Power by the pound

Mercury’s V-8 outboards pack serious punch in a weight-conscious design
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With narrow profiles, the new motors mount on 26-inch centers, making them compatible for repower.

With narrow profiles, the new motors mount on 26-inch centers, making them compatible for repower.

Mercury Marine continues to aggressively develop new outboard motors, and in May introduced 13 models with V-8 powerheads and one V-6.

Like the V-6s introduced at the Miami International Boat Show in February, the new motors are naturally aspirated and designed to have impressive power-to-weight ratios. The Pro XS checks in at 505 pounds, while the FourStroke version weighs 527 pounds and the Verados weigh 600 pounds. This gives the 300-hp Pro XS a power-to-weight ratio of 1.68 pounds per hp. The 300 FourStroke’s number is 1.76:1 and the Verado 300 is a straight 2:1. From the Mercury Racing side, the lightest version of the 300R is 512 pounds, which results in a ratio of 1.71:1. That’s comparable to the Mercury Racing Verado 400R, which has a ratio of 1.67:1, but that engine is supercharged. There’s also a 250-hp engine from Mercury Racing.

New Verado series motors come with Mercury’s Advanced Midsection designed for vibration reduction.

New Verado series motors come with Mercury’s Advanced Midsection designed for vibration reduction.

“Early on in the program, we set very lofty targets for weight on all of the new V-6 and V-8 variants, and to hit these targets, every component had to meet a stringent weight target of its own,” says Mercury Marine President John Pfeifer. “Everything from lightweight cowling materials to our proprietary alloys contributed to the achievement of these aggressive targets.”

In the Verado series, there are two new 250- and 300-hp versions. The FourStrokes come in 250 and 300 hp, while the Pro XS is available in 200, 225, 250 and 300 hp. There is a new six-cylinder Pro XS 175 and, for commercial use, there are a 300-hp AMS SeaPro and 225-, 250- and 300-hp CMS SeaPros.

The AMS and CMS designations stand for advanced midsection and conventional midsection. The conventional midsection models are aimed at performance-minded consumers for whom top speed and acceleration are key. The advanced midsection motors are for more luxury-minded boaters who want more mitigation of noise and vibration. The new motors will use the same mounting brackets and systems as the V-6s.

Three model designations explain the target uses. The Pro XS designs are for weight-conscious applications such as bass boats, performance V-bottoms and catamarans. The FourStrokes are more mainstream, to be used on vessels ranging from pontoons to runabouts and center consoles. The Verados are more full featured and are the only ones compatible with Mercury’s Joystick Piloting, which is part of a SmartCraft digital package that includes digital throttle and shift, Skyhook Digital anchor, Integrated AutoPilot and VesselView 4 or 7 displays. SeaPro engines come with a boat-mounted fuel-water separator, diagnostic SmartCaft gauges and a graphic owner’s manual supplement.

Pfeifer says the motors’ 4.6-liter displacement is the highest in the 250- to 300-hp class, a characteristic that should translate into some strong torque, especially at midrange. There’s no replacement for displacement, and having two extra cylinders compared to the competition is going to give Mercury some strong bottom-end and hole-shot numbers.

The engines are built with a quad-cam design that has been proven on multiple Mercury Racing stern drives. To minimize complexity, the new engines have a single throttle body and long, performance-tuned intake runners to pack more air into the cylinders. More air means more fuel, which translates into more potent combustion.

The 175-hp Pro XS is a new  V-6 outboard targeted at fresh and saltwater anglers.

The 175-hp Pro XS is a new V-6 outboard targeted at fresh and saltwater anglers.

Mercury says the CMS engines are the lightest in their respective classes. All the engines use Advanced Range Optimization that automatically adjusts fuel delivery to achieve maximum range. Pro XS and Verado models have Transient Spark to boost torque during hole shot. Patented closed loop fuel control uses a wide-range oxygen sensor to optimize air-to-fuel ratio throughout the power band. The engines run on 87 octane, and the Pro XS and Verados can be rigged with digital or mechanical components to make them more compatible for repower applications. For the SeaPro models, Mercury calibrates the engines to generate more torque at lower rpm levels, to move workboats that are typically heavier and designed to run at lower speeds.

Mercury has made big investments to control noise and vibration in the new motors. The exhaust has been tuned to provide a performance-inspired sound that is 20 percent quieter at cruise and 30 percent quieter at wide open. The manufacturer says the Verados are 35 percent quieter at wide open with 66 percent less vibration at the helm. A tuned multichamber design minimizes air intake noise, and fuel-injector covers reduce frequency noise. Additionally, a multichamber idle relief system is tuned for the lowest idle noise. The cowls also have multiple sealing features to keep out moisture and contain engine noise. Verado owners can toggle between ultra-quiet operation and a throatier-sounding sport mode.

The 300-hp FourStroke has the bottom-end torque to push a large pontoon boat.

The 300-hp FourStroke has the bottom-end torque to push a large pontoon boat.

Adaptive speed control allows for engine rpm to be maintained regardless of changes in load or condition, without frequent throttle adjustments. To keep electrical accessories humming, the motors have idle-charge battery management that automatically raises the rpm to boost alternator output to recharge the batteries. Net charging output is 20 amps at idle and 85 total at wide open throttle. SeaPro V-8 and V-6 CMS models make 20 amps net at idle and 85 peak amps. The 300-hp AMS model boasts a 115-amp alternator.

As with the V-6s, the larger siblings have the Top Cowl Service door that lets owners check and fill the oil without having to remove the cowl. Speaking of the cowl, Verado and FourStroke motors are available in traditional Phantom Black and three shades of white- — Warm Fusion, Cold Fusion and Pearl Fusion — with colored accent panels. An optional electronic oil level sensor is available, and the filter mount is designed to contain oil that spills during a change. The valve train is engineered to require no adjustment for the life of the engine. SeaPro engines have the gear case drain in the torpedo.

To put the power to the water, the V-8 series engines have a 5.4-inch diameter gear case that is an evolution of the lower unit used on the L6 Verado. The V-8 AMS Verado is available with 1.85:1 or 1.75:1 gear ratios, while the CMS-designated FourStroke and Pro XS all have 1.75:1 gearing. Inside spins a 1¼-inch diameter propshaft and the outside has low-water pickups so the motor can be installed on a jack plate and run in an almost surfacing application.

For multiple-engine installations, the V-8 models mount on 26-inch centers. Pfeifer says meeting this specification was a priority from the start of the project. The Pro XS models are available in 20- and 25-inch shaft lengths. The 200- and 300-hp FourStrokes come with 20- or 25-inch shafts, while the 225- and 250-hp FourStrokes can be had in 20-, 25- and 30-inch shafts. Owners can get the 175-hp V-6 in 20- or 25-inch shafts. SeaPros come with gear cases that were validated at three times the lifespan of a recreational gear case.

The Pro XS series is designed for weight-conscious applications like this Nitro multi-species fishing boat.

The Pro XS series is designed for weight-conscious applications like this Nitro multi-species fishing boat.

Mercury also considered corrosion resistance on the new motors. A 49,000-square-foot electro-deposition paint plant that opened in 2017 has doubled Mercury’s processing capabilities. More than 95 percent of all parts go through the EDP system.

Taking a look at retail pricing, the 250 Verado starts at $23,540, while the 250 FourStroke is $21,790. The 250 Pro XS has a sticker price of $21,450. Step up 50 hp and the 300 FourStroke is $23,570, while the 300 Verado is $25,450 and the 300 Pro XS retails for $24,965. In the SeaPro series, the 250 is $22,070 and the 300 is $23,845.

The new motors replace the 2.5L and 3.0L OptiMax, L4 Verado and L6 Verado models in the same horsepower ratings.

Because Mercury is seen as the high-performance company, some people have asked when the manufacturer is going to come out with a bigger motor than the Verado 400R. The company is keeping the 350- and 400-hp supercharged Verado models, but the boys in black aren’t saying anything beyond that. The 350-hp Verado will remain in the Mercury Marine portfolio while the Verado 400R will be a Mercury Racing product.

This article originally appeared in the July 2018 issue.

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