Most mainstream boat builders have relied on big-block engines to do their heavy lifting. In the last few years, Volvo Penta had the 8.1L, and MerCruiser offered the 8.2L V-8, both blocks built by General Motors (MerCruiser uses its own heads). But for model year 2013, Volvo Penta chose a different path, with its new 6.0L V-8, which produces 380 hp. Following the GM auto/truck division’s “smaller is better” philosophy, Volvo Penta is replacing cubic inches with more advanced technology.
The 6.0L is a marinized long-block version of the Vortec L96, the largest gas engine offered on the Chevy 3500 Silverado “dually.” Able to tow up to 14,100 pounds, it’s packing some guts. It uses an iron block with a high-flow aluminum cylinder head, and it comes standard with a closed cooling system, which should help increase its longevity. Boaters using it in salt water can choose the optional Ocean X outdrive, which has a titanium-ceramic coating that is applied using an electro-depositation (aka electroplating) process. The Ocean X outdrive has a sensor that trips an alert if water enters the bellows, which has traditionally been a vulnerable area and the cause of boat sinkings through dry rot or from animals such as otters nibbling on the bellows.
The 2012 version of the 8.1L was available in either a 380 or 420 hp version, but since Volvo Penta has discontinued the 8.1L model (as did GM), it no longer produces a gasoline-powered package with more than 380 hp. By bowing out of the high-horsepower niche market, the Goteborg, Sweden-based builder is letting MerCruiser take ownership of it, with engines that crank up to 1,350 hp. Volvo Penta briefly made a foray into the high-performance arena when it marketed the DPX 500 and DPX 600, built from 2000-2003 by the highly regarded Innovation Marine Corp., based in Sarasota, Fla., plenty of which are still running. But Volvo Penta chose to concentrate on its core market, which is reliable, fuel-efficient gasoline sterndrives (built in Tennessee) for recreational pleasureboats, in addition to its diesel engines designed for both work and play.
The major advantage of the 6.0L vs. Mercury’s 8.2L 380 hp model is the 6.0L weighs an astounding 270 pounds less, which is like kicking NFL lineman Dwight Freeney off your boat’s stern bench (something I definitely won’t be attempting). During a recent press event at Volvo Penta’s test center in Suffolk, Va., a pair of Formula 260 Sun Sports were outfitted with a single sterndrive: One had the new 380 hp 6.0L Volvo Penta with the Duoprop setup, and the other had MerCruiser’s 380 hp 8.2L model with the twin-prop Bravo 3 outdrive. While I’m normally skeptical of side-by-side tests of two motors conducted by only one of the companies, it did appear that Volvo Penta tried to make this as even as possible. They weighed both boats without the engines and found one to be 150 pounds lighter, so it was given ballast to make them equal. The center of gravity was then checked to ensure a match. The engines were weighed with all the accompanying components and fluids, and the Volvo Penta package was 270 pounds lighter. (The published difference is 245 pounds.)
The weight disparity was noticeable from a distance, as the Merc-powered Formula sat lower in the water at the stern. We piled an equal number of passengers aboard each and tested them in a drag race. When the proverbial checkered flag fell, the Volvo Penta-powered Formula had less bowrise, planed quicker and accelerated faster. One writer questioned whether the passenger weights were equal, so we stacked the deck by putting the beefiest passengers on the Volvo Penta boat, and it still won. These results were later verified during performance tests I conducted with identical loads on board. Time to plane for the MerCruiser boat was 5.2 seconds, with the Volvo Penta model clocking in at 4.2 seconds. Zero to 30 mph took 9.8 seconds for the Merc and 8.7 seconds for the Volvo. Top speed for the Volvo Penta was 53.5 mph, with the MerCruiser boat reaching 52.5 mph.
The dramatic difference in weight comes in part from smaller displacement: smaller pistons, block, etc. Both have cast-iron blocks, but the Volvo Penta uses an aluminum head as well as composite components such as the intake manifold. Another big difference is that the V-8 380 hp has Variable Valve Timing (VVT), which flattens the torque curve to give you more usable power throughout. It does this by using a hydraulic cam phaser to retard cam timing to improve the low end and advance cam timing at high-rpm operation. While the MerCruiser is rated to achieve 4800 rpm at wide-open throttle, the Volvo Penta engine hits 6000 rpm at WOT and emits a different yet pleasant sound.
According to Volvo Penta tests, its 6.0L engine gets 12 percent better fuel economy, on average. Its results showed that at 30 mph the MerCruiser was getting 2.7 mpg and the Volvo Penta was achieving 3.1 mpg.
While many folks subscribe to the “there’s no replacement for displacement theory,” the folks at Volvo Penta would respectfully disagree.