New engines debut at the Miami International Boat Show

Throwing down the throttles of new twin Mercury 150-horsepower four-stroke outboards to power a boat across Biscayne Bay in mid-February, I was grateful for the hands-on new engine introductions at the 2012 Miami International Boat Show. Four new powerplants were on boats captained by representatives ready to explain all the nuances of the cleaner and more fuel efficient propulsion packages.

Cummins MerCruiser Diesel, Honda Marine and Mercury Marine delivered on promises of new engines. In-water offerings ranged from Mercury Marine’s new 150-hp FourStroke on a 24-foot Mako, to Mercury Racing’s twin 565-hp stern drive engines on a Formula 400 SuperSport. In between were Honda Marine’s BF250-hp four-stroke outboard, its largest engine to date, and Cummins MerCruiser Diesel’s QSB6.7 480-hp engine. The new engines are all in production or soon will be, available for purchase as repower or on new boats. Here’s a look at the new technology that includes higher fuel efficiency and more sophisticated electronic operation.

Honda Marine BF250-hp Four Stroke

By adding a 250-hp engine, Honda is now a valid option for center consoles equipped with 250-hp outboards and larger. The boat I ran was an Everglades 295CC, powered by twin Honda BF250s, and it offered plenty of low- and high-end power. One noticeable feature on the new BF250 (priced at $24,353 with a 25-inch shaft) is air intakes on the top of the cowling. These intakes are part of the direct-air dual-circuit induction system. The first circuit draws air into the front and around critical engine components, and a top-mounted cooling fan draws cooling air over the alternator. The second circuit routes cool air from the upper intake vents, removes moisture and then inducts it into the throttle body.

In addition, when the electric load increases from power-hungry electronics, an adjustable idling-charge system enhances the charging performance of the engine. At idle speeds, an AMP Plus (Amp+) feature senses a need for more amperage and automatically raises the engine rpm by 100 to produce an additional nine amps. This allows for the simultaneously running of electronics. hondamarine.com

Mercury Racing 565-hp sterndrive

The new 565 (retail approximately $42,000) is based off the same block as its race-proven sibling, the 525 EFI. The stroke was increased for an additional 31 cubic inches of displacement to 533-C.I.D. (8.7 L). The larger displacement combined with redesigned cylinder heads, multiport fuel injection and twin electronic throttle bodies results in 565 hp in  the 5000-5400 rpm operating range on 89 octane pump gas. At Miami, twin Mercury Racing 565 engines were installed in a Formula 400 SuperSport. The engine can be mated to Bravo One XR or Bravo One XR Sport Master drives. mercuryracing.com

Mercury 150 EFI FourStroke

Mercury’s new 150-hp four-stroke outboard offers the versatility to fit on fresh or saltwater transoms right out of the box, making it a fit as both a single engine on pontoon boats to twin engine power on a center console. On the Mako 24-footer that I ran, there was plenty of power and the holeshot was outstanding. Cruising up and down Biscayne Bay we encountered all manner of choppy water and the twin Mercury 150 outboards propelled the boat right through the slop.

 The 3.0-liter, four-cylinder in-line configuration makes the engine perform on everything from the lightest flat skiffs to larger saltwater offshore hulls. And the price is right: $12,980 retail.

The 150 FourStroke is also simple to rig, with standard mechanical cables, dual cable or hydraulic steering compatibility; optional power steering on dual-engine setups; and the ability to run on either standard analog or full SmartCraft instrumentation. mercurymarine.com

Cummins MerCruiser Diesel QSB6.7L

The new QSB6.7 liter engine replaces the QSB5.7, and will be offered with 380, 425 or 480 horsepower. Cummins had its 44-foot express cruiser test boat at the docks. Previously, twin QSB5.9 480-hp engines were installed in the Zeus pod-driven boat, and accelerated the boat to 20 mph in 14 seconds. Now, with the same boat powered by QSB6.7 480-hp engines, it accelerated to 20 mph in 8 secondswith little change to the fuel economy. Other improvements include a new air filter designed from Walker Engineering, which reduces the noise level at cruise, and the engine also meets the new EPA Tier 3 emissions standards effective in 2013.

The QSB6.7 (price approximately $43,000) also employs a new fuel-calibration strategy. Unlike most marine engines, the QSB6.7 is calibrated for optimal fuel economy at cruising speeds, where the engine is most often used, rather than at wide-open throttle. cmdmarine.com