<write this down>
this is good stchuff Jon - thanks!!!!
<mumbles something about 33 inch tires for the BBQ>
jon@dakota-truck.net wrote:
> This should get you close:
>
>
> (RPM * tire height * .00297) / (rearend ratio * tranny ratio)
>
>
> For example, a truck with 28" tall tires and 3.55s in 4th gear at 3,000 RPM
>
> (3000 * 28 * .00297) / (3.55 * 1) = 70.3mph
>
> Tranny ratios can be found in the FSM, or I think they are in the DML
> FAQ also. Just use the number to the left of the colon. For example,
> an overdrive ratio of 0.80:1 is just .8, a ratio of 3.42:1 is just 3.42)
>
> I simplified the formula a bit, so there's some rounding in there. If
> you want to go through the whole process, here's the thoery:
>
> - Engine RPM divided by tranny RPM gives you driveshaft RPM.
> - Driveshaft RPM divided by rearend ratio gives you wheel RPM.
>
> Now that we know the rate at which the wheel is turning, we need to
> figure out how much distance the truck moves per every revolution.
> That's the circumference of the tire.
>
> - PI (3.14159...) times tire height gives you the distance traveled
> per revolution, in inches.
> - Distance in inches divided by 12 is distance in feet
> - Distance in feet divided by 5280 is distance in miles
>
> Putting it all together:
>
> - Distance in miles times wheel RPM equals miles traveled per minute
> - Miles traveled per minute times 60 equals miles traveled per hour
> (Also known as miles per hour) :-)
>
> --
>
> -Jon-
>
> .---- Jon Steiger ------ jon@dakota-truck.net or jon@jonsteiger.com -----.
> | I'm the: AOPA, DoD, EAA, NMA, NRA, SPA, USUA. Rec & UL Pilot - SEL |
> | '70 Barracuda, '92 Ram 4x4, '96 Dakota, '96 Intruder 1400, '96 FireFly |
> `----------------------------------------- http://www.jonsteiger.com ----'
-- -----------------------------------"Hey Ray! Granpa done gone'n hit another light pole!"
Granpa - (Silver98) http://members.aol.com/silvereightynine/
1989 Reg Cab, V6, Auto, 8 footer, 4x2 1989 Reg Cab, V6, Auto, 8 footer, 4x4 w plow
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