Im scared to sit down and figure ours out. We run 2, an 8.3 Cummins and a 3208. Cummins pumps 850gpm at 80psi and the bowls are set at 375ft. 3208 pumps 500gpm at 80psi from about the same depth. We use a rule of thumb of around 7gph on the 8.3. Sometimes it feels like we should just go out and throw money in the field but what else are you gonna do?