A Unique Solution

Navistar’s MaxxForce Big Bore’s non-SCR approach to 2010 emissions offers strong fuel economy and performance.

Navistar impressed the market with the 2008 introduction of its 11- and 13-liter MaxxForce Big Bore engines, featuring common-rail injection and a compacted graphite iron block. The 15-liter engine was introduced this year. The truck and engine maker drew attention again when it declared it would use advanced exhaust gas recirculation rather than selective catalytic reduction to meet the extremely low 0.2 grams/hp/hr NOx standard for 2010.

No other competitors followed suit.

Navistar’s Tim Shick says the Big Bore’s air and fuel handling systems, such as on this 15-liter model, “help deliver peak torque at 1,000 rpm versus a typical 1,200 rpm for competitors.”

 Part of the recipe is Navistar’s ability to burn credits from the U.S. Environmental Protection Agency so that its 2010 engine, which reduces NOx to about 0.5 grams/hp/hour, gets EPA certification, while further development work proceeds. The result, the engine maker says, is an engine that delivers fuel economy that equals its 2008 version because of injection and air handling system developments. Add to that the freedom of not having to add diesel exhaust fluid and the combination of a 12.4-liter block and no SCR catalyst or DEF tank, and the engine’s ability to enhance operational ease and payload capacity is clear.

Navistar says the CGI cylinder block itself, the only one in the Class 8 industry at the engine’s introduction (the Paccar MX also uses the material), is vital for making such an engine quiet, fuel-efficient and durable. “This incredibly strong platform handles the loads that deliver the best combustion and dampens vibration and noise,” says Tim Shick, director of marketing for MaxxForce engines. “It carries the load without weighing you down.”

Tim Coffren, vice president of management and maintenance at Hirschbach Motor Lines, says the trucks in his refrigerated fleet with the 2010 MaxxForce Big Bore engines have been getting nearly 7 mpg.