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Discussion Starter #1
I believe it is untrue that the hardtop Z06 is slower than the Coupe. I just did a top speed projection (believed to be accurate) on 2001 vs. 2002 Z06s. The results suggest to me that both model years of the Z06 have higher top speed than generally assumed.

I used a rather conservative approach to the projection and still the full speed #s were better than most people might think.

A bone stock 2001 "should" (under normalized test conditions) achieve 174+ and stock 2002 at least 176. Again, these projections are rather conservative, not exaggeration.

When the 1990 ZR-1 first came out the mags said it could do "173". That # eventually went up to 180 over the years, but fact is the majority of ZR-1s (stock), including the 405hp cars, are not up to that mark without modifications to the engine for more high end HP and/or other than stock gearing.

Interesting counterpoint, I've had mine up to an honest 180 "exactly" but my 1990 ZR-1 is no longer stock nor geared as it came from the factory. It took a considerably long, straight stretch of road to get up to that speed.

Now here's a shock. I managed to do the same thing in my LT4 C4. It had factory gearing, but an uncorked exhaust.

I've always felt the LT4 Corvette is what I call a "sleeper". It's engine power was under rated and so is it's top speed.

Testing of Z06s at top speed have been few and far between in the mags. In fact, there may not have been any tests with that sole intent over the past year.

I believe the 2002 Z06 is now not only the quickest Corvette ever produced, but also the "fastest". It's only a matter of time before this will be confirmed and I do feel it will happen.

Just remember you heard it from me first, right here on the Z06vette.com forum.
 

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Are you getting these numbers from yur speedometer? If you are, you might want to reconsider your findings.

A stock speedometer always has a a margin of error of about 5%.

The only true-way of testng a vehicle for top speed is by way of a Stalker radar gun, like the ones used by law enforcement agencies and by speed traps.
 

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Discussion Starter #3
VPRKLR, I have used independent means for verification, not speedometers. I do not have access to a Stalker but have been caught on radar doing 177 once and did not have go to jail. I also have several high speed runs on video.

Actually, the speedo in my LT4 is extremely accurate, and my ZR-1 indicated 185 when I was actually driving exactly 180. No guess work, I have driven both cars to an honest 180 mph on several occasions. I can't wait to attempt the same when I get my new Z06 in a couple months.

The best part about this is that there's a way to drive these cars very fast LEGALLY even on a public road - open road racing - which I have been doing for the past six years.
 

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On 2001-07-08 18:00, dsinned wrote:
.... The results suggest to me that both model years of the Z06 have higher top speed than generally assumed.
If GM says the Z06 is gearing limited to a 171 top speed in 5th gear at just below the point where the rev limiter kicks in, how will you get more mph out of it?

Shifting to 6th you will lose speed due to its taller gear ratio.

Can't blow past the rev limiter.

So how is the additional speed to be achieved?

I'm curious.

Ranger
 

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I guess we will all find out if the Z06 is rev limited to 170 to 175 mph like GM and the auto press say it is. I always thought there is a direct relationship in a manual tranny car between revs and speed in a gear so that lets say 85 or so mph at 3300 rpms in 5th will tell you that 170 or so mph at 6600 rpms is IT! My tach and mph in 5th at 3300 rpms seems to verify GM's top speed claims.
 

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The November 2000 Road & Track tested several cars in Germany and they clocked the Z06 at 174.8 mph. They did use an external device to measure, not the speedo.
 

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Discussion Starter #8
The Z06 is "drag limited" at top speed not rev limited. And I'm referring to speeds obtainable in 5th gear, not 6th.

My prediction program predicted 174.19!!!

The R&T test turns out to be RIGHT ON for a 385hp Z06. Their test car must of hit the aerodynamic "wall" a tiny bit higher then the speed I predicted but darn close. A 0.61 mph positive deviation is statistically indeterminate.

Unfortuately, I'm not familiar with that particular magazine test, but allowing for altitude, wind and a number of other very relavent atmospheric conditions, as well as gradient and/or surface quality of the road, a measured speed of 174.8 serves to confirm my suspicion.

A stock 2001 Z06 is "underated" by GM.

Did that magazine test happen to run a 2001 C5 Coupe in the same test? Probably not, but the comparison would have been very insightful. I'm betting the Z06 would have been the faster of the two Corvettes.

Incidentally, a 2001 Z06 is not even at 6000 rpm (actual, not indicated) at 175mph flat out in 5th gear.

This means my prediction for a 2002 Z06 can only be within reason, since it makes more horsepower and has more area under the curve from 3700 rpm to redline. Thus, the 405 hp version has a greater ability to overcome aerodynamic drag and the LS6 will "pull" the car to an even higher top speed.

Under ideal "test" condition, in theory, a stock 2002 Z06 should be able to make exactly
180 mph at 6500 rpm in 5th gear. That is the point at which it reaches equilibrium in terms of rear wheel horsepower vs. aerodynamic drag.

Hail to the new KOTH Corvette, the 2002 Z06.
 

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dsinned... you are d-lirious! /phpBB/images/smiles/icon_wink.gif

My Z-06 showed 171 MPH and about 6400 RPM's... well past the 6K mark! You are wrong to think the '02 will have any higher top speed... in perfect conditions both '01 & '02 can redline 5th gear, the cars ARE GEAR LIMITED! NOT HP, and DRAG... sorry! Our 5th gear is shorter than a coupe... if you put a Coupe 5th gear (or Trans) in the Z-06 then the numbers you are talking about would be attainable!

Peace,
Dave
 

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Discussion Starter #11
I don't smoke, but you guys can believe whatever you want. Maybe it is just as well, so you can more easily afford your insurance payments. /phpBB/images/smiles/icon_smile.gif

I've done a top speed analysis using a highly developed software prediction tool that has NEVER proven to be inaccurate on any other car before. There's also that article . . . that reported 174.8. Is that R&T writer just using creative license to stretch things to sell more magazine?

Or, could it be, some of you just don't know enough about your car's top speed characteristics to make a constructive comment. I though we had established that going by speedos is rather foolhardy, so why is just observing your "indicated" mph on the speedo to be believe? What we need is more scientific evidence to help settle this argument and I quite agree a radar gun to make the measurement is generally certainly preferrable to less accurate methods.

Has anybody rear wheel dyno'd their car and determined how much error exists between the dyno's speed readout and you car's speedo?
Now something like that would be of value in this discussion.

I don't have my Z06 yet fellas, so I can't confirm my prediction. But that's just a matter of time. /phpBB/images/smiles/icon_wink.gif)
 

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I have no doubt that a stock '01 Z06 will will hit 174 to 175 mph. But that is where it will hit the rev limiter from everything I've read. It is rev limited in 5th. I ran 175 mph (speedometer idicated on the HUD) in my '99 FRC last year (yes it was a late '99 FRC with HUD). I was still accelerating, but my wife made me slow down. I may have a chance to test the Z06 rev limiter in 5th in a week or so. Of course, it will be based on the speedometer. I have read that the speedometers are pretty close on these cars, less than a couple mph typically.
 

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dsinned, I think everything here has been constructive. The difference is you are trying to compare your computer simulator to real world experiences!

Also... Nobody doubts 174-175 has the Top Speed limit for the car, the difference is I think most of us see this limitation as 'GEAR Limited' however you are stating there is ton's of RPM left... and that in fact it is Drag Limited... This we know to NOT BE TRUE! For those of us who have redlined 5th gear.

And Like RippiedZ wrote... these cars are usually within 1 or 2mph indicating at those speeds.

Peace,
Dave
 

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Discussion Starter #14
Fine. We can settle this later. But, I think (okay, I'm speculating) a "stock" 2002 Z06, under favorable conditions, is gonna be able to reach 180 and it's just a matter of time till someone can verify it. Everyone is entitled to their opinion, but I'm sticking to mine . . . a "stock" Z06 is drag limited.
 
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