454 Magnum Mercruiser Engine

Includes approximately 425 horsepower with approximately 375 horsepower at the prop. The 454 Magnum includes dome pistons that increase torque and horsepower. The 454 Magnum that includes 2" intake ports has increased torque over the 454 Magnum that includes 2 1/2" intake ports. Our tests have shown that the 454 Magnum Mercruiser engine is worth the extra money and offers a great return on investment. For RPMs over 4,000, large intake ports are best. RPMs of 1,500 to 4,500 get better power with smaller intake ports.  Those who are replacing a 454 Chevy marine engine and desire to get more power while reducing fuel usage, should install the 454 Magnum engine.