Alpha One Gen 2 Sterndrive Change from ratio 1.65 to 1.5

T

tom03

Seaman Apprentice
Joined
Apr 17, 2004
Messages
46
Hi,

I need to replace my Alpha One Gen 2 Sterndrive.

Current Alpha One Gen 2 ratio: 1,65
New Alpha One Gen 2 ratio: 1,50

Engine 1992 Merruiser V8 5.0l. w/4bbl. Edelbrock carburator.
Bayliner 2655. prop: mercury Enertia 16 pitch, max. rmp 4500.

Can I use the ratio 1,50 drive ?
How far will the rpm drop with the 1.50 ratio drive ?

regards, Tom
 
achris

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: Alpha One Gen 2 Sterndrive Change from ratio 1.65 to 1.5

The calculation is just a straight math problem.

With the new ration and the same prop..

New ratio/old ratio * old engine revs...

So the new drive will drop the revs to about 4100... Way too low. So using the same sort of math, we can estimate what prop you would need to maintain the revs....

New ratio /old ratio * old prop....

Old prop = 16", new prop would need to be about 14" to get the revs back up to about 4500....

What you should be doing is going the other way... Put a 1.81:1 drive on....

Chris.......
 
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