New supercharged Mercury puts out 450hp

Claimed to be over 130kg lighter than the nearest competitor, the new 450R delivers industry leading power-to-weight ratio in a compact, efficient package. Multiple gearcase control system, tie bar and styling options are available, and it is designed to deliver all of its performance on readily available 89-octane (95 RON) pump fuel.

Designed and developed in-house and manufactured in Wisconsin on a dedicated Mercury Racing production line, the 450R is based on the same 4.6-litre V8 powerhead used for the normally aspirated Mercury Racing 300R outboard models.

Mercury Racing has applied its supercharging expertise to extract incredible power from the 4.6-litre V8 with a 2.4-litre, belt-driven twin-screw supercharger that delivers pressure charging with zero lag for instant throttle response.

To maintain peak performance, a boost bypass valve automatically adjusts maximum boost pressure in response to changing ambient conditions. To better manage engine heat, the Mercury Racing 450R is fitted with a special high-capacity oil cooler and an exclusive poppet valve in the midsection to provide a higher volume of cooling-water flow on-demand.

The electronics and engine components are all designed and positioned to create the tightest package possible while maintaining good service access. The design and placement of the new supercharger and charge-air coolers allow the 450R to use the same slim-line cowl as the 300R model while incorporating higher flow intake vents.

Like all Mercury Racing outboards, the 450R accommodates 26-inch centre-to-centre mounting on multi-engine transoms.

The exclusive Mercury Racing Advanced MidSection (AMS) features heavy-duty stainless-steel guide plates and stiffened engine mounts to stabilise the outboard and enhance high-speed handling. The AMS also isolates the powerhead from the transom to insure run quality is smooth and quiet.

The surface-piercing Sport Master gearcase, designed for boats capable of speeds in excess of 85 mph, features low water pick-ups and a crescent leading-edge for maximised efficiency, and for the 450R application, a new, one-piece, 1.25-inch diameter stainless-steel propshaft.

By Jake Frith