“We’ve certified our new ISC and ISL engines to the 2004 standards through the use of credits generated via reducing emissions from other engine lines below EPA requirements,” Carol Lavengood, Cummins’ director of market communications and operations, told Fleet Owner. Lavengood stressed, however, that Cummins considers EGR a foundation technology for all its engines in order to meet the 2007 requirements. She said that means EGR will be integrated at some point into its medium-duty engine line.

“We’re not talking any timeframe now, though,” Lavengood added. “We feel that by using credits this way we can offer customers a better integrated product later on.”

There have been several notable upgrades to Cummins’ ISC and ISL, added David O'Brien, the company’s market product leader.

”The upgrades/changes for the ISC and ISL are a new fuel system, increased engine block and cylinder head strength, a more robust breather, and a variable geometry turbocharger on ISL,” he said. “Performance will be equal to or better than pre-04 engines as well.”

The ISC and ISL engines use a High Pressure Common Rail (HPCR) fuel system, which provides multi-injection capability, reduced noise and emissions, and improved cold starting. The design maintains high injection pressures regardless of engine rpm, Cummins added.

Cummins said that the current ISB engine uses both HPCR and cooled EGR, an air handling technology used to reduce NOx emissions by re-circulating a small amount of cooled exhaust into the combustion process.

O’Brien noted that maintenance intervals for the ISC are the same, but have been extended for the ISL, with overall maintenance simplified on both engines for lower life cycle costs.