Chris,Ok I understand a little of the friction loss. Here is my question if you running 5.5 gpm 4000psi do you still have friction loss with 3/8 hose or do you notice friction loss more so when you get up in the larger pumps.
there is always some friction loss, it's a matter of how much. Not actual numbers here just for illustration... if you use 300' of 3/8" hose with 5gpm you may lose 300 psi. Use 8gpm and you may lose 900 psi. Now switch to 1/2" hose and the psi drop for 8gpm may be more resonable at 150 psi.
Hope this helps. I'll try to find a chart tomorrow if I have time, Delco (RAHSCO) use to have one on their board if you are familar with them.