Mercury - Verado 350
According to the manufacturer’s testing program, the Verado 350 rigged to a 24’ 7” (7.49 m), 4,750 lb. (2,155 kg), center-console bay boat, reached a top speed of 52.3 mph while netting 1.8 mpg at 6400 rpm. Running a 1.75:1 drive ratio and a Mercury Enertia ECO prop with a 17” pitch, cruise speed for this application was found at 4000 rpm and resulted in a speed of 32.4 mph while delivering 3.3 mpg from 89 octane gas.
We’re told by the folks at Mercury that the engine will run fine on 89 octane fuel without harming the engine, but the 91 octane fuel is suggested for peak performance.
The robust in-line six cylinder block and head are made up of Mercury’s low-copper aluminum alloy derived from Mercury low-pressure lost-foam casting process. The cylinder configuration is made up of four valves per cylinder and two overhead camshafts. The engine design utilizes a long-bolt configuration for securing the head to the cylinder block and case.
Long Bolt is Better. Rather than the typical format of the heads and lower case being bolted to the cylinder’s themselves, the Verado 350 uses long bolts that fasten through the cylinder block and in through the lower case, effectively clamping the cylinders like a sandwich to handle the additional air from the self-compensating supercharger and stronger overall construction.
Lower Maintenance. Mercury designed the valve train to be maintenance free, so the task of adjusting valve lash after the first few hundred hours has been eliminated. And since the Verado 350 can spin up to 6400 rpm, that is a big deal over the long haul. Keeping these internals happy is an integrated oil cooler that lowers the operating temperature of the lubricant and extends its service life as well as that of the engine.
Advanced Mid Section (AMS) with perimeter mounts virtually eliminates vibration in the boat, according to Mercury. That is a good thing when sneaking up on fish or cruising on luxury pontoon boats which are known for transmitting engine vibration to passengers.
Low-Vibration Construction. To harness the engine’s potential, its perimeter is attached to a cradle bracket using four oversized, specially calibrated elastomeric mounts that variably compensate for vibration as engine rpm changes. At low rpm, the mounts are soft, and as engine speed increases, the mounts progressively stiffen to provide optimal dampening. Mercury calls this its Advanced Mid-Section or AMS, and it provides the boat with a low-vibration transom, which will result in a smoother, quieter ride and better handling.
With the cowling off, we can see the cold-air intake at the top of the motor and the easy oil-check and fill locations. Other than routine oil service, the Verado 350 is said to require little maintenance.
The Verado 350’s induction system is where most of the engine’s technology comes into play. It all starts at the top of the engine cowling, where cool, fresh air is funneled into ducting that reduces engine noise and keeps any stray water out of the system. The air is then treated to a roots-style supercharger that uses two precision ceramic-coated screws to compress the air charge before it is fed to the engine.
It is this dense air charge that provides the cylinders with greater combustion potential and the engine with torque-on-demand despite varying ambient conditions that rob horsepower. In order to compensate for high altitude or hot weather, the Verado 350’s boost control is computer controlled, ensuring optimal fuel-air mixture for maximum power and increased reliability. In order to help keep the supercharger’s housing cool, the unit shares the engine’s raw water circulation system.
This cutaway view of the belt-driven supercharger shows the two screws and how they squeeze the engine’s air charge for maximum power.
The Verado 350 is managed by the modernized Mercury SmartCraft ECU that includes all the benefits of Joystick Piloting for Outboards (JPO). This technology allows multi-engine rigged boats the ability to be controlled by a joystick, an option that greatly enhances the boating experience. Combined with the platform’s Digital Throttle and Shift (DTS) and the Verado’s electro-hydraulic steering setup, piloting just can’t get any easier.
Mercury’s “shadow technology” eliminates the hassle of grappling with multiple engine levers when running with triple or quadruple outboards. Shadow mode controls up to four engines with just two levers from as many as two helm stations.
But there’s more, SmartCraft has standard integrated autopilot, and offers the available Skyhook feature that provides digital positioning of the vessel while fishing via GPS.
Fingertip control is now available for Mercury equipped outboards in multi-engine riggings.
The Verado 350 features a stout 5.44” (0.14 m) diameter lower gear case for the gears, and all the internal components are cut in-house at Mercury Marine. This attention to detail ensures better quality control for the motor’s hard-core offshore use by big, heavy vessels slogging through the blue. The drive unit comes in three choices of shaft length: 20”, 25” or 30” (508 mm, 635 mm or 762 mm).
There is nothing harder on outboard engines offshore than when the boat catches air, the props spin up in the air and then a second later they grab hard water, putting tremendous strain on gears and shafts. Mercury Racing first broke the code on how to make lower units reliable and that same technology is being used in the Verado 350.
To stave off corrosion, the Verado 350’s mass of aluminum requires special attention, especially in salt water. So Mercury casts housing parts from low-copper content aluminum-silicon alloy. Then, the parts go through a chromate-conversion coating, followed by an electro-deposition process for the primer and final paint job. These laborious steps fight the effects of corrosion, and significantly extend the motor’s life. Finally, Mercury covers the Verado 350 with a three-year limited parts and labor warranty, as well as a three-year corrosion warranty.