Thinking outside the engine

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Of late, much attention has been lavished on engine manufacturers’ challenges, and fleet operators’ concerns, with adapting to 2007 emissions regulations. (See this month’s Special Report, “Passing the Test”.) But the new engines eventually must be mounted in trucks, and that has required closer collaboration with OEMs.

For example, at last month’s meeting of the Technology & Maintenance Council, Steve Ellison, Freightliner’s director of field service, noted that, to deal with the increased heat load from higher EGR levels, a truck’s cooling capacity needs to be 20 to 50 percent larger than the industry standard. That means larger radiators, but how to fit them? In Freightliner’s case, there will be wide, front frame extensions, splayed to accommodate extra radiator width; a 32-inch fan will be used to pull extra air.

Dave McKenna, Mack’s powertrain sales and marketing manager, revealed that, instead of using frame extensions, Mack frames would be spread 2 inches on either side for radiator fit. He added that new Mack engines would be mounted lower and more to the rear of the engine compartment, again for improved airflow.

According to Tom Tahaney, district service manager for Kenworth, radiators will need to be 8 to 22 percent larger, and charge air coolers 16 to 38 percent larger. To contend with the additional heat rejection, Kenworth will move windshield washer reservoirs and coolant surge tanks as far away from the engine as possible, and will fit silicone hoses as standard.

Vince Lindley, Volvo’s manager of national account fleet service, offered that Volvo will continue to use engine-mounted fan shrouds for tighter tip clearance and better airflow, and will offer electronically controlled, viscous-drive fans, which can cut horsepower losses when full fan operation isn’t needed.

To power additional equipment and electronics, noted presenters, 160-amp alternators will be common. And in the cab, drivers will face a new array of lights indicating the state of the emissions system in general, and regeneration in particular. They may be laid out differently from brand to brand, said Tahaney, but they’ll serve pretty much the same functions.

On the exhaust side, Freightliner’s optional, vertical stacks will be attached, not to the cab, but to the frame, to support the added weight of new engines’ diesel particulate filters (DPFs). And to prevent exhaust interference with optional equipment like power takeoffs, wheelbases may need to be extended.

Also, where it’s necessary to use exhaust diffusers to cool DPF regeneration heat, added Tony Sutton, International’s program manager for 2007 HDD emissions, extra wheelbase length will be needed to fit them, and fleet operators will find heavier exhaust brackets, as well as some traditional clamps replaced with welds for extra strength and support. International would offer no less than 35 different exhaust systems, but Sutton warned that, due to high regeneration temperatures, bright exhaust pipes definitely will discolor.

Engine manufacturers always have worked closely with OEMs to integrate their products, but it’s clear that ’07 takes the process to a new level, and presenters admitted that there would be more changes prior to Jan. 1. The advice to fleet operators? Spec carefully, and do your planning at the front end. Unlike in the past, trying to change chassis layout after a ’07 truck is built will be extremely difficult – and very expensive.