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.

Hatz

Hatz engine models ranging from 3 to 72 hp meet Tier 4 requirements, reports David Priestley, president of Hatz Diesel of America Inc. Most Hatz engines will comply with Tier 4 by internal mechanical methods, which include higher injection pressures, new injection pumps and injectors, combustion chamber changes, valves, camshaft timing and lift, etc. The four-cylinder models in the L and M engine families (4L and 4M, which are 60 hp and 65 hp) will have a system that includes an electronic gas recirculation (EGR) valve that's controlled by an ECU (electronic control unit).

Maintenance on Hatz engines will remain basically the same with the exception of the four-cylinder engines, which because of their EGR valve and ECU are a little more complex.

But, Priestley adds, "This is a relatively simple system so it should not be too difficult to work on."

Hatz engine components are expected to last just as long as the company's Tier 2 engines. "Hatz engines will be just as reliable as they have always been," Priestley says.

Caterpillar

Caterpillar's compact engines that are 2.2 liters (50 hp) and below are compliant with Tier 4A (Tier 4 Interim) with no visible differences.

Maintenance for Caterpillar engines in this range is going to be very similar to engines designed to meet the requirements of previous tiers. Oil change intervals will remain at 500 hours, which is standard on Caterpillar products.

No changes are expected in component lifespan.

"Our compact engines are recognized for durability and reliability," says Mike Reinhart, marketing manager, Caterpillar industrial power systems. "Going from Tier 3 to Tier 4 Interim, there's no impact on componentry. What we're trying to do when we go from one emission level to the next is improve the overall content, processes and parts' reliability."

Maintaining or improving cost of ownership also is important, he says. Caterpillar engines in Tier 4 will be cleaner while maintaining the company's set standards in fuel economy, reliability, durability and service intervals, he says.