am i getting all the speed from my 90

Joined
Sep 28, 2003
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7
here i am again guys/gals. 98 90hp evinrude. at WOT, she reaches 5100 trimmed out...boat is a 18.5 kenner, center console. v hull,,,with a tunnel v. prop is a 14 x 17. i believe that was factory prop. ive been reading and it appears im not in the rpm range that i should be...could this be because of the tunnel v at the back of the boat?.
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
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45,907
Re: am i getting all the speed from my 90

Hi, Learning.<br /><br />You could probably make your engine happier with a bit "less" prop. See if you can borrow a 15" for a demo. That should get you to 5500rpm at WOT.<br /><br />Before you do that, though, check your engine and rigging for optimum tune and positioning.<br /><br />Good luck. :)
 
Joined
Sep 28, 2003
Messages
7
Re: am i getting all the speed from my 90

thxs....would the cav plate play a role in speed here...ie...to high or too low below bottom of boat???
 

JB

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Mar 25, 2001
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45,907
Re: am i getting all the speed from my 90

Too low would definitely slow you down some, Learning.<br /><br />Should be even with, to an inch or so above, the bottom of the hull immediately in front of the foot.<br /><br />Good luck. :)
 
Joined
Sep 28, 2003
Messages
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Re: am i getting all the speed from my 90

jb???<br /><br />are you saying try using a 14 x 15 prop? i thought going to a smaller prop would increase rpms but lower the speed due to lower water displacement off the prop...guess thats why im here and not in a boat shop giving advice...lol...
 

The Marine Doctor

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Joined
Jul 25, 2003
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2,177
Re: am i getting all the speed from my 90

You might lose roughly 2 inches per revolution<---that is a very loose estimate...but you will gain more revolutions.<br /><br />TMD
 
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