Re: Interesting point (archive)

according to C&D, the top speed was reached in 5th gear at redline. With the Z06's final drive ratio, I would bet even money (again I don't own one) that the top speed in 6th is lower than in 5th (C&D backs me up) (155 vs 168mph)

Actually the Corvette numbers are posted on the Chevrolet website for several months. I was too lazy to check that both the 5th and the 6th gears are overdrives and as such, the 6th gear would likely be too weak to hold a top speed.

Since the torque put to the road at 155 in 6th is (roughly 360ft-lbs at the engine) * 0.56*3.42=689ft-lbs vs the 808ft-lbs in 5th @ ~6500rpm. Using a square relationship of drag with speed, such a torque difference equates to (assuming that 5th gear gets you 168mph) a top speed in 6th gear of 154.8mph or DAMN close to C&D's number of 155.

Your numbers are NOT adding up again. The gear ratios for the 5th and the 6th gears are respectively, 0.84 and 0.56. Depending on the exact RPM at the maximum speeds in each gear [~6,300 RPM (5th) vs. ~3,800 RPM (6th and drag limited) with the torque peak at 4,800 RPM], the rear-wheel torque in 5th gear would be ~135 % of that in 6th gear. The square dependence of velocity to aerodynamic drag would give a maximum speed of only ~145 MPH in 6th gear. The more probable answer is that the top speed is essentially limited by redline in 5th gear, since the top speed quoted at the Chevrolet website is only ~5 MPH below redline speed in 5th gear. And until approaching redline, the rear-wheel torque in 5th gear is more than aerodynamic drag and hence, a direct conversion (through the square dependence of velocity in aerodynamic drag) of the top speed in 5th gear to the maximun speed in 6th gear is incorrect.

Basically I think the top speed of the Z06 is ~170-172 in 5th gear, the C5 maybe 1-3mph more. Weather conditions and etc and change this by a few mph thus giving the range of mag. figures of 168-175 for the Z06, and speedo error, weather, or luck, accounts for anyone that has run 180 in a stock Z06

-m

All the test results can actually be found on the Web for several months. It is funny that you can claim numbers close to those and yet errors keep on showing up in your "calculations".

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