1984 40 hp Evinrude horsepower increase?

[heavy_duty]

Is it possible to increase the HP of my motor and maintain the same bore & stroke.

 

[JB]

Re: 1984 40 hp Evinrude horsepower increase?

Howdy, Heavy_Duty. Yes, it is possible, but definitely not worth the cost and trouble. You would need so many parts from a 50 that it would be much cheaper to simply trade for the 50.<br /><br />Red sky at night. . .<br />JB

 

[Hooty]

Re: 1984 40 hp Evinrude horsepower increase?

H/D,<br />Somebody makes some hotdog reeds for that puppy, can't remember who right now, but like Capt Cornwell sez, lots of bucks but pretty easy to install.<br /><br />c/6<br /><br />hooty

 

[blanchy]

Re: 1984 40 hp Evinrude horsepower increase?

Boysen I think thats the spelling make reeds for nearly everything. If you get a straight answer on what 50hp parts are needed, please tell me.

 

[JB]

Re: 1984 40 hp Evinrude horsepower increase?

Blanchy, you wont quit will you? This is the third time I've answered your question.<br /><br />Go buy a 50 block, heads, pistons, carbs, complete exhaust system, complete ignition system and reed plates.<br /><br />Or, cheaper, go buy a 50 and a set of 40 bonnet decals.<br /><br />Now, is that a straight enough answer for you?<br /><br />Now, knock off your * whining. I didn't design the * thing OMC did.<br /><br />JB

 

[blanchy]

Re: 1984 40 hp Evinrude horsepower increase?

Hi again. I don't wish to start a public slanging match here but its possible that we have different motors sold in Aust than the US. The 40 & 50 for 1998 are the same size 45cu.in or 737cc. They run the same pistons.

 

[Mark R Groves]

Re: 1984 40 hp Evinrude horsepower increase?

To the best of my knowledge all the large 2 cylinder OMCs (40,48,50,55,60hp) from early 70s to late 90s were the same displacement 45cid. However, there are significant differences in several critical parts. According to my parts manual for an 1989 the difference between the 40 and 50 are:<br /><br />1. carbs<br />2. reeds<br />3. crankcase/cylinders<br />4. cylinder head<br /><br />I purchased a parts book for my '89 40hp to research a cheap upgrade. However, the replacing the block and head kinda burst that bubble. I'd be interested someone could tell me you can squeese more hp from this engine without power head replacement. Unfortunately, the evidence suggests otherwise.

 

[JB]

Re: 1984 40 hp Evinrude horsepower increase?

Thanks, McG. You have more specific data than I. I guess I guessed wrong on the pistons, but the bottom line is little altered, isn't it?<br /><br />The investment in a set of Boyesen reeds would show improvement on a dynomometer, but hard to notice on the water, except in head-to-head competition.<br /><br />I think I'll just stop trying to answer these "how can I get horsepower that isn't there" questions. Too many people seem to blame me for answers they don't like.<br /><br />Red sky at night. . .<br />JB

 

[evin300]

Re: 1984 40 hp Evinrude horsepower increase?

Hey Heavy, how good is your set-up? I think this is overlooked many times, you could easily be wasting 10hp with poor motor hieght, inferior propeller, improper trim angle and neglected hull condition. <br /><br />Have you looked into this? Most people seem to focus on the motor, but miss 20% of the issue. Its not always the motors fault that causes poor performance. Disagree? I can show you a 10mph speed improvememt from X-dimension and prop alone. (on my boat) Good Luck

 

[Dhadley]

Re: 1984 40 hp Evinrude horsepower increase?

Evin300 is correct -- concentrate on the set up first. While there are different parts like heads, the major difference between a 40 and a 50 is the reed stop dimension. Don't try to figure it out, just get the Boyesen reeds (#124 if I remember right). Keep in mind that if you are only turning 5000 RPM now, you wont see much, if any, improvement. Take his advise, work on your set up to establish a reliable baseline.<br /><br />Good luck!

 

[Hooty]

Re: 1984 40 hp Evinrude horsepower increase?

...and for real serious tweeking, invest in a jack-plate.<br /><br />c/6<br /><br />hooty