The four-stroke field strengthens, as Mercury introduces four outboards. Left: The supercharged Mercury can crank out 275 horsepower—the most of any four-stroke to date. Right: We tested a pair of 250s on a 32’ Whaler.

What’s the best way to generate horsepower in a small package? Two trains of thought exist in the automotive and aviation fields. One camp believes more displacement is the best way to create more ponies, while the other crowd prefers smaller engines with a blower—either a supercharger or a turbocharger. In today’s big four-stroke outboard market, we have a similar engineering contrast.

Suzuki’s 250-hp four-stroke makes its power via lots of cubic inches. Mercury’s new Verado is smaller displacement-wise but has a supercharger that juices the engine to a maximum of 275 hp. There is even a rumor this engine will get a 300-hp rating down the road. …