PowerTech 4.5L and 6.8L engines
Better known for its famous green-and-yellow tractors, John Deere is a respected name in marine propulsion. Its Tier III offerings come in two series of engines, the 6068AFM85 and 6068SFM85 and the 4045AFM85 generator and propulsion drive engine and the 4045TFM85 generator drive engine. The PowerTech 4045AFM85 is rated at up to 225 horsepower. The 6.8-liter engines feature high-pressure common-rail fuel systems, four-valve cylinder heads, and low-temperature aftercoolers and are rated from 249 hp to 400 hp. The redesigned PowerTech 6068SFM75 can produce up to 550 horsepower while the 6135SFM75 cranks out 750 horsepower. For big Tier II engines, John Deere offers the 6.0-liter 550-hp 6090SFM75 and the 13.5-liter 613AFM75 that’s rated up to 575 horses.