WASHINGTON, DC.  A 400-hp. rating of the new ISX12 G natural gas engine has been approved and will begin shipping to truck makers in August, according to Jim Arthurs, president of Cummins Westport.  Considered the first true heavy-duty natural gas truck engine, the ISX12 G was initially introduced with a 350-hp. rating just last April and is currently offered in heavy-duty models from all of the major truck OEMs.

The company, which is a joint venture between Cummins Engine Co. and Westport, entered the natural gas truck engine market with the 9L ISL G in 2007. While it’s proved popular in transit, refuse and some vocational markets, the smaller displacement engine lacks the power for longhaul 80,000-lb. GVW applications.

Speaking on a panel of heavy-truck manufacturers at the ACT Expo, Arthurs said “all the pieces are coming together now” for accelerated adoption of natural gas as an alternative truck fuel. In addition to a suitably powerful engine, there is now a sustainable supply of natural gas, an emerging fueling infrastructure, OEM investment in vehicle development, as well as emerging choices in engines and onboard fuel storage, he said. “We now have really serious customers buying [NG] trucks now.”

The market still needs a 1,550 lbs.-ft. torque NG engine on the heavy end and perhaps a smaller 6.7L one for lighter vehicles, according to Brian Daniels, powertrain product manager for Daimler Trucks North America. Predicting that NG trucks would account for 2 to 3% of the Class 8 trucks built in North America this year, Daniels called the new 400-hp. rating “a big deal” that would help escalate adoption.

Although Volvo Trucks North America believes “diesel will remain the mainstay for many years to come,” the company will introduce its own proprietary 13L LNG engine next year, which will join its current ISL G and ISX12 G offerings, according to Ed Saxman, product manager for alternative fuels. “Customers want options,” he said, adding that Volvo will also add another alternative fuel choice with a dimethyl ether (DME) engine next year as well.

No longer an emerging technology, NG trucks are now a rapidly growing market, according to Andy Douglas, national sales manager for Kenworth Trucks. “Natural gas will account for 4 to 5% of the heavy truck build in 2013,” he predicted, reaching 11,000 to 12,000 units. “The [ISX12 G] is a huge part of that growth.”

Large orders from leasing companies for NG trucks with the new 12L could be causing “a spurt in growth” that may fall off a bit as fleets try out the leased trucks before committing to large scale purchases, according to Nadine, Hauptmann, Navistar director of alternative fuels and product marketing.  Citing a just released study from Citi Group, she said their forecast has NG trucks capturing 25% of the heavy-duty market by 2020.

“That’s the kind of steady ramp up we want,” added Bill Kahn, manager of advanced concepts for Peterbilt Motors. The ISX12 G will account for almost 30% of the 2,000 NG trucks the company expects to sell this year, he said.