Mercury Racing introduced its inline-6 Verado 400R outboard in 2015, announcing a revolution in the high- performance boating world. Suddenly, a boat could run 100 mph without a pair of 1,000-plus-hp loud, bellowing sterndrives that needed to have valves adjusted every handful of hours.
The outboards were just the beginning of go-fast-boat enthusiasts’ hunger for more power. But when the 450R came out in 2019, Mercury Racing was still focusing on its primary customers.
“We were turning it toward our known customers, the go-fast, lightweight boats,” Mercury Racing general manager Stuart Halley says. The problem was that boatbuilders of all kinds were capitalizing on the lust for big outboards. They started bolting them on big cruisers, pontoon boats, you name it. “We had forecast a certain volume, and we blew past that level,” says Halley, who estimates the company has produced more than 10,000 units of the 450R. “It was almost a perfect storm. The industry was growing, and then we had the pandemic, and it grew even more.”
Additionally, when Volvo Penta purchased and then shut down Seven Marine, which made high-output, large displacement outboards, it created a void for high-power outboards designed to develop lots of thrust to push larger boats, like the 50-plus-foot offerings from such companies as Scout and HCB Yachts. “There were new boats being created, and there wasn’t an engine for them,” Halley says.
He and his team of engineers started working on a new high-performance outboard for their current high-speed customers and for the builders of heavier center consoles and cruisers. On June 14, Mercury Racing held a 50th anniversary celebration in Charleston, S.C., attended by more than 250 of the best-known names in high-performance boating, including tunnel-boat racing’s Bill Seebold and his sons, Mike and Tim; offshore racing throttlemen John Tomlinson and Grant Bruggemann; and virtually every go-fast-boat manufacturer in the game. After dinner, Halley presented the new supercharged Mercury Racing 500R to the crowd. The next day, media members were treated to rides on high-speed catamarans, performance center consoles, larger vee-bottom cruisers and a pontoon boat that ran 85 mph.
The 500R is based on the same platform as the V-8 300R, but it has a supercharger to make the extra power. This is a strategy Mercury Racing has applied before, but the most significant changes were made to the midsection and the lower unit. For example, there are two versions of the gearcase, one for boats that will run faster than 100 mph and one for those that don’t hit triple digits.
Through his 30-plus years at Mercury Marine and Mercury Racing, mostly spent in new-product development, Halley has had to find compromises between over-engineering and efficiency. The 500R is the latest example. It comes on the heels of Mercury Marine and Mercury Racing introducing the V-10 400 Verado and 400R, respectively, at the Miami International Boat Show. The 400R makes more power than the Verado version.
The 500R also rounds out Mercury Racing’s lineup, with the 400R at $45,500, the 450R at $62,900 and the 500R between $72,800 and $84,400. (Final pricing is based on color, shaft length, gearcase and application.)
Choose Your Weapon
One of the biggest challenges engineers face when designing an outboard for a high-performance application is making sure enough water makes it from the lower unit and up through a midsection as tall as 35 inches to keep the powerhead cool when it’s turning a maximum rpm of 6,600. Couple that with having to do so for high-speed catamarans and larger vee-bottoms that create vastly different water flow coming off the bottom and transom.
Mercury Racing came up with what sounds like an obvious solution: an
adjustable water-intake system on the new gearcase/lower unit known as the R-Drive. It’s designed to provide more durability with larger gears in a bigger housing and to swing bigger propellers to push bigger boats.
The 450R and the 400R have a lower unit that is 5.44 inches in diameter. On the new 500R, that dimension increases to 5.9 inches. Focused more on heavy cruisers, the 400 Verado has an even bigger gearcase at 6.4 inches.
“As a corporation, on the main-line and racing applications, we work closely with the main line to ensure that we have our own space,” Halley says.
There are two versions of the R-Drive. Each has a crescent leading edge and a long aspect torpedo hydrodynamically tuned for high speeds. They also have a 1.60-to-1 gear ratio and a new intermediate spray rail plate that reduces drag in submerged and partially surfacing applications.
Arguably, the most noteworthy feature is an adjustable nose cap water pickup system that lets a boatbuilder or rigger choose the amount of water flowing into the engine. The nose cones are available in two basic shapes, one for submerged and partially surfacing applications, and one that is shaped to run fully surfaced on high-speed boats. A new water pump increases cooling capacity by 57%.
For improved durability, the driveshaft diameter was increased to 1 inch from 7/8 inch, and the propeller shaft diameter was boosted from 1.25 inches on the 450R to 1.5 inches on the 500R. This is good for durability, but not so great for an owner’s budget. With Mercury’s UltraLock hub kit, props like the Ventera and Max 5 can be used on the 500R. Boats that need cleaver-style propellers will need new wheels.
The base R-Drive is designed for submerged and partially surfacing applications on boats that run between 85 and 100 mph. Many high-speed center consoles fall into this range. The R-Drive has a standard length skeg with a parabolic cross section shape, and is offered with left- or right-hand camber to balance steering forces with standard and counter-rotating propellers.
The R-Drive Sport is designed for high-speed surfacing applications, primarily high-performance catamarans and stepped vee-bottoms that can exceed 100 mph. It has a longer skeg than the base R-Drive, and the skeg is shaped with a wedge from the leading edge aft. The R-Drive Sport is available with no camber or with a right-hand camber for single-engine boats. The R-Drive Sport is also equipped with a prop shaft made from an aerospace stainless-steel alloy like the material used for the Mercury
Racing M6 and M8 sterndrives that are paired with engines making as much as 1,500 hp.
Strengthening the Core
One of the purest proving grounds for performance products is racing. When the 450R was introduced, Marine Technology Inc., built a 39-foot cat with an enclosed cockpit for a new class in offshore powerboat racing.
The boats in the class are all powered by twin 450Rs, and the category has grown in popularity, but Mercury Racing also saw some elements of the engine that were improved after the racing experience. “We started learning there were some structural things around the [motor mounts] that weren’t as durable as they would be if it was a race motor,” Halley says.
The result is a new Advanced Racing Core on the 500R. It’s a midsection that upgrades the engine’s durability. A stronger, redesigned transom plate can accommodate 3 inches of vertical adjustment via seven transom mounting holes. This is twice the adjustment range available on the 450R. The trim system was also enhanced with two main hydraulic rams plus two booster units that improve the precision of trim settings and adjust the engine more quickly. Heavy guide plates and stiffened engine mounts stabilize the engine at high speeds.
And the hydraulic power system has been upgraded to produce 18% more torque than the 450R’s power steering. To support the added torque, a new steering arm, tube and cylinder are 20% stronger with an upgraded tube material (from aluminum to stainless steel). An optional rear tie-bar bracket integrated to the ARC provides a strong, light mounting point.
The 500R is available in 20-, 25-, 30- and 35-inch shaft lengths.
Controlling the Air
The 500R is the first marine engine equipped with a new sensor located in the intake attenuator to measure the humidity of the incoming air. This lets the engine’s ECM combine reported humidity with air pressure and temperature data to determine the ideal spark timing for prevailing conditions. It also gives engineers the opportunity to use a more aggressive calibration to optimize performance in almost any condition.
Mercury Racing says this solution provided up to 30 additional horsepower than an engine without humidity control, and a 15-second reduction in acceleration times from 0 to 70 mph in a test on a 27-foot Tidewater powered by a single 500R.
Power to Spare
The 500R is built on a 4.6-liter, 64-degree, 4-stroke, V8 powerhead boosted by a supercharger. It makes 50 more ponies and 10% more torque than the 450R. It runs on 89-octane fuel.
A new crankshaft designed specifically for the 500R rides in 230-degree groove main bearings for improved oiling, and has more robust, 1-inch driveshaft splines. Connecting rods, rod bearings and pistons are strengthened to handle increased combustion pressure and the higher 6,600 rpm redline. A new, low-inertia flywheel lets the engine reach those rpm in less time.
Supercharger boost is increased by 26% over the 450R, and increased air flow demand is accommodated by a larger intake. Throttle-body diameter is increased by 15% from 80mm to 92mm, and the shape of the supercharger inlet is redesigned, as well.
Precise Control
The 500R is paired with Mercury Racing’s Digital Throttle, Shift and Zero Effort controls. The Adaptive Speed Control feature maintains engine rpm as loads change. The 500R also supports Mercury Racing SmartCraft technologies, including the Engine Guardian monitor system and VesselView multifunction displays. A top cowl service door provides access to the oil fill and dipstick without having to remove the cowling.
Consumers can choose among three looks: Phantom Black or Cold White Fusion, which are finished with Mercury Racing graphics and Devil Eye Red trim, or “ready for paint” in Phantom Black with no graphics.
Perhaps the biggest indicator of how far performance outboards have come in terms of reliability is that the 500R comes standard with a three-year warranty. Up to five additional years of coverage is available.
This article was originally published in the August 2023 issue.
