6.2L 300HP to 350HP

[Hai Nhi]

Hello all. I have another newbie question please.

I see Mercruiser new 6.2L engines have 2 setups: 300 & 350HP but the physical specs seem to be identical.

Question is: is the different HP rating just some programming, like an auto tuning, or it’s something else as well?

I ask because I heard someone said you can have the 300 HP re-programmed to be 350HP. And if this is true, what would be the down side?

Thanks.

 

[alldodge]

The differences are
Virgin bore 6.2 is actually 377 cubic inch, 320 HP at the flywheel and 300 HP at the prop

Reman bored .030 over is 383 cubic inch, 350 HP flywheel and 320 or so at the prop

Edit:
The above is prior to ECT or catalyst motors
Here is the skinny with CAT motors
https://www.boatingmag.com/mercury-mercruiser-62l-300-350-ect/