An evolution of the ISX11.9, released about 18 months ago primarily for vocational use, the revised engine is said to deliver fuel economy improvements of as much as 12% in such work. The gain is "up to 5%" in regional hauling.
The ISX12 is said to be a step above the previous model in this power range -- 310 to 425 hp -- by way of improvements realized through optimized calibrations.
Featuring better pulling power, "excellent" driveability, and strong clutch-engagement torque, says Cummins, the ISX12 is designed for rigorous duty cycles, including those for work trucks such as dump, mixer, and refuse trucks. Full suites of horsepower and torque ratings are also available for fire and emergency vehicles, recreational vehicles, and motor coaches as well as regional-haul and daycab operations in class 8 trucks.
The engine flows out of what was called the Dakota project several years ago, a co-operative venture with a couple of truck makers. The effort dissipated and today's engine is a much different beast than that original, though the 12-litre capacity has remained. It uses several components in common with the ISX15, including an enhanced cooled exhaust gas recirculation (EGR) system, a single variable-geometry turbocharger, and the proprietary XPI common-rail fuel system. Like all the company's big-bore and midrange engines, the ISX12 sports selective catalytic reduction aftertreatment.
For regional hauling and LTL distribution, standard ratings range from 310 to 425 hp (231-317 kW) and SmartTorque ratings from 330 to 425 hp (246-317 kW). For vocational applications, the ISX12 is said to offer a high power-to-weight ratio and 800 lb ft (1085 Nm) of clutch-engagement torque. Eight vocational and five refuse ratings are available, along with integrated rear- and front-engine power take-off and hydraulic drive options.
The ISX12 will be in full production in March 2012.