Peterbilt will offer the Cummins Westport ISL G 8.9L engine for Models 320, 365, 382 and 384 in 2013,” says Charles Cook, vocational market segment manager for Peterbilt. “This is a carryover from the previous year. It is rated for 320 hp. with 1,000 lbs.-ft. of torque and is suitable for both CNG and LNG.

“Also this year,” he continues, “Peterbilt will offer the Cummins Westport ISX12 G 11.9L engine for Models 320, 365 and 384. This will be a new engine in 2013 and will be offered with up to 400 hp. and 1,450 lbs.-ft. of torque. It too is suitable for both CNG and LNG.

“The Westport HD 15L engine will also be available in 2013 for Models 367, 386 and 388,” Cook adds. “This carryover engine will provide up to 475 hp. and 1,750 lbs.-ft. of torque. It is suitable for LNG/diesel fuel.” Cook relates that the maximum torque ratings [for these engines] are comparable to some diesel engine ratings with similar displacement. For more detail on that aspect, he advises contacting the engine suppliers to review torque curves for variations.

“NG engines are not for every application today,” suggests Cook. “However, with a properly specified truck in the right application, the feedback on driveability has been positive. The introduction of the Cummins Westport ISX12 G will provide additional ratings and make natural gas an option for more applications,” he remarks.