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April 25th 2015. By Lenny Rudow.

Most Powerful Outboard Engine Ever: Seven Marine 627

Seven Marine shocked the world with its 557, and now ups the ante with a 627 HP model.

We don’t usually think of outboard engines are being for yachts, yet when we looked at the crème of the crop to pick our Top 10 Fantasy Yachts, no less than three of them turned out to have outboard power. This is due, in no small part, to the advent of bigger and better outboards; in the past decade we’ve seen the power cap go from 250 HP to 350. Then, with the introduction of the Seven Marine 557, even that top end was surpassed.

seven marine

Seven Marine first announced the 557, seen here on a Hydra-Sports 42, in 2011.

Seven Marine accomplished the feat by taking a 6.2L V-8 with a supercharged aluminum powerhead, built by GM for the Cadillac CTS-V, adding a computer-controlled disc-clutch ZF Marine transmission and double-walled stainless-steel exhaust, and turning the engine horizontal. Latham Marine helped design an internal power steering system, and the engine swings custom Herring propellers.

These monster outboards immediately became popular, especially on high-powered center console fishing yachts, and you can already find listings for boats ranging from 36’ to 42’ that are powered by the 557.

But getting beyond the mid-40 foot range, while possible with this much power, was still a challenge. And with new and even bigger center console yachts hitting the market, more power would clearly be more better. (Read about one example, the Hydra-Sports 53 Suenos, on boats.com.)

Enter the Seven Marine 627. Here’s a video of boats.com Outboard Expert Charles Plueddeman explaining how the company boosted this block’s output by another 70 horses (and another 50 foot-pounds of torque).

We’ll begin seeing the 627 on boats this year, on monster fishing boats as well as speed boats and even some performance cruisers. Pricing hasn’t been announced just yet, but considering that the 557 starts at over $70K, it’s a fair bet that those who feel price is a serious consideration probably don’t want to ask.

For more information read about the Seven Marine engines on boats.com, or visit Seven Marine.



Lenny Rudow
With over two decades of experience in marine journalism, Lenny Rudow has contributed to publications including YachtWorld, boats.com, Boating Magazine, Marlin Magazine, Boating World, Saltwater Sportsman, Texas Fish & Game, and many others. Lenny is a graduate of the Westlawn School of Yacht Design, and he has won numerous BWI and OWAA writing awards.