CONDITIONS AFFECTING OPERATION
41
•
High humidity.
The conditions listed above reduce air density to the engine which in turn
reduces the following:
•
Boost pressure on supercharged engines
•
Horsepower and torque throughout the RPM range
•
Peak RPM
•
Cranking compression
EXAMPLE: An engine running at an elevation of 2,438 m (8,000 ft) will have
over a 30% power loss while engine power on a hot and humid day can be
reduced by as much as 14%. These losses apply to both normally aspirated
and supercharged engines.
Compensating for power robbing conditions:
•
Switch to a lower pitch propeller.
•
Change the gear ratio.
Some boat performance can be regained by dropping to a lower pitch
propeller, but engine performance will remain lower. In some cases, a gear
ratio reduction may be more beneficial. To optimize engine performance,
prop the engine to allow it to allow operation at or near the top end of the
recommended maximum RPM range at wide open throttle with a normal
boat load.
Other advantages to propeller or gear ratio changes:
•
Reduces the possibility of detonation.
•
Enhances overall reliability and durability of the engine.
Summary of Contents for HP1075 SCi
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