go out have a blast on the track, With a few upgrades the Z is a beast. With upgraded intercoolers its still the best bang for buck super car!!!

Marc
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Old 06-16-2019, 12:26 PM
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I never said not to touch the brakes, keep me out of that one, but I do know plenty of great track stars who run the steel rotors with only an upgraded pad, so I can't argue against that one, which is why I stayed out of that discussion.

As far as the trans goes, have you ever ridden in the z06 A8 once it enters into performance shift mode? It stays revved to the moon at all times as Bill mentions.

It stays revved higher than most manual trans guys drive by nature.

So not only has the A8 lost a HX relative to the manual, it typically has more engine rotations in any given amount of time, so it is also creating more heat.

I was simply saying if GM offered other transmission tunes, which would allow the driver to choose where they want their rpm to hover, I believe it would be a hit in the marketplace and many people would add it to their cars.

The other upgrade of course is the extra needed HX to bring it back to par with a manual trans car.

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Old 06-16-2019, 05:39 PM
  #99  
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I think having different levels for performance shifting is a great idea. 3 settings would be perfect, and they could be tied to tour, sport, and track suspension modes. Or selected separately in the infotainment system like the exhaust and steering modes.
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Old 06-16-2019, 07:58 PM
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in my imagination, all 3 settings would still hold gears, it just depends what RPM it likes to hold them at, and what RPM the person wants to have the car shift by.

In one of the lower lower settings, the car could hold gears around 5000rpm, and shift by 6000, and only downshift when a person goes below 4000rpm... as an example.

Or, it could be set up even lower yet.

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