Last year Mercury Marine unveiled its new 4.5L V-6 sterndrive engine, the first of a new generation of powerplants designed from the get-go to be marine engines — no more taking an automotive engine and modifying it for marine use. It grabbed the attention of the press during a drag race between identical Sea Ray 220 Sundecks, one with the new 250 hp V-6 and one with a 260 hp 5.0L V-8. Out of the hole, the smaller V-6, with less horsepower, ran away from the V-8. This year, Mercury added the MerCruiser 6.2L V-8 — in 300 hp and 350 hp configurations — to its new-gen line of sterndrives. And like the 4.5L engine, it solves a number of problems facing manufacturers who build sterndrive-powered boats.
The first major issue with using modified General Motors blocks, which has been the norm for decades, is that all automakers have been under pressure by EPA mandates to achieve increasingly better fuel economy. The trend has been to employ overachieving smaller engines that often use technology such as turbocharging to make up for the lack of inherent grunt the bigger blocks produce. To achieve optimal fuel economy, car engines also use transmissions with up to nine forward gears to keep them humming along in the increasingly narrow sweet spot in the power band. Conversely, boat engines need lots of low-end power that comes on fast, to get a boat on plane quickly, and a fat power curve, to operate efficiently at all rpm without the aid of multiple forward gears. The diverging mission of car and boat engines has resulted in availability issues as automakers have been discontinuing popular boat engine blocks. Already gone is the 7.4L block, but also slated for extinction are the 4.3L, 5.0L and 5.7L blocks, which power many trailerable boats. Knowing all this led MerCruiser to design and build its future sterndrive engines, such as the new 6.2L V-8, entirely in house. Its engineers boast there is not a single GM part on its 4.5L and 6.2L motors.
Because Mercury wasn’t modifying a car engine, it was able to correct the many issues that arise from one basic difference: Car engines are designed to be in front of passengers while boat engines sit behind them. First, the new V-8’s throttle body faces rearward, to reduce the annoying sucking sound of air rushing into the combustion chamber when the driver hammers the throttle. And because the spaces under boat engine hatches are generally more claustrophobic than under car hoods, all routine maintenance service points are placed in front and on top for easy access. Car oil filters are on the bottom and are designed to be changed with a car on a lift, which has been frustrating marine mechanics for decades, but the 6.2L V-8’s oil filters are placed on top, so anyone can change them. As an added bonus, owners can scan QR codes that link smartphones to videos that show them how to perform common service procedures, including winterizing. And to help you extend boating season into the transition to winter, there’s an easy-to-use drain system to make sure water doesn’t freeze internally should the temperature plummet. The valve train is designed to be maintenance-free for the life of the engine, and for this new generation of motors, the 20-hour required dealer service pit stop is history.
We got a chance to test the 350 hp MerCruiser 6.2L engine on a Bryant Calandra, a beefy 23-plus-footer with a dry weight approaching 5,000 pounds. Hammering the throttle produced a pleasingly angry engine note as the Calandra reached plane in 3 seconds flat. There’s nothing jerky about the power curve, just hard, smooth acceleration to 30 mph in 7.6 seconds and no letup until it reached a maximum velocity of 52.5 mph. While the 6.2L reached a peak reading of 95 decibels on the soundmeter, that relatively high reading had more to do with the Calandra’s engine compartment insulation than the MerCruiser itself, which is quieter than its previous models.
One of the features that makes the MerCruiser 6.2L a great ski boat engine is the Adaptive Speed Control (ASC), which maintains engine rpm even during hard turns, without the driver having to “work” the throttle. As a result, a skier won’t have to face that sinking feeling from a loss of speed or stretched-arm syndrome if the driver overcompensates for the anticipated loss of rpm during a 180 at the end of the lake. It’s also available with Active Trim Control that automatically keeps the boat running at the proper attitude. For dual-engine applications, the 6.2L MerCruiser is Axis-joystick compatible.
Mercury Marine is also running a Five Year Engine Package Limited Warranty for all 2016 model sterndrives and inboards, providing they are sold before July 2, 2016, and registered by July 17, 2016.
Type: Two valves per cylinder MPI V-8
Full throttle range: 5000-5400 rpm
Weight: 885 lbs.
Gear Ratio: N/A
Tested with Bryant Calandra (w/350 hp version)
Time to plane: 3.0 sec.
0-30 mph: 7.6 sec.
Top speed: 52.5 mph
Decibels @ idle: 62 dBA
Cruise: 31.7 mph/3500 rpm/85 dBA
Peak: 52.5 mph/5300 rpm/95 dBA