Mercury Racing’s latest muffler system takes noise reduction to another, much-quieter level.

By Matt Trulio

The roar of twin supercharged big-block engines might be music to your ears—it certainly is to ours—but to most people it’s just noise. That’s why sound restrictions on engines of all kinds continue to rise, and why exhaust/muffler systems continue to improve.

And if you think noise restrictions on the water are tough in North America, a trip to Europe is all it will take to let you know how good you have it. You can argue about whether Europeans are more environmentally sensitive or just overly sensitive, but the fact is restrictions on engine emissions and noise are stricter than those in California, which leads the nation in such standards.

In April 2007, we reported on Mercury Racing’s EU662SCi engine in this column (“Mercury Rising—Again,” Page 43), which was unveiled weeks prior at the Miami International Boat Show. A detuned version of Mercury Racing’s HP700SCi, the EU662SCi was developed to meet emissions standards as laid out in the European Union (EU) Recreational Craft requirements. The EU guidelines also contained noise restrictions, but Mercury Racing’s position at the time was that noise-regulation compliance in Europe was for boatbuilders to handle, not Mercury Racing.

That was then. Mercury Racing has since developed a new muffler system for the EU662SCi, in single- and twin-engine applications, that reportedly meets the EU’s 75 (single) and 78 (twin) db noise standards.

So why the change of heart from “boatbuilder” problem to Mercury Racing’s “solution?”

“A lot of boatbuilders do a great job at designing efficient hulls and building boats, but they just don’t have the technical expertise to design and develop a muffler system like this,” said Fred Kiekhaefer, president of Mercury Racing. “It’s one thing to create a good-behaving, neighbor-friendly package. It’s another to be able to meet an actually absurd regulation like the one by the EU.”

So new is the muffler system that it didn’t have a name at press time. (“All the names we wanted to use, someone else is using,” quipped Kiekhaefer.) The system essentially consists of a Y-pipe from each engine that exits a boat’s transom just above the waterline and enters a transom-mounted box. Inside the box are two chambers and three tubes. Two of the tubes “communicate” sound between the chambers. The third tube exits the box, which is above the waterline when the boat is on plane and below it when the boat is idling at the docks or off plane.

The muffler system reduces noise in several ways, explained Kiekhaefer. Some of the “acoustic energy cancellation” happens simply by bringing both banks of cylinders into a single outlet, hence the Y-pipe design. For further noise reduction, the two chambers in each box are fed by a pair of acoustically tuned tubes. Last, there is an exit tube from the box, which is underwater when a boat is off plane. When a boat is on plane and the exit tube is above the waterline, the two wakes created reportedly direct the sound “up and aft.”

“Nor-Tech runs a similar type of system,” Kiekhaefer said. “They were the first to innovate this kind of system in a performance boat. We took it a step further by adding an external box.”

Each engine requires one external box for the complete muffler system. In side-by-side twin-engine setups, the boxes mount between the drives. With staggered twins, the boxes are mounted outside of each drive. Even without the external boxes, said Kiekhaefer, the Y-pipes can bring most twin-engine boats equipped with the EU662SCi to the 80 db level.

So what does this mean to you? After all, you can’t get the EU662SCi in this country—and the majority of the performance-boat market is based in the United States. Well, when it goes into production (and gets a name), likely by this spring, the muffler system will work right out of the box with the Mercury Racing HP600SCi engine.

“We’ll also be packaging it for the 700SCi and 850SCi, and we’ll even see if we can get it done for the 1075SCi,” Kiekhaefer said. “The concept is so good we think we can make it work with our entire line.

“We’re still nameless, but the hard part is done,” he added. “The damn thing works.”

Contact Information
Mercury Racing, N7480 County Road UU,
Fond du Lac, WI 54935, 920-921-5330,
www.mercuryracing.com