Maximum horsepower for 21 ft islander

[sleddogs13]

My boat had a V6 OMC cobra setuo. I am thinking about installing a V8 350 mercruiser with an Alpha One outdrive. Is the motor to much horsepower and weight?
It is hard to find a V6 Mercruiser. I think I read the transom cutout will work with the Alpha. I am putting in a new floor and transom.
Thanks

 

[dozerII]

I don't think the V8 would be too much power and is only about 80lbs heavier than the V6, but you are going to have to increase the length of the dog house about 8 inchs, which takes up a lot of interior space. I also think there is some difference in the cutout of a Cobra drive where as the King Cobra is the same. A 4.3 LX is 220hp and the 5.7 is 260 I think I would would look real hard for the V6 before I would make all the changes needed to move up 40 hp just my 2 cents

 

[elkhunter338]

Does the OMC use the chevy v-6 like the mercruiser? If so you don't need to find a v-6 motor if yours is in good order. Just the outdrive/housing compents

 

[Watermann]

My boat had a V6 OMC cobra setuo. I am thinking about installing a V8 350 mercruiser with an Alpha One outdrive. Is the motor to much horsepower and weight?
It is hard to find a V6 Mercruiser. I think I read the transom cutout will work with the Alpha. I am putting in a new floor and transom.
Thanks

Was your V6 a 3.7 L OMC or a 4.3? I would echo the advice to go 4.3L V6 and to search for a donor boat with the complete 4.3L MC A1 set up. The 4.3 L goes from 175 HP to 220 HP for the newer Vortec. I lucked upon an older 4.3 LX 205 HP 4 BBL non vortec for my upgrade.

Here is a pic posted up by Don S with the cutouts for various serndrives