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Evinrude 20 HP Needs more speed Joe

D

deano

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" Hi Joe... I didn't thank

" Hi Joe... I didn't thank you for your advice on my problem with the anti siphoning valve on my 120 HP. Johnson. It will be maybe 7or 8 weeks before I get it out of storage,then I will try to get it solved,and I will let you know how it worked out. You see its still winter here in Southern Ontario complete with ice on the lakes and more snow in the forecast. I have another question for you though. I own a 1980 20 HP. Evinrude that I have mounted on a 12' [Glen L TNT]runabout and I was wondering did O.M.C. ever make a quickie lower unit for the 20 HP. fishing motor and if so are they readily avalable in North American market? We're lucky to maybe get 25 to 28 mph and there are some Merc,s on our lake with the same boat that get 34 or 36 mph with A high pitch SS prop. Do you know if there are high pitch SS Props for this motor too? Thank you for your time. Deano. P.S. This is wonderfull site. "
 
"Deano... I'm not aware of

"Deano... I'm not aware of any alternative lower units that might increase the speed of a 20hp, and I must admit that selecting a prop is something not in my line of expertise. OMC and other manufactures do make stainless steel props for the engine but exactly which one might improve your speed is unknown to me. I'd suggest that you check out the propeller selection chart at your local OMC dealership, or any marine dealership for that matter.

Joe
"
 
You are never going to get 34

You are never going to get 34-36 mph out of a 20 hp johnson motor on that sized boat. The reason all the mercury's are passing you is because they are prop rated and have 20 hp at the foot. Johnson motors are powerhead rated so by the time it is transfered to the foot your johnson only really has about 17-18 hp.
 
"J White.... I can remember as

"J White.... I can remember as far back as 1962 when one of OMC's big selling points were that the horsepower was rated at the propeller and Mercurys (who was their big competitor) was not. Through the years, I've caught OMC repeating that claim. Apparently I have missed something. When did OMC change that horsepower rating method?

Joe (30+ Years With OMC)"
 
" I've heard the same thin

" I've heard the same thing about OMC motors, that their HP is rated at the prop, not the powerhead. A stainless prop probably would improve your top end speed because it does not slip or flex as an aluminum prop does. Be prepared to cough up some serious cash for the SS prop though. I've been searching in vain for a used SS for my OMC 9.9 HP motor. I'm just not quite sure I want to pay 150 to 200 dollars for 3-5 mph. You could also improve your speed by going with a bigger diamater and or pitch prop. If you do that, just be careful not to exceed your maximum rpm rating and possibly burn out the powerhead. If you are dead set on getting a stainless, check out the parts and propellers suppliers section on this site. To that I would add ptprops.com If anyone has a used SS prop to fit the 9.9/15 Johnson/Evinrude that they're willing to part with, they should post here and we'll deal. "
 
" I don't know when they c

" I don't know when they changed it, but we have a dyno here at the shop and every johnson/evinrude I have ever put on it has come up short on hp. For instance i tested a 2001 90 johnson today and it only had 86 hp at the foot. "
 
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