Ford Focus Forum, Ford Focus ST Forum - View Single Post - 1/4 mile not making sense?? Help!
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Old 08-03-2011, 03:48 PM   #39
iminhell
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I made some graphs.
Use the equation listed by the line to get exact numbers.
The graphs are Time on the up axis and RPM on the horizontal ... as RPM goes up time goes down, which is obvious.
The graph is figured by,
- finding the MPH vs gear ratio and tire diameter
- converting that # to Feet Per Hour, multiply by 5,280
- convert that # to Feet Per Second, divide by 3600
- divide 1,320 by ^ and you get the time it takes to reach the end of the 1/mile, if at a constant RPM


22" tire:




26" tire:





22" MPH and RPM drop:





26" MPH and RPM drop:




If I shift @ 8,000,
2nd drops to 4,700
3rd drops to 5,500


So I'm really/still confused on why a smaller tire supposedly gives a better time. By everything I can figure a taller tire should be faster providing the car has good power above the rpm each shift drops too ... in my case I need good TQ up high.
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