I'm curious what formulas are used to calculate scale power and weight, and if they're even necessary in modeling. 1:87(.1) is HO scale, so an SD40-2 which is 68'10" in length is about 9.5" in HO scale. But that's only one dimension. To say that it is 1:87 the size of the real thing is not including all thre dimensions. It's also 1:87 the width, and 1:87 the height. An HO model is in fact 1:658,503 the size of the real thing, meaning it would take 659,503 SD40-2 models to occupy the same space as 1 of the real thing. Does that mean that power and weight are the same ratio? They're definitely not 1:87 - that would mean an HO scale SD40-2 would have a miraculous 34.5HP ... shazzam! But it would also weigh 4230 pounds - not likely to be supported by ... anything. So should weight and power be divided by the cube of 1:87, or 659,503? That would mean the HO version of an SD40-2 would be .004556HP. Though rediculously small, it actually sounds right to me. And what about weight? The 184 ton SD40-2 would be a wopping 8.9 ounces. Or am I just way off base? Does it even matter? Without proper testing it seems like one of my Athearn F7s could pull literally hundreds of HO rolling stock, which is completely unrealistic. And probably do it up a 4% grade. Any thoughts or advice? Mathmaticians who can educate me?