Continuing to celebrate its 50th anniversary, Mercury Racing on Wednesday released the new 500R outboard and two drives for the V8 package during a gala in Charleston, South Carolina.
By Gregg Mansfield
The supercharged 500-hp outboard is the second major product launch this year from Mercury Racing, following the 400R V10 outboard that debuted at the 2023 Miami International Boat Show.
Taking more than three years to develop, the 500R features a host of new features including a new crankshaft, a beefier midsection and humidity compensation technology.
“We’re really proud of this flagship. We’ve got two nice, normally aspirated engines (the 300R and 400R) and now when you go to the 500R you get that supercharged performance,” said Stuart Halley, Mercury Racing’s general manager, after the curtain dropped on the new outboard. “We needed a new gearcase, our team took the challenge, and they invented the R-Drive.”
The event featured the who’s who of the high-performance industry. Attending the Mercury Racing event in Charleston’s historic district. A few of the attendees included industry legends Peter Hledin of Skater Powerboats, Mystic Powerboats’ John Cosker, Marine Technology’s Randy Scism and TNT Custom Marine’s John Tomlinson.
Representing the West Coast builders were Eliminator Boats’ Jake Fraleigh and DCB Racing’s Jeff Johnston and Tony Chiaramonte.
According to Mercury Racing, the 500R delivers more than 500 horsepower, 50 more horsepower and 10 percent higher torque than the 450R model. Its 4.6-liter 64-degree V8 FourStroke powerhead is boosted by a Mercury Racing supercharger. The engine runs on a minimum of 89-octane fuel.
To handle the power, Mercury Racing upgraded the powerhead, cooling system, midsection and steering system. Engineers developed a new gearcase specifically for the 500R outboard dubbed the R-Drive.
The R-Drive, available in a base or sport variant, features a crescent leading edge and long aspect torpedo hydrodynamically tuned for high speeds, according to Mercury Racing. The new 5.9-inch gearcase can accommodate propellers up to 17 inches in diameter, one inch larger than the 450R gearcase. Both drives are designed for semi-surfacing or full-surfacing applications, and a 1:60:1 gear ratio.
“That is a new gearcase from scratch, just for this product,” said Chris Jenks, Mercury Racing’s technical development manager for the 500R. “It’s a larger input shaft, it’s a larger prop shaft, it’s larger internals, larger bearings. We really focused on the water pickups and the hydrodynamics.”
The 500R features the first humidity compensation technology for a marine engine. A new sensor in the intake attenuator measures the humidity level of the incoming air. This allows the engine ECM to combine reported humidity with air pressure and air temperature data to determine the ideal spark timing for prevailing conditions.
Mercury Racing says boaters will notice a significant power gain in very humid conditions. The technology reportedly provides an additional 30 horsepower that otherwise wouldn’t be available because of high humidity.
The 500R is designed for catamarans, center consoles and pontoon boats, and comes with a three-year warranty. While the industry was anticipating a 500-hp outboard to make its debut at the Mercury Racing gala in Charleston, it caught some folks by surprise it was based on a V8 platform and not the V10 platform for the 400R that launched in Miami.
Halley said the planning for the 500R started after the release of 400R in 2019, which is a V8 platform. Mercury Racing now offers six outboards from 60 to 500 horsepower.
“There is things that were kind of thought about during the 450R but couldn’t quite be integrated,” Halley said. “We always kind of knew we were going to do a follow on.” 
