9.5 evinrude prop

[mrbell83]

Hey guys, I have a 1971 9.5 evinrude and I need to know what prop is best for me, it has a 8 1/8 x 8 (factory std) right now and it is beat up. I figure that with all my gear and people, the weight of the boat, motor, and the gas it will sit around 500 pounds, what size prop would be best all the way around for this app. and what kind of speed ( cruise and top end) am I looking at, also i was told that I should not run this motor WOT all the time is this true? I have not ran this boat/motor yet so I have no basis for comparison................<br /><br />Thanks allot,<br />Chris

 

[Richard Petersen]

Re: 9.5 evinrude prop

Whoever told you that knows more than all of us normal people. My 1988 9.9hp runs wide open all the time or slow approaching something. HELL, they don't go that fast WOT. AND there is no HI SPEED adjustment that you can lean out and burn up the engine. Run it. The factory has a fixed RICH main jet to protect it from damage. ---------Get the prop fixed or replaced. If it allows over revving, THAT will blow up the engine. Good prop, Floor it.

 

[mrbell83]

Re: 9.5 evinrude prop

Thanks for the help................

 

[walleyehed]

Re: 9.5 evinrude prop

Let's look at that from the other side....If it comes out of the hole sluggish, doesn't really come up to the intended RPM at WOT, it's gonna be worse than Over-reving. High combustion temps, coking, carbon....soon to be dead if run at WOT at the wrong RPM (Low).<br />Those smaller engines tend to be alot more forgiving of set-up than larger engines, but the closer you have it to the top of the RPM range, all the better.

 

[mrbell83]

Re: 9.5 evinrude prop

So what you are saying is that I need to trial and error the props until I find one that runs in the 4500rpm range? If I find a prop that runs that rpm and it doesn't move / plain the boat right should i invest in some type of hydro foil?<br /><br />I know that setup is important and thats all I am looking for the best setup I can get out of this old girl.<br /><br />Thanks,

 

[WillyBWright]

Re: 9.5 evinrude prop

Very few boats will plane with a 9 1/2. Sorry. And a hydrofoil will probably just slow you down.

 

[walleyehed]

Re: 9.5 evinrude prop

mrbell83, there is no formula or document that will tell us the correct prop for any one rig.<br />The ONLY way to find that prop, is test a known, good prop, record the numbers, and by theory, seek the correct prop by rules of thumb, then throw that out the window and go test every prop you can get your hands on....No joke.<br />If you can give us the model of prop, the pitch, general condition and an RPM figure, I think we can get you close on your next prop.

 

[mrbell83]

Re: 9.5 evinrude prop

Well I will have to post some test numbers in the spring and maybe then I will have enough info to make an informed decision. <br /><br />Thanks for the help guys.................<br /><br />One more question, if I were to upgrade to a 1970 something 15hp Evinrude, what do you think I should pay for one in good condition?<br /><br />Thanks again,