C7 Zo6

[Groundpilot]

[QUOTE=gthal;15423614]2LT with GT seats. GT seats were fantastic... can only imagine how nice the competition seats will be.

I think competition seats=bucket seats. Will be great for the track, but pain in the butt for daily driving

[Petros]

You're putting words in my mouth and making strawman arguments. I never mentioned peak torque. That's an irrelevant number. What I meant was the torque curve at the wheels. Your argument seems to hinge on using power to weight for its predictive value regarding vehicle performance. And I agree it's a good metric with some predictive power. However, it is also based on the assumption that peak power correlates with overall power throughout the rev range, and that is mostly true for modern engines since they're designed to have a semi-constant torque curve. But hp/lb isn't always a good predictor of performance.

For example an Evo X GSR has 291 hp and 3527 lb of weight for a power to weight ratio of 0.08251. 0-60 is 4.9 s and 1/4 mile time is 13.6 s

On the other hand an AP1 S2000 has 240 hp and 2745 lb of weight for a power to weight ratio of 0.08743. However, 0-60 is 5.9 s and 1/4 mile time is 14.4 s.

Your metric of power to weight ratio would predict the S2000 would be faster, yet it is substantially slower than an Evo X.

[Petros]

Originally Posted by bruce.augenstein@comcast.

Swamp.

Stop. Just stop.

He doesn't get it. He may never get it. Why bother?

He's also the kind of guy who feels the need to demonstrate that he knows the difference between mass and weight. (!)

My dad once told me to never get into an argument with an idiot, because people may not be able to tell the difference.

Good advice. Take it.

Bruce

I would say the biggest sign of an idiot is making inane comments that don't add any value and insulting people from behind the safety of a computer screen. Seems like your dad forgot to teach you how to act like a human being and keep it classy. I'd be happy to teach you that if I ever saw you face to face.

[Groundpilot]

Originally Posted by Petros

I would say the biggest sign of an idiot is making inane comments that don't add any value and insulting people from behind the safety of a computer screen. Seems like your dad forgot to teach you how to act like a human being and keep it classy. I'd be happy to teach you that if I ever saw you face to face.

Very good Lets see if he accepts your challenge

[Handy Man]

Originally Posted by Petros

For example an Evo X GSR has 291 hp and 3527 lb of weight for a power to weight ratio of 0.08251. 0-60 is 4.9 s and 1/4 mile time is 13.6 s

On the other hand an AP1 S2000 has 240 hp and 2745 lb of weight for a power to weight ratio of 0.08743. However, 0-60 is 5.9 s and 1/4 mile time is 14.4 s.

Your metric of power to weight ratio would predict the S2000 would be faster, yet it is substantially slower than an Evo X.

Bad example. AWD gives the EVO a huge advantage in 0-60. After the 60' mark the S2000 is faster, which is exactly what its hp/lb predicts.

[bruce.augenstein@comcast.]

Originally Posted by Petros

I would say the biggest sign of an idiot is making inane comments that don't add any value and insulting people from behind the safety of a computer screen. Seems like your dad forgot to teach you how to act like a human being and keep it classy. I'd be happy to teach you that if I ever saw you face to face.

Really. You want to get physically confrontive?

Sheesh. I fought quite a bit in high school, but then I grew up. I suggest you do the same.

On the other hand, see my next note. I feel the need to apologize.

Bruce

[Groundpilot]

Originally Posted by bruce.augenstein@comcast.

Really. You want to get physically confrontive?

Sheesh. I fought quite a bit in high school, but then I grew up. I suggest you do the same.

On the other hand, see my next note. I feel the need to apologize.

Bruce

[bruce.augenstein@comcast.]

Originally Posted by Petros

You're putting words in my mouth and making strawman arguments. I never mentioned peak torque. That's an irrelevant number. What I meant was the torque curve at the wheels. Your argument seems to hinge on using power to weight for its predictive value regarding vehicle performance. And I agree it's a good metric with some predictive power. However, it is also based on the assumption that peak power correlates with overall power throughout the rev range, and that is mostly true for modern engines since they're designed to have a semi-constant torque curve. But hp/lb isn't always a good predictor of performance.

For example an Evo X GSR has 291 hp and 3527 lb of weight for a power to weight ratio of 0.08251. 0-60 is 4.9 s and 1/4 mile time is 13.6 s

On the other hand an AP1 S2000 has 240 hp and 2745 lb of weight for a power to weight ratio of 0.08743. However, 0-60 is 5.9 s and 1/4 mile time is 14.4 s.

Your metric of power to weight ratio would predict the S2000 would be faster, yet it is substantially slower than an Evo X.

OK, I apologize. Sincerely. Schoolboy fisticuffs threat aside, it seems you really do get it.

On the other hand, quarter mile ET is hard to predict from power to weight deltas. What weight over power predicts with some accuracy is trap speed. No it's not perfect. Far from it, in fact. But on the other hand weight over torque predicts absolutely nothing in terms of acceleration performance, over a quarter mile or whatever.

Having said that, however, it's true that if you compare two cars with roughly equal power-to-weight numbers, the car with better torque-to-weight numbers will tend to win the drag race, because it will make more power after each shift, backing up your statements regarding average power over whatever duration. The early C63s vs E92s demonstrated this point. The bimmer had a slightly better power-to-weight number, but couldn't stay with the Merc over a quarter mile.

As an example of variances within a power-to-weight spectrum, I predict the M4 will outperform normal expectations based on power to weight, because it will essentially continually stay at max power from third gear on, quite unlike, say, the E9X M3, or the new Corvette. Those cars drop quite a bit of power after each shift.

Bruce

PS - Just as a rule of thumb, quarter mile trap speed varies as per the cube root of the power to weight delta. Torque need not be considered. As an example, the Dynojet folks calculate power by having your drive wheels accelerate a known mass from some speed to another speed. They don't bother with torque unless you want to hook up a tach feed. Then they'll calculate torque from their power readings at whatever rpm - but they don't need that and don't give a damn about it.

[swamp2]

Originally Posted by Handy Man

Bad example. AWD gives the EVO a huge advantage in 0-60. After the 60' mark the S2000 is faster, which is exactly what its hp/lb predicts.

Thank you, spot on. Not directed at you, since you "get it" but I've never claimed (peak) power to weight is an omniscient predictor, just the best simple predictor by far.

[swamp2]

Originally Posted by Petros

You're putting words in my mouth and making strawman arguments. I never mentioned peak torque. That's an irrelevant number. What I meant was the torque curve at the wheels. Your argument seems to hinge on using power to weight for its predictive value regarding vehicle performance. And I agree it's a good metric with some predictive power. However, it is also based on the assumption that peak power correlates with overall power throughout the rev range, and that is mostly true for modern engines since they're designed to have a semi-constant torque curve. But hp/lb isn't always a good predictor of performance.

For example an Evo X GSR has 291 hp and 3527 lb of weight for a power to weight ratio of 0.08251. 0-60 is 4.9 s and 1/4 mile time is 13.6 s

On the other hand an AP1 S2000 has 240 hp and 2745 lb of weight for a power to weight ratio of 0.08743. However, 0-60 is 5.9 s and 1/4 mile time is 14.4 s.

Your metric of power to weight ratio would predict the S2000 would be faster, yet it is substantially slower than an Evo X.

You said (again),

Originally Posted by Petros

Power is just a number used by marketing departments to sell cars. What makes you accelerate is torque.

If you are speaking consistently then you must be talking about a single peak number, just above you are comparing power "a number" to torque. I'd never argue that knowing peak power is somehow better than knowing an entire torque curve. It seems to be clear that what you said and what you meant weren't quite the same.

I already addressed your example above on the two specifics. But again, finding an exception to the rule does not detract from the rule's simplicity and predictive power.

As a small concession I think I understand where the idea that torque is "what matters" or torque is what accelerates a car comes from. Torque is simple, concrete, its just a force acting through a distance (typically on a rotating object). When you think about the physics of the car, the drivetrain and its acceleration and of course when writing a spreadsheet or vehicle acceleration simulation tool, the first thing one would likely do is make tables of torque at the wheels as a function of each gear and all rpms. Then a basic force and torque balance provides the net thrust force on the car (with some careful treatment of losses and interias). After all torque twists that wrench when we work on our cars and torque twists the crankshafts and ultimately the wheels. There is nothing wrong with this point of view. Power on the other hand is slightly more abstract, especially to the lay person (not you, obviously with your background). It's not until one carefully dissects the problem and resolves my prior numbered statements about torque and power (even those are actually only "first order" correct, there are corrections abound which have all been discussed in great detail here on this forum) that the simplicity and importance of power and then peak power becomes transparent and even enlightening.

Last but not least, I ain't a mod here, but I will try to help self police the forum. Bruce made a uncalled for insult. However, the threat (even a loose one) of physical violence is totally unacceptable here. Please keep that in check to insure this is a place we all want to hang out.

Cheers.

[swamp2]

Originally Posted by bruce.augenstein@comcast.

On the other hand, quarter mile ET is hard to predict from power to weight deltas. What weight over power predicts with some accuracy is trap speed. No it's not perfect. Far from it, in fact.

Not so. It's sort of all about the R^2 value... Really.

There is only a 3% difference in the predictive capability of power to weight vs. trap and power to weight vs. ET. And in fact the model for ET actually has fewer outliers:

http://www.stealth316.com/2-calc-hp-et-mph.htm

Originally Posted by bruce.augenstein@comcast.

But on the other hand weight over torque predicts absolutely nothing in terms of acceleration performance, over a quarter mile or whatever.

As much as I thought the data would make a massively worse correlation (hence my challenge to Petros) the short answer is that is is way better than I expected. The data just happened to be present in the link above so I grabbed it and did the work.

We have to accept (observe) that average power correlates reasonably well with peak power. If that wasn't the case we would not have such a strong predictive power in this model. However, power and torque are certainly correlated as well. Of course since peak torque and peak power pretty well never occur at the same rpm we can't use the rigid relationship at a given rpm. However, not surprisingly peak torque and peak power as well as average power are all correlated. The R^2 value when running the regression is a surprisingly high, 0.78. Again that is compared to a 0.93 for trap speed vs. (peak) power to weight. So in short the torque to weight model is only capturing 15% less of the observed variation.

Last but not least, we should observe that despite this reasonable correlation this relationship is still entirely less CAUSAL than regressing vs. power to weight. Recall the important distinction between correlation vs. causation. The physics indicate we should observe a correlation in the power to weight case and we do. It just so happens that peak torque also correlates with peak power. There is no reason this has to be so, as evidenced by F1 cars that make absurd power with very little torque. And again we can do the thought experiment where we double peak torque and performance won't change appreciably, we can't do the same with power.

I won't be surprised if you have a more elegant way of explaining why the correlation is much better than expected.

[DieGrüneHölle]

Originally Posted by sunsweet

You got me wrong if you think i'm angry, I'm having fun here seeing GM trying so hard with the same old platform over and over. Grandpa's condo association are big supporters of vettes

They will continue to win races and championships with their "same old platform". Back to back ALMS championships against your so-called superior platform competition. Do you have the same opinion about Porsche and their "same old platform" for the 911?

And since you are into generalizations and think only grandpa's drive Corvettes. Here is a generalization for you, anyone that lives in North Carolina a redneck.

[V8FunNaturally]

Originally Posted by Blipit_

anyone that lives in North Carolina a redneck.

really ?? you just discredited yourself big time.

[///M3AN]

Does it have leaf springs?

[DieGrüneHölle]

Originally Posted by sunsweet

really ?? you just discredited yourself big time.

You did that to yourself many posts ago. See how that works. Pot calling the kettle black.

[V8FunNaturally]

Originally Posted by Blipit_

You did that to yourself many posts ago. See how that works. Pot calling the kettle black.

The topic is about individual views on the C7 zo6 which is what my posts are. You don't like my views, go deal with it (to put it politely). Everyone is welcome to express their views on the topic without having some ____ like you go personal on them and namecalling an entire state for it.

[swamp2]

Originally Posted by ///M3AN

Does it have leaf springs?

From a similar thread in a similar topic a couple years back...

Originally Posted by swamp2

As much as the somewhat low tech approach of certain Corvette systems do not appeal to me from a technical perspective, you can not argue with results. Bruce is spot on here. The transverse composite leaf spring rear set up on the Vette (Z06 and ZR1) is not your father's pick up truck leaf spring set up. It is light, highly refined and effective. That being said the GT2 C6.R Vette did go with an upgraded to the leaf spring set up to a full coil over in the rear. From that we can conclude either the performance or adjustability dictated the upgrade. I would guess a bit of both, not just adjustability. So even though we might conclude there is a bit more performance to be had from a more traditional rear suspension set up for the production Vette, you simply can not argue with its handling prowess.

And yes the new C7 car still uses a leaf springs and I'll guess the Z06 will as well. There are a plethora of advantages to this design including, lower center of gravity, less weight, less reinforcement structure/weight in the shock tower, built in anti-roll function meaning less weight in the formal roll bar. They system also offers height/corner weight tuning. The only draw back I see to the design is lack of ability to easliy change the spring rate.

[bruce.augenstein@comcast.]

Originally Posted by swamp2

Not so. It's sort of all about the R^2 value... Really.

There is only a 3% difference in the predictive capability of power to weight vs. trap and power to weight vs. ET. And in fact the model for ET actually has fewer outliers:

For me, that 3% is essentially a yawning gap. At least it is out on a drag strip. I admit that numerically speaking, 3% is a relatively tiny amount.

Originally Posted by swamp2

http://www.stealth316.com/2-calc-hp-et-mph.htm

Nice find! Thanks.

Originally Posted by swamp2

As much as I thought the data would make a massively worse correlation (hence my challenge to Petros) the short answer is that is is way better than I expected. The data just happened to be present in the link above so I grabbed it and did the work.

We have to accept (observe) that average power correlates reasonably well with peak power. If that wasn't the case we would not have such a strong predictive power in this model. However, power and torque are certainly correlated as well. Of course since peak torque and peak power pretty well never occur at the same rpm we can't use the rigid relationship at a given rpm. However, not surprisingly peak torque and peak power as well as average power are all correlated. The R^2 value when running the regression is a surprisingly high, 0.78. Again that is compared to a 0.93 for trap speed vs. (peak) power to weight. So in short the torque to weight model is only capturing 15% less of the observed variation.

Last but not least, we should observe that despite this reasonable correlation this relationship is still entirely less CAUSAL than regressing vs. power to weight. Recall the important distinction between correlation vs. causation. The physics indicate we should observe a correlation in the power to weight case and we do. It just so happens that peak torque also correlates with peak power. There is no reason this has to be so, as evidenced by F1 cars that make absurd power with very little torque. And again we can do the thought experiment where we double peak torque and performance won't change appreciably, we can't do the same with power.

I won't be surprised if you have a more elegant way of explaining why the correlation is much better than expected.

Sans elegance, three things:

First, taken across a plethora of data points, torque-to-weight will generally be a rough average percent (compared to power) across many internal combustion engines.

Second, expect the rough average to change as we move further into force-fed proliferation of engines, and particularly, force-fed diesels. In these cases, the torque-to-power relationship changes pretty dramatically, while quarter-mile performance changes only somewhat..

Lastly (and just in agreement), power and weight will be a strong predictor of quarter mile performance case by case, and torque and weight will not be. The fact that you've found a moderately loose relationship across a large number of cars is interesting, but no more than that.

Bruce

[Groundpilot]

Very interesting video, that demonstrates how much stronger the CF drive shaft is vs the conventional steel one. CF will used in C7 Z06

[swamp2]

Originally Posted by Groundpilot

Very interesting video, that demonstrates how much stronger the CF drive shaft is vs the conventional steel one. CF will used in C7 Z06

That is a good video. It has been discussed in some detail in the M4 section as that new car also has a CF drive shaft. One of the main points I made over there was that this is definitely neither new nor exotic. The 2001 Mitsubishi Montero had one. The 350Z had one in the Japanese version in 2002. The Mazda RX-8 had one as well in 2003. The Acura RL in 2005. I think maybe even earlier Nissans had them as well. Don't drink all of the CF this and CF that BMW Kool-Aid.

[Wolfinwolfsclothing]

Originally Posted by swamp2

That is a good video. It has been discussed in some detail in the M4 section as that new car also has a CF drive shaft. One of the main points I made over there was that this is definitely neither new nor exotic. The 2001 Mitsubishi Montero had one. The 350Z had one in the Japanese version in 2002. The Mazda RX-8 had one as well in 2003. The Acura RL in 2005. I think maybe even earlier Nissans had them as well. Don't drink all of the CF this and CF that BMW Kool-Aid.

+1

[Groundpilot]

Shark grey c7z06
http://www.youtube.com/watch?feature...&v=eucnb7Qf08U