when your doin 70 mph....
Drifting
Joined: Dec 2000
Posts: 1,733
Likes: 0
From: Sarasota FL
Re: when your doin 70 mph.... (miker61588)
I do 2000rpm @ 70mph. I have the performance ratio and I'm supposed to have 2:73 gears.
The post above by vader86 gives the same info for 3:07. Whats up with that?
The post above by vader86 gives the same info for 3:07. Whats up with that?
Drifting
Joined: Dec 1999
Posts: 1,319
Likes: 2
From: Douglasville GA
Re: when your doin 70 mph.... (DON M)
You also need to specify what transmission gear.
The best way is to match transmissions and gear selected. IE auto and 4th or auto and 3rd, or ...
To cross transmissions, you should use auto 3rd and manual 4th, as both are 1:1 ratio in those gears.
You also need to know it the tires are stock sized.
Now, that being said, my 86 with 3.07 auto in 4th gear is 2000 RPMs with stock sized tires.
Tom Melton
82 CE
86 Z51 Coupe
The best way is to match transmissions and gear selected. IE auto and 4th or auto and 3rd, or ...
To cross transmissions, you should use auto 3rd and manual 4th, as both are 1:1 ratio in those gears.
You also need to know it the tires are stock sized.
Now, that being said, my 86 with 3.07 auto in 4th gear is 2000 RPMs with stock sized tires.
Tom Melton
82 CE
86 Z51 Coupe
Race Director
Joined: Oct 2001
Posts: 19,653
Likes: 428
From: Melbourne Florida
Cruise-In IV Veteran
Re: when your doin 70 mph.... (miker61588)
I have 3:73's w/ auto and stock size tires...at 75 mph I'm right at 2600 rpm...sorry I don't remember the 70 mph revs...
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Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: when your doin 70 mph.... (miker61588)
Posted this last night in a different thread...
I will get you started on this one so you can compute it for any size tire, RPM, gear ratio, or tranny ratio
MPH = (RPM * TD * pi) / (GR * TR * 1056)
where:
MPH-Miles per hour
RPM-Revolutions per minute
TD-Tire diameter in inches
pi-3.1415926...
GR-Rear gear ratio
TR-Tranny gear ratio (4th on a 6 speed is usu. 1:1)
1056-Constant that takes care of inch-mile and minute-hour conversions
For tire diameter, tires are rated like 255 50ZR16
where
255-(SW) sidewall width in millimeters
50- (AR) aspect ratio
16- (WD) wheel diameter in inches
TD = [([(SW) * (AR/100)] * 2)/25.4] + WD
So for your case,
RPM = (MPH * GR * TR * 1056) / (TD * pi)
What did [i]you[i] come up with?
With granny gears and locked TC, I am pushing about 1650 RPMs (.70 4th gear) and 255 50ZR16's. -Matt-
I will get you started on this one so you can compute it for any size tire, RPM, gear ratio, or tranny ratio
MPH = (RPM * TD * pi) / (GR * TR * 1056)
where:
MPH-Miles per hour
RPM-Revolutions per minute
TD-Tire diameter in inches
pi-3.1415926...
GR-Rear gear ratio
TR-Tranny gear ratio (4th on a 6 speed is usu. 1:1)
1056-Constant that takes care of inch-mile and minute-hour conversions
For tire diameter, tires are rated like 255 50ZR16
where
255-(SW) sidewall width in millimeters
50- (AR) aspect ratio
16- (WD) wheel diameter in inches
TD = [([(SW) * (AR/100)] * 2)/25.4] + WD
So for your case,
RPM = (MPH * GR * TR * 1056) / (TD * pi)
What did [i]you[i] come up with?
With granny gears and locked TC, I am pushing about 1650 RPMs (.70 4th gear) and 255 50ZR16's. -Matt-
Pro
Joined: Oct 2001
Posts: 525
Likes: 0
From: Newport MI
Re: when your doin 70 mph.... (miker61588)
my '88 3.07 rear, 700R4 auto 2000 rpm
email me if you want a "windows" program that lets you specify, tranny, gear, rear end & wheel size, correlates RPM to MPH. Includes all the Vette tranny's & let's you add others to the data base. program is about 2MB, let me know & I'll mail it :chevy
email me if you want a "windows" program that lets you specify, tranny, gear, rear end & wheel size, correlates RPM to MPH. Includes all the Vette tranny's & let's you add others to the data base. program is about 2MB, let me know & I'll mail it :chevy
Instructor
Joined: Nov 2001
Posts: 242
Likes: 1
From: Hershey PA
Re: when your doin 70 mph.... (miker61588)
trying to find out if someone had maybe changed the gears in my car, just wondering how many rpms are you doin around 70 mph and with what gears
GH0 Rear Axle, 3.54 Ratio
GM1 Rear Axle, 2.59 Ratio
GU2 Rear Axle, 2.73 Ratio
GW4 Rear Axle, 3.31 Ratio
G44 Rear Axle, 3.07 Ratio
I can't check my mph/rpm today, I'll try tomorrow.
Also, nice to see someone else with a red '89 vert. What is the interior color? Factory options? Mine is as stock as yours is modified.
[Modified by Cigarman, 2:07 PM 2/19/2002]
