TORONTO, Ont. – The penetration of the EPA07 engines into the North American marketplace has been predictably slow, with record engine sales last year signaling a significant pre-buy that would stall engine sales in early 2007.

Couple that with a softening of the US economy and a decline in overall freight volumes, and you have a perfect storm of sorts for North American engine suppliers. Nonetheless, a growing number of fleets are slowly integrating the EPA07 engines into their fleet, allowing manufacturers to gain a better understanding of just how well their engines are holding up under real-world pressures.

There have been few surprises so far, according to engine manufacturers.

That’s not too surprising, considering that unlike previous generations of EPA-compliant engines, the 07 version of ultra-clean heavy-duty truck engines underwent extensive lab and real-world testing prior to rollout.

“The engines are performing very well as expected,” confirmed Jim McNamara of Volvo Trucks North America. That response is resonated by each of the major engine manufacturers when asked how their 07 engines are faring.

“The drivers have for the most part been very pleased with the performance,” added Mike Powers, product development manager, global on-highway engines with Caterpillar. “I think as a rule, we have had unanimous feedback from the field that performance has exceeded expectations. They run as well as any engines they have ever operated – above our expectations.”

One of the biggest concerns heading into 2007 centered around the fuel mileage the new engines would achieve. After all, the diesel particulate filter (DPF) regeneration process requires a dose of additional diesel to trigger the cleaning process. For the most part, manufacturers have insisted the EPA07 engines are as good as, or better, than their predecessors when it comes to mileage.

“When we went to the marketplace, we said our expectations were equal to the EPA04-certified engines, but to date that has almost unanimously been the worst case,” said Powers. “Most people are reporting slightly better fuel mileage.”

Detroit Diesel director of marketing, David Siler, said his company has found “customers have, in general, experienced roughly the same fuel economy that they did with our EPA04 Detroit Diesels. Any fuel economy gain or loss over the EPA04 engines has been negligible.”

Customers may see a slight improvement in fuel economy, thanks to improved fuel mapping aimed at stretching every litre of diesel.

And how about those DPFs? The EPA had mandated they run at least 150,000 miles between ash cleanings. Very few 07 engines have yet reached that mile marker, but manufacturers all report they expect the DPF will go well beyond 150,000 miles before requiring its first cleaning. Some are saying the DPF can reach up to 500,000 miles before its first cleaning, meaning it’s conceivable that one ash-cleaning will be all that’s required during a typical life cycle. Passive regeneration cycles have been occurring as expected, minimizing the driver’s involvement in the regeneration process.

David McKenna, powertrain marketing manager for Mack Trucks, said “In a typical single shift vocational application, regen’s are occurring approximately twice per day and roughly every 15 to 16 hours in longhaul highway applications.”

Passive regenerations are transparent to the driver, save for a light on the dash which indicates one is underway. A High-Exhaust System Temperature (HEST) lamp will light up when exhaust temperatures are high, possibly to facilitate a regeneration.

“Don’t be surprised to find yourself asking ‘Is that all there is?’ when you experience your first DPF regeneration – it’s really a non-event,” warned McKenna.

For the most part, drivers don’t have to concern themselves with the regeneration process at all.

“Just leave the regeneration system in automatic mode,” advised Powers. “The driver should just go and operate the truck in the usual manner as he has before. The system is designed to take care of itself.”

In the months leading up to the launch of the EPA07 engines, there was a lot of talk of ultra low-sulfur diesel and CJ-4 engine oils. Both ULSD and CJ-4 are recommended for 07 engines, but truck fleets and O/Os can get away with using CI-4 Plus oils in some circumstances. As for ULSD, that’s not an option.

“The system was designed around ULSD,” Powers said. However, finding ULSD is not always as easy as it should be, particularly south of the border where only 80% of available diesel fuel must have a sulfur content of 15 PPM or less.

“There have been spots where ULSD availability is not what it should be,” Powers admitted. “Requirements have been placed on fuel refiners as far as the 80% rule, but there really isn’t a specific requirement that each retail outlet has ULSD, so we found some places in the country you can find it, but it’s not as straightforward as it should be. Drivers have to pay attention to where they go to get fuel.”

Here in Canada, ULSD is more widely available as it has become the industry standard. Failure to use ULSD will result in premature clogging of the DPF, a reduction in fuel economy and possible damage to engine components, which may even void warranty coverage.

As for CJ-4 oil, some engine manufacturers have relaxed their requirements on its use. Mario Sanchez, heavy-duty product manager with Cummins, said customers operating the ISM and ISX engines can continue using CI-4 Plus motor oils. However, they can expect the DPF to require an ash cleaning earlier if they choose to do so.

“We recommend the use of CJ-4, but with further testing we did find and we will allow customers to use CI-4 Plus. The reasoning is that we found it’s more convenient for customers to use one oil as they transition their fleet to the new 07 engines,” Sanchez said.

Ultimately, however, the improved performance delivered by the CJ-4 oil formulation is expected to be motivation enough for fleets to make the switch, he added.

“The use of CJ-4 oil is optional on our heavy-duty engines,” added Detroit Diesel’s Siler. “It is required on our medium-duty engines. The heavy-duty particulate filters are sized such that they can still achieve very long maintenance intervals even with the higher ash levels of the CI-4 oils.”

As far as driving performance is concerned, drivers and owners should be aware of a few subtle changes.

“Highway cruising speed for all Volvo engines is now 1,300-1,500 RPM as opposed to 1,400-1,600 RPM with US04 Volvo engines,” pointed out McNamara. “So trucks need to be geared to cruise at this engine speed.”

Mack’s McKenna said “Given the improvements we’ve made in low-end torque and torque rise with the new MP engines, don’t be surprised if you find yourself pulling grades in a higher gear.”

For those who drive Cat-powered trucks, the traditional rule of “gear fast, drive slow” holds true.

“The slower the engine speed at cruise, the better the fuel economy,” said Powers.

Detroit Diesel’s Siler suggested drivers simply “Relax and utilize the added torque characteristics and low RPM performance to get the job done.”

Cummins drivers are finding the new engines are “more responsive to the throttle actuator command,” according to Sanchez.

“The engines are more responsive when launched and the braking is more responsive; this is because of the variable geometry turbocharger technology that we have enhanced and the advantages of having an aftertreatment system that takes care of particulate matter so we can focus on performance,” he added.

Drivers of all makes will also notice a quieter engine brake, which is muted by the aftertreatment system. But for the most part, said Sanchez, “trucks powered by 07 engines are not noticeable. They blend in perfectly with the population of the fleet and it’s hard for people to distinguish the difference. And that was our target – to make it transparent.”