Even with my Case 580ck hoe,--- I only run the motor at a fast idle when I dig with it!! No need for wide open! just enough speed to pull/lift the bucket is all thats needed for our use.
The excavator I made runs at a fast idle and dont even know the hyd. is even on it! It's a 230 Chrysler industrial motor off an Oliver 525 combine, so you want to talk about overpowered!! LOL!!!!
My valve bank has flow controls built in so each cylinder runs at optimum power/speed from what I can tell. It digs fast and has enough power to drag a 10,000 pound dump truck with brakes locked across the yard. 8,000 pound farm tractor wont hold it back either!
In summary, --- engine power is not really the important thing here. Its the control of the hydraulic part of the systems. cylinders, motors, etc. as each one can be slowed to a speed that suits your needs. I like medium speed with as much power as I can get on mine that way you move a lot of dirt in a short time. Flow control is the key.
You can kinda test out what start speed you feel good with and go up from there ( if needed) after you run it and get the feel for things!
