All, I'm trying to estimate (for my own personal benefit) gains that can be had by shaving two pounds off the crank shaft in the engine used in my race car. To simplify the problem, I am estimating the weight savings to be on the outer edge of the crankshaft. I also know from on board data that it takes approximatly 4.5 seconds to go from 5500 to 6000 RPM in top gear. So I am trying to calculate the horespower required to accelerate a ring with a WEIGHT of 2lbf, 3" OD and 2.5" ID, from 5500 to 6000 RPM in 4.5 seconds. I keep coming up with an answer of .011 Horsepower, but that just seems too small. Anyone else want to try? My method: I calculated the rotational energy of the ring at both 5500 and 6000 rpm. I took that difference in enegry over the 4.5 seconds to get the work needed. Convert to HP's.