Tier 4 requirements for engines refers to a generation of federal air emissions standards established by the U.S. Environmental Protection Agency (EPA) that apply to new diesel engines used in off-road equipment. And compliance with Tier 4 standards is basically on top of us now.

Essentially Tier 4 requires manufacturers to reduce the levels of particulate matter and oxides of nitrogen (NOx) to a level that is 50 percent to 96 percent lower than previous generations of diesel engines. Tier 4 emission requirements apply to new products only and do not apply or require retrofitting existing machines or equipment in use today.

U.S. EPA and California EPA have adopted the same standards, so there are no separate Tier 4 diesel emission standards for any states, according to Diesel Technology Forum information.

Forum report information also says that tiered emissions regulations have been in effect in some manner or another during the past 15 years for governing new off-road engines and equipment. These standards have established progressively lower emissions of nitrogen oxides and particulate matter (PM).

Complicated is the best way to describe the compliance dates and engine emission specifics based on the horsepower and other factors. There is some flexibility allowed manufacturers in developing their engines to be compliant as long as the engines meet reduction in PM, NOx and hydrocarbon (HC) emissions.

Manufacturers have to only build engines that meet the standards per calendar deadlines, and they cannot continue to manufacturer older model engines that are producing emissions outside the standards.

Diesel engine emissions, according to the Diesel Technology Forum, have been progressively moving toward zero levels for several years, and the claim is that Tier 4 emissions are near zero.

Will additional EPA regulations require additional engine changes? That could happen because the EPA will be establishing future standards based on air quality and technical advancements that might occur. A focus on carbon dioxide (CO2) related to climate conditions is a broad issue that will be addressed.

Manufacturers are not only meeting emission standards, but also are taking the opportunity to redesign for increased engine and power train performance. Manufacturers introducing Tier 4 technology engines have been able to actually improve performance in some ways.

Diesel Technology Forum information suggests that manufacturers have been able to increase performance in areas such as cold-weather starting, transient response time, power bulge, peak torque, low-speed torque and fuel efficiency.

For the first couple years, there is the potential that ag retailers will decide to keep their older model equipment longer than they have been, but manufacturers are making good headway in producing engines and machines that are more fuel efficient, which will intrigue potential buyers to evaluate old against new. The general thought is that older equipment that isn’t Tier 4 compliant will not lose value for selling or trade-in.