02HREBlue

The mistake is yours funny man. I said "A" previous generation turbo, not "THE" previous turbo. You obviously can't read.

I definitely know my cars and facts as well as Porsches.

The OP had no problem with what I said either guy. He understood, whats your beef?

I guess no one on the forums here can know or have anything other than a Corvette, or they must have read it in Road and Track? I happen to have and have had quite an array of cars and driving experiences.

Beyond amusing.

ibleedgreen

Gotcha, no beef, just didn't sound right I guess. The amount of misleading info on here is amazing, was just trying to keep it clear.

02HREBlue

Except for cost, the McLaren wins hands down. Its the real deal.

02HREBlue

Thats fair

ivanjo11

Whatever is the weight of the AFM 20,25 or 30 lbs, i don't see any true sports cars like Ferrari 458 or Porsche GT3 with that stuff you want those cars to be as light as possible.


Seems like you have to see it to believe it here is the S63 weight reduction: http://www.caranddriver.com/news/201...easures-page-2

OJCrush08

It is, but given my own proclivities and now entering into my "dream state", the Ferrari 458 Speciale is my ultimate toy of choice.....

harlold

Just wait until they roll out with the ZR1 that has KERS and weights 200# more.

The bench racers are going to implode.

zeshawn

indicating curb weight vs torque without considering RPM is a huge mistake, some of those cars hit 9000rpms hence make shitloads of power there regardless of the low torque, HP vs curb weight is the correct way of doing it and changes everything.

Callsign_Vega

Nonsense. All of those cars have high TQ and high HP numbers. Take a vehicle with high TQ numbers and low HP numbers, they are dreadfully slow.

A NISMO GTR does the Ring in 429 seconds, 10 seconds faster than the next fastest on your list. It has 595 HP and only 481 ft/lb of TQ, weighs ~3800 lbs. Pretty much invalidates your post.

zeshawn

I just saw Ching Ho's other explanation and it makes even less sense now. Dear Ching ho, using nurburgring times to validate your point is a VERY bad example on how to approach this, you have to take into consideration that ASSUMING you are on the throttle for 50% of the time, you are on the brakes the other 50% of the time on a road course (those %'s are not accurate by any chance, just trying to make a point for the sake of the argument), then your calculations are falsely taking into consideration how good the brakes are, and the conditions of the track, the weather, driver, tires, transmission shift speeds, gear ratios, aerodynamics and so on.

The second problem I see here if your using advertised HP and curb weight figures for those vehicles, both numbers which are usually underrated or measured with different vehicle options, which could change the weight a good bit.

Third, those vehicles aren't being driven by the same driver (guess I mentioned this already), this itself is big factory in the equation.

Finally, the sample size is far from enough to even conclude such a thing, the three things that make a car fast is the amount of torque it can generate at the rate the engine is spinning at (rpm) vs the weight it has to act upon which inevitably equates to HP/lbs regardless of how we try to look at it.

User24

It just stems from a breed of drivers who consider the underlying design, whether or not it is sound according to their biases, whether or not it gives them peace of mind prior to considering ownership.

An economy chassis car with a somewhat powerful engine, aka pony car is supposed to weigh a certain amount. Once a beloved sports car creeps up there, people will be disappointed. Whether the expectations were realistic or not, or pure fantasy, it's really nothing to be upset about. We are a mix of disciplines, we like cars but approach from different viewpoints. Some are track time folks, some 0-60, some style, some GT, some a balanced mix of everything.

Loosing 50 lbs off my midsection would be impossible; 50 lbs would have to come from other parts of my body as well and I'd be dead.

1985 Corvette

I don't find the weight to be a bother. If it crept past 3800 pounds, I'd start to feel differently. I have no problem trusting that, for a street car, all the materials and parts used on the C7 Z were necessary and not fluff. Maybe in time they will offer delete options for people who are really serious to shed weight and get rid of everything short of a steering wheel and a seat.

amgman

Weight?

nuck

Yes^. The 3900lb GTR is an obese tank and still a tremendous track performer. No the Z won't have AWD but if it out handles and gets more power to the ground than the ZR1 it should be a standout.

HolyRoller

Hard to tell from the maker's specs. http://www.braillebattery.com/index....batteries/i65s says "19.5lb/5.22kg" but 19.5lb = 8.9kg and 5.22kg = 11.5lb so let's say it weighs 19.5lb and we know we can buy one for $2,400. Here's the most expensive battery for the C7 at Batteries Plus http://www.batteriesplus.com/product...2L-615CCA.aspx which is $170 for 45.5lb. Wow, $2,230 extra saves an entire 26lb. But if that forces all sports car snobs to admit that the C7 Z06 is now a sports car because it's 26lb lighter, it's money very well spent.

jimmyb

I got it the first time....you think the C7 Z06 should not have AFM.
You better get used to mileage stretchers on higher volume, high power sports cars as mileage standards tighten. All 911 Carreras have stop/start now, which adds weight through heavier, higher capacity batteries, more stout starters, and alternators. For very limited cars (like the GT3/Speciale) there's NO need to do these type things. In fairness, while you keep comparing those two cars (GT3/Speciale) to the Z06, you should also keep in mind that there will probably be 3 times as many Z06's built as GT3/Speciales combined. In theory, you're comparing "track" cars, in reality the Z06, because of it's production level, HAS to, at least give the impression of being somewhat "green".


Jimmy

PS. While I'm not sure why the M-B S63 AMG got into this conversation (the car was GROSSLY overweight, now the new one is just really overweight), I looked up the battery required for the 2013 model. It is a HUGE battery (Motor Trend called it "Freakishly huge") and it weighs nearly 60 pounds! That said, I seriously doubt that the new lithium battery weighs 15 pounds so I think Car and Driver got this wrong.

Lavender

You should definitely do some research..

Lavender

SBC_and_a_stick

Let me give it a shot.

Hypothesis: Correlation analysis is insufficient to capture the relationship between torque and car performance.

Theoretical approach:
1. Your model cannot distinguish between two engines that are equal in every way except one has more torque. It cannot distinguish between the Hell Cal engine and the LT4. This is in fact, a most important point. The manufacturers are hell bent on using forced induction and DCT transmissions nowadays. DCTs are generally torque capacity constrained. That's why we see turbo cars like the GT-R and 911 increasing power from year to year while keeping torque relatively unchanged. Your model cannot account for increases in torque at the top of the rev range unless peak torque increases as well. In other words, your model cannot even capture the torque curve, but rather one single point in a continuous distribution.

2. Your model fails to take into account power and other publicly available information about the cars in question. Why limit yourself to kerb weight and peak torque when you can improve the predictive ability of your model significantly using information readily available just about anywhere? The coefficient of correlation may be the best predictor for car performance if we only observed weight, torque, power, but we were only able to use a ratio of two of them. In reality, these restrictions don't exist, and therefore your correlation analysis can be easily beaten by the smallest modifications.

3. Correlation does not imply causation. To see why this is true consider that I could use correlation to predict the chance of rain. I observe the number of umbrellas out of my window and run a correlation analysis by observing whether indeed it is raining outside. Even if this correlation is .9 and I can easily use this model to predict the chance of rain, the number of umbrellas does not CAUSE rainfall. Therefore, if you and me both opened our umbrellas we would not make it more likely for rainfall to occur. In your model, it is unclear whether the weight to peak torque ratio predicts performance due to torque characteristics or other features of high torque vehicles.


Empirical proof:

1. Regress Nurburgring time on your ratio variable while controlling for dry weight, and a polynomial fit to the power curve. Given that no other confounding factors exist you should get a coefficient that is statistically insignificant for the ratio. Anything else is a spurious relationship.

2. Tire patch, power, and many other 3rd factors are correlated to both Nurburgring times and torque/weight. A simple predictor like weight/torque ratio is therefore a biased estimator of Nurburgring times.

QED, next.

Ching Ho

Whoa there. You do know my intent is not to enter a nerd dick-measuring contest, right? I'm merely stating that, mathematically speaking, no other metric correlates to performance better than torque-weight.

Of course correlation doesn't equal causation - we're not going for FDA approval here. Winning in professional basketball correlates highly to being tall (and black). Does it prove causation? No. But everyone knows it's true. 55% correlation on torque-weight alone is pretty damn strong.

Once again, I'm not building a multi-variable regression model... I'm just providing mathematical proof on what the single most important variable is. It remains 100% true that no other individual metric exceeds torque to weight. Test any other individual metric...I challenge you to run the numbers yourself & prove me wrong.