Some info on heat issue from GM
 

About 3-4 weeks ago, I sent out a request to Spring Mt. for some info on their driving school for the new Z. It took them a couple of weeks to respond because they forwarded my request to GM. Here's what I received.

(First, my original request to SM):

When do you anticipate putting your incoming fleet of C7 Zo6s into service? My interest is in both taking your driving course with the Z and the potential heat soak issue with the new Z that is controversially being reported over the internet. Will you be able to resolve this controversial heat issue as real or not with your fleet? I'm interested in purchasing the new Z but I'm waiting to see how this issue plays out. Best regards and thank you.
DN

(SM's reply via GM):

Thanks for your interest in Z06. There has been a lot of discussion about the Z06 “heat soak” issue – which seems to be based on a small handful of cars with limited break-in miles. We currently have 1,500 Z06s en route to customers. Once we get a critical mass of cars in customer hands, we think are going to be very, very happy with the performance of the Z06.

It is true that you will have some heat soak anytime you’re compressing the intake charge. For comparison, the new Z06 heat soaks at similar rates to the C6 Corvette ZR1. However, heat soak has proven to not be an issue for ZR1 owners: it hasn’t impacted the value of the car, and people still regard the ZR1 as a performance benchmark.

We think the same will be true of the new Z06: Even after a full tank of fuel of running flat out at Virginia International Raceway, the new Z06’s “slowest” lap was faster than the best lap recorded in a ZR1.

Monte Doran
Chevrolet Communications
313-348-2317
monte.doran@chevrolet.com


Mike Weeks
Vice President of Sales
Spring Mountain Motor Resort and Country Club
800-391-6891
mike@racespringmountain.com

I find it interesting that SM handed this request over to GM. To me, it kinda hints that they (SM) think the heat soak is a valid issue, and that probably GM underestimated this issue preproduction, but is now back-tracking in some way to address it. But that's just my interpretation. I welcome anyone else's comments and your take on this. DN

A PC response.... that's the gist of what I read.

Thank you for posting this!

Here's my take... "take what you get, and if you don't like it, don't buy it. plenty of people will buy it and like it, so our sales will more than make up for the few that express disappointment."

Guess for those who have issues (and there are a number already who have documented power-reduction), they will need to turn to the aftermarket. I know many/most guys who race their cars make mods of some sort, so maybe this really isn't a big deal for those guys.

Interesting Doc and thanks for sharing!

I think there is confusion because the primary issue with the Z06 probably isn't the classic heat soak loss of power and efficiency that occurs with increased intake air temperature but is more of an issue with engine self protection strategies that occur with higher oil (and coolant) temperatures. But the good news is if the major power loss is from these protection strategies then addressing it should be pretty straightforward.

:iagree: Good point. Many people that seriously race their corvettes modify them (at the risk of voiding the warranty). Reflashing the ECU is a pretty easy and inexpensive mod.

Rob,

Correct although I really think a DeWitt's or other high capacity radiator is going to be a key part of the solution if power is being pulled due to excessive oil temperature. The oil cooler is an oil to water type and as was posted in the tech discussion section the regular LT-1 C7 and the Z06 share the same radiator. When I saw the coolant capacity was the same for both vehicles in the 2015 manual I assumed that was a misprint but apparently not.

Sounds like typical GM PC marketing info. Yea I cant wait to get to spring mountain this summer and scream the guts out of their car. Its going to over heat indeed. I see GM making these statements so they continue selling cars. Maybe lets get a larger group together then create a class action "False advertisement-Lemon law lawsuit" on them this summer when our most track capable car begins to fail in the summer heat.

The biggest problem here guys is I book a track event 3 to 4 months ahead of time prepaid, travel to track, Hotel expense, Car prep expense, and many other things that go into a track weekend. Only to get out on the track on Saturday am to have this car go into limp mode after only a few laps. Then basically your whole weekend is chasing this overheating problem. This indeed will become a big issue for GM.

Sure this is not a race car we bought. But it damn well is "GM's most track capable car" for $100,000 and it better perform like it. I got the resources and the money if we have to force GM into a resolution.

I am sure SM doesn't have enough experience with the Z06 yet to really respond themselves also I doubt they would say anything negative about the car since they are kind of in a partnership with GM.

Their comment about the slowest lap time at VIR being faster then ZR1 is somewhat laughable. I am sure it is true, just misleading since VIR is a much faster track since it has been repaved and widened after the last time the ZR1 was tested there.

although larger or more efficient cooling systems will help, isn't the most straightforward solution to modify GM's values for variables that reduce performance?

the general consensus seems to be that the values they chose are far too conservative. the engine does have DI which is more resistant to detonation and forged crank, rods and pistons as well as squirters to spray oil under the pistons.

since it is new engine, they had to be conservative to satisfy the accountants watching warranty costs. this must have been discussed when the car was intended to be heavily marketed as a track monster.

undoubtedly, they went overboard on the tune and are likely to modify in the future, possibly not before 2016 models which are now about 6 months away.

the rest of us are left to the aftermarket for mods to make the car perform to advertised levels. this may void our warranties. it is a risk we must take if the rewards are great enough.

the reason that the tune is so appealing, is that you can still run in a stock class. if it is drag racing, you can run down to 10.00 w/o a roll cage on any NHRA strip, even with DOT drag radials. the cup 2 tires are legal in most stock road racing circuit classes. no official can tell if you have a tune, but they can tell if you have a cold air system or headers.

i just hope that tuners can get substantial increases in torque and hp without engine damage.

by midsummer it all the questions will be answered.

need to get a number of cars into customer's hands and need to have those customers use them in warmer weather, both on the road on and on racetracks.

until then there isnt much other than some limited information that seems to indicate that the ecu pulls timing for some reason (as yet determined) during extended high speed runs.

personally i think there is so much performance in many cars today that it is going to be harder and harder to get significant performance increases unless completely new technologies are implemented (think significant weigh reduction due to new materials). and this is for all cars, not just the corvette.

my gut tells me the z06 was a bit of a compromise. by the time they added all the creature comforts and tech to keep at least the manual version free of the gas guzzler tax the end result was a bit heavier car with a blower designed to fit under the hood but spins at a high rate.

its a hell of a lot of car for the money nevertheless. you need to spend well north of 100k to get more performance.

As well as the slight improvement in tires Neil. :thumbs:

This x1000! The thing is, most customers won't even mind and possibly ever notice the issue. To those buyers, this car will be more than they could have dreamt, and amidst all of the debate, they are the real winners.

I'd like to hear some response from some ZR owners, especially if you now have the current Zo, to Doran's comment mentioning the heat soak for the Zo and ZR being similar. Anybody care to comment on this? DN

Maybe a little more than slight ;)

I don't have a Z06 but have a ZR1 that I have tracked. The ZR1 doesn't really show heat issues for 20 min track sessions until the ambient gets above 90-95 deg F.

I agree with Racerns. It has to be pretty damn hot out to see a noticeable drop off in the ZR1's performance. I haven't had an opportunity yet to see how my Z will do in this regard, as obviously haven't had the ambient temps to see. Will be interesting to see what affect a 90 degree day has on it.

I kept my ZR when I got my new Z, as I my 'ol ZR and I have formed a pretty good bond. The car is a blast. Love my new Z as well - and hope it can run in the summer as well as it runs now, which is pretty stout.

btw - Just today I got my ZR back from Lingenfelter. I just pulled it into the garage after taking it for a fun 45 minute drive. Wow. It was a bad boy factory stock. It's a reeeaaalllly bad boy now. What a beast.

As to the question posed by OP and answered by GM, given some of the IAT data we've seen - all of which has been pretty good, the ecm may be pulling power not because of IAT (the classic heat soak item many think of and refer to), but rather oil and/or coolant temps based on a conservative setting for those.

I wonder if the question was posed to GM whether the engine is pulling power based on oil/coolant temps at more conservative settings than the LS9, what the answer would be.

If this is what is happening, then GM answered the way they did on basically a technicality - anchoring to "heat soak" as it may relate to IATs (which this car may have no issue with).

I don't have a C7 Z06 yet, but I have been tracking my ZR1 in hot temps for the last couple years - including the Nat'l Corvette Museum HPDE at VIR, which is held the end of June every year, and it can be very HOT!!

I have never noticed any heat-soak issues with the ZR1 in 25 or 30 minute sessions.

I hope to have a C7 Z06 for VIR this year, but if not I'll be there with the ZR1 again.

Registration for the NCM VIR event is now open. They are using the motorsportreg site to register for events now, so check out this link to register:

https://www.motorsportreg.com/events...9#.VNQgDtE5DIU

It would be a good venue to check out the heat-soak issue!!!
.

Sounds great. Maybe whatever has been working on the ZR1 regarding this can be applied to the Z06 to resolve the issue.

OP, I want to know what their answer was about running classes with their Z06s. When will those start?

Yeah, that was the other thing. Apparently in their haste to defer to GM, SM forgot to answer that one. I think they have the Zs in hand already, at least some of them. They may already be offering the class. I know Lawdog149 has signed up for the Summer, maybe he knows more about when classes start. You could send SM another email inquiring the exact date, maybe you'll get an answer this time around. DN