2007 Engines: It's All About DPFs The big unknown with the 2007 engines is what effect the new particulate filters will have on operations. By Jim Galligan Medium-duty fleet managers waiting for the next generation of low-emission diesel engines sound a little like parents waiting for a new baby: they know what's coming, they're anxious about the change, but they want more details. That was what we heard from fleet managers contacted by Light & Medium Truck for the accompanying articles in this issue (Preparing for the Unknown, page 18, and The Cost of Progress, page 52). They are aware that changes in fuel and diesel engines are coming, and they want to prepare for it, but they're not quite sure how. Beginning next June, the Environmental Protection Agency is requiring that refineries produce on-highway diesel fuel with much lower sulfur content than the current formulas. By next September, ultra-low-sulfur diesel fuel should be available nationwide. The fuel will be required so that 2007-and-later diesel engines with their updated emission control technologies - specifically diesel particulate filters - will be able to meet EPA's particulate matter emission standards of .09 grams per brake horsepower hour. That represents about a 90% reduction in current levels. Now, there are questions about whether ULSD will be avaialble everywhere it's needed in the condition it's needed. Refiners say they can produce the ULSD with sulfur content well below the 15 parts-per-million required by EPA, but the fuel may not be that clean by the time it makes it through pipelines, storage tanks and into the trucks. For more details on this situation, see the May issue of LMT. Every medium-duty engine maker L&MT contacted said they would have 2007 emission-compliant products ready in time. But they are in different stages of development. Suppliers offering both medium- and heavy-duty engines are putting development of their heavy-duty products first. That's not surprising considering that, with the exception of perhaps International Truck and Engine Corp., the other engine suppliers sell more of their bigger engines - and at higher profits -than their mid-range products. Cummins Inc., for example, when contacted by L&MT in April, said they would have a full range of emission-compliant engines for the 2007 model year, but were not prepared to discuss the status of their medium-duty products at the time. Cindi Nigh, spokeswoman, said they weren't really sure when they would. Regeneration is the Key For 2007, engine manufacturers are essentially tweaking their current emission control systems and adding diesel particulate filters in the exhaust stream to reduce PM emissions. Looking like large mufflers, the DPFs will collect the particulate emissions. Periodically, the filters will have to be cleaned, or regenerated, and that will be done by burning off the collected residue. This is one area where medium-duty engines likely will operate differently than their big-bore brothers. The reason is heat. Over-the-road engines are expected to generate enough exhaust heat during normal operations to keep the filters clean. But because of their operating cycles, medium-duty engines typically don't generate exhaust temperatures that hot, so the engine suppliers are working on auxilliary regeneration systems. The most likely system will add a little fuel into the exhaust stream to burn off the deposits. "You have to have some way to generate heat," said Mike Powers, product development manager for Caterpillar on-highway engines. "We're working on a system for heavy and medium [engines] that's self-regeneration; that takes care of itself even if it doesn't get a lot of hours or is cold." In most cases, the regeneration will be automatic, but the variety of applications in the medium-duty sector complicates that, said Dan Cutler, director of commercial product planning for General Motors' Duramax diesel engine. "We're trying to put the best compromise in so you're not regenerating all of the time - or not enough. You have to know the vocations and set the parameters and find a mid point that's right for everybody. All the [engine] manufacturers will end up with about the same process. Everybody has to figure out what that programming is to that engine," he said. David Skupien, program maanger for Detroit Diesel's mid-range MercedesBenz 900 model engine program, said that the drivers may need to activate the regeneration program if, for example, the truck is idling when regeneration is needed. The MBE 900 series engines are used in Freightliner and Sterling trucks. "If regeneration is needed and the vehicle is at idle, a light will be illuminated and the driver will be required to initiate the regeneration," he said. The auxiliary burns will use up more fuel, but suppliers said the additional amount of fuel would be negligible and would be compensated by improvements in engine efficiency. "The requirement to actively regenerate the DPF will vary by application," said Mark Stasell, vice president of engine engineering and development with International. "For lightly loaded applications, regeneration will occur more frequently. For more heavily loaded applications like longhaul, active regeneration will be less necessary. A larger DPF may require more fuel to regenerate, but the overall regeneration frequency may decrease, so it is hard to make general statements regarding the relationship between DPF size and fuel used by active regeneration. "On average, we expect that we will be able to offset any fuel loss due to active regeneration with improved combustion and other methods. Our goal is fuel economy neutrality with 2007 engines," he said. International's diesel engines are also used in Ford Motor Co.'s commercial trucks. "Everybody's trying not to lose what they already have," said GM's Cutler. "Everyone is aware there will be some kind of hit on fuel, so they're compensating on other elements." Skupien said they wanted to wait until they had finished testing the engines, "where we will 'optimize our' fuel maps and particulate filter regeneration strategy," he said. Caterpillar is a little more aggressive about fuel economy for its 2007 mid-range C7 and C9 engines. Powers said they were expecting up to a 4% improvement in fuel economy in some medium-duty ranges. "It won't be consistent across the board. It will vary by ratings," he said. Ultimately, said Mike Eaves, director of product development at General Motors Isuzu Commercial Truck, the marketing division for GM and Isuzu trucks, much of the fuel economy issue for the medium-duty trucks will depend on how they're used. "A lot depends on the applications they're in. Their duty cycle will play a pretty significant role. Our intent is to make this as seamless as possbie. We're hoping the majority of customers don't really know what's going on. They're driving their trucks and it's performing ok," he said. Size, Weight and Other Considerations The size of the DPF will vary depending on the engine size and the application. The bigger the engine, the bigger the filter system. The medium-duty DPFs will add somewhere between 100 to 150 pounds to the trucks, according to several engine suppliers. A more significant issue for some medium-duty models will be how to route the system on the chassis, especially some low-cab-forward trucks, said GMICT's Eaves. "We're concerned about these on shorter wheelbases where the exhaust will take up more of the total real estate than before," he said. Also, placing DPFs on the larger low-cab-forward trucks could be an issue. Exhausts typically are placed behind the cab on LCFs, but the bigger the truck, the bigger the LCF and the more difficult it will be to run it behind the cab. "There will be some challenges in some applications, as well as with the upfitters," he said. Engine makers are pushing to get prototypes of their '07 engines into test fleets as soon as possible, but in most cases, medium-duty fleet testing will begin after heavy-duty tests. International will have its V6, V8 and I6 engines in test fleets by September, according to Stasell. Caterpillar's Powers said they have a few of their mid-range C7 and C9 engines in test fleets now and hope to get a few more out this year, although he acknowledged that it might extend into the first quarter of 2006. "A lot has to do with packaging the aftetreatment," said Powers. "It's a big event, so to speak, replacing the [diesel oxidation catalyst] with DPF. The challenge is to find out where you're going to put these things. Trying to get it packaged in all the various chassis configurations is driving a lot of that." Detroit Diesel's Skupien said the company planned to have 30 customer demonstration engines out next year. He added that they have started testing the engine in different DaimlerChrysler vehicles, such as Freightliner and Sterling trucks, in Florida. There are few other component changes expected in the 2007 models compared with the current versions, said the engine makers. Caterpillar will add a variable geometry turbochargers to its mid-range units. They currently use a traditional waste-gate turbo. International's new V6 will have cooled EGR and a high pressure common rail fuel system, new piston and cylinder head intake ports, said Stasell. "All of these will reduce engine noise and possible operating costs, while meeting the more stringent 2007 emissions standards." The V6 is the power in the company's new LCF truck (as well as Ford Motor's LCF, which is being built by the Blue Diamond joint venture between the two companies). Web Source: http://www.ttnews.com/lmt/June05/dpfs.asp
