I like to ask people about the HP average over the RPM range that their motor sees. When we build a motor going in a power glide we try to design the engine to make its power over the wide RPM range it experiences behind that tranny.Paul
Paul,
My thinking is that the same logic should be used when designing & building a motor (be it N/A'd or Blown) for a boat ... Especially a High Performance Motor for a Jet Boat where the Hp Range and Impeller must be Matched (typically in the 5,500 to 7,500 RPM Range). Example: If you take a motor designed for asphalt that outputs its Tq & Hp in a higher RPM Range, say in the 7,500 to 9,500 + range, and put it into a Jet, your faced with dealing with the mismatch of the motor's output range vs. what an impeller/jet pump can handle ... some compensate for this by using a gear reduction box ... something I personally think is somewhat a Klugh due to the inefficiency's involved.
Note, a V-Drive is somewhat more forgiving in terms of Tq/Hp output range as props need the higher RPM's and you have the gears in the V-Drive, the strut and the prop, etc. to 'Tune' with.
For me, the Dyno is (for under 2,500 Hp motors ... most Dynos can't handle more than that) to break the motor in, check and verify, in a controlled environment, the motor's design (that it does what it was built for), establish a Baseline to 'Tune' from and, match drive components .......