Cummins ISX15 is North America’s most popular heavy-duty engine, and the only engine offered as an option by every major Class 8 truck manufacturer. The ISX15 boasts ratings from 400-600 horsepower with up to 2050 pound-feet peak torque. This legendary engine is a favorite among drivers and fleet operators alike.

The ISX15 is the industry leader in fuel economy. In 2013, we refined our proven technology, including more efficient fuel and water pumps to provide additional usable horsepower. Together with optimized combustion and fewer active regenerations of the aftertreatment system, today’s ISX15 delivers up to 2% better fuel economy.

Each element of the ISX15 is manufactured to maximize fuel economy, performance and durability, while delivering the lowest operating costs of any engine in its class. Integration and optimization of every system from air handling to exhaust aftertreatment results in the most reliable engine on the road.

ISX15 ratings range from 400-600 hp (298-447 kW) with up to 2050 lb-ft (2779 n•M) of peak torque. These include SmartTorque ratings that add 200 lb-ft of extra torque in the top two gears so Class 8 trucks can make it up steep grades with fewer downshifts. Vocational ratings have additional torque in the lower gear ranges. Operators can tailor ISX15 operation for any on-highway application using Cummins PowerSpec.