MIDRANGE IMPACT
Regeneration heat, exhaust designs worry upfitters.
Upfitters people who build and install specialized bodies and equipment on new truck chassis have begun learning about exhaust aftertreatment devices that will come with '07 diesels, and they don't see good news. Sessions at the recent National Truck Equipment Association's annual meeting in Atlanta, apparently gave many upfitters their first detailed glimpse of what's coming, and they grew wary.
Light- and medium-duty trucks will get the same basic exhaust-treatment devices as heavy-duty vehicles, they were told. These include oxidation catalysts to remove carbon monoxide, as most diesels already have, and diesel particulate filters to trap particulates from combustion and ash from motor oil something new for '07. Builders explained how they plan to install the devices, so upfitters could begin thinking about them. At NTEA's fall meeting, "measuring sessions" will pinpoint locations that are now only approximated.
Almost no changes to the exhaust systems will be allowed, so bodies might have to be built with them in mind. And the higher heat expected during active DPF regeneration, when burning fuel helps burn off accumulated soot, can affect operations especially in town while trucks are sitting still. Truck manufacturers are aware of this and are formulating strategies to safely control the operation of DPFs.
Representatives of Dodge, Ford and General Motors all said they will split the oxygen catalyst and DPF, mounting the catalyst closer to the engine and then the DPF a few feet downstream in the exhaust system. Although those two parts will muffle most noise, the builders also will use a resonator to take out whatever "rapping" might be left.
The resonator, slightly smaller in most cases than a present-day muffler, will be ahead of the rear axle of a pickup-type truck or crossways at the very rear of a cargo van. These systems will be hung on vehicle frames and shouldn't present difficulty except where power take-offs are used. Then access to transmissions might be limited.
Midrange tractors, such as those used in pickup and delivery operations, probably will get vertical stacks with the aftertreatment device also mounted vertically. The device will be heavier than a current muffler, so mounts will be more hefty. Devices will also be bulkier and take up a few more inches behind cabs, which should be all right on most tractors. On tractors and trucks powered by Caterpillar diesels, only a DPF will be used, because Cats will not be using separate oxygen catalysts come '07.
Midrange trucks are more complicated. Because they are fitted with a wide variety of bodies and equipment, manufacturers must design several configurations for each chassis. Sometimes the catalyst and DPF will be split, as on light trucks, but more often they'll be combined into a single unit, as on heavies. Usually the combined aftertreatment device will go beneath the cab, off to the right. In some cases it will be under the steps on the curb side. The tailpipe will run rearward on the frame or up a rear corner on the cab.
The longer the chassis and wheelbase, the easier it will be to accommodate the aftertreatment parts. However, some bodies are low beverage and utility bodies are prime examples and take up all the frame space behind the cab. Here the exhaust system must be as compact as possible. Short-wheelbase chassis, or those fitted with pusher axles, as on heavy dump trucks, also leave little room for the new exhaust systems.
Furthermore, once installed at the factory, the '07 exhaust systems should not be altered, which would probably compromise their emissions-reducing performance, builder reps said. Also, each configuration will be certified with the Environmental Protection Agency, so any changes could negate certification. Thus manufacturers will strongly discourage any changes from the DPF forward to the engine, including the pipe between the turbocharger and aftertreatment device. Only the tailpipe and resonator if a system has one can be changed.
This will complicate life for dealers, who derive some of their midrange business by stocking popular truck chassis that can be fitted with a variety of bodies. In a session at the Technology and Maintenance Council's annul meeting, one attendee asked if a dealer could alter an existing exhaust system on a chassis right on the lot, maybe by using a factory supplied kit. In this session, run by a truck manufacturer, no one on the podium knew. If there aren't going to be such kits, dealers will have to estimate demand for given chassis more carefully and order accordingly, or find a chassis at another dealer or in the factory pool.
The many questions that dealers, upfitters and operators will have about the new diesel trucks will probably be answered as the January '07 deadline gets closer. Meanwhile, concerns should assure good attendance at upcoming engine sessions of any organization willing to set them up.
Tom Berg
