Motor Trend vid: GT-R NISMO vs Z06

[SVT666]

GM totally and completely dropped the ball.

[FlatBlackCaddy]

I think the power issue is only a small fraction of the problem.  At this point,  the bulk of this "disaster" is the way they are giving everyone the bs runaround.

Own up to the issue, and solve it,  problem solved.

[MX793]

IMO that would only occur if CR wasn't raised along with DI. Since typically CR is raised, it decreases the "safe" operating windo, and in particular, margin of safety when something doesn't go exactly to plan.

The whole reason the CR can be as high as it is with forced induction is due to DI.

Audi's supercharged DI engine runs a higher compression ratio than the LT-4 and doesn't seem to have the issue of the ECU pulling power when the motor gets hot.  Subaru's FA motor in the WRX likewise has a higher CR.

[GoCougs]

The whole reason the CR can be as high as it is with forced induction is due to DI.

Audi's supercharged DI engine runs a higher compression ratio than the LT-4 and doesn't seem to have the issue of the ECU pulling power when the motor gets hot.  Subaru's FA motor in the WRX likewise has a higher CR.

Got it, but again the higher CR shrinks the safe process window.

Audi's 3.0 TFSI isn't in any sort of ultra high performance vehicle and the WRX like most any turbo engine these days has a separate intercooler.

[MX793]

The specific output in Audi's motor is about the same as the LT4.  And the WRX's intercooler is mounted horizontally right above the engine.  And unlike the LT4, it isn't a liquid to air heat exchanger.  All of the heat transfer from charge to atmosphere takes place above the engine.

[12,000 RPM]

Im telling you guys, its the frontal area.



This is all the area the C7 has to feed air to the radiator, oil cooler, intercooler (which is intergrated in the blower and not even at the front of the engine bay) and brake ducts... compared with these





I mean u look at the Vette's grille, it looks like damn near half of it is closed too. You can't cool these heat exchangers without airflow. If I ran Jim Bob's Rootn Tootn Performance Shack Id be making front bumpers with way more openings. To hell with aero as these things will just be occasionally run at the strip and mostly paraded around parking lots anyway.

[Minpin]

GM totally and completely dropped the ball.

LOL


You think a minor performance hiccup that 99% of buyers won't even know about is going to affect sales?

[SVT666]

LOL


You think a minor performance hiccup that 99% of buyers won't even know about is going to affect sales?

Minor? Hardly. Besides, who said anything about sales? GM fucked up, and they are refusing to admit there's a problem when every single review and comparo states it's a problem. It may or may not affect sales, but it certainly affects performance and it's a black eye for GM when your "most track capable Corvette ever" (GM quote) can't do more than a single lap without having the ECU rob large amounts of power.  What good is 650 hp, if it only makes it for one acceleration run?

[Minpin]

Minor? Hardly. Besides, who said anything about sales? GM fucked up, and they are refusing to admit there's a problem when every single review and comparo states it's a problem. It may or may not affect sales, but it certainly affects performance and it's a black eye for GM when your "most track capable Corvette ever" (GM quote) can't do more than a single lap without having the ECU rob large amounts of power.  What good is 650 hp, if it only makes it for one acceleration run?

Sales is all that matters.

[GoCougs]

Im telling you guys, its the frontal area.

I mean u look at the Vette's grille, it looks like damn near half of it is closed too. You can't cool these heat exchangers without airflow. If I ran Jim Bob's Rootn Tootn Performance Shack Id be making front bumpers with way more openings. To hell with aero as these things will just be occasionally run at the strip and mostly paraded around parking lots anyway.

Again, for like the 7th time, the issue isn't "air flow". Just as with exhaust, air intake, etc., GM ain't gonna throw $100MM+ at a car only to then botch air flow. If the ECU is indeed pulling timing or w/e because of hot air charge, it is doing so for systemic reasons. But again, I am not convinced that is what is going on.

[GoCougs]

Sales is all that matters.

Such as it is the C7 Z06 is still the highest performance front engine/RWD factory car on the planet, a car Ford and Chrysler can only dream of developing, and only costs ~$80k...

[Minpin]

Such as it is the C7 Z06 is still the highest performance front engine/RWD factory car on the planet, a car Ford and Chrysler can only dream of developing, and only costs ~$80k...

Indeed. The GM haters are out in full force on this one. It'll sell like hot cakes like they always do, and the execs will get a congratulatory trip to Hawaii.

[r0tor]

Again, for like the 7th time, the issue isn't "air flow". Just as with exhaust, air intake, etc., GM ain't gonna throw $100MM+ at a car only to then botch air flow. If the ECU is indeed pulling timing or w/e because of hot air charge, it is doing so for systemic reasons. But again, I am not convinced that is what is going on.

Yea its not like they made the Z28 so marginal in cooling that they had to come up with a " flowtie" emblem.  Obviously they have a strong thermal management program

[GoCougs]

I say it again for like the 42nd time, GM would have been better going after a N/A "LT7" 550-600 hp style motor for the upscale C7 and Camaro rather than this F/I nonsense. F/I will always be fairly sucky for reasons I've carried on about for a very long time.

[AutobahnSHO]

Apparently one of the guys in our Clash Clan is a salesman, said he does ok on vette sales but really makes out on z06 sales...

[r0tor]

Such as it is the C7 Z06 is still the highest performance front engine/RWD factory car on the planet, a car Ford and Chrysler can only dream of developing, and only costs ~$80k...

Hellcats will walk it in a straight line.  AMG has been doing a TTV12 with 600hp forever now.  Viper is at 645hp.  They all have their shit together with thermal management.

[GoCougs]

Yea its not like they made the Z28 so marginal in cooling that they had to come up with a " flowtie" emblem.  Obviously they have a strong thermal management program

First, the Z/28 is powered by the LS7 which is a N/A motor.

Second, WRT the C7 Z06 the working hypothesis is not a problem with engine cooling but a problem with cooling the intake charge (i.e., output of the supercharger).

[GoCougs]

Hellcats will walk it in a straight line.  AMG has been doing a TTV12 with 600hp forever now.  Viper is at 645hp.  They all have their shit together with thermal management.

You mean 4,400 lb Hellcat cars? 2nd grade math will tell you this can't possibly be so (4,400 lb/707 hp vs. 3,500 lb/650 hp).

And do you know the difference between a turbo intercooler and supercharger intercooler?

Also, the Viper has a N/A V10.

All in all, I don't recommend this course of action - things did not go well for you in the F150 vs. Silverado and they won't go well here either.

[r0tor]

Intercooler outlet temperature revolves back to thermal management and engineering which GM seems to not have a good handle on... Just like the marginal design of the Z28.

They use a liquid intercooler which the design itself usually suffers from heat soak issues without tremendous amounts of cooling.  They have next to no cooling of the intercooling and u heard of levels of heat soak.

[MrH]

I'm still not convinced it's pulling power in this motor trend test. Just watching the side by side video is pretty clear. Huge difference in corner exit speed. Even with more power and less weight, it's not enough to catch up to the GTR. Even steady state handling favors the vette, but it gets completely destroyed on every corner exit.

[Minpin]

Goodness some of you folk are like a broken record in here

[r0tor]

You mean 4,400 lb Hellcat cars? 2nd grade math will tell you this can't possibly be so (4,400 lb/707 hp vs. 3,500 lb/650 hp).

And do you know the difference between a turbo intercooler and supercharger intercooler?

Also, the Viper has a N/A V10.

All in all, I don't recommend this course of action - things did not go well for you in the F150 vs. Silverado and they won't go well here either.

You think the Z06 can manage to not go into limp mode?

[FoMoJo]

Hmmm...

After several laps on the track or a few hard acceleration runs on the highway, owners of the brandy new Super Vette are reporting noticeable power loss from the supercharged LT4 V8. Originally it was thought that it was heat soak from the supercharger, but, it is, in fact, conservative tuning of the ECU to help the drivetrain survive for 100,000 miles as well as allow the Z06 to meet stringent US emissions regs.

...so it's the governments's fault .

[GoCougs]

I'm still not convinced it's pulling power in this motor trend test. Just watching the side by side video is pretty clear. Huge difference in corner exit speed. Even with more power and less weight, it's not enough to catch up to the GTR. Even steady state handling favors the vette, but it gets completely destroyed on every corner exit.

That's why I don't really buy into this ECU stuff. If the ECU is pulling power because of a temp issue (engine temp or intake charge temp) one would think it's not gonna pull only 5 or 10% but would pull huge amounts of power to prevent thermal runaway.

[GoCougs]

Intercooler outlet temperature revolves back to thermal management and engineering which GM seems to not have a good handle on... Just like the marginal design of the Z28.

They use a liquid intercooler which the design itself usually suffers from heat soak issues without tremendous amounts of cooling.  They have next to no cooling of the intercooling and u heard of levels of heat soak.

Again, please review the differences between a Roots/screw/scroll style supercharger and a typical turbocharger, and in particular, the location of the intercooler.

[hotrodalex]

I'm still not convinced it's pulling power in this motor trend test. Just watching the side by side video is pretty clear. Huge difference in corner exit speed. Even with more power and less weight, it's not enough to catch up to the GTR. Even steady state handling favors the vette, but it gets completely destroyed on every corner exit.

+1 definitely not going into limp mode or seeing the same HP losses that others have claimed.

Hmmm...

...so it's the governments's fault .

That was the original assumption (along with ensuring proper break-in), which was thrown out the window by GM haters.

[SVT666]

Owners are still experiencing the problem well beyond the "break-in period".  GM fucked up. Period. GM apologists can keep making excuses, but no other car does what the Vette is doing.  If it there yo protect the drivetrain, then GM did a shit job of engineering the drivetrain.

[hotrodalex]

but no other car does what the Vette is doing.

Punching way above it's weight?

[SVT666]

You mean 4,400 lb Hellcat cars? 2nd grade math will tell you this can't possibly be so (4,400 lb/707 hp vs. 3,500 lb/650 hp).

And do you know the difference between a turbo intercooler and supercharger intercooler?

Also, the Viper has a N/A V10.

All in all, I don't recommend this course of action - things did not go well for you in the F150 vs. Silverado and they won't go well here either.

The 4400 lbs Hellcats do indeed outrun virtually everything in a straight line.

[GoCougs]

Punching way above it's weight?

If you'd hitched yer wagon to Ford or Chrysler you probably would be a Corvette hater too.