Mack Engine Specifications

by Phil Whitmer
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Mack engines are designed and assembled at the company's Hagerstown, Maryland plant. They're used in commercial Mack trucks, including the popular line of Mack off-road trucks. Mack engines were the first to allow heavy trucks to use a five-speed transmission.


The Mack Maxidyne MP8 USO7 diesel engine is an in-line, six-cylinder, turbocharged, direct fuel injected motor with a displacement of 780 cubic inches. It has 24 poppet valves, steel dual-ring pistons and a single overhead cam. Its factory dry weight is approximately 2,560 pounds.


The USO7's peak rating is 485 horsepower at 1,500 to 1,900 rpm, with a governed rating of 340 horsepower at 2,100 rpm. It has a bore of 5.16 inches and a stroke of 6.22 inches, with a compression ratio of 16:1. It produces 1,700 ft.-lbs. of torque at 1,100 to 1,500 rpm, with a low idle speed of 650 rpm and a high idle speed of 2,100 rpm.


The MP8 USO7 features a cast iron block, cast aluminum flywheel housing and a forged, carbon steel crankshaft. It has a cooled exhaust gas recirculation system and a Mack PowerLeash engine brake with a retarding power of 435 horsepower at 2,100 rpm.

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