The shape of the res is as or more important than capacity. You have to have surface area to dissapate heat. I can build over 150 deg of heat in any of my truck hydraulic systems thay I build. 20GPM over a 2000psi restriction will go from 70deg to 150deg in about 30 minutes with 60 gallons of oil. If I crank it up to 70gpm I can do it in 10 min .There are ALOT of variables in a hydraulic system. Also I ran my engine at about 2500rpm on my splitter. It was way nicer to stand next to a twin cylinder liquid cooled engine at 2500 than next to a air cooled at 3600 rpm. You could actually talk to each other. Just food for thought. CJ