Designed, developed and manufactured in-house, the naturally aspirated, 9.0 liter 860 sterndrive engine features Mercury Racing’s exclusive aluminum four-valve cylinder heads and dual overhead camshaft valve train.  This proven valve train, which greatly enhances engine performance and durability over a standard two-valve design, enables the engine to produce 860 horsepower at 6800 rpm on 89 octane (Rec 90) pump fuel. The engine’s 6300-6800 rpm operating range offers unsurpassed acceleration for its power rating. The higher rev limits expand the range of propeller options available for a variety of applications.