Cost and reliability. Just guessing here not really had a chance to examine the new series of engines, but will they not be using Timing Belts that needed to be constantly examined/replaced instead of a timing chain? I have yet to see a timing chain from the old tech engines fail.

The OHC engine is enormously expensive to make; no need for it in this horsepower range. That platform would, however, make a great 800 hp N/A engine.

Aren't the 525 and 565 crank-rated rather than prop-rated? If so, this engine makes ZERO sense unless the 525 and 565 are going away. What makes even less sense is to keep whipping on the old, heavy BBC architecture when every other marine drivetrain manufacturer has gone to the lighter and more efficient LS-based engines. What Mercury really needs to introduce is a 700 hp rated version of the Bravo.

While they would gain economies of scale, I suspect this platform would be too costly for the market segment.

Right, I understand. I've alwaysheard that all things being equal N/A OHV engines make more torque than N/A OHC engines.

I think a 750-850 hp N/A quad cam motor would be great and I would think they could make it for not much more than the current 700sci cost. Back to the 520 I see how it could be a great motor especially if the 525 goes away. Now I know this form is predominately inboard fans but does anyone else think its about time merc gives the high performance outboards some attention? I mean the 300xs has been unchanged since 07

With a less aggressive valve train and the problematic headers gone, looks like
they're trying to market it as something that might run a while before it needs attention.

Too bad they didnt do anything with the drive

$7,000 of the $11,000 in savings is coming from dumping the CMI headers. I am surprised with all the tech that Merc has that they have not started making their own header design.

Ironically, with the addition of those (POS) CMI's on this same engine, it would likely be close in power to the 525.

Nice that it runs on 87 octane too. That's a big savings over the course of its lifetime.

I'm thinking maybe the "propshaft hp" in this article is a typo since Mercury Racing rates horsepower at the crank. Then I could see it replacing the 525. That would make more sense.

That's a nice package but I've got to say that the exhaust don't look like it would have much flow . I'd prefer a set of quality headers and the sound that goes with them .