We’re running at 48 knots onboard a Strider 11, one of the most successful RIBs by Sacs. The stern accommodates two Mercury 450 R 900 HP outboards. We push the throttle down and we feel there’s still much power available. So, we speed up and the boat reacts promptly despite the speed. The sea is rough, waves are clearly perceivable and visibility is even reduced right now.
Despite the high speed, we can easily appreciate the ease of driving offered by the electro-hydraulic helm. The high-frequence noise of the volumetric compressor is significantly reduced by an intake silencer without sacrificing the “sound” of high performance. Well, once again, the engineers of Mercury Racing have made an excellent job ad the 450R, the most powerful outboard of the company of Wisconsin (USA), has all the characteristics to make its owners feel good.
Designed by the Racing department of the American giant Mercury Marine, this engine is perfect for those looking for “monstrous” performance, even higher than 70 knots. Outboards and RIBs are certainly the hot trends of the Mediterranean market. The 450 R is great: its acceleration, the optimized torque, a weight of just 313 kg, its appealing design and sturdy structure are the key ingredients of its success. Discover its secrets on the next page.
Why is it so powerful? (Also) because it is supercharged by a water-cooled twin-screw volumetric compressor. The double intercoolers (heat exchangers) cool the compressed air, increasing its density and therefore the power generated.
When running at 70 knots, you need stainless steel guide plates and reinforced supports to stabilize the engine at high speeds. This engine features a valve that provides a volume greater than the flow of cooling water.
Among the options available, the Sport Master stern drive is the most “racing” one. It has water intakes at the bottom of the attachment fitting. The curved skeg balances the thrust of the propeller, improving performance and maneuverability in single-engine applications.
Oil-bathed transmission chain camshafts, without timing belt, require no maintenance. The electronics and engine components are compact, but easily accessible.
Torque, power, weight
The 4.6-liter V8 four-stroke is supercharged to produce 450 horsepower on the propeller shaft with 40% more torque than the 400R. It has an unmatched weight/power ratio among the “pleasure” engines: 1.43 hp per kg (313).
To get the most out of these engines you need a MAX 5 propeller, which you can see here, or an Outboard CNC Cleaver developed and handmade by Mercury craftsmen. outboards [ mercury 450r ]
Tratto da: Barche a Motore 11/2019