ForConstructionPros.com

New diesel engine technology designed to meet the latest Environmental Protection Agency (EPA) emission regulations will make a big difference to the environment, but manufacturers of lower horsepower engines say, for the most part, rental businesses will not experience change in their day-to-day operations.

In 2004, the EPA announced a rule to reduce emissions from nonroad diesel engines. Specifically, emission levels from construction equipment, agricultural equipment and industrial diesel-powered equipment will be reduced by more than 90 percent. (The rule also removes 99 percent of the sulfur in diesel fuel by 2010. Sulfur not only contributes to particulate matter formation, but can damage advanced emission control technology.)

Tier 4 regulations are to be fully phased in by 2015. Different size engines have different emission standards and different deadlines. Standards for new engines start with the smallest engines (less than 25 hp) needing to be compliant this year (2008) and continue until the very largest diesel engines meet nitrogen oxide (NOx) and particulate matter (PM) standards in 2015. (Special provisions in Tier 4 regulations give nonroad manufacturers additional flexibility and lead time to transition to the new Tier 4 standards.)

To gain the greatest emission reductions, the EPA rule specifies integrating engine and fuel controls similar to those already used in highway trucks and buses. While there are only a few engine models for trucks and buses, there are many engine models and ratings for relatively lower volumes of specialized non-road machines, such as track-type tractors or industrial power equipment. Caterpillar alone, for example, offers more than 200 engine models and ratings used to power its own equipment.

It only makes sense then that engine manufacturers with diverse models and ratings are taking different approaches to integrating engine and fuel controls and meet Tier 4 EPA standards.