Many OEMs see the move toward Tier 4 as placing them closer to the unknown, says Russell Peterson, senior application engineer, John Deere Power Systems, Waterloo, IA. "Off-highway OEMs have little experience with aftertreatment systems and other requirements they will need to meet. That raises concerns."
At the very least, the aftertreatment devices required will have to fit inside an engine compartment that already lacks room. "The good news is the size of the engine itself won't change that much," says Peterson. "But it's the other equipment, such as the cooling and the aftertreatment systems, which will make an impact."
Four ratings of the PowerTech M 2.4 L engine are planned for EPA Interim Tier 4. The PowerTech M engines are either naturally aspirated or turbocharged. "With some of our PowerTech M and PowerTech E engines below 75 hp, we chose to go straight from Tier 2 to Interim Tier 4. Because our 2.4 L engines have demonstrated Interim Tier 4 and Stage III A capabilities, we've met our 2008 deadline," says Gita Rao, manager of strategy and long-term planning for JDPS, Waterloo.
JDPS will leverage the technology developed to meet Tier 3/Stage III A emissions as the base for future emissions regulations. It is exploring various technology options, including in-cylinder and aftertreatment solutions.
"We have narrowed down the technologies we are exploring for Tier 4, but have not yet settled on the solution that will be right for our customers and us," says Rao. "For Tier 4, we are planning to continue with the multiple-platform option. We're trying to include many potential solutions for Tier 4. The goal is to determine which concepts work best together in order to provide a solution that meets the needs of each given application."
As decisions are made, JDPS intends to release information to OEMs, well in advance of the deadline, to enable engineers to design the engine into their machines. Peterson says the goal is 12 to 18 months ahead of the Tier 4 deadline. "The first information that will likely be publicized will be in regards to the aftertreatment system," says Peterson. "We are planning a guide showing the aftertreatment and cooling components JDPS has proven will work with its engines."
JDPS is reviewing a number of aftertreatment technologies, including diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) systems. John Deere is also working on NOx adsorbers, lean NOx catalysts and selective catalytic reduction (SCR) solutions. Homogeneous charge compression ignition (HCCI) continues to be explored as an alternative solution.