FNM HPEP 225 Installation Manual page 99

MAXIMUM RPM TEST
Power package should be equipped with a propeller that will allow engine to operate at its
specified maximum wide open throttle revolutions per minute (rpm), with an average load
aboard the boat. Best all around performance is obtained with the engine propped at or near
the upper limit of the specified Engine Recommended Operating RPM Range.
IMPORTANT: Consider this additional information:
The engines covered in this manual, depending upon the model, are equipped with
either a governor or a device that limits engine rpm. Be sure that propeller being used
does not allow engine to run against the governor or limiter, as a significant loss in
performance will result.
MCM Model
HPEP 225-250
To check that the correct propeller has been installed, operate the boat with a light load (one
person, fuel tank half full) at wide open throttle and optimal trim. (Optimal trim is the point
where boat speed no longer increases when trimming-out. High rpm caused by excessive
trimming should not be used when checking for correct propeller.) The rpm should be near
the top of specified range so that under a heavy load, engine speed will not fall below
specifications. If engine speed is too high, replace propeller with one that has a higher pitch.
If engine speed is too low, replace with a lower pitch propeller. Generally, there is a 200 rpm
change between propeller pitches.
If a propeller cannot be obtained that will place the engine in the proper rpm range, it may
be necessary to have the propeller reworked at a propeller repair station.
IMPORTANT: To run engine at maximum rpm before the Engine 20-Hour Break-In
Period is complete, follow this procedure only after the Engine Initial Break-in
Procedure has been completed:
1. Complete Engine Initial Break-In Procedures if not already accomplished.
2. Start engine and run at IDLE rpm until normal operating temperature is reached.
3. Run boat up on plane.
4. Advance engine rpm in 200 rpm increments until engine reaches its maximum rated
IMPORTANT: Do not run at maximum rpm for more than 2 minutes.
Engine Recommended Operating RPM Range
rpm. If maximum rated rpm is not possible or engine runs against governor / limiter refer
to preceding information for correct propeller selection.
Engine RPM Limits
4200
99
Governor or Limiter
rpm Setting
(Begins At:)
4400