Thread: Gear ratio & tunes?
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Old Wed, October 14th, 2009, 11:35 AM
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Originally Posted by JackandJanet View Post
Guys, I'm going to ask a question here. That figure "65535 rev/mile" seems awfully high to me. There are 5280 ft in a mile. If a tire rotates 65535 times in that distance, it only covers about 0.081 feet per revolution! You're running on really tiny tires (diameter would be about 0.31 inches)! Are you sure that rev per mile figure is correct?

- Jack
It's not correct, Jack. With the 95-97 trucks, the data given in the tuning software shows a 64:1 final drive ratio and a 65535 rev/mile. Why? I don't know but it has little to no effect on the operation of the vehicle even when correct numbers are given like 4.10:1 or 635 rev/mile. I don't think that the PCM in those trucks use that particular value when figuring shift points. The automatic-equipped Super Duty trucks are sensitive to those values though.
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Tuning, PCM flashing, and burning chips for 7.3s since 2008. Repairing all aspects of 7.3L Powerstrokes for 25 years.
Eight 7.3L PSDs in the driveway including a 1994 Crown Vic and 1973 F100/2002 F350. Looking for the next victim.
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