The usual rule of thumb for VFD's is that you have rated torque up to
the nameplate RPM (ie less than your 5 hp), and rated HP above nameplate
RPM (this is a function of the amount of power the motor can handle
without overheating. )

Your application would require running the motor at 180 hz and 3 times
the rated rpm. Pumps require pretty much full output for extended
periods of time. I doubt if the motor would take it for any reasonable
period. You could might get a test run in without too much grief.

Karl Townsend wrote:
Kind of a follow up to my pump RPM question.

I found a 1200 RPM 5 hp motor and an old Hitachi SJ200 5hp. vfd in the spare
stockroom (er junkpile)

Any reason I can't spin this combo at 3600 RPM? Still have 5 horse?

Karl