1982 Evinrude 20 vs 1978 25

[jande9]

Hi,

I have a 15' Aluminum Starcraft with a 1982 Evinrude 20 on it. It has a 9.25X10 prop.

The boat is under powered and I have been looking for a larger motor.

I have just been given a 1978 Evinrude 25 with a 9X10 prop on it. (shear pin)

The 25 needs a new water pump so I haven't used it yet but I am wondering about the prop size on the 25. It is smaller than the prop on the 20, and by more than the quarter inch because the hub is smaller also.

Is this something I need to worry about, or will the 25 give me more speed even with the smaller prop?

Thanks

Jan de

 

[steelespike]

Re: 1982 Evinrude 20 vs 1978 25

There is no 82 20 hp 85 would be earliest if it has a flow through prop
they started in 85.I'm wondering if yoiu could use components from the 25 to make the 20 a 25 thus gaining the more modern gearcase.Don't know if you could swap powerheads.
The 25 is basically the same motor as your 20.weighs about the same.
The diameter doesn't usually mean too much in fractions of an inch.
I believe they came with the same props.Of course the final selection
would depend on the application.Someone should know thew best way to do it.