ForConstructionPros.com

It is a dynamic environment for anyone involved in the manufacture or use of diesel-powered equipment. The Environmental Protection Agency (EPA) has been tightening the noose around diesel emissions, with an emphasis on NOx and particulate (PM) matter reduction.

The regulations are phased in over time on a Tier system based upon engine horsepower ranges. (See Table 1 for Final Tier IV implementation.) "Generally speaking, the higher the horsepower, the more stringent the emissions regulations and the more technology needed," says Doug Laudick, manager of product planning, John Deere Power Systems.

In the past, the implementation of each tougher set of standards has resulted in more efficient engines. "Power and productivity generally improved from Tier II to Tier III," says John Bartz, wheel loader and articulated hauler product portfolio planning, Volvo Construction Equipment.

Laudick agrees, noting, "When John Deere transitioned from Tier II to Tier III, most engines realized significant performance gains."

The final verdict on whether Tier IV will continue this trend has not yet been determined. One factor that could influence performance is the mandated move to ultra-low-sulfur diesel (ULSD) fuel, which typically has a lower British Thermal Unit (BTU) energy content.