2007 merc 15 to 20 conversion?

[grossman]

What is the difference between the 15 and 20 mercury 4-strokes? I see the 20 revs 250rpm more. Is it just a different carb?

I'll be adding some weight to the boat over the winter so I was just looking for a "cheap" way to maintain the same performance. I wonder if that 5hp will even be noticeable though.

I'd love to upgrade to a 25 or 30hp but realistically that's not going to happen.

Any help is appreciated, thanks.

 

[Swampfox88]

Sorry I don't have any help for you, but I own a 2004 mercury 15hp 4 stroke, and would be curious if I could do this same thing? , maybe the extra 250rpms is to much strain for the motor. ??

somebody has to know about this..

 

[tnriverluver]

I am by no means an expert on this but I don't think it works like that with the four strokes. The 2 strokes were pretty simple but due to camshafts, valve springs, etc, I don't think you can upgrade a 15 to a 20 4 stroke. It took them several years to come out with the 20 hp 4 strokes where the 15 had been around for ever. Hopefully someone that works on these can answer your question accurately.