8
L510023-07
GEAR RATIO SELECTION
The propeller shaft speed is determined by engine
speed and transmission gear ratio. Fast boats operate
best with direct drive or small reductions. Heavier boats
respond best with larger ratios of gear reduction.
If shaft speeds are too high, a smaller than normal
propeller must be used resulting in poor performance.
Conversely, if shaft speeds are too low, a larger than
normal propeller must be used, again resulting in poor
performance.
PROPELLER SHAFT / COUPLING
Installed angle of the engine should not exceed
maximum of 16 degrees from water line.
Propeller shaft diameter should be suffi cient size for the
type of application.
Coupling must be keyed to the propeller shaft. The key
should be a close fi t with keyway sides, but should not
touch the top of the keyway in the coupling hub. The
coupling should be a light press fi t on the shaft.
TRANSMISSION AND PROPELLER
ROTATION
For best all-around performance, it is recommended
that the engines be installed so that the propellers turn
outboard in dual engine applications.
NOTICE: Propeller rotation is not necessarily the same
as engine rotation.
PROPELLER SELECTION
IMPORTANT: Installed propeller must allow the
engine to run at its specifi ed, Preferred, wide-open-
throttle RPM.
It is the responsibility of the boat manufacturer and/or
selling dealer to equip the boat with the correct propeller.
Specifi ed engine WOT RPM is listed in the “Master
Engine Specifi cations” found within this manual.
Because of many variables of boat designs, only
testing will determine the best propeller for a particular
application. A propeller should be selected that will allow
the engine to operate at or near the recommended WOT
operating range with a normal load. Refer to the engine
RPM chart, right, or the Master Engine Specifi cations
found in this manual.
In general, a 1 inch change in propeller pitch will result in
a 100 to 200 RPM change in engine speed.
IMPORTANT NOTICE:
Engines equipped with
the ECM-07 engine management system incorporate
an RPM “MAX Governor” in order to prevent the
engine from over-revving. Engine operation above the
Maximum RPM listed will appear normal, but will not
exceed the “MAX Governor” RPM (100 RPM above
the Maximum RPM specifi ed for an engine model).
Operation above the maximum RPM specifi ed for your
engine model is not recommended. If the engine is
operating above the maximum RPM, a higher pitched
propeller would be required to lower the engine
maximum RPM to the Preferred RPM specifi ed for your
engine model.
Minimum
Model Full Load Maximum Preferred
Carb. 5.7L 4800 5200 5000
CAUTION
Prolonged WOT operation will shorten the life of your
engine and could cause premature engine failure.
See Cruising RPM (Max) in the Master Engine
Specifi cations. Problems caused by WOT operation
are considered abuse and are not covered under the
Crusader Warranty.
ENGINE RPM CHART
Minimum
Model Full Load Maximum Preferred
MP 5.0L 4600 5000 4800
MP 5.7L 4800 5200 5000
MP 6.0L 4800 5300 5200
MP 8.1L STD 4400 4800 4600
MP 8.1L HO 4800 5200 5000
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