WARRENVILLE, Ill. -- In the seemingly endless war of words between the EGR and SCR camps, decorum has not always been evident.

But in a combination online and telephone press conference earlier this week, Navistar executives were seemingly a little more measured, and perhaps, more confident too.

Jack Allen, president, Navistar North American Truck Group, was joined by Jim Hebe, executive vice president of North American sales, and Ramin Younessi, group vice president of product development and business strategy, in presenting the Navistar case to the usual assemblage of transport writers and business media.

The reason for the conference was to announce pricing for 2010 Navistar truck engine products (click here for more on that), but it also served as an update on the company's progress with "advanced" EGR technology and its lawsuit against the EPA.

Younessi joined the conversation from Colorado where, along with 30 engineers and 14 2010 trucks, he’s conducting hot-weather and high-altitude final-validation tests. That also includes time spent in Death Valley and the infamous Baker grade. Extensive cold-weather testing has been done in Minnesota.

As todaystrucking.com reported earlier this summer, Navistar is claiming that while the EPA’s 2007 guidelines for engine-makers allowed no loopholes for anyone, the 2010 rules change that, and the company is adamant that the playing field is not level.

"What they [EPA] have really done is create a loophole for SCR manufacturers,” said Allen. There are a few such breaks, he added, offering one example: in 2007 an engine wasn’t allowed to run in a non-compliant state at all, but in 2010 there are situations -- like after a cold start -- in which an engine can run non-compliant for as long as 70 minutes.

Using EGR, an International engine will never that break, but SCR engines will, he claims.

The EPA has yet to respond to the suit.

Allan also went on to dispute the claims by SCR engine makers that their motors will be more fuel-efficient in 2010. He said their claims are based on a class-8 truck engine operating in optimum conditions, but things are different in vocational and medium-duty applications where International trucks spend much of their time.

This one, though, remains to be better understood after a lot of real-world use.

Back to Navistar's engineering work: Changes from 2007 technology aren’t radical, the techs say.

“What we’re really doing is an evolutionary change,” said Allen, “the derivative of a proven technology.”

Younessi said what they’ve done is really “a lot of little tweaks.”

Changes include advancements in fuel injection, with the “next generation” fuel injection systems delivering fuel to the combustion chamber multiple times per cycle at higher pressures.

Air-intake management is improved with the use of dual turbochargers. And Younessi says the two-stage cooler should reduce the number of DPF regeneration events but couldn’t quantify the extent of those reductions.

On its heavy-duty engines, Allen and company are comfortable in allowing that they’ll need emissions credits to meet EPA 2010 rules at the outset.

They’re going to hit the New Year with nitrogen-oxide output of 0.5 grams per horsepower/hour whereas the EPOA rule demands NOx be at just 0.2 grams. But Allen wouldn’t say when they’ll get to the lower level.