Bigger Boats, Bigger Horsepower, Smaller Engines?

Technology has finally packed the proverbial 10 pounds of power into the five-pound bag.

350 Triple Center Console Saltwater IT REALLY DOESN’T MATTER WHAT type of internal combustion engine you consider — cars, trucks, boats — they all have transformative technology that makes them better and more efficient than at any time in history. But with those improvements comes greater complexity. So what technologies have delivered the most noticeable benefits in our new outboards? Here’s what makes the outboards on your transom tick.

MERCURY MARINE STILL builds direct-injected OptiMax two-stokes, but its technology push has been focused on its four-stroke offerings. Unlike some builders, Mercury doesn’t repurpose engines from other applications, and thanks to a collaboration by some talented former Porsche engineers, its Verado line of outboards gets up to 400 hp from a smallish 2.6L block.

Reducing friction means everything during a holeshot. Mercury minimizes friction in bearings and sliding contacts as well as cold oil effects, and it takes every gram possible out of rotating and reciprocating masses, allowing its engines to spin up as fast as possible. In its Verado engines, it boosts max engine speed to 7000 rpm, to make running lower-pitch props feasible, which makes for faster planing. But what really gives Mercury’s Verado a holeshot edge is its supercharger. An intercooler supplies cool air to the supercharger, which allows it to pack more gas/air into the combustion chamber for better performance. Unlike turbochargers that need to spool up before providing boost, a supercharger gives instantaneous acceleration when the throttle is pushed forward — no matter what speed the boat is traveling.400R Supercharger detail

Merc considers frictional effects and hydrodynamics of gearcases crucial for mid-range effi ciency and top-end speed.

Despite its incredible technology, Mercury believes that complexity must be easy to understand, so it provides a comprehensive set of instruction for maintenance via a QR code that’s ubiquitous under the cowl of its engines.

YAMAHA QUALIFIES AS a very diverse company, producing a wide range of products besides outboards, PWCs and boats. Products such as motorcycles, ATVs, generators and a wide variety of musical instruments bear the iconic Yamaha triple tuning fork logo. Yamaha’s huge engineering base carries over to its marine division, whose engines include many features taken from its racing divisions: dual overhead cams, four valves per cylinder, streamlined exhausts, etc. Despite its myriad engineering resources, however, the company designs all its marine products from scratch. Nothing is just marinized.

Early criticism of four-stroke technology targeted its low-end torque. As the technology developed, Yamaha engineers found ways for the engine to breathe better, boosted displacement, improved the fuel and air charge, and designed a more effi cient exhaust. For example, a long-tube intake packs as much air as possible into the cylinders.

Reducing weight is the mantra of Yamaha’s racing division, and that philosophy is carried over to its outboard division. For years, two-stokes held a weight and acceleration advantage, until Yamaha introduced its V MAX SHO line of four-strokes. Using a plasma-fused textured coating on the inside of the cylinder did away with heavy steel sleeves and allowed Yamaha engineers to increase the displacement to 4.2L on its VF250 without increasing the block size. Shaving weight in places such as motor mounts and replacing metal non-load bearing components with lightweight composite materials shaved enough weight to make it 34 pounds lighter and 13 percent faster out of the hole than the two-stroke it replaced.

Yamaha color-codes all user access points, so owners can more readily perform their own routine maintenance. Additionally, it has embarked on a “Maintenance Matters” campaign that helps owners understand the basic requirements of any outboard. Yamaha makes it a point to remind owners of the importance of using only marine formulations in oil and lubricants. Don’t perform your own routine maintenance? That same info helps when you get your invoice from the dealer.

HONDA INTRODUCED THE very first fourstroke outboard to the marketplace, which was mainly designed by the chief engineer from Honda’s Formula 1 racing team. When asked about his outboard work, he admitted that optimizing the torque curve over the entire rpm range with only one gear ratio was the hardest job he’d ever had, mostly because boats are constantly “driving uphill” thanks to water’s relentless drag.
Honda outboards incorporate technologies and components used in vehicles such as the Accord, Odyssey, Pilot and Fit — vehicles that have proven themselves over millions of miles. Honda’s Variable Valve Timing & Lift Electronic Control (VTEC) system provides the optimal torque curve the design team sought; it’s the “replacement for displacement.” Varying the lift and duration of the intake valves to deliver optimal performance at both low and high rpm resulted in peak performance at all speeds.
Another Honda innovation is its BLAST system (Boosted Low Speed Torque). It responds when the captain moves the throttle quickly by advancing the ignition curve aggressively. Holeshot is vastly improved, as more horsepower gets the hull on plane quicker.
Honda’s VTEC also uses two different cam lobe profiles (differently shaped cams that move the valves) to operate the intake valves. The low-lift, short-duration cam lobes provide strong torque at low rpm. High-rpm horsepower is achieved by engaging the third rocker arm on a highlift cam, which results in a combination of power, torque and fuel economy. Honda BF250 Action Shot.
Honda’s Variable timing has much to do with its engines’ top-end performance, but it also boasts separate dual air circuits. The first is used to cool the engine, as air is drawn into the front of the engine and circulated around critical engine components. A top-mounted cooling fan draws cooling air over the alternator. The second intake circuit directs cool air from the upper intake vents, separates out moisture and then inducts it into the cylinders. The system provides for cooler, denser air for better combustion as compared to conventional under-cowl induction systems.
Most people confuse fuel efficiency with fuel economy. Economy is how far you go on a gallon of gas. Efficiency is how much fuel an outboard uses at any given rpm.
Honda’s Lean Burn Control increases fuel economy by allowing combustion to operate on a leaner air-to-fuel mixture. At cruising speed, Honda engines run on up to 21 percent less fuel than comparably sized outboards.
Convenient DIY maintenance items include long-lasting automotive spark plugs and easy access to all oil filters, fills, and crankcase and gearcase oil drains. Added conveniences include easy-access ports to many internal anodes, easy flushing systems, a low-maintenance valve train system with no shims or buckets, and well placed access doors to maintenance areas.

SUZUKI’S OFFSET DRIVESHAFT in all models 70 hp and up represents one of its major differentiators. Since most of a four-stroke’s weight is in the powerhead, the offset drive shaft moves weight forward to improve the center of gravity. Suzuki also uses lower gear ratios and thus can swing bigger-pitch props for better holeshot and midrange speed.
Suzuki contributes to greater durability and ease of maintenance by eliminating the usual timing belt atop the engine. Rather, it uses a timing chain bathed in oil at the powerhead base. Doing so lowers the overall profile of the engine and changes the dreaded timing belt into a maintenance-free affair for the life of engine while narrowing the angle of its cylinders to 55 degrees, for lighter weight. Combined with its other design features, the package provides exceptional top-speed performance. Suzuki’s Multipoint Sequential Electronic Digital Fuel Injection also allows one to jam the throttle at cruise speed and experience that sudden pin-you-back-in-your-seat feeling that’s necessary at cruising speed.
To help its holeshot performance, Suzuki typically has the largest displacement in each class and employs a lower standard gear ratio to swing bigger props for better torque. Technology such as variable valve timing and multistage air induction conspire to send riders tumbling backwards if they aren’t holding on when the captain shoves the throttle forward.
All Suzuki engines, from the 9.9 hp to its 300 hp model, come equipped with Multi Point Sequential Digital Fuel Injection and Lean Burn Technology, the latter of which is controlled by the onboard computer and monitors engine performance and operating conditions to determine the air/gas mixture needed to meet the load demands the outboard is under. The system can lean the ratio of fuel-to-air mixture down to 18 parts of air to one part of fuel, instead of a constant, standard mixture of approximately 14.7 parts of air to one part fuel. Lean Burn results in 18 to 22 percent better fuel economy through its operating range until near wide-open throttle.
Suzuki wants its customers to be as independent as they choose when it comes to maintenance. The company puts videos online to instruct customers how to do things such as service their engine’s water pump, change the gear case oil and change fuel filters.

SEVEN MARINE — the industry’s newest and most unique outboard manufacturer — utilizes an automotive-based engine that it mounts atypically, horizontally rather than vertically (like all other outboards). Open the cowl and it looks like an automobile engine, and not just any engine. It’s General Motors’ mammoth 6.2L supercharged Cadillac V-8 engine, the one found on its CTS-V Porschekiller that has proven durability and acceptance. It’s coupled to a German-built ZF inboard transmission beneath the engine that allows significantly more horsepower through the drivetrain. Seven Marine builds the most powerful outboards in the world: 557- and 627-hp models that target the bigger and heavier fishing boat and yacht tender markets. Its 6.2L supercharged V-8 delivers more torque than any available outboard. That’s across the board, from holeshot to top end. There’s a very simple explanation why: Raw horsepower rules. 557-engine-transparent
According to Seven Marine, the most common point of failure on any outboard — especially at top speed — involves the gearcase (lower unit), so the manufacturer uses high-performance offshore racing technology in the form of twin pinion gearing that handles much more power. Interestingly, though its lower unit promises to be more robust than any other, its diameter is a mere 4.75 inches compared to competitors’ 5.44 inches, which cuts drag immensely. With today’s big outboard-powered boats loading between 6,000 and 10,000 pounds per propeller, performance is a challenge. Seven’s designs and engineering have proved radically different enough from any other outboards that it has received a patent for its propulsion system architecture.
Seven Marine also handles service differently. Certainly, the engines qualify as masterpieces of complex engineering, and its customers pay a premium price — triple 557s with joystick docking cost around $270,000 — but it will fly company techies anywhere in the world to fix your engine, if needed. At the same time, remember that this General Motors V-8 powerhead with traditional fluids can be tended to by any GM-trained mechanic in a pinch. Though Seven Marine engines haven’t been around long enough to determine long-term durability, they all have a closed cooling system, so no corrosive salt water runs through the powerhead. It uses a much higher strain of stainless steel in its parts, too. As one can imagine, pushing the throttle forward on an engine this powerful can’t help but impress with its holeshot, mid-range response and top speed.

BRP (QUEBEC-BASED BOMBARDIER Recreational Products, builder of Evinrude) has a long history of developing combustion engines for many different applications, including aircraft, motorcycles, snowmobiles, personal watercraft, all-terrain vehicles and outboards.
Evinrude represents the only mass-produced outboard exclusively using two-stroke technology (as founder Ole Evinrude intended): the E-TEC Direct Injection fuel system. BRP has expertise in developing and producing both four- and two-stroke engines, but historically two-strokes provide greater low- and mid-range torque and other attributes crucial to both snowmobiles and outboards, which is why E-TEC technology is found on both. With two times the number of power strokes per revolution, this technology has an inherent performance advantage.
E-TEC’s dedicated fuel injector for each cylinder injects a precise amount of fuel at very high pressure into each cylinder, delivering the instant torque and acceleration required to get a boat up on plane for an astounding holeshot.
Evinrude maintenance qualifies as arguably the easiest in the industry. E-TEC outboards have no valves to adjust, no crankcase oil to change, and no timing belts or chains to adjust. Scheduled dealer maintenance is required once every three years or 300 hours. With the new Evinrude E-TEC G2, the maintenance interval is five years or 500 hours.


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