This year, Daimler Trucks North America will be offering both the Cummins Westport ISL G 8.9L, with ratings up to 320 hp. and 1,000 lbs.-ft. of torque, and the new Cummins Westport ISX12 G 11.9L, with ratings up to 400 hp. and 1,450 lbs.-ft. of torque, according to Greg Treinen, segment manager-vocational & alternate fuels product marketing for Freightliner Trucks.

“Both engines are fuel neutral—it doesn’t matter if you use CNG or LNG,” he notes. “Torque curves for the ISL G are similar to the ISL diesel of the same rating while torque ratings on the ISX12 G are slightly lower than ratings for ISX12 diesel with the same horsepower.

“The durability of these engines is expected to be at least as durable, if not more durable, than their diesel counterparts,” Treinen continues.

“The drivability is very similar [to diesel] if these engines are being used in the right application,” he contends. “Drivers shouldn’t notice much of a difference, especially when an engine is paired with an Allison automatic transmission with its torque converter technology.”

Treinen points out the ISX12 G will be able to provide “significantly more horsepower (up to 400 hp.) and torque (up to 1,450 lbs.-ft. torque) than the ISL G, opening up the market to more regional-haul carriers that need the additional power and torque to haul more freight and drive routes with steeper grades.

“Maintenance costs might be slightly higher [with NG],” he continues, “given that Cummins Westport recommends shorter oil and filter change intervals for their NG engines vs. Cummins’ diesel engines. And since these engines are spark-ignited, they require spark plug replacement every so often. However, fleets don’t have to worry about maintenance or repairs on any diesel aftertreatment components such as diesel particular filters.”

Full production on the Freightliner Cascadia with the ISX12 G engine and Allison 4000 HS automatic transmission will begin in the late third quarter of this year, according to Treinen.