It’s confusing. That’s for sure.
You’ve got your different engine categories — depending on cylinder displacement — and you’ve got your escalating tiers that reduce emissions limits. You’ve also got engine emission category deadlines based on overall engine power, for which the regulations are listed in kilowatts, not horsepower, which is also confusing.
Engine categories based on displacement were important during implementation of EPA Tiers 1, 2 and 3. We are now in Tier 3 territory, whatever the category.
Next up is Tier 4, which is as far as the EPA emissions-reduction program goes, as far as anyone knows. Tier 4 implementation dates for Category 1 and Category 2 engines, which includes everything smaller than 30 liters per cylinder, vary depending on power.
After looking at various tables and talking with some engine experts, it is clear that by 2017 all new engines above 600 kW (804 hp) will meet Tier 4 standards, usually with exhaust aftertreatment. The last group of engines required to meet Tier 4 standards are at the smaller end of the spectrum, those between 600 kW (804 hp) and 1,400 kW (1,877 hp). Next year, engines in the 1,400 kW (1,877 hp) to 2,000 kW (2,682 hp) will have to meet Tier 4 emissions standards.
The good news is engines smaller than 804 hp will never have to meet Tier 4 standards. Tier 3 is the end of the line for engines this size and smaller. This means that we may start seeing more triple and even quadruple engine installations with these smaller engines.
Another point of confusion is retroactive compliance. If you have a Tier 3 engine, will you have to install some aftermarket scrubbers after we’re completely in Tier 4 territory? The answer is no, unless perhaps your client insists on it, but the EPA will not.
The other good news is that all of these changes are cleaning the air. Tier 4 engines emit significantly fewer dangerous, unhealthy emissions than any engines before them. It’s a pain and it’s expensive, but the goal is worthwhile.