MERCURY RACING 500R

Supercharged power for a variety of boats.

- Kevin Falvey

Move the throttle lever, and Mercury Racing's 500R outboard crushes you into the seat or bolster. There's torque to spare all the way to its max-rated 6,600 rpm. It proved a blast testing aboard various boat types, from pontoons to center-consoles to high-performance catamarans. The 500R's supercharged whine will appeal to serious speed and power devotees.

This 4.6-liter V-8 delivers this visceral experience thanks to its supercharger. Belt-driven, the supercharger forces more air into the engine, resulting in more torque and power. Mercury Racing says it delivers 10 percent more torque than the 450R, which it replaces, and it increases boost pressure by 26 percent.

The 500R also boasts many technological innovations. For instance, a humidity sensor monitors intake air. This allows the engine ECM to combine humidity, air-pressure and air-temperature data to determine the ideal spark timing. It is the first marine engine with humidity compensation.

Mercury Racing claims that 30 more horsepower is made available in high humidity thanks to this technology.