The story of Mercury's four-stroke program reads like a cold war spy novel. For what seemed an interminable period of time Project X was a shadow motor, much whispered about, but never actually seen in the light of day. Then after five years of anticipation and an investment of more than $100 million the mystery motor came in out of the cold. Verado was born.
In the beginning Verado was available in 200-, 225- 250- and 275-hp, a 2.6 liter Inline-6. More recently 135 and 150 hp I-4s have become available According to an inside source, eventually we might also see I-3s and I-5s. And now after only a few months on the water the outboard is winning high praise, including the coveted IBEX award for innovation. Here's a quick overview of the technology.
Mercury engineers designed Verado from a blank sheet of paper. None of the components are derived from automotive engines, unlike some competing four-strokes. Also compelling, Verado is founded on an in-line cylinder block where competing four-strokes are all V-4s and V-6s. Because they're relatively skinny, multiple in-line Verados (twins and triples) can often times be more easily rigged on a narrow transom.
Verados are inter-cooled and supercharged. The design includes state-of-the-art cylinder heads, populated with four valves per cylinder, actuated by double overhead camshafts (DOHC). These free-breathing components, and especially the supercharger, lend Verado potent low rpm torque. That's an important characteristic with a four-stroke, because compared to two-strokes, they tend to be anemic at lower rpm. To compensate, most outboard builders deepen the gear ratio to multiply torque. That means the engine turns a higher rpm for a given speed. But the four-stroke Verado gearset ratio remains a conservative 1.85 to 1 on the I-6s and 2.08 to 1 on the I-4s., That's about what you'd expect to find on a two-stroke.
Verado maximum torque is generated at about 4500 rpm, with an operating range of 5800 to 6400 rpm. The bottom line: a Verado outboard matches two-stroke performance at any rpm. Fuel economy is also very good, with the 275 tuned to burn premium, while the less powerful Verados burn the cheap stuff, 87 octane.
On any engine reliability is another characteristic worth looking at. Cast pistons with individual oil galleries extract heat out of the skirt extending life and maximizing horsepower. The block and cylinder head are lost foam castings, albeit with a unique refinement. Aluminum shoots into the mold under extreme pressure for greater density, yielding a particularly strong and lightweight parts. Also, with its closed-deck cylinder block there is no gap between cylinder walls and deck. That makes it stiffer.
Conventional cylinder head bolts have been replaced by special fasteners that attach from below. Once again, that makes the assembly stiffer. Similar to a Formula One race engine, a reinforcing plate girdles the crankshafts main-bearing journals holding the crankshaft tightly in its grip. Built like the Rock of Gibraltar, Verado appears to be destined for a long life.
True to the state of the art Verado relies on an array of sensors to monitor vital signs, and then adjusts performance, fuel economy and emissions to compensate for fuel quality, ambient temperature, coolant flow and altitude. Firmware pushes ignition advance and fuel/air mixtures right up to the razor's edge, almost to the point of self destruction. It is the rock solid block and crankshaft that allows the engine to hold itself together when lesser creations would be pooling molten aluminum in the cylinder bores.
Beyond raw, a bloody horsepower, Verado's voiceprint is whisper quiet. At idle the sound meter records a barely audible 52 decibels. At wide-open throttle (WOT), it's still just 86 decibels. That WOT reading is so quiet the wind and waves are sometimes louder than the engines.
Another user-friendly item, Verado features digital throttle and shift (DTS). DTS is a fly-by-wire control that communicates directly with the engine control module (ECM) to more precisely activate speed and gear changes. Action is delightfully smooth and devoid of hesitation. There's absolutely no resistance or backlash. A welcome complement to DTS is the built-in automatic engine synchronizer which allows the helmsman to concentrate on running the boat instead of watching tachometers while adjusting throttle levers.
Another user friendly item, Verado features digital throttle and shift (DTS). DTS is a fly-by-wire control that communicates directly with the engine control module (ECM) to more precisely activate speed and gear changes. Action is delightfully smooth and devoid of hesitation. There's absolutely no resistance or backlash. A welcome complement to DTS is the built-in automatic engine synchronizer which allows the helmsman to concentrate on running the boat instead of watching tachometers while adjusting throttle levers.