Gear ratio

[55excl]

Please explain 1:81 gears 1:75 gears does this mean motor turns once prop turns .81 or .75 of a turn? Enrico

[PSM207]

The correct expression would be 1.81:1, 1.75:1, 2:1, etc. The engine will turn 1.81, 1.75, or 2 revs, and the prop will turn 1.

[201pro]

If you divide your rpms by the gear ratio, it will tell you how many rpms your prop is turning..
example- 6000 engine rpms
1.75:1 = 3429 prop rpm's
1.81:1 = 3315 prop rpm's
2:1 = 3000 prop rpm's

[55excl]

Thank you everyone now I understand.