[Z06] 3.90 Gear???
Burning Brakes
Joined: Oct 2000
Posts: 1,094
Likes: 2
From: Seattle suburb wa
Re: 3.90 Gear??? (ApeelinC5)
approx speed in gears for stock Z06 with 3.90 rear
1 043 6600 &nb sp; 2.97 &nb sp;3.9
2 062 6600 &nb sp; 2.07 &nb sp;3.9
3 090 6600 &nb sp; 1.43 &nb sp;3.9
4 128 6600 &nb sp; 1 3.9
5 153 6600 &nb sp; 0.84 &nb sp;3.9
a stock 02 Z06 (in my humble calcs) will not be able to pull more than 5000 rpm in 6th gear (.56) into the wind, thereby being drag limited to 174 with very poor acceleration above 150 mph...
6 174 5000 &nb sp; 0.56 &nb sp;3.9
shiny side up y'all
1 043 6600 &nb sp; 2.97 &nb sp;3.9
2 062 6600 &nb sp; 2.07 &nb sp;3.9
3 090 6600 &nb sp; 1.43 &nb sp;3.9
4 128 6600 &nb sp; 1 3.9
5 153 6600 &nb sp; 0.84 &nb sp;3.9
a stock 02 Z06 (in my humble calcs) will not be able to pull more than 5000 rpm in 6th gear (.56) into the wind, thereby being drag limited to 174 with very poor acceleration above 150 mph...
6 174 5000 &nb sp; 0.56 &nb sp;3.9
shiny side up y'all
Burning Brakes
Joined: May 2002
Posts: 1,086
Likes: 0
From: Coral Springs FL
Re: 3.90 Gear??? (no cure)
approx speed in gears for stock Z06 with 3.90 rear
1 043 6600 &nb sp; 2.97 &nb sp;3.9
2 062 6600 &nb sp; 2.07 &nb sp;3.9
3 090 6600 &nb sp; 1.43 &nb sp;3.9
4 128 6600 &nb sp; 1 3.9
5 153 6600 &nb sp; 0.84 &nb sp;3.9
a stock 02 Z06 (in my humble calcs) will not be able to pull more than 5000 rpm in 6th gear (.56) into the wind, thereby being drag limited to 174 with very poor acceleration above 150 mph...
6 174 5000 &nb sp; 0.56 &nb sp;3.9
shiny side up y'all
1 043 6600 &nb sp; 2.97 &nb sp;3.9
2 062 6600 &nb sp; 2.07 &nb sp;3.9
3 090 6600 &nb sp; 1.43 &nb sp;3.9
4 128 6600 &nb sp; 1 3.9
5 153 6600 &nb sp; 0.84 &nb sp;3.9
a stock 02 Z06 (in my humble calcs) will not be able to pull more than 5000 rpm in 6th gear (.56) into the wind, thereby being drag limited to 174 with very poor acceleration above 150 mph...
6 174 5000 &nb sp; 0.56 &nb sp;3.9
shiny side up y'all
Since we don't have a consensus, someone now has to get a 3.9 rear end and settle the dispute with an attempt at breaking 180!! :jester :cheers:
[Modified by Bertrand, 12:22 AM 8/23/2002]
Burning Brakes
Joined: Oct 2000
Posts: 1,094
Likes: 2
From: Seattle suburb wa
Re: 3.90 Gear??? (Bertrand)
well, for one thing, I'm using the measured tire height, not the theoretical.
every test I've done with my car has borne out using measured vs theoretic. of course, I have 3.42 and M6 ratios, but still, I am satisfied that I'm close with the calcs. I've timed myself on a measured 10 mile stretch (1 mi increments) at 60 and my speedo was dead on.
so, making the leap that for a Z06 the same will hold true, I get the following, for comparison's sake. many have verified these against actual:
stock Z06, 6600 rpm
1 49
2 71
3 102
4 146
5 174
so, with a 3.90 rear, 5000 rpm = 174, not 4895.
my calcs say can't overcome the wind. the point 56 6th gear just dies.
but I agree, we need some one to install 3.90's n get their speedo calibrated and do some empirical data collection..
every test I've done with my car has borne out using measured vs theoretic. of course, I have 3.42 and M6 ratios, but still, I am satisfied that I'm close with the calcs. I've timed myself on a measured 10 mile stretch (1 mi increments) at 60 and my speedo was dead on.
so, making the leap that for a Z06 the same will hold true, I get the following, for comparison's sake. many have verified these against actual:
stock Z06, 6600 rpm
1 49
2 71
3 102
4 146
5 174
so, with a 3.90 rear, 5000 rpm = 174, not 4895.
my calcs say can't overcome the wind. the point 56 6th gear just dies.
but I agree, we need some one to install 3.90's n get their speedo calibrated and do some empirical data collection..
Burning Brakes
Joined: May 2002
Posts: 1,086
Likes: 0
From: Coral Springs FL
Re: 3.90 Gear??? (no cure)
What tire diameter did you use? I am using 26.1.
I would not assume that the figures in your calcs necessarily carry over as is. I can tell you that according to my Garmin V GPS reciever, the speedometer on my Z06 reads LOW. Specifically, 78.3 mph on the speedo is actually 80 mph. This is in a mode with very high GPS resolution. For comparison, in both my Lexus cars the speedo is much closer to the GPS reading 80.3 on the speedo is actually 80 mph in those cars. My calculations measure REAL speed, not measured according to the speedo.
Extending the error pattern of my Z06 speedometer error up the speed chart, this amounts to a 3.7 mph discrepency between indicated speed and true speed. In other words, your speedometer would indicate 174.1 mph at 5000 rpm but you would really be going 177 mph. At an idicated speed of 170.4, in my car, you are really going 174 mph (at 4895 rpm assuming a 3.9 rear end...).
My point here is only that you can't trust your speedo for such high speed calculations because they are not that accurate and even vary from car to car and based on air pressure and tire wear. Just my two cents.
Anyway, someone just needs to try it so we can stop debating and just get to :cheers:
[Modified by Bertrand, 1:00 AM 8/23/2002]
I would not assume that the figures in your calcs necessarily carry over as is. I can tell you that according to my Garmin V GPS reciever, the speedometer on my Z06 reads LOW. Specifically, 78.3 mph on the speedo is actually 80 mph. This is in a mode with very high GPS resolution. For comparison, in both my Lexus cars the speedo is much closer to the GPS reading 80.3 on the speedo is actually 80 mph in those cars. My calculations measure REAL speed, not measured according to the speedo.
Extending the error pattern of my Z06 speedometer error up the speed chart, this amounts to a 3.7 mph discrepency between indicated speed and true speed. In other words, your speedometer would indicate 174.1 mph at 5000 rpm but you would really be going 177 mph. At an idicated speed of 170.4, in my car, you are really going 174 mph (at 4895 rpm assuming a 3.9 rear end...).
My point here is only that you can't trust your speedo for such high speed calculations because they are not that accurate and even vary from car to car and based on air pressure and tire wear. Just my two cents.
Anyway, someone just needs to try it so we can stop debating and just get to :cheers:
[Modified by Bertrand, 1:00 AM 8/23/2002]
Burning Brakes
Joined: Oct 2000
Posts: 1,094
Likes: 2
From: Seattle suburb wa
Re: 3.90 Gear??? (Bertrand)
My point here is only that you can't trust your speedo for such high speed calculations because they are not that accurate and even vary from car to car and based on air pressure and tire wear. Just my two cents.
Anyway, someone just needs to try it so we can stop debating and just get to :cheers:
Anyway, someone just needs to try it so we can stop debating and just get to :cheers:
we're not debating, we're middle of the night theorizing :)
instead of driving our cars. but since I'm sipping some vino, it's best to leave her in the garage. did enough (cough cough, ahem) street driving today. it's so much fun being the over 400 corr rwhp spectacle. very addictive. just testing, officer..
someone with a gps and very big baseballs will install 3.90's and report back, I'm sure. how bout w/4.10's?
cheers
Burning Brakes
Joined: May 2002
Posts: 1,086
Likes: 0
From: Coral Springs FL
Re: 3.90 Gear??? (no cure)
it's so much fun being the over 400 corr rwhp spectacle. very addictive. just testing, officer..
cheers
cheers
Had a little fun but the bogeys were everywhere. My Passport 8500 expert display was lighting up like a christmas tree. In 30 minutes, I picked up and visually confirmed no less than 7 cruisers that were broadcasting. 3 full on Ka, 3 Instant on Ka and one full on K band unit on an older cruiser from a small local city. 4 of those were on the side of the road explicitely as speed traps! :cuss :cuss :cuss So it curtailed the 'testing' a little but it was still fun.
Nice exchanging ideas! Gotta hit the sack... Conference call at 9:00 am :U :cry :( :sad:
:cheers:
[Modified by Bertrand, 2:36 AM 8/23/2002]
