Gasoline sterndrive development has become like a boxing match of late as two heavyweights punch and counter-punch with engines of the same horsepower, but dissimilar in size and made with contrasting strategies. Volvo Penta in late August countered the introduction of Mercury Marine’s new MerCruiser 6.2L V-8 with a 5.3-liter V-8 powerplant. Both Mercury and Volvo Penta offer their V-8s in 300- and 350-hp configurations.
Mercury in this summer held a press introduction for its 6.2L engine, the second gasoline sterndrive motor the Fond du Lac, Wis., manufacturer has built in-house. Mercury had been building its engines using General Motors blocks, but the company says that by going it alone it can design and build its MerCruiser I/Os specifically for the marine environment.
“We are continuing to push the importance of a marine purpose-built engine, which is exactly what the new 6.2L is,” Mercury vice president of product development, engineering and racing David Foulkes said at the July media event. “With in-house design and manufacturing we have been able to be super-responsive and more agile to market demands.”
Volvo Penta has opted to continue using GM engines, saying the advanced automotive technology, durability and reliability of the power plants can’t be beat. The GM engines “give us even more reliability — they manufacture 4,500 engines a day, 1.3 million per year,” says Volvo Penta of the Americas president Ron Huibers. “There are already 2 million of these things out there.”
Mercury and Volvo Penta’s summer introductions were actually the second round of their new sterndrive engines. Mercury splashed its first home-grown engine about a year ago — the 4.5L 250-hp MerCruiser. Volvo Penta answered with the first of a fleet of sterndrives with the fifth generation of GM engines — 200- and 240-hp V-6s with a 4.3-liter displacement — at the 2015 Miami International Boat Show. Volvo Penta also debuted a forward-facing sterndrive with twin props — the Forward Drive — for all of its Gen V engines.
Huibers said he welcomes the back-and-forth competition between the two companies during his presentation of the 5.3L engines at the company’s Chesapeake, Va., test center. “Competition is a great thing — it’s what drives us here at Volvo Penta,” Huibers says. “We are a technology and innovation company, and innovation is our passion.”
Heightened product development by the two companies can only benefit the marine industry as a whole, says Foulkes. “It’s important that companies in the boating industry continue to invest in new products that will both enhance the boating experience for existing boaters and draw new customers into the market,” says Foulkes.
The two options for consumers and boat dealers — in-house (Mercury) or GM (Volvo Penta) — “is now crystal clear,” adds Marcia Kull, vice president of sales for Volvo Penta of the Americas. “We’ve always been exceptionally strong in the sterndrive portion of the engines, but the engine package itself was pretty similar with the competition. But now both dealers and consumers have big choices to make — much like with outboards with their different technologies [2-stroke and 4-stroke].”
Under the hood
Since the 2005 introduction of its Inboard Performance System, Volvo Penta has been on a mission to help make owning, operating and maintaining a boat easier, but the fun factor has spiked, as well, as the engines have become more technologically advanced.
I tested four sterndrive boats (all under 30 feet) with the new V-8 300 and 350 and V-6 280 engines at the Volvo Penta test center in Chesapeake.
The throttle response on the single-engine runabouts and bowriders brought a smile to my face as I pushed through wakes, cut quick corners and weaved through lines of crab pot buoys.
As I drove the Cobalt 232 WSS with the new Volvo Penta 280-hp V-6, I looked back at my crew. Each time I pushed the throttle forward — even with just a nudge — the giddy-up pushed my mates back in their seats or had them tightening their grips on a grab rail or seat back.
Several factors foster this quickness, mainly common rail fuel injection and variable valve timing. These technologies allow for the more efficient use of fuel that provides that extra “oomph.”
“Customers may not care about what direct injection is because it’s technical,” says Huibers. “It contributes to higher pressure ratios and higher performance and fuel efficiency, and that’s what people want. Consumers want more fun, and that is what direct injection equates to.”
Variable valve timing across the horsepower range from 200 to 430 is another strength for Volvo Penta’s next generation of engines, says Huibers. “People spend their days with the engine in its cruising ranges; they are slowing down and speeding up, not at full throttle,” he says. “The engine [performance] makes boats feel like a new boat, so it gives customers a new boating experience.”
Volvo Penta displayed many of the parts of the new GM engines, along with the entire engine and drive completely built.
Mel Cahoon, manager of new products, showed me the innards of the Gen V GM engines that provide the punch. He pointed out the direct fuel injector, with its high-pressure output, which counts on “piston cooling jets” to reduce heat. “This is a very crucial component to the acceleration,” he says.
Cahoon says the new engines are lighter and more compact than previous versions. The 280-hp weighs 77 pounds less than its 270-hp predecessor, but the 280 block’s fore-aft footprint is 4 inches shorter than that of the Gen IV engine.
The fuel economy of these engines deserves some attention, too. On the Cobalt, the 280-hp engine burned about 6 gph at 25 mph, which equates to about 4.2 mpg. At 30 mph the power plant consumed 7.5 gph, for a fuel burn rate of 4 mpg. Even at full throttle (47 mph) we got 2.2 mpg.
An engine larger than 5.3 liters is expected to be the next new model — with a 2016 launching — in Volvo Penta’s gas sterndrive engine upgrade from GM Gen IV to Gen V engines.
This article originally appeared in the October 2015 issue.