Let's talk about the C8 vs the GT500

[martinjlm]

Honestly, I think this is gong to be one of those time that people will be so influenced by the "mid engine" mystique and the claimed 0-60 times that non will likely hold him to his claims...which quite frankly don't make sense. This goes beyond being skeptical. There isn't enough pixie dust in GM's arsenal for the C8 to beat out the C7 Z06 in the 1/4 mile. Stoplight to stoplight, yes...it will likely kill it with it's 60'. It just doesn't have to hp/weight ratio to out-muscle cars like the z06.

Skepticism understood. I keep bringing up the comparison of Porsche GT3 vs ZL1 (and Z06 for that matter) and the fact that despite a 207 hp disadvantage and a 260 lb-ft torque disadvantage, the GT3 is right on top of both these cars with respect to acceleration measures. It has a significant weight advantage over ZL1, but that can’t totally compensate for the large disparity in power and torque. It is not just coincidence that I refer to the GT3. A lot of the bench-marking activity for C8 development included deep study of the GT3 and Ferrari 488. The Corvette team understands what makes those cars tick and I’m pretty sure engineered the C8 structure to deliver similar results.

At the end of the day, only time and hands on testing of C8 Z51 will tell the story. When I was still at GM in Competitor Intelligence, people on the Camaro team were telling me that C6 SS would perform on par with C5 ZL1 and that C6 SS 1LE would perform on par with C5 Z/28. I didn’t believe it. Until they did. Now the guy that led engineering development of both C7 and C8 is saying publicly that C8 Z51 outperforms C7 Z06. I believe him.

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[shogun32]

Now the guy that led engineering development of both C7 and C8 is saying publicly that C8 Z51 outperforms C7 Z06. I believe him.

You didn't hear the caveat in his statement which was "up to X mph" where aerodynamic resistance becomes a dominating force and thus must be countered with ever more HP. But given the shape of the C8, I suspect the value of X has moved significantly higher than before and into "it's not like you'll ever achieve X except on a 1/2+ mile long straight, anyway, so point is moot". If you have a 5000+ ft runway to do top-speed runs, I would expect the C7 Z06 to reach a higher terminal velocity.

The interesting thing about gearing is that it could well be the case that the Z06 can't maintain speed in 6th once into those speeds and so has to use a lower gear and now top speed is limited by engine RPM.

Someone opined how the GT500 was limited to 180mph. My answer was 'likely aero problems or liability' which might be lift related or instead the issue as stated above. It doesn't matter if you have 760HP if you can't gear it to overcome drag and general resistance at speed.

But really, the cars will never see north of 120mph anyway, so who cares about performance beyond that envelope? The car has to be usable and livable at well south of 80mph.

 

[ALUSA]

Gentlemen, who doesn't believe the C8 Z51 beating a C7 ZO6 can spend some time and understand how a Ford GT with 647 HP can beat a 755 HP Corvette ZR1. Their actual WHP differences are 505 WHP for the Ford GT and 650 WHP for the ZR1. That is around 150 whp difference. Its the combination of Lighter Weight, Aerodynamics, Friction Losses, Mid Engine Weight Distribution with Better Traction, and DCT. I am sure all these play a huge role when comparing the C8 Z51 and C7 ZO6.

We don't even know the exact weight on the C8 either. Even though on paper the power difference of 155 hp (650-495) does not translate that high as WHP. If the C8 is putting down 450 whp average and C7 ZO6 550 whp, we are already down to 100 whp difference.

GM maybe is only comparing 1/4 mile times, 0-60 times, and lateral G's. 1/2 mile and beyond straights the ZO6 should be able to dominate the C8 Z51. That's my take on this matter. There is more than just comparing specs on paper.

 

[Cardude99]

Honestly, I think this is gong to be one of those time that people will be so influenced by the "mid engine" mystique and the claimed 0-60 times that non will likely hold him to his claims...which quite frankly don't make sense. This goes beyond being skeptical. There isn't enough pixie dust in GM's arsenal for the C8 to beat out the C7 Z06 in the 1/4 mile. Stoplight to stoplight, yes...it will likely kill it with it's 60'. It just doesn't have to hp/weight ratio to out-muscle cars like the z06.

The new z51 is similar to a 458. Specs are all close. I would assume that 1/4 mile times are going to be close as well. The z06 is right in the same range so it is entirely possible that it could beat a z06. What I am a little skeptical about is if it will beat a z06 on the road course

 

[ALUSA]

The new z51 is similar to a 458. Specs are all close. I would assume that 1/4 mile times are going to be close as well. The z06 is right in the same range so it is entirely possible that it could beat a z06. What I am a little skeptical about is if it will beat a z06 on the road course

Road coarse is more logical than the straight line. Mid engine setup, lighter weight, better traction, better cornering, and better gearing. As long as you don't have a very long stretch the Z51 C8 should be able outperform the ZO6. Lets hope GT500 can outperform the Z51 C8 because the C8 ZO6 version will be on another level.

 

[Andy13186]

Differences in performance between the two is more likely to be rooted in the interval gearing strategies. For the C8, 7th and 8th gears are both overdrive, so all the “fun” happens in the first 6 gears. Not sure for GT500, but I would expect 7th to be overdrive. If 6th is not overdrive, then it becomes a question of what do the 6 non-overdrive gears bring to the party for each car. I would expect the gearing for the cars to be different because they are tailored to supplement wildly different engines with different power bands. So comparing them ratio-to-ratio makes for an interesting mathematical exercise but proves pretty much nothing. It comes down to which transmission provides better access to optimal power band position in most parts of the driving experience.

I agree with this, but I was referring to max HP they can handle before breaking or slipping or needing to be upgraded. For example if a C8 guy wanted to SC his car and hit 700 rwhp, would their DCT be able to handle it like a gt500's. I think the gt500's should be more stout, but maybe they made the c8's DCT transmission with the future z06 and zr1 power levels in mind too.

 

[Hack]

Differences in performance between the two is more likely to be rooted in the interval gearing strategies. For the C8, 7th and 8th gears are both overdrive, so all the “fun” happens in the first 6 gears. Not sure for GT500, but I would expect 7th to be overdrive. If 6th is not overdrive, then it becomes a question of what do the 6 non-overdrive gears bring to the party for each car. I would expect the gearing for the cars to be different because they are tailored to supplement wildly different engines with different power bands. So comparing them ratio-to-ratio makes for an interesting mathematical exercise but proves pretty much nothing. It comes down to which transmission provides better access to optimal power band position in most parts of the driving experience.

I would think you would be correct, but shift strategies alone would only be critical for at high speed straight line acceleration.

Maybe we are thinking the same thing and I just don't understand from how you are explaining it, but to me the key will be traction management. At most legal speeds and many road course speeds both cars will have some traction limitations. In other words, more power available than the tires can handle.

I believe electric cars are quick at least partially because they can react and make changes to how much power is applied very rapidly. IC engines have too much internal momentum to easily do that.

So, those are my logical steps that gets me to thinking "traction management". If one or the other DCTs allows clutches to slip in order to reduce wheel spin, that factor in addition to other techniques could be key in improving performance. That is why I got really excited when I heard the information about the wet clutches in the Ford GT500 with additional cooling for "thermal events". I could be wrong but I see this as a potential game changer.

 

[shogun32]

maybe they made the c8's DCT transmission with the future z06 and zr1 power levels in mind too.

It's the same manufacturer is it not? You can bet the 2 teams (if they are even 2 teams) are comparing notes. For reliability purposes it's possible Ford required thicker gears to be used. And GM wanted 8 gears more than they wanted a bump in reliability - or since the C8 torque is far less, can run thinner gears which gives them enough room for the extra. Or maybe Ford can't package the extra length of an 8 into the legacy Mustang platform whereas the C8 being clean sheet can be as long as they want to accommodate 8 gears.

It'll be interesting to see what the Z06 gets equipped with. Anyone want to lay bets it gets a "wide" ratio 7 speed and the C8+Z51 is running a "close" ratio 8?

 

[millhouse]

Skepticism understood. I keep bringing up the comparison of Porsche GT3 vs ZL1 (and Z06 for that matter) and the fact that despite a 207 hp disadvantage and a 260 lb-ft torque disadvantage, the GT3 is right on top of both these cars with respect to acceleration measures. It has a significant weight advantage over ZL1, but that can’t totally compensate for the large disparity in power and torque. It is not just coincidence that I refer to the GT3. A lot of the bench-marking activity for C8 development included deep study of the GT3 and Ferrari 488. The Corvette team understands what makes those cars tick and I’m pretty sure engineered the C8 structure to deliver similar results.


At the end of the day, only time and hands on testing of C8 Z51 will tell the story. When I was still at GM in Competitor Intelligence, people on the Camaro team were telling me that C6 SS would perform on par with C5 ZL1 and that C6 SS 1LE would perform on par with C5 Z/28. I didn’t believe it. Until they did. Now the guy that led engineering development of both C7 and C8 is saying publicly that C8 Z51 outperforms C7 Z06. I believe him.

Understand. If that’s all we had to go off of, I could see some hope. We have other vehicles to compare against however….and to get a sub 11 second ¼ mile (Z06 performance) is going to take a hell of a lot of weight reduction (see response below).


Your comparison to the C5ZL1 is taken, but the differences between those two cars included a transmission change and a significant weight reduction. Honestly, the c8 would have to come in significantly lighter than what people are thinking to get to the ¼ mile performance levels of the cars we are comparing.

Gentlemen, who doesn't believe the C8 Z51 beating a C7 ZO6 can spend some time and understand how a Ford GT with 647 HP can beat a 755 HP Corvette ZR1. Their actual WHP differences are 505 WHP for the Ford GT and 650 WHP for the ZR1. That is around 150 whp difference. Its the combination of Lighter Weight, Aerodynamics, Friction Losses, Mid Engine Weight Distribution with Better Traction, and DCT. I am sure all these play a huge role when comparing the C8 Z51 and C7 ZO6.


We don't even know the exact weight on the C8 either. Even though on paper the power difference of 155 hp (650-495) does not translate that high as WHP. If the C8 is putting down 450 whp average and C7 ZO6 550 whp, we are already down to 100 whp difference.


GM maybe is only comparing 1/4 mile times, 0-60 times, and lateral G's. 1/2 mile and beyond straights the ZO6 should be able to dominate the C8 Z51. That's my take on this matter. There is more than just comparing specs on paper.

Here is the problem with what you’re saying. The Z06 runs a 2.95 second 0-60 time and a ¼ mile in 10.95@127mph. The car weighs ~ 3500lbs, equating to 5.38lbs per horsepower. The Ford GT runs a 3.0 second 0-60 time and a ¼ mile in 10.8@134 mph. The car weighs~3500lbs equating to 5.18lbs per horsepower. And you are thinking that the C8 with the same drivetrain configuration as the GT weighing 150lbs more with 150 less horsepower is going to even come close to the same ¼ mile time? Think about that for a second. It would need to weigh in at no more than 2700lbs to even sniff at ¼ mile times comparable to these.


There are on occasions car with different transmissions, tires, drivetrain configurations etc. can run faster or slower than expected. The C8 doesn’t have a miracle pill that is going to allow it to perform anywhere near the GT or the Z06.

The new z51 is similar to a 458. Specs are all close. I would assume that 1/4 mile times are going to be close as well. The z06 is right in the same range so it is entirely possible that it could beat a z06. What I am a little skeptical about is if it will beat a z06 on the road course

You mean the 458 Italia that has 60 more horsepower (and is lighter to boot)? HP to weight ratio on the Italia comes in at 6.13 lbs/hp. Again, to get close to this vehicle, the corvette would need to come in right around 3000lbs.


All of the specs on this corvette point to this car being a mid-low 11 second ¼ mile car at mid-low 120mph. The 0-60 is inline the with the Z06…meaning it’s not going to be able to make up the horsepower deficiency on the top end. Aero isn’t going to account for this, nor with the transmission (Z06 already has a fast shifting auto). The only place where the c8 can gain ground on these higher horsepower, better hp/weight ratio vehicles is either on the launch or with superior gear spacing. With the c8’s engine already having a broad torque and horsepower curve, gear spacing isn’t going to do squat.

 

[mavisky]

Differences in performance between the two is more likely to be rooted in the interval gearing strategies. For the C8, 7th and 8th gears are both overdrive, so all the “fun” happens in the first 6 gears. Not sure for GT500, but I would expect 7th to be overdrive. If 6th is not overdrive, then it becomes a question of what do the 6 non-overdrive gears bring to the party for each car. I would expect the gearing for the cars to be different because they are tailored to supplement wildly different engines with different power bands. So comparing them ratio-to-ratio makes for an interesting mathematical exercise but proves pretty much nothing. It comes down to which transmission provides better access to optimal power band position in most parts of the driving experience.

It looks like 5th, 6th, and 7th will be overdrive in the new Tremec DCT. Not clear exactly which gearset Ford has chosen, but looks like some seriously long gearing for the GT500.

http://www.tremec.com/menu.php?m=155

 

[ALUSA]

Understand. If that’s all we had to go off of, I could see some hope. We have other vehicles to compare against however….and to get a sub 11 second ¼ mile (Z06 performance) is going to take a hell of a lot of weight reduction (see response below).


Your comparison to the C5ZL1 is taken, but the differences between those two cars included a transmission change and a significant weight reduction. Honestly, the c8 would have to come in significantly lighter than what people are thinking to get to the ¼ mile performance levels of the cars we are comparing.





Here is the problem with what you’re saying. The Z06 runs a 2.95 second 0-60 time and a ¼ mile in 10.95@127mph. The car weighs ~ 3500lbs, equating to 5.38lbs per horsepower. The Ford GT runs a 3.0 second 0-60 time and a ¼ mile in 10.8@134 mph. The car weighs~3500lbs equating to 5.18lbs per horsepower. And you are thinking that the C8 with the same drivetrain configuration as the GT weighing 150lbs more with 150 less horsepower is going to even come close to the same ¼ mile time? Think about that for a second. It would need to weigh in at no more than 2700lbs to even sniff at ¼ mile times comparable to these.


There are on occasions car with different transmissions, tires, drivetrain configurations etc. can run faster or slower than expected. The C8 doesn’t have a miracle pill that is going to allow it to perform anywhere near the GT or the Z06.





You mean the 458 Italia that has 60 more horsepower (and is lighter to boot)? HP to weight ratio on the Italia comes in at 6.13 lbs/hp. Again, to get close to this vehicle, the corvette would need to come in right around 3000lbs.


All of the specs on this corvette point to this car being a mid-low 11 second ¼ mile car at mid-low 120mph. The 0-60 is inline the with the Z06…meaning it’s not going to be able to make up the horsepower deficiency on the top end. Aero isn’t going to account for this, nor with the transmission (Z06 already has a fast shifting auto). The only place where the c8 can gain ground on these higher horsepower, better hp/weight ratio vehicles is either on the launch or with superior gear spacing. With the c8’s engine already having a broad torque and horsepower curve, gear spacing isn’t going to do squat.

Lets not even get into torque argument of ZR1 vs Ford GT. One with a 550 lbft vs 715 lbft. By the way do we even know the weight figure of the C8 Z51? I was hoping a healthy 200 lbs difference for the supercharged ZO6 C7 vs C8 Z51.The comparison words are coming out of a lead engineer who worked on both C7 and C8 development. If he is saying his A car is faster than his B car, what is the point of argument? Who else knows better?

 

[ALUSA]

Understand. If that’s all we had to go off of, I could see some hope. We have other vehicles to compare against however….and to get a sub 11 second ¼ mile (Z06 performance) is going to take a hell of a lot of weight reduction (see response below).


Your comparison to the C5ZL1 is taken, but the differences between those two cars included a transmission change and a significant weight reduction. Honestly, the c8 would have to come in significantly lighter than what people are thinking to get to the ¼ mile performance levels of the cars we are comparing.





Here is the problem with what you’re saying. The Z06 runs a 2.95 second 0-60 time and a ¼ mile in 10.95@127mph. The car weighs ~ 3500lbs, equating to 5.38lbs per horsepower. The Ford GT runs a 3.0 second 0-60 time and a ¼ mile in 10.8@134 mph. The car weighs~3500lbs equating to 5.18lbs per horsepower. And you are thinking that the C8 with the same drivetrain configuration as the GT weighing 150lbs more with 150 less horsepower is going to even come close to the same ¼ mile time? Think about that for a second. It would need to weigh in at no more than 2700lbs to even sniff at ¼ mile times comparable to these.


There are on occasions car with different transmissions, tires, drivetrain configurations etc. can run faster or slower than expected. The C8 doesn’t have a miracle pill that is going to allow it to perform anywhere near the GT or the Z06.





You mean the 458 Italia that has 60 more horsepower (and is lighter to boot)? HP to weight ratio on the Italia comes in at 6.13 lbs/hp. Again, to get close to this vehicle, the corvette would need to come in right around 3000lbs.


All of the specs on this corvette point to this car being a mid-low 11 second ¼ mile car at mid-low 120mph. The 0-60 is inline the with the Z06…meaning it’s not going to be able to make up the horsepower deficiency on the top end. Aero isn’t going to account for this, nor with the transmission (Z06 already has a fast shifting auto). The only place where the c8 can gain ground on these higher horsepower, better hp/weight ratio vehicles is either on the launch or with superior gear spacing. With the c8’s engine already having a broad torque and horsepower curve, gear spacing isn’t going to do squat.

Weren’t you the same guy who argued with me about the mustang gt pp2 having better straight line times with wider front and rear tires and i told you the friction losses due to aero and tire will overcome the traction. I don’t want to tell you i told you so again lol. Mid 11’s you say. Even a 10 speed mustang gt pp with E85 tune traps mid 11’s with 120+ mph.

 

[millhouse]

Lets not even get into torque argument of ZR1 vs Ford GT. One with a 550 lbft vs 715 lbft. By the way do we even know the weight figure of the C8 Z51? I was hoping a healthy 200 lbs difference for the supercharged ZO6 C7 vs C8 Z51.The comparison words are coming out of a lead engineer who worked on both C7 and C8 development. If he is saying his A car is faster than his B car, what is the point of argument? Who else knows better?

We do know the weight. The dry weight is listed as 3366lbs. Adding fluids this brings the weight up to 3600 lbs, 150lbs more than the C7 corvette.

https://www.caranddriver.com/news/a28448822/2020-corvette-mid-engine-size-comparison/

Words from the engineer...are just those. Notice they mentioned a sub 3 second 0-60 (when properly optioned) yet don't mention a sub 11 second 1/4 mile? There is a reason for this.

As for the engineer, he never said the C8 is faster in the 1/4 mile. Again, this is intentional. The C8 just doesn't have the power to weight ratio to keep up at the drag-strip...where traction is much less limited than the street.

Weren’t you the same guy who argued with me about the mustang gt pp2 having better straight line times with wider front and rear tires and i told you the friction losses due to aero and tire will overcome the traction. I don’t want to tell you i told you so again lol. Mid 11’s you say. Even a 10 speed mustang gt pp with E85 tune traps mid 11’s with 120+ mph.

No idea. The pp2 performs exactly as expected. The 1/4 mile is on par with the pp1..having a better 60' but lower trap.

As for a mustang gtpp with an E85 tune, you have just accidentally proven my point. A 2019 coyote with an e85 tune cranks out 532hp. This amounts to 7.14 lbs/hp. This C8 corvette is going to have 7.27 lbs per horsepower. And there you have it.

https://www.hotrod.com/articles/ford-5-0l-coyote-dyno-test-cai-e85-tune-makes-532-hp/

 

[Cardude99]

You mean the 458 Italia that has 60 more horsepower (and is lighter to boot)? HP to weight ratio on the Italia comes in at 6.13 lbs/hp. Again, to get close to this vehicle, the corvette would need to come in right around 3000lbs.


All of the specs on this corvette point to this car being a mid-low 11 second ¼ mile car at mid-low 120mph. The 0-60 is inline the with the Z06…meaning it’s not going to be able to make up the horsepower deficiency on the top end. Aero isn’t going to account for this, nor with the transmission (Z06 already has a fast shifting auto). The only place where the c8 can gain ground on these higher horsepower, better hp/weight ratio vehicles is either on the launch or with superior gear spacing. With the c8’s engine already having a broad torque and horsepower curve, gear spacing isn’t going to do squat.

The Italia has significantly less tq and has a slightly less favorable weight distribution. I have no reason to believe that the c8 is not running low 11's stock. Also didn't say it would win I said it gonna be close and in the ballpark which is exactly where the z06 is. It is entirely possible that it could put up better numbers than z06. I just think a lot of people are discrediting the car before giving it a chance.

 

[WildHorse]

The Italia has significantly less tq

Doesn't matter.. The Italia is geared much better then the vette.

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