COLUMBUS, Ind. — Cummins Inc. has received certification from the EPA and the California Air Resources Board (CARB) for two new school bus ratings.

The new ratings for the ISB6.7 engine are certified at 0.20g oxides of nitrogen (NOx) per brake horsepower (hp) hour without the use of emissions credits. They include offerings of 220 hp with 520 lb.-ft. of torque and 250 hp with 660 lb.-ft. of torque.

Officials said the ability to deliver these new ratings can be attributed to Cummins' total system integration, from the air intake to the exhaust aftertreatment system with selective catalytic reduction (SCR) technology, all of which are designed and developed in house.

The system integration, coupled with the highly capable base engine, results in the ability to deliver near-zero emissions without compromising fuel economy, reliability or durability, according to the company.

The certification of these new ratings has been achieved without any hardware or software changes to the ISB6.7 engine.

"This is a great example of Cummins' capability to deliver the cleanest diesel engines to the school bus market while continuing to validate that we are on the right path with SCR technology," said Tom Hodek, general manager — North American bus business. "We confirmed, through two years of experience with the product, that these ratings are operating well below the 0.20g-NOx level, and will continue to do so through the life of the engine."

Officials said that Cummins will begin production of these ratings for the ISB6.7 this month.