Volvo Penta Marine Products     44-0 8

Gasoline Sterndrives

High Altitude Gear Ratio

Boats that consistently operate at high elevations may require carburetor modification and a gear ratio change to compensate for power loss. These changes may be necessary to allow the engine to obtain its recommended maximum RPM. When determining if these changes are necessary, use the following recommendations. If there is any question as to which model you have contact Volvo Penta of the Americas, Inc., Technical Service Department at 1-000-445-2620 art 5901,for gear ratio recommendations at higher altitudes.
For high altitude carburetor modifications, see Service Bulletin 23-1, No.5.
In some applications which operate between 3,500 - 5,000 ft. the propeller pitch should be reduced approximately 4" (SX Models) or reduce propeller set by 2 sizes DuoPropTM (DP). If reducing propeller size allows the engine to reach its maximum RPM while producing acceptable acceleration characteristics, a gear ratio change may not be necessary.
The following are gear ratio recommendations for "BY" Model sterndrives only at various altitudes.
Gear ratio modifications exceeding these guidelines may result in loss of warranty coverage.
Volvo Penta's limited warranty does not cover any expenses for changing the gear ratio for altitude.

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Note: If the gear ratio has been changed, the owner should be notified that the unit has been modified for high altitude use. The boat should be marked as well as any paperwork that would be passed to a future owner.
For example:

"Caution: This boat has been altered for high altitude usage and should not be used
 at low elevations without consulting a Volvo Marine repair center."


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