Jet boat engines are from a very different world than any thing else we build and use , trust ,me on this. Until you driven a jet boat and a prop driven boat it is hard to imagine the differences The pump is trying to compress liquids, impossible to do, correct You can turn water into steam trying to do that though, it is called cavitation and very harmful to the pump parts
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)