This is out of my element but here is a link for udor sewer pumps
I know they make a jetter valve that basically stops one of the check valves and causes the water flow to hammer. I guess the jumping around of the hose helps it get thru bends or tight spaces. Like running a 4 cyl engine on 3. Basic math to determine horsepower is psi X gpm divided by 1100. So, 3500psi times 8gpm equals 28000 divided by 1100 equals 25.4 horsepower. Bear in mind the pressure pro series uses an none Honda muffler which doesn’t dissipate the heat or vent exhaust to Honda specs so instead of 21 hp you are probably closer to 20.
