500hp outboard: What makes Mercury’s new V8 500R so special?

Nick Burnham explains why the Mercury Racing V8 500R outboard represents a big step forward for this type of engine…

Twenty years ago if you wanted a fast 30ft+ sportsboat then your choices were limited to basically which kind of inboard engine and outdrive combination you preferred.

Then we started seeing outboards, previously the go-to on smaller runabouts, RIBs and speedboats, start to appear on ever larger and faster vessels. Firstly it was all-American offshore center console boats, often with multiple outboards across the transom.

Then the kind of high performance racer that traditionally wouldn’t be seen afloat without a pair of high capacity petrol V8 inboards started turning up with a set of outboards powering them past 60 knots. Now we’re even seeing 40ft flybridge cruisers with outboard engines.

The reasons generally revolve around packaging (with the engine mounted directly above the drive leg, virtually none of it is actually inside the boat), reliability, accessibility (a crane and some tools is mostly all that’s required for an engine swap), lower servicing costs and choice (design a boat for an outboard and you can choose from any make that offers the correct horsepower).

Outboard manufacturers have responded keenly to the increased demand, bolstering their ranges with ever more powerful and glamorous offerings, and one of the latest, most powerful and most glamorous has just been launched by Mercury.

In fact it’s almost the most powerful outboard engine in the world. Since Seven Marine, builders of the awesome 627hp outboard was bought by Volvo Penta in 2017, only to inexplicably stop making outboards in 2021, only Mercury’s own 7.6 litre V12 600hp Verado beats it. But that’s a big heavy unit at over half a tonne, more suited to cruisers.

The new 500R outboard by comparison starts at a svelte 326kg, and is fitted with a 4.6 litre V8 engine, boosted by a Mercury Racing supercharger. Connecting rods, rod bearings and pistons are strengthened to handle increased combustion pressure and a higher 6,600rpm redline.

It’s a set-up designed for high-performance applications where the power-to-weight ratio is critical. Indeed Mercury claims it ‘establishes a new benchmark for outboard power density’.

Mercury Racing has designed an all-new gearcase for the 500R outboard. R-Drive is available in two versions, both featuring a crescent shaped leading edge and long aspect torpedo hydrodynamically tuned for high speeds. The new 5.9in gearcase can house propellers up to 17in in diameter.

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The R-Drive Sport version is for faster boats. Mercury describes it as “optimised for ultra-high-speed surfacing applications, primarily high-performance catamarans and centre consoles capable of speeds beyond 100 mph”.

It features a longer skeg than the R-Drive version, which allows it to maintain steering control while operating in surface piercing mode at the high mounting positions needed for these hull designs.

The 500R outboard is available in four lengths – 20”, 25”, 30” and 35”. The 26in centre-to-centre mounting distance on multi-engine transoms “enables easy installations on new boats and repower applications. Tech includes Digital Throttle and Shift (DTS) with available Mercury Racing Digital Zero Effort controls.

Available in Phantom Black or Cold Fusion White, as standard they are finished with Mercury Racing graphics and Devil Eye Red trim. For anyone planning a custom paint application, the 500R outboard is also available in “ready for paint” in Phantom Black with no applied graphics or trim panel.

The Mercury V8 500R outboard is covered by a three-year limited factory warranty, but up to five additional years of Mercury Product Protection extended factory warranty is available in the UK.

Power: 500hp / 372KWRPM (WOT): 6000-6600Engine type: V8 (64 Degree) with 32-Valve Dual Overhead Cam (DOHC)Displacement: 4.6LInduction system: Supercharged with Charge Air Cooling and Electronic Boost ControlFuel requirements: Unleaded Regular 89 Octane Minimum (R+M/2) or 95 RONCharging: 115 amp / 1,449WThrottle and shift: Digital Throttle & Shift (DTS)Midsection: Advanced Racing Core (ARC)Shaft lengths: 20”, 25”, 30”, & 35”Gearcase: R-Drive, R-Drive SportGearcase ratio: 1.60:1Dry weight: 326 kg / 726lbsWarranty: 3-year limited as standard, 5-year available