Gear Ratio to Elevation Question

[tahoejag]

Ive been reading that gear ratio has some effect on elevation. Ive never heard of this before and am looking for knowledge of said subject. I have posted in prop forum, advice of 4 blade over 3 on my set-up. Thats when i noticed that gear ratio affects elevation and prop pitch. Any advice/knowledge is greatly appreciated on this subject. Hopefully I've posted in the right subject...being a Alpha I Gen II drive.....

4.3l carb 190 hp
Alpha I gen II
1:81-1 ratio
MW alum 14 1/4x 21p 3 blade
43 mph (gps) at 4800 (WOT)
Great Lakes area (aprx 600 ft evel)

 

[achris]

Re: Gear Ratio to Elevation Question

Most manufacturers recommend using the next higher reduction for elevated use. Then prop to attain recommended WOT revs. The 4.3 has been supplied over the years with 2 different drive ratios, 1.62:1 and 1.81:1, and since you already have the 1.81:1 (higher reduction) I would suggest you have the right ratio for the altitude you're operating at. You're attaining 4800rpm at WOT... Perfect... Go boating and enjoy...

Chris......

 

[haulnazz15]

Re: Gear Ratio to Elevation Question

600 msl is not high altitude.