Anyone know the math to convert OSS to MPH?
Anyone know the math to convert OSS to MPH?
2013 Mustang GT - Twin Turbo
2016 Mustang GT
2011 Suburban Z71 - Tow Machine
the OSS signal rate that is fixed by your tire size, axle ratio and OSS reluctor wheel to an 8000 pulse per mile rate
OSS Signal Rate = Tire Revs/Mile * Axle Ratio * OSS Reluctor Wheel Tooth Count
For example, with an 03 Cobra T56 in a 96 Cobra with stock tire size and a stock 3.27 axle ratio, you would multiply 815 tire revs per mile times 3.27 axle ratio to get 2665.05 ouput shaft revs per mile. Then you mulitply that by 12 teeth on the T56 reluctor wheel to get 31980.6 OSS pulses per mile.
tire diameter = 27.3"
multiply by Pi to get its circumference = 85.7" per revolution
convert to miles by dividing by 63360" = .00135 miles per revolution.
OSS divided by rear end ratio Example 1500/ 3.55= 422.5 revolutions per minute
multiple by 60 to get revolutions per hour = 25350 revolutions per hour
multiply miles/rev by rev/ hour to get miles per hour. .00135 x 25350 = 34.2 MPH
So OSS 1500RPMs with a 27.3 inch tire and 3.55 final ratio is 34.2 mph.