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Mariner 100 RPM

K

kw502bbc

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Does anyone know what the safe RPM range on the 1988 4 cylinder 100 Mariner is? I recently bought one on a Norris Craft fishing boat that is pretty light. I was getting 6000 RPM with the 19 pitch prop that came on it, which I know is sky high. I have a 24 pitch High Five on it now, but it still runs 5500. Is this within range, or do I need a 25? Thanks!
 
These fours don't like to rev! That must be quite the light boat, for a 100hp to be pushing even a 24P prop. It does have a 2.3:1 gearbox so I reckon that does make a difference with prop selection, you can swing a larger-pitched prop.

The mfr-recommended rpm is 4750-5250 rpm and I wouldn't push it 'cause they don't make much more power at higher rpm (unlike its Inline Six predecessor), and the crankshaft & internals won't tolerate the higher rpm, either.

HTH...........ed
 
Ed-Mc said:
These fours don't like to rev! That must be quite the light boat, for a 100hp to be pushing even a 24P prop. It does have a 2.3:1 gearbox so I reckon that does make a difference with prop selection, you can swing a larger-pitched prop.

The mfr-recommended rpm is 4750-5250 rpm and I wouldn't push it 'cause they don't make much more power at higher rpm (unlike its Inline Six predecessor), and the crankshaft & internals won't tolerate the higher rpm, either.

HTH...........ed
Click to expand...

Thanks for the info! The boat is very light, as Norris Crafts are always a speedy design. It is only a 16 footer, too. Guess I may need to try a 25 or 26 and get it down a little more. Appreciate the input!
 
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