Gear Test: Suzuki ‘big block’ outboards


Suzuki Marine earlier this year held sea trials for its new “big-block” 150- and 175-hp 4-stroke outboards at TableRockLake outside Branson, Mo.

Suzuki Marine earlier this year held sea trials for its new “big-block” 150- and 175-hp 4-stroke outboards at TableRockLake outside Branson, Mo.

Soundings contributing writer Erik Klockars, a marine technician with more than 30 years of experience, tested the inline 4-cylinder power plants in single- and twin-engine configurations, on boats ranging from a 17-foot aluminum fishing boat to a 26-foot power catamaran. He was impressed by the outboards’ responsiveness, smooth operation and narrow profile.

Suzuki touts the new DF150 and DF175 outboards as the largest-displacement (2,867 cubic centimeters) and lightest engines in their class. Based on what he saw in the trials, Klockars says the performance of the new engines was comparable if not stronger in some instances to that of 2-strokes.

He tried several maneuvers with the test boats — from high-speed and tight turns to accelerating out of the hole at a variety of trim angles — and found the engines responsive. “These motors threw the boats around,” says Klockars.

The DF175 has variable valve timing to increase low- to midrange torque. Klockars says both the 150 and 175 had a lot of low-end torque, idled smoothly, and were quiet and easy to shift. A member of Suzuki’s technical staff explained that a function of the engines’ computer network is to slow the engine down to assist shifting.

The 32-bit engine control module monitors and processes engine data. Among its duties is controlling the multipoint sequential electronic fuel injection system. The system saves fuel, increases performance and efficiency, and helps the engines meet California Air Resources Board 2008 regulations and pass Environmental Protection Agency 2006 regulations, according to Suzuki.

Other key features of the 150- and 175-hp engines are multistage induction to adjust the intake manifold pipes for low- or high-rpm operation; a counterbalance system to counteract vibration; and an offset drive shaft to keep the engines compact.

Because the engines are compact, Klockars says, they don’t need a special cowling and use a standard bolt pattern for hanging on the transom.

The company also succeeded in keeping the weight of the engines down, he says. Both outboards weigh in at 465 pounds, according to Suzuki.

Klockars says the difference between the latest 4-stroke outboards and their predecessors is akin to the advances being made in diesel technology. The new diesel engines on the market today generally are lighter, more responsive and cleaner than their predecessors.

“Big-horsepower 4-stroke technology is not that old,” Klockars says. “As they get further and further down the line they can figure out what they can get rid of, what they are overbuilding, and what they can lighten up without hurting reliability and strength.”