Suzuki was the first outboard builder to commit its entire product line to four-stroke power. Now Suzuki is bringing its first second-generation four-stroke to market, a new 1.5-liter, four-cylinder powerhead that will be rated at 70, 80 and 90 horsepower. According to Suzuki motors in this range account for 15 percent of the total market, and are sold all over the world. In fact, the odd-ball DF80 is really intended to the inflatable market in Europe.
With this motor, Suzuki will replace its previous 1.9-liter 90 and its 1.3-liter 70. Size and weight improves in both instances. The previous DF90 was over-sized, sharing its powerhead with the DF115 and a DF140. The old DF70 was a bit undersized, and was also sold as the DF60. This new 1.5-liter engine is the perfect displacement for this popular rating, and at 341 pounds it's significantly lighter than both motors it replaces — weighing 76 pounds less than the old DF90 and 16 pounds less the old DF70. The weight savings was achieved in a variety of ways, from better casting techniques to hollow camshafts to a new cowl material that drops the weight of that part from 18 to 10 pounds. The new motor is also three inches shorter than the old DF90
All versions of the new motor employ several features we've seen in previous Suzuki outboards. It's a double over-head cam with EFI (the previous 70 had a single cam), and features an off-set driveshaft, which positions the powerhead forward of the driveshaft, and then mates the end of the crankshaft to the driveshaft through a set of gears. Honda uses a similar design on some of its mid-size engines, and the benefits include less vibration to the boat and better weight distribution, because the weight of the motor is placed closer to the transom. Suzuki puts the timing chain under the powerhead, where it runs in an oil bath. Suzuki also uses this gearset to accomplish 1.24:1 of the 2.59:1 final drive ratio reduction.
This gets Suzuki a gear ratio low enough to turn a 13.75-inch-diameter prop without having to accommodate a big pinion gearset in the gearcase, which would create more drag. A larger prop offers more blade area, which is like getting more traction in the water for better acceleration and handling. This new gearcase could also be down-sized because it no longer has to handle 140 hp, and is 25 percent lighter and 36 percent more hydrodynamic than the previous DF90 case, according to Suzuki. A new line of aluminum propellers was designed specifically for this motor, with a pitch range of 13 to 23 in two-inch increments.
New on this motor is a lean-burn control system that Suzuki says improves fuel economy by 20 percent at cruising speeds by leaning out the mixture when the motor is under moderate load. The transmission and shifting mechanism were redesigned to improve shifting performance, with a new ignition-interrupt mode that unloads the gears to enable smoother gear changes. The starting system was revised and the motor now starts on less than one revolution of the crankshaft, and you don't need to hold the key as the motor cranks - just click it once and release. If the motor's running and you turn the key, the starter will not engage. A new trim pump turns itself off when it reaches the bottom of its range, so you're not just pumping away at nothing. This saves wear on the pump and is mechanically more elegant. Finally, the motor has dual flushing ports that can be reached from inside the boat or from behind when the boat is on a trailer or stack.
I ran the DF90 on a 18-foot four-inch Blue Wave 180 V-Bay (www.bluewaveboats.com), a 975-pound center-console skiff rated for up to 115 hp. Running a 17-pitch prop, I averaged 35.6 mph top speed, and got best fuel economy of 10 mpg at 3500 rpm and 19.5 mph. That's really outstanding economy. At WOT the motor burned 6.4 gallons per hour, or about 5.5 mpg. Suzuki did not make a big deal about the sound quality of this motor, but it should have. The first time I shifted into neutral I thought the motor killed because it idled down so quietly. Suzuki did a good job on the gearcase, as the shifting really is smooth. From a performance standpoint, I was most impressed with the motor's mid-range punch. Nail the throttle from 4000 rpm and the boat leaps forward. That's the big prop and low gear ratio at work.
The new DF70 has an MSRP of $9,000 with a 20-inch shaft. The DF90 is $10,000. (www.suzukimarine.com)
New Camo Option from Mercury
Just in time for duck season comes the Mercury Flyway 25 EFI FourStroke outboard with Advantage MAX-4 HD camouflage and matching low-gloss paint, so hunters seeking total stealth no longer need hide an outboard under spray paint, stickers or a bag. Mercury says if you look carefully, you'll see that the pattern incorporates cattails, millet, milo, corn stalks, sunflowers, oak and maple leaves, cedar and oak limbs, plus a variety of other plant life. The Flyway 25, available at participating dealers, features battery-free electronic fuel injection system and is available in both electric and manual start models. Automatic decompression and a manual recoil are standard, even on electric start models. For easier shallow-water operation the motor is available with power trim or gas tilt assist and standard dual water pickups in the gearcase. The engine is available in both tiller and remote control versions. The camo finish adds $200 to $250 to the cost of a standard black 25 EFI Four Stroke. (www.mercurymarine.com)