Propeller Selection; Conditions Affecting Operation - PCM HO303 MPI Owner's Operation And Maintenance Manual

CONDITIONS AFFECTING OPERATION - 6

PROPELLER SELECTION

Best all-around performance and maximum engine life is
achieved when the engine is propped to run near the top
of (but within) the recommended full throttle RPM range
with a normal load. See ENGINE SPECIFICATIONS for
rated full throttle RPM for your model engine.
Generally, gross weight (total weight of the entire
boat, including full fuel and water, optional equipment,
passengers and other miscellaneous gear) is one of
the major factors and should be one of the primary
considerations when selecting a propeller. Other factors
to take into consideration are as follows:
• Warmer weather and higher humidity will cause
an RPM loss.
• Operating the boat in a higher elevation will
cause an RPM loss.
• Operating the boat with an increased load
will cause an RPM loss (additional equipment,
passengers, etc.).
24
If full throttle RPM is above or below the recommended
range as stated in ENGINE SPECIFICATIONS,
the propeller must be changed to prevent loss of
performance. A one-inch change in the pitch of a given
propeller will generally change engine RPM by 150 to
250 RPM.
Model
HO303
EX343
ZR409/ZR450
Prolonged WOT operation will shorten the life of
your engine and could cause premature engine
failure. See NORMAL CRUISING SPEEDS in
SPECIFICATIONS. Problems caused by prolonged
WOT operation are considered abuse and are not
covered under the PCM Warranty.
IMPORTANT NOTICE:
incorporates an RPM "MAX GOVERNOR" in order
to prevent the engine from over-revving. Operation
above the Maximum RPM listed, in the chart above,
is not recommended. If your engine is operating
above the maximum RPM listed, a higher pitched
propeller would be required to lower the engine
maximum RPM to the Preferred RPM listed in the
chart above.
L510010-11
ENGINE RPM CHART
Minimum
Full Load Preferred
4800 4900
5000 5200
5400 5500
CAUTION
Your new PCM engine
Maximum
5000
5300
5600