|Type of Engine||4-Stroke|
|Number of Cylinders||8 Cylinders|
|Shaft Length Options||20” (50.8 cm) / 25” (63.5 cm) / 30” (76.2 cm)|
|Recommended Fuel||87 Octane|
|Alternator Output||115 Amps total|
Mercury has introduced an all-new 4.6-liter (279 cubic inch) V8 engine. The company says the naturally aspirated outboards will provide smooth, quiet power and optimize fuel economy, all in a package with a dry weight package ranging from 505 lbs. to 600 lbs. (229 kg to 272 kg), in the lightest weight units available of each of the four series. The powerhead is a large-displacement designed for more power and greater low- and mid-range torque, and for better acceleration. It’s 35 lbs. (16 kg) lighter than the previous-generation Mercury Verado 300, an inline-6 configuration.
This new platform, along with the new V6 launched in February, replaces the 2-stroke OptiMax and the L6 supercharged Verado, except for the L6 350 Verado and 400R Racing engines.
Type of Engine: 4-stroke
Number of Cylinders: 8 cylinders
Configuration: V-8, 32 valve DOHC
Weight (lb./kg): 505 – 600 lb. / 229.06 – 227.16 kg
Displacement (liter/cubic inch): 4.6 liter / 279 cubic in.
Gear Ratio: 1.85:1 or 1.75:1
Shaft Length Options: 20” (50.8 cm) / 25” (63.5 cm) / 30” (76.2 cm)
CARB Rating: 3-Star
Recommended Fuel: 87 Octane
Alternator Output: 115 Amps total
Mercury has introduced its next generation of large outboards and the company has based the new models on two displacement sizes and configurations, a 3.4-liter V6 and a 4.6-liter V8. These 4-stroke engines will be sold under the Mercury brand lines FourStroke, Verado, Pro XS, and SeaPro, as well as the Mercury Racing brand. Their horsepower ranges from 175 to 300, depending on the platform.
The concept driving these outboards is to offer a compelling amount of power by means of displacement, fuel injection, and electronic engine control. The electronic system is used to dial-in fuel efficiency. It does this by controlling the fuel-air mixture in a closed-loop fuel system. For more torque at the low end and better hole shot times, Mercury is using what is known as a “Transient Spark”, which the company says will give the engine 5% to 7% more torque at the low end.
FourStroke. Mercury’s 250- and 300-hp FourStroke outboards are built on the 4.6-liter V8 platform, while the 175-, 200-, and 225-hp FourStroke outboards are built on the 3.4-liter V6 platform. These engines are designed for use on pontoon boats, sportboats, center consoles, dual consoles and other applications where lighter weight (24 lbs. lighter than the V6 Yamaha), better torque, and reliability are important.
Pro XS. The Pro XS engines are designed primarily for bass, multi-species, and bay boats. Here, many consumers want fast hole shot times as well as high top speeds, something that is difficult to produce with the same prop. Mercury’s solution is lightweight – 505 lbs. (229 kg), the brand’s lightest V8 engine. The torpedo has been redesigned for reduced drag, and a Torque Master unit is optional. And a transient spark calibration is said to increase torque somewhat. This line of outboards gets a 175 based on the 3.4-liter V-6, and the 4.6-liter V8 platform is used in four models — rated for 200, 225, 250, and – for the first time – a 300-hp model. This line of engines replaces the 2-stroke OptiMax engines, which will no longer be made.mercury_verado46lv8platform_displacement_2018.jpg This Mercury Pro XS 250-hp outboard is built on the 4.6-liter V8 platform and has the greatest displacement of any outboard in its class.
SeaPro. Designed specifically for commercial applications, which means that it is more ruggedly constructed in the hub, and has options that are not available in some of the other models. The SeaPro line gets a 200-hp outboard based on the 3.4-liter V6, and three choices built on the 4.6-liter V8 platform: a 225, a 250, and a 300-hp model. Both the Advance MidSection and the Conventional MidSection (CMS) are available on SeaPro units.
Verado. The Verado takes its name from the famous L6 supercharged engine it replaces, but it is not supercharged and because of its large displacement, lightweight and transient spark ignition, it doesn’t need to be. Nevertheless, it is Mercury’s premium engine of the four lines, and it has its own set of standard and optional features designed for its intended market. Most notable is the fact that it comes standard with the Advanced MidSection, a 5.4” gearcase, electro-hydraulic power steering and additional sound abatement in its cowl. It is also the only recreational engine that can use the Joystick Piloting system.
It has been specifically designed for saltwater in single and multi-engine applications for center consoles, express fish boats, and express cruisers where consumers want lots of quiet power. The engines can be installed on 26” centers – 2.5” less than on V6 Yamaha engines – making this engine more advantageous for quad installations.
The Powerhead. Much of the innovative design of the 4.6-liter V8 platform comes from the mandate for the new line: It had to be powerful, have high torque at the low end, be lightweight, quiet, and efficient. Consider that the 4.6-liter V8 is 2 liters greater than the supercharged 2.6-liter displacement of the inline-6 Mercury and yet it weighs 35 lbs. less. Displacement is the way to generate more torque in a 4-stroke engine, a job that the supercharger fulfilled in the L6 2.6 models. The double-overhead cam design, with four valves per cylinder, combines with an enlarged intake to deliver plenty of air and fuel when it’s needed.
These new outboards use two intake valves to charge each cylinder, with the injector for each cylinder positioned between them in the intake manifold. We asked Mercury why the injectors were placed in the manifolds instead of in the cylinders themselves. The answer--
“A port fuel injection (PFI) system has many advantages, chief among those being simplicity, reliability, and cost,” says Brian Meyer, category manager for 75+ hp outboards for Mercury Marine. “Direct injection (DI) systems certainly can improve fuel economy and performance of an engine. However, Mercury has chosen to address the performance needs of our customers by optimizing the displacement and efficiency of our PFI engine, while also employing our Advanced Range Optimization (ARO) technology. We believe that the ARO system yields comparable improvements in fuel economy to a DI fuel system at a significantly lower cost.”
This is one of the most innovative aspects of the engine because it reduces the width of the engine, reduces its weight, and helps contain engine noise – all with one design. The exhaust manifold is in the middle of the V, instead of being on the outside. It is then routed from the top of the engine, down the centerline, between each side of the V of the engine. This allowed Mercury to keep the cowl width slimmer so that the outboard could be installed on 26” centers – 2.5” less than its primary competitor.
The exhaust-system design uses a multi-chamber muffler system located beneath the “chaps,” as the manufacturer calls the panels on either side of the midsection. The muffler chambers connect the main exhaust passage to the idle relief port, and include an electronically controlled bypass valve.
Boating is meant to be fun, and sometimes boaters want to hear the throaty growl of a V8 (or two), letting everyone know they’re there. Mercury designed Verado to be exceptionally quiet, and never is that more apparent than when using a setting called Sport Exhaust. When it’s turned on, on the VesselView touchscreen, the system routes exhaust through the idle relief and one of the two mufflers.
Let’s Rumble. This creates an unmistakable throaty rumble that’s been tweaked to impress friends and neighbors and call attention to the new outboards – to say nothing of the boat’s proud owner. And when it is toggled off, the outboards sounded even quieter than we initially thought. It’s a system that Mercury says has never been offered on an outboard before.
Perhaps one of the more noteworthy features of this new outboard line is the watertight hatch in the top of the cowl to provide access to the dipstick as well as the oil fill. There’s a decal outlining service requirements along with a QR code to allow a smartphone to link to additional service information.
Under the top cowl service door, there’s a handle that lifts with a red button. Lifting that handle releases the latches all around the cowl, so it can be lifted off easily.
Once the cowl is removed, many service points are apparent. The oil filter is easy to spot near the fuse box on the port side. The spark plugs are arrayed in neat columns aft and the fuel filter is handy there as well, on the starboard side.
All four lines of V8 have 115 AMP alternators. But the name of the game is “net AMPs” – the AMPs left over from the running of the engine to power onboard accessories, electronics, and to keep the batteries fully charged. At WOT these alternators produce 90 net AMPs, we’re told. At high cruising speeds they produce 65 net AMPs. These are high numbers and are important for owners of well-equipped boats, particularly the larger cursing boats that are now being fitted with outboard engines. But, that’s not all…
The alternator on the Verado 4.6-L engine has a maximum output of 115 amps the highest output of any engine in this class. At idle the alternator provides 20 amps for the boat.
Simply put, the engine-management system detects when the batteries drop below acceptable levels due to increased power draw. Today’s boats have more electrical and electronic devices on board than ever before, and they all require a flow of clean juice to keep operating properly. Whether the onboard systems are charging trolling-motor batteries, keeping the sound system thumping, or running big-screen helm electronics including a chart plotter, CHIRP sounder, and radar, the system increases idle rpm to boost alternator output, to help charge batteries to compensate for power draw. It gently raises the idle level from 600 rpm to around 800, to get to the next level on the curve of the alternator, and in this mode, it delivers 30 AMPs of usable power to the house batteries. While the engine is revving slightly higher, it’s still at a speed where it’s able to shift.
The lower unit gearcase on the FourStroke and Pro XS outboards is the 4.8” unit. 5.4” gearcases are standard on Verado and SeaPro, but is available as an option on the other two lines. The robust 5.4” gearcase is an evolution of the one that has been used on previous Verado models and has proven itself in tens of thousands of hours of rugged use over the last few years.
This proprietary system maintains engine speed regardless of condition, and Mercury has the system patented. The idea is that the rpm remains constant even when seas are rough, the driver puts the boat into a hard turn, or a tow sport requires steady power. Adaptive Speed Control is a function of the ECU, where operator demand and engine load are measured and the electronic throttle position is adjusted. It is standard on all of the engines.
Because the outboard uses a digital throttle control, it can also improve its own fuel economy. It begins when the system detects a steady-state mode, where the driver isn’t adjusting the throttle constantly. Once the operator variable appears to be set, the digital control tunes the throttle plate and the spark to lean out the fuel burn to maximize fuel economy, optimizing the boat’s range. It is available on all of the engines.
All four of the V8 lines are rigged with SmartCraft Digital Throttle and Shift (DTS), which gives the responsive control by wire. In multiple-outboard installations, Joystick Piloting for Outboards can be made part of the Verado package, offering simple fingertip control around the dock.
While expert drivers may sneer at the idea of the optional Active Trim, it has been shown to work in our testing, and can even offer something to those who may think their feel for boat trim is more effective than that of a computer: Active trim synchs up the trim of the engines, letting the expert trimmer tune the rig more effectively, rather than dealing with trim motors that adjust the engines at varying rates in a multiple-outboard installation.
The outboards have received a three-star emission rating from CARB, and are compliant to the U.S. and E.U. regulations as well, all on one calibration.
Historically, outboard engines in salt water have suffered from corrosion. When electrons flow through dissimilar metals the weaker metal is eaten away or corrodes. Outboard engine blocks, cylinder heads, gear cases, driveshaft housings and swivel brackets are made out of an aluminum alloy by all manufacturers. But all aluminum alloys are not the same.
Low-Copper Alloy is Key. Mercury's die-cast components, are all made from XK360 aluminum-silicon alloy. The same goes for the new 4.6L block of this outboard platform, which is made with a high-pressure die-casting in a 4,500-ton press, which is among the largest in the world. This process shows significant investment by Mercury and contributes to the weight loss of the new engines. Mercury is generally regarded to have the best corrosion-resistant alloy in the recreational marine industry. All four lines use the same alloy.
The new V8 platform has been designed to be light, but also to keep its noise to itself. The design starts blocking noise with the cowling – and the Verado has more sound abatement qualities than the other models, we’re told. The entire outboard is sealed to keep engine noise in. The engines all use an air intake that’s baffled to be quieter. Mercury has been using a variant of this design since it introduced the Verado line, and it works.
All of the lightweight parts used were designed to also keep sound in, including the plastic valve covers to mask the noise of the valves and injectors.
Another way to keep the outboard quiet is to engineer less internal friction into its design. Mercury says its engineers designed the oil-flow scheme and sized the bearings with this in mind.
Mercury looked closely at the mounting system on the mid-section of the outboard and calculated where the vibration comes from on the engine. Engineers determined the vectors of vibrational force, i.e., whether the vibration is moving fore and aft, or athwartships, or some angle in between. The engineers then designed the mounts to offset that vibration at a suitable angle. Because of this analysis, the mounts can be engineered to be firmer, rather than just softer to damp any vibration – and in this way they are also designed to maximize engine performance, says Mercury.
The new Verado has what Mercury calls an Advanced MidSection (AMS). It is a next-generation enhancement and a step up from the Conventional MidSection (CMS) used on the FourStroke outboards, and it is a next-generation version of the mounting system initially developed for the L6 Verado. The AMS uses perimeter mounts to damp vibration and contain noise, and it has a multi-piece welded structure that reduces its size and weight. This allows the Verado to have electro-hydraulic steering, and makes them compatible with the company’s Joystick Piloting system in multiple-outboard setups. The Verado outboards are standard with Mercury’s Digital Throttle and Shift controls.
It may not seem like a huge development, considering what some other outboard manufacturers have done with custom finishes and even LED lights. But it wasn’t so long ago that Mercury owners were told they would void their warranty if they painted their outboard anything but Phantom Black.
Mercury has introduced three shades of white – Cold Fusion White, Warm Fusion White, and Pearl Fusion White — in addition to its traditional black engine color.
There’s also an accent panel that comes in four colors – Pacific Blue, Graphite Grey, Redline Red, and Mercury Silver – plus a ready-to-paint accent-panel option that boatbuilders and dealers will use to custom-match a hull color.
The propulsion system diagnostics are integrated into the Mercury VesselView display, which is a Simrad unit rebadged for Mercury. Some boats will be able to integrate the engines into the Simrad helm electronics and not require a standalone display. The Simrad units have a specific, branded Mercury engine page. Screen sizes run from 7” to 24” (.18 m to .61 m).
The touchscreen unit lets the user tap with a fingertip to open a display window on the left side of the helm screen with a number of data categories which can be set to display consistently across all functions, including chartplotter, fishfinder, and radar displays. Speed data is available and any tap will bring out more detailed information. The display screen also offers analog-looking gauge treatments.
The Simrad-Mercury VesselView interface allows the operator to set Mercury’s proprietary electronic control features, including Cruise Control, which allows the user to set a speed or rpm and have the engine maintain it, and Troll Control, which will let the engines slow-troll down to 550 rpm. Additionally, the Active Trim system can be set to tune engine trim to optimize efficiency.
Mercury’s Skyhook Advanced is also available, with different settings that allow different levels of control in specific situations and are easily downloaded via Wi-Fi connection – and advantage over the competitive brands that require dealer installation.
For in-depth descriptions of these features and videos showing how they work, see the “Control” model pages under the Mercury heading in BoatTEST’s engine scroll down.
Mercury’s VesselView engine monitor helm display lets the user know the oil level is fine prior to the first startup of the day. The system only works if the engines are in the down position and the oil temperature indicates the engine is cold, since a tipped up engine or one that is warm wouldn’t get an accurate reading, so it won’t work each time a boat starts throughout the day. This feature is standard on Verado V8 models and optional on all of the other new V8 and V6 outboards.
As an option, Mercury has added a Moving Prop Alert system, which consists of a unit outfitted with LED lights mounted on the aft engine housing. The LEDs illuminate when the engine is running, and an LED prop graphic animates and appears to turn. As quiet as these outboard engines are, this makes sense, especially when one considers the joystick and position-holding systems that move and operate engines beyond the driver’s direct control. The engines are prewired for this addition, and multi-engine boats that use skyhook have it added at the boatbuilder or dealer level.
Obviously, the engines should not be turned on when swimmers are in the water and close to the boat. It is, nevertheless, an important safety feature in our opinion.
In future issues of BoatTEST Reports we will drill down even deeper into each of the engines and give complete testing results on boats powered by these new Mercury engines. Stay tuned.
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