Figure 20+ PTO HP to turn the baler over, another 10 at the drawbar to pull it -- add a safety factor for hills, wagon, etc and you get the 30-35 minimum mentioned previously, BUT the first response is the real question. I have a Model 46 IH that either my little AC (20 HP) or the Mahindra (65 HP) will turn. The AC will pull it too, but not at the same time it is turning it over. <grin>. However, it shakes that little AC like a rag dool in a bulldog's mouth. You can still feel it on the Mahindra (with fluid filled tires), but it is more like a slight rocking. Ran a neighbor's JD 336 today and it moved the Mahindra more than the IH. They've both got big flywheels to smooth out the stress on the rotating shafts, but you still have a whole bunch of weight moving forward and back with each plunger stroke.