mercury 9.9 vs 15hp. is it just a carb difference

[papapike]

For johnson and evinrude outboards, the difference between a 9.9 and 15hp is just the carb, everything else is the same so I am told. Is this the case for mercury also? If I want to make my merc 9.9 a 15hp, can I just get a 15hp carb and put it on? Thanks in advance.

 

[oldman570]

Re: mercury 9.9 vs 15hp. is it just a carb difference

I belive that the gearing of the LU gears are diffrent also. JMO
Oldman570

 

[79Merc80]

Re: mercury 9.9 vs 15hp. is it just a carb difference

It's also the port placement and size that makes the extra HP. Check the block #'s. Even though they are the same CID, I'll bet they are different part #'s.

Craig

 

[MH Hawker]

Re: mercury 9.9 vs 15hp. is it just a carb difference

It looks like at least on a 1996 model its the same block.

 

[JMichael]

Re: mercury 9.9 vs 15hp. is it just a carb difference

I was checking the differences on the 89 models and noticed the 6, 8, and 9.9 were all the same but the 15 uses different part numbers for the crankshaft and piston.