Cummins ISX11.9 Boosts Fuel Economy

By Tom Berg, Truck Editor | January 30, 2012

The heavy duty Cummins ISX11.9 diesel has been recalibrated and now gets as much as 12 percent better fuel economy in construction and other vocational trucks, and it has a new name: ISX12.

Recalibrating the engine’s electronic controls has also resulted in fuel economy betterments of up to 5 percent in road tractors, the company said. The ISX12 is physically the same as when it was introduced for 2010, and is equipped with urea injection, a particulate filter and advanced combustion design to meet EPA 2010 emissions limits.

The engine replaced the similarly sized ISM, but with a design based on the big-bore ISX15, the company said at the time. The new rounded-up numerical designation is easier to read and say, and is consistent with those for ISX15 and ISL9, Cummins’ other heavy duty truck engine products.

The ISX12’s vocational ratings start at 320 horsepower and go to 425, with torque outputs of 1,150 to 1,650 pound-feet. On-highway ratings range from 310 hp and 1,150 lb-ft. to 425 hp and 1,650 lb-ft, plus variable Smart Torque ratings of 1,250-1,350 to 1,450-1,650 lb-ft.

Torque output at clutch engagement is a strong 800 lb-ft, making the ISX12 an excellent engine for construction, refuse and other vocational applications, the company said. Integrated rear- and front-engine power take-off drives are available.