With just months left before the EPA’s tightened diesel emissions standards for new engines are to take effect, motorcoach operators need to be aware of some of the key changes that they will see in engines manufactured after Dec. 31, 2006. The most obvious change will be a cleaner-burning engine and new aftertreatment equipment. Under the new EPA standard, nitrogen oxide (NOx) emissions will be reduced by more than 50% and particulate matter emissions will be cut by 90%. Another round of emissions reductions will be mandated in 2010, taking emissions to an even lower level. But let’s not get ahead of ourselves here. A key byproduct of the new EPA standards will be higher costs borne by the engine manufacturers and passed through to the bus manufacturers and end users. Engine OEMs for the North American coach industry — Detroit Diesel, Cummins and Caterpillar — will be charging more for their engine offerings. How much more? It may be too early to tell. Engine makers say the coach manufacturer will set the price. The increase is due to enhancements to the engine itself but also to the addition of a diesel particulate filter (DPF) that removes particulate matter from the exhaust stream. This particulate matter — composed mainly of ash that comes from the motor oil — must be removed periodically. The EPA has mandated that the filters be designed so that they do not require maintenance for at least 150,000 miles. Engine manufacturers will be recommending intervals well beyond 150,000 miles, however. Detroit Diesel spokeswoman Liane Bilicki says the DPF interval for the Series 60 engine could range from 200,000 to 400,000 miles, depending on the duty cycle. A Cummins spokesperson says cleaning intervals are still being finalized and will depend on duty cycle, oil consumption and type of oil used. Caterpillar says it’s targeting 300,000 miles. “Depending on the use by coach operators, that means that every two or three years the unit will have to have the ash removed,” says Caterpillar spokesman Jason Phelps. The process of cleaning the filter can be done on-site with a special cleaning unit or it can be performed by the engine dealer. ULSD will be mandatory In addition to the higher cost of the engines, motorcoach operators will be paying more for diesel fuel. That’s because the engines and filters will require ultra low sulfur diesel (ULSD), which is more expensive than traditional diesel. Refiners say the price of ULSD will come down as its production increases nationwide. Availability of ULSD could be a factor, however. Although a federal mandate requires oil refiners to start replacing standard diesel fuel (500 parts of sulfur per million) with ULSD (15 parts per million), it could take a few years before ULSD is available nationwide. Detroit Diesel’s Bilicki says availability of ULSD should not be a problem, explaining that oil refiners are on track with the federal government’s implementation deadlines. “Oil refineries are expected to have 15 ppm fuel in the pipeline by the summer, followed by extended retail coverage by Oct. 16,” Bilicki said. “We expect no significant issues with availability.” Should ULSD not be available everywhere, however, coach operators are warned against using 500 ppm fuel. “That could have serious consequences for the DPF because the sulfur will bond to the precious metals in the filter and reduce its efficiency,” Phelps said. In addition, damage caused by misfueling will not be covered under warranty, he added. To prevent engine damage caused by a blocked filter, bus manufacturers will install a warning light on the dashboard to alert drivers to unusually high backpressure. Most importantly, representatives for Detroit Diesel, Cummins and Caterpillar say performance and driveability will not be negatively affected by the implementation of the 2007 standards.