Bo,

I have combined both equations that you used, including your revised constant of 175,281 in place of Cooper's 146,806, and used your most recent weight (740 lbs.), tire pressure(42 psi), coefficient of friction (.45) and area (7.46) assuming that these will remain constant, at least in the near future and I came up with the following formula for total horsepower required:

Horsepower required for speed V (mph)=.012V + (.00002425) V cubed. (note this only applies to Bo's conditions)

I derived the general formula, but typing it out on the keyboard is a bit cumbersome when you can't use math symbols. I could write it out and photograph it and post it as a jpeg if anyone is interested.

For 165 mph, I get an answer of 110.9 hp at the rear wheel. I think you got 111 with your methods which is probably just rounding differences. With this equation, you should be able to determine hp for any speed. The interesting thing is that except for the first term which only adds 2 hp, the total equation can be boiled down to the following, ignoring that 2 hp:

Horsepower required for speed V (mph) = .00002425 V cubed = 109 hp for a speed of 165 mph

Although I used Bo's drag area, tire pressure, and weight for this calculation so the constant only applies to his bike, this formula allows us to see that basically horsepower required increases at the cube of the increase in speed. For anyone who has a rear wheel horsepower number which can be directly associated with a speed at Bonneville, new horsepower requirements can be calculated without knowing any other info, as long as weight, tire pressure, and shape (drag area coefficient) remains constant.

Tom