When we look at horsepower ratings of our old two cylinder John Deeres and compare them to modern horsepower ratings, the phrase I often hear is that "they measured things differently back then". This seems to be the go-to response for most people to explain, for example, why a 27 HP, or so, 44 A can pull a two bottom plow but when you hook the same plow to a modern 3 cylinder diesel of a higher horsepower, it struggles with it, if it can even can pull it at all.
Now I realize that the A has a lot more inertia with all those heavy pistons, rods, crankshaft and flywheel parts spinning around, but was a horsepower back then measured differently than now or what exactly is it that allows a smaller horsepower tractor from years ago to do more effective work at the drawbar than a higher horsepower modern tractor?
Now I realize that the A has a lot more inertia with all those heavy pistons, rods, crankshaft and flywheel parts spinning around, but was a horsepower back then measured differently than now or what exactly is it that allows a smaller horsepower tractor from years ago to do more effective work at the drawbar than a higher horsepower modern tractor?