The Cummins ISM is a straight-6 10.8-liter diesel engine designed and produced by Cummins. The ISM is the product of applying the Interact System to improve the M11. Changes include a dual-pulse fuel injection for improved fueling quality to the power cylinder and a redesigned piston bowl. The ISM is still often known as Cummins M11 engine. The Cummins ISM is available in 4 different configurations, with slightly different emphasis on maximum horsepower (450 vs. 500) and peak torque.