C6 ZO6 Top Speed Question
10-02-2005, 04:32 PM
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C6 ZO6 Top Speed Question I have the October issue of Car and Driver here and something puzzles me:
Gear Speed in Gears
I 59 mph (7000 rpm)
II 88 mph (7000 rpm)
III 121 mph (7000 rpm)
IV 157 mph (7000 rpm)
V 198 mph (6500 rpm)
VI 160 mph (3600 rpm)
What's with the 6500 rpm in 5th gear? Why don't they use 7000 like the rest of the gears (except 6th)? It seems the top speed would be higher or am I missing something?
Gear Speed in Gears
I 59 mph (7000 rpm)
II 88 mph (7000 rpm)
III 121 mph (7000 rpm)
IV 157 mph (7000 rpm)
V 198 mph (6500 rpm)
VI 160 mph (3600 rpm)
What's with the 6500 rpm in 5th gear? Why don't they use 7000 like the rest of the gears (except 6th)? It seems the top speed would be higher or am I missing something?
10-02-2005, 04:50 PM
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Blue six is exactly correct. There just ain't enough power left to pull beyond 6500 in 5th. A lot of people just do not understand the relationship between speed and frictional loss associated with it. The frictional loss goes up by the square of the velocity, if all else is equal. If it takes 100 horsepower to make a particular car go 100 mph, it will take 400 hp to make that same car go 200! This is why aerodynamics is so important, if you can lower the CD, you can travel faster without the need for more horsepower.
Regards, John McGraw
Regards, John McGraw
Last edited by John McGraw; 10-02-2005 at 09:13 PM.
10-02-2005, 05:37 PM
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So, then how much extra HP would the ZO6 need to break the awesome 200MPH barrier. Are we talking about a set of long tube headers, or a radical cam. I would think that 2 mph could definitley be added to the top speed with just a set of headers or even a computer tune.
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10-02-2005, 08:31 PM
#9
Originally Posted by John McGraw
Blue six is exactly correct. There just ain't enough power left to pull beyond 6500 in 5th. A lot of people just do not understand the relationship between speed and frictional loss associated with it. The frictional loss goes up by the square of the velocity, if all else is equal. If it takes 25 horsepower to make a particular car go 100 mph, it will take 625 hp to make that same car go 200! This is why aerodynamics is so important, if you can lower the CD, you can travel faster without the need for more horsepower.
Regards, John McGraw
Regards, John McGraw
10-02-2005, 10:10 PM
#12
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P Mack,
I knew the Qubeing formula was used in centrifigual fan calculations, but I did not know that it applied here. I allways just thought that it was a simple square of the velocity. So, if I understand you correctly, a 100 hp at 100 mph would be 800 hp at 200mph?
Regards, John McGraw
I knew the Qubeing formula was used in centrifigual fan calculations, but I did not know that it applied here. I allways just thought that it was a simple square of the velocity. So, if I understand you correctly, a 100 hp at 100 mph would be 800 hp at 200mph?
Regards, John McGraw
Last edited by John McGraw; 10-02-2005 at 10:23 PM.
10-02-2005, 10:22 PM
#13
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P Mack,
Never mind. After thinking about it, it only makes sense! I was thinking of force (drag), but totally discounting the effects of velocity.
Regards, John McGraw
Never mind. After thinking about it, it only makes sense! I was thinking of force (drag), but totally discounting the effects of velocity.
Regards, John McGraw
10-02-2005, 11:50 PM
#17
Originally Posted by P Mack
To get back on topic, the reason it only goes to 6500 in fifth is because at 7000 rpm it would be going about 213 mph. And to do that would take roughly 25% more horsepower. Instead of 505 hp at 6500 rpm, it would need around 630 hp at 7000 rpm.
10-03-2005, 10:06 AM
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Hi All: I think the reason it didn't go over 200 mph is more to do with limitations of the stock ECM and speed sensor. I don't think it is calibrated for over 200 mph operation. If you could recalibrated the ECM and sensor I think you would see a higher top end? Maybe FAST will come out with an aftermarket unit for these motors? Just my thoughts I could be wrong. Bye
10-03-2005, 12:59 PM
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Is there some politics involved too? If a car has a claimed top speed of 200 mph or more does something happen? (Insurance, price, etc.) I mean, 198 is so close that it seems Chevy could have made a very minute change to push it over 200, or do they just not care?