The Isuzu 6H is a family of inline-6 cylinder Diesel engine installed in Isuzu medium duty trucks, and also installed in GM medium-duty trucks as the Duramax LG4. It is mated to the Allison 2500, 3000 and 3500 Series transmissions. Engine Specifications 6HK1/Duramax LG4 Displacement: Bore and stroke: Block: gray iron Cylinder head: cast iron Fuel cutoff: 2400 rpm Aspiration: Turbocharged and Intercooled Valvetrain: SOHC, 24 Valve Compression: 17.5:1 (17.0:1 for motor) Injection: high-pressure common-rail direct injection Power / Torque: to , to 6HH1 Displacement: Bore and Stroke: Aspiration: Naturally Aspirated Valvetrain: OHC 24 valve Compression Ratio: 18.5:1 Injection: Reformed Bosch, Inline Injection Pump with Automatic Timer and All-Speed Mechanical Governor Power / Torque: and 6HE1 Displacement: Bore and Stroke: Aspiration: Naturally Aspirated and Turbocharged Valvetrain: Direct Injection 24 valve Compression Ratio: 16.9:1 Injection: Direct Injection Power / Torque: and Engine Variants Vehicles Isuzu F-Series Chevrolet T-Series Isuzu H-Series References Diesel engines by model Isuzu General Motors engines Straight-six engines