9.9 vs 15hp

[mikewoller]

I am looking at purchasing a 1979 johnson 15 hp. I currently have a 1990 9.9hp. My problem is that my 9.9 wont plane out my 14' modified V jon boat. Motor is running fine, just don't seem to have enough to plane it out. My question is.....will the 79 15hp have enough? An old timer once told me that the older 15hp, till the year 1985 are equivilent to the newer 9.9s? Any truth, or will the 79 15hp be a noticable difference?

 

[mikewoller]

Re: 9.9 vs 15hp

anyone??

 

[wbeaton]

Re: 9.9 vs 15hp

There is some truth to it as the old motors were hp rated at the powerhead whereas newer ones are at the prop. However, the 15 hp will still be more powerful then the 9.9 hp, but it still may not be enough. What is the max hp capacity of your boat? The excepted rule is to stay above approx. 75% of the max cap.

 

[mikewoller]

Re: 9.9 vs 15hp

boat is rated for a 25

 

[kenmyfam]

Re: 9.9 vs 15hp

Personally I would head nearer the 25hp mark to be sure that you get the performance that you are looking for.

 

[rolmops]

Re: 9.9 vs 15hp

You can upgrade your 9.9 to a 15.They are the same engine.The 9.9 was originally intended to be a 15 but then regulations came through, limiting horse power to 9.9 on many lakes.OMC put a slightly smaller carburetor on the design and the 9.9 appeared.
Today you can get the parts to upgrade back to a 15 horse.
Just be careful with the different years because changes were made during later years.

 

[jbjennings]

Re: 9.9 vs 15hp

If your 9.9 won't plane it out, then a 15 might, but you won't be at all pleased with the speed. It sounds like to me you need at least a 20 and probably a 25hp. I agree with Kennyfam. Get a 25 evinrude or johnson 2-stroke and be done with it. A weak sister on the back of a boat isn't any fun.
I suspect your 1990 9.9 will need the tuned exhaust and the carb. to actually get it up to 15. Seems like every person that ever owned a 9.9 is trying to upgrade it to a 15, so you can imagine how many 15hp carbs. and tuned exhausts there are lying around. I'd forget that and get a bigger motor.
JMO,
JBJ

 

[wbeaton]

Re: 9.9 vs 15hp

Simple math (25 hp x .75) says you should consider nothing less than 18.75 hp. So, pick out a nice Johnson/Evinrude 18, 20 or 25 hp. You can't go wrong with any of them. The 15 hp will probably still be too small.