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Trickle-Down Effect

Technology developed for racing engines can end up improving recreational outboards.

Mercury’s 360 APX

Mercury’s 360 APX

In September 2020, Mercury Racing announced its new 360 APX, a four-stroke V8 competition outboard that will replace the 2.5L EFI, which is used almost exclusively in Formula 1 tunnel-boat racing. The new engine will reduce fuel costs by an impressive 80 percent and emissions by 90 percent. It also raises an important question: What improvements and innovations will make their way from the 360 APX to the consumer line of Mercury outboards?

“The racing industry has historically been a place companies innovate and transfer technology to main-line products,” says Stuart Halley, Mercury Racing’s general manager. “The best example may be Formula 1 and Le Mans sports cars.” That’s not quite how it works in the marine racing world, though, because there aren’t enough competing manufacturers or volume to justify a massive investment in developing new racing technologies.

At Mercury, the innovation often starts with mass-market products and travels in both directions. “If you look at Mercury Racing’s outboard business model, we need the main-line products, and those products have quite a bit of innovation versus their competition,” says Halley. “We build on that, adapting the platforms to our customers’ needs.”


As an example, Halley offers up the 300-hp L6 Verado, which was introduced to the general public in 2004. Five years later, Mercury Racing released the 350 SCi, a tuned-up version of the Verado that produced 350 hp at the prop. The improvements included a new cowl and air-induction system and a reworked supercharger that created a 30-percent increase in boost pressure. Parts throughout the engine were made stronger and more durable with tighter tolerances.

More importantly, Mercury Racing remade the gearcase, which because of the engine’s vertical crankshaft, harbored a pool of oil that sapped horsepower. The racing team found ways to eliminate the heat buildup and minimize the amount of oil in the gearcase, leading to the widely used 5.44-inch HD gearcase. The team also beefed up the midsection with stainless-steel guide plates and stiffer mounts to stabilize the engine for better handling at high speed and smoother, quieter running.

Many of the improvements made for the 350 SCi showed up in the L6 Verado that came out in 2015. And the two more prominent advancements—low-oil gearcases and sturdier midsections—have found numerous uses, particularly on large center consoles and big-water performance boats.

There are other examples as well. Halley cites the 250 XS OptiMax Torque Master gearcase, which became the 250 Pro XS Torque Master gearcase used in consumer outboards. Mercury Racing’s X-haust technology made its way into the idle-relief muffler system used in the new V6/V8 platform. Then there’s the 8.2L sterndrive, which is a detuned version of the racing program’s 525EFI.

“Overall, we have good ties to the main-line engineers, and we work together with them to develop products for future needs,” Halley says.

So what innovation will filter down from the new APX 360i to the showroom floor? “You never know what will emerge. Problems come up, and they put together a team to work on it. You never know where it will go,” he says.

This article originally appeared in the January 2021 issue of Power & Motoryacht magazine.