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Discussion Starter · #1 ·
Does anyone know what the RPMs should be for a bone stock wrangler with 6 cyl and 5 speed at 70 MPH ???? Approx?
 

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Discussion Starter · #3 ·
Im not sure im thinking 4.10s. But im trying to figure what it should be un motified.
 

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equations

tire diameter x (times) PI (3.1416) = tire circumference in inches

5280 ft per mile x 12 in per ft /(divided by) tire circumference = axle rotation per mile

axle rotation per mile x rear end ratio = drive shaft rotation per mile

drive shaft rotation per mile / transmission ratio = engine rotations per mile
miles per hour / 60 = miles per minute.

miles per minute x engine rotations per mile = engine revolutions per minute

You can get the transmission gearing for each gear for the AX15 transmission and figure the rpm for any gear at any speed.
 

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tire diameter x (times) PI (3.1416) = tire circumference in inches

5280 ft per mile x 12 in per ft /(divided by) tire circumference = axle rotation per mile

axle rotation per mile x rear end ratio = drive shaft rotation per mile

drive shaft rotation per mile / transmission ratio = engine rotations per mile
miles per hour / 60 = miles per minute.

miles per minute x engine rotations per mile = engine revolutions per minute

You can get the transmission gearing for each gear for the AX15 transmission and figure the rpm for any gear at any speed.
:)) Yeah, that...

I have that all in a spreadsheet calculator. It says using 28.x inch tire, with 3.07 gears, and an ax15 the tach should read about 2000rpm at 70.

If 4.10s, the tach should read about 2700 rpm.

Honestly, I like mine set up to spin about 2400 at 70 with 4.10s and 33" tires.
 
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