You have to have some way to add power....on our cart since we have both the 35 and a 75C with PTO, we have put a pump on the PTO to run the second auger in the cart. 

If you mean to somehow increase the power without using anything but hydraulics as the source, there's no free lunch, can't get more out then you put in.  Best you can do is to optimise the motor for the availible hydraulic system, which IMHO should be capable of driving a single auger cart from the likes of the 55.  Not sure what is availible from the CIH hydraulic wise.   Someone should be able to give you a formula to figure hp availible....my memory is saying 35 gpm at 2750 from the C75C calculated to 54 hp if I'm remembering right.    Think of it this way....if a 5000 Ford or 2510 Deere would have enough PTO power to turn the auger, the hydraulics on most large modern tractors will also, provided that you can get things set up perfectly.