Designed, developed and manufactured in-house, the naturally aspirated all-new 250R and 300R 4.6L V-8 four-stroke engines share Mercury Racing’s venerable Quad Cam Four Valve (QC4) sterndrive DNA – complete with aluminum four-valve cylinder heads and dual overhead camshaft (DOHC) valve train.
The four valve heads and DOHC valve train is integrated with Mercury’s proprietary V-8 cylinder block, packed with high performance hardware. The new platform replaces the two-stroke V-6 250XS and 300XS models.
No Replacement for Displacement
The stout V-8 powerhead provides a 44% in increased displacement compared to the legacy two-strokes. That, combined with four valves per cylinder and the DOHC valve train, enables the new four-strokes to generate unprecedented torque and unmatched acceleration from the lower end of the power band up to maximum engine speed while maintaining a comparable weight as their legacy two-stroke cousins. The weight savings can be attributed to the state-of-the-art powerhead components including composite intake runners.
The 250R pumps out 250 prop shaft horsepower and much higher torque than the 250XS it replaces. The efficient and durable Sport Master gearcase, in the correct application, will enhance boat handling, top speed and efficiency.
The 300R is the most powerful engine in its class. The 300R powerhead features Racing specified intake cam shafts, valves and an exclusive short runner intake manifold. An integrated oil cooler keeps oil temps down throughout the Racing exclusive 5800-6400 rpm operating range. A multitude of models with two midsections and three gearcase options in varying shaft lengths are available to revolutionise nearly any boating experience.