convert a 1971 6hp Chrysler into a 15hp

[Vintage Boat Guy]

So I've got this 1971 6hp Chrysler given to me by a friend, it runs great except the recoil is junk, anyway, I want to convert it into a 15hp. I think this is possible only because they look to have the same block. What will I need to do this? This is my first Chrysler and one of my newest outboards. model number is 62BB and serial number is 1376.

 

[jerryjerry05]

Re: convert a 1971 6hp Chrysler into a 15hp

I think the 6 is different bore size.
The 9.9 and 15 are the same(I think) just a different carb??

 

[Nordin]

Re: convert a 1971 6hp Chrysler into a 15hp

As jerryjerry says not same size. 6Hp block is smaller then 9,9 and 15Hp. The lower cowl and the hood is larger at the 15Hp.
You can not get 15Hp out of a 6Hp powerhead. No way.

 

[Vintage Boat Guy]

Re: convert a 1971 6hp Chrysler into a 15hp

As jerryjerry says not same size. 6Hp block is smaller then 9,9 and 15Hp. The lower cowl and the hood is larger at the 15Hp.
You can not get 15Hp out of a 6Hp powerhead. No way.

Ok then what can I get out of it 8hp?

 

[Frank Acampora]

Re: convert a 1971 6hp Chrysler into a 15hp

With the correct prop and proper modifications you can get----Oh, about 6 HP! You are not dealing with a world beater and most modifications simply won't be felt as increased power or speed. 8 horsepower would be a 25% increase in power and the engine simply does not have the cubic inches or design to gain this, even with port work.

Be satisfied with what you have.

Now, Of course, if you wanted to spend big bucks, buy a 55 gallon drum of nitromethane, re-jet the carb way richer (find out how much richer from the car racers), and go for that extra 3 MPH.