how to calculate speed from rpm

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06-14-2008, 04:12 PM

wave1957

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how to calculate speed from rpm

Could someone please tell me how to calculate car speed from the RPM? my speedo is not connected yet...
Also, does someone know the gear ratios for a 4L80E?
Thanks

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06-14-2008, 04:34 PM

fouz65

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http://www.f-body.org/gears/

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06-14-2008, 04:38 PM

ChevyChad

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Assuming you want velocity in MPH and you use inches for the tire diameter:

PI*Tire Diameter*Engine RPM/(1056*Diff Ratio*Trans Ratio)

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06-14-2008, 09:07 PM

Scooter70

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Excel sheet

Change the yellow boxes for your rear tire and the gear ratios to match your A4.

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06-14-2008, 10:28 PM

dman

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this is a formula i use mostly to calculate what RPM i'll go thru the traps at.

mph x 336 x final drive ratio / tire size (diameter)
130 x 336 x 3.08 / 25.5 = 5276 rpm