[Mr. Wyndham]

Originally Posted by Bhobbs

The GT350's issues were not related to engine heat, but transmission heat. As far as I can tell, there haven't been any issues with GT350s that have overheated with the track pack. It does seem the engine vibrations are causing havoc with the oiling system. Four GT350s on Mustang6g alone have had engine failures that seem to be caused by lack of oil pressure.

I agree the Camaro may have a better chance at keeping the LT4 cool, but I don't know if I would want to bank $60k+ on that.

Cooling is cooling...my point is that a dedicated track car needs all of its components to function flawlessly under some of the most extreme conditions. And a mass-produced street-wanna-be-race-car like a Z/28 or GT350R need to do so again and again and again without a rebuild or overhaul like someone mentioned NASCAR and F1 engines undergo each race.

I think team Corvette underestimated the amount of heat they would need to displace during track use, be it from the engine or the transmission, and I don't think the design's front air intake let's enough air flow to do it. (My opinion only)

I doubt Camaro team made the same mistake with the ZL1 (partly because of what happened with Z06). And that would be your test bed for a Z/28 before you plop money down. If the ZL1 can perform without terrible overheating issues, then there's no reason a Z/28 couldn't do the same with a similar engine.


I would love to see a thermal analysis done with the intent on documenting the BTU's output by a 500hp F/I engine, and a 500hp naturally aspirated engine.

[SpeedIsLife]

I just find it very ironic that the C7Z was the "testbed" for the LT4/cooling issues...

$85,000+ is a mighty big entry price to essentially being a super-CTF member.

I know that running improvements and changes are always happening, but it seems like it was a big SNAFU to kind of biff the Z06 so early and tarnish the reputation of a truly stellar performing car.

[jessrayo]

Originally Posted by Nataphen

Uuuum, I think you just answered on your own about why people are infatuated with NA engines. Traditionally, FI motors are harder to cool, heavier, less consistent, and less linear in the case of turbos. They can be cooled and engineered for endurance, but at greater expense and/or weight.

I also think that FI takes away from the character of engines. If everyone uses FI, it sort of muddles everything together across all car brands. Much of the individual personalities of different engines are lost. I've had just about every combination of engine available: turbo, PD blower, high winding NA, 4 cylinder, rotary, V8, and a few more I'm sure. I've come to enjoy my NA engines more than anything else.

Besides, how much more power do you need for a road course car than what NA motors make anyway?

The bottom line for me is that the NA engine just does not have as much power. It is definitely easier to drive fast with a light car with less power that you can just lay into without oversteer but for me it is so much more enjoyable to have enough power that you have to modulate it.

Originally Posted by SpeedIsLife

FI makes more pure power, easier, with less fuel and can be more drivable.

However, it is dramatically less capable and reliably making that power. FI motors heat-soak, and are more heat sensitive than N/A motors, no matter how many intercoolers, radiators and other equipment you strap to it. You can't point to F1 or Indycar and say "look they can do it!"...I mean..after all..NHRA top fuel produces 10,000 HP on 500CI Hemi's with a blower..that means there's no reason a street car can't do that, right?

Okay, lets talk endurance racing.... some of these FI cars are running hard for 24 hours... you can't even compare NHRA races that now last less than 5 seconds.

Originally Posted by Mr. Wyndham

I think another member posted that one of the cars had a failure unrelated to overheating...

Anyways, the early Z06's were having issues. They've made changes to the cooling systems to correct the issue since then.

Cooling is as much a function of the vehicle's design as it is the engine. The Camaro has the benefit of more airflow than the Corvette...a FI engine could work...

Overheating is not solely a result of FI. Sure, the extra pressure is a challenge, but naturally aspirated engines can have issues, too....heat is directly related to power. More power = more heat...if you don't cool it, stuff goes wrong, doesn't matter if there's a blower, turbos, or not. Some GT350's has had some issues, too...and that car has a "racing engine".

I think we are kind of on the same page. More power is more heat, doesn't matter if it is NA or FI. A 650 hp engine is going to have to be a monster if it is NA. It is all about engineering the cooling to handle the power available.

I do think most of the GM cars need more cooling from the factory. I had a 2014 C7 Stingray with Z51, completely stock except for brake fluid exchange, and never did get the car to run all out for 30 minutes without overheating the transmission. Now if I would just back out to about 80 to 90% it would keep running with no warning lights.... but why should I have to buy a bigger fluid pan or an accessory cooler on a Z51 factory track upgrade car? I think GM team Camaro heard all of this on the stingray because the SS has a lot more trans cooler at least. I have not put my '16 SS on the track yet....but mine will be FI the first day out. AGP is still working on the twin turbo install. I'll be sure to let everyone know how it does. I will say the '16 SS has a big trans cooler and a rear diff cooler just like the Gen5 ZL1. I expect the Gen6 ZL1 to be as even better!

[mkorgan]

I don't want to make a big fuss about this but heat-soak on the ZL1 was a concern that ended of being mostly unjustified. I have spent long days on the track with my ZL1 in 90 degree plus weather and high humidity and my last lap was just as good as my first lap. There may be cars that don't handle FI heat well but I have to say that GM did a marvelous job on the Gen5 ZL1 and it has made a believer out of me in favor of FI if that is what is needed to get HP with the new CAFE standards.

[Bhobbs]

Originally Posted by Mr. Wyndham

Cooling is cooling...my point is that a dedicated track car needs all of its components to function flawlessly under some of the most extreme conditions. And a mass-produced street-wanna-be-race-car like a Z/28 or GT350R need to do so again and again and again without a rebuild or overhaul like someone mentioned NASCAR and F1 engines undergo each race.

I think team Corvette underestimated the amount of heat they would need to displace during track use, be it from the engine or the transmission, and I don't think the design's front air intake let's enough air flow to do it. (My opinion only)

I doubt Camaro team made the same mistake with the ZL1 (partly because of what happened with Z06). And that would be your test bed for a Z/28 before you plop money down. If the ZL1 can perform without terrible overheating issues, then there's no reason a Z/28 couldn't do the same with a similar engine.


I would love to see a thermal analysis done with the intent on documenting the BTU's output by a 500hp F/I engine, and a 500hp naturally aspirated engine.

The only GT350 that had the issues was the base GT350, and the GT350 is no longer available without the track pack. You can't add a package to the Z06 to keep it from overheating. It's just part of the was the car is.

[RLHMARINES]

Originally Posted by Bhobbs

The only GT350 that had the issues was the base GT350, and the GT350 is no longer available without the track pack. You can't add a package to the Z06 to keep it from overheating. It's just part of the was the car is.

As stated that was true of the pre-fixed Z06's and not of the post-fixed Z06's. How many of these cars were track prepped properly per GM's guidelines with the proper wt. oil, etc. Just a thought since we are talking about some of the issues that a few owners have experienced in the past with this gen car.

[Jon A]

Originally Posted by Mr. Wyndham

...heat is directly related to power. More power = more heat...if you don't cool it, stuff goes wrong, doesn't matter if there's a blower, turbos, or not.

That's not quite accurate. In short, a 500 HP Supercharged engine will produce more total heat than a 500 HP N/A engine. Most obvious of reasons is that it takes power to turn the supercharger so the engine itself must make more than 500 gross just to net 500. Secondly, the act of compressing the air generates a bunch of heat which is not useful for anything--it's either put into the engine hurting its efficiency or (some portion of which) removed via an intercooler.

While the powertrain cooling system guys do in-depth detailed calcs as you were suggesting while sizing components, the easier way to get an idea of such things for the average guy is to look at BSFC which can be measured on a dyno. Supercharged engines average much higher BSFC which means they're burning more fuel per HP. If you burn more fuel for the same HP that means the excess is heat which needs to go somewhere.

Naturally to make matters worse, when you compare a 640 HP supercharged engine with a 500 HP N/A engine, the cooling requirements are in completely different zipcodes.

That said, with excellent Engineering and execution anything can be done. Hopefully this will turn out to be the case with the ZL1 and Z28 (if they do supercharge it). But it is a much higher bar and a small miscalculation here or cheaped out part there can cause big problems.

[MrChrisLS3]

I don't know, I personally like the idea of a higher out put N/A engine, and who knows what the guys and gals at GM small block have up their sleeve? But let's face it, forced induction is here to stay. Whether you look at it as cheap easy horsepower, or a necessary evil, it's here and it ain't leaving the party anytime soon.

Now, if the biggest problem with the LT4 is cooling, at this point, that's a good problem to have. I mean, if it were eating pistons, and throwing piston rods all over race tracks, that would be a "problem". Considering that GM has been playing with superchargers and turbos for awhile now, and how far they've come, this will get sorted out. I guess we'll just have to wait and see, but I'm betting on a lightweight, track prepped, low option, LT4 equipped, low production Z/28 in the $75K range.

[Mr. Wyndham]

Originally Posted by Jon A

That's not quite accurate. In short, a 500 HP Supercharged engine will produce more total heat than a 500 HP N/A engine. Most obvious of reasons is that it takes power to turn the supercharger so the engine itself must make more than 500 gross just to net 500. Secondly, the act of compressing the air generates a bunch of heat which is not useful for anything--it's either put into the engine hurting its efficiency or (some portion of which) removed via an intercooler.

While the powertrain cooling system guys do in-depth detailed calcs as you were suggesting while sizing components, the easier way to get an idea of such things for the average guy is to look at BSFC which can be measured on a dyno. Supercharged engines average much higher BSFC which means they're burning more fuel per HP. If you burn more fuel for the same HP that means the excess is heat which needs to go somewhere.

Naturally to make matters worse, when you compare a 640 HP supercharged engine with a 500 HP N/A engine, the cooling requirements are in completely different zipcodes.

That said, with excellent Engineering and execution anything can be done. Hopefully this will turn out to be the case with the ZL1 and Z28 (if they do supercharge it). But it is a much higher bar and a small miscalculation here or cheaped out part there can cause big problems.

I agree. All good points.

[Bhobbs]

Originally Posted by RLHMARINES

As stated that was true of the pre-fixed Z06's and not of the post-fixed Z06's. How many of these cars were track prepped properly per GM's guidelines with the proper wt. oil, etc. Just a thought since we are talking about some of the issues that a few owners have experienced in the past with this gen car.

What exactly was updated on the Z06 to combat the overheating issues?

I'm not just talking about customer cars. Cars GM has provided for reviews have had issues as well, and I would hope GM followed their own guidelines for prepping those cars.

[SpeedIsLife]

Originally Posted by Bhobbs

What exactly was updated on the Z06 to combat the overheating issues?

I'm not just talking about customer cars. Cars GM has provided for reviews have had issues as well, and I would hope GM followed their own guidelines for prepping those cars.

I was wondering that too...what was the "fix" in later production cars that corrected the issue?

Was there or was there not a design issue? If it was a design issue, then the whole "the cooling system wasn't burped" and "it was damage" story was a lie.

If there wasn't a design issue, then what difference does it make if it's early or late production.

[Nataphen]

All electric Z/28. That's what they should do.

[2cnd chance]

Originally Posted by Bhobbs

What exactly was updated on the Z06 to combat the overheating issues?

I'm not just talking about customer cars. Cars GM has provided for reviews have had issues as well, and I would hope GM followed their own guidelines for prepping those cars.

I'm hoping and waiting that the "Corvette Museum Bash" at the end of this month will answer that. It will let me know which direction to go.

[Mr. Wyndham]

Originally Posted by Bhobbs

What exactly was updated on the Z06 to combat the overheating issues?

I'm not just talking about customer cars. Cars GM has provided for reviews have had issues as well, and I would hope GM followed their own guidelines for prepping those cars.

I believe they enlarged some of the heat exchangers, and there were engine manufacturing changes to improve coolant flow through the engine. Might be more, or at least more details...but that's what I remember off the top of my head.

One of the cars they gave to Motortrend was, indeed, not prepped properly. In fact, less than properly...there was air in the intercooler circuit.