Skip navigation

Cat says it’s ACERT again for EPA ‘07

Cat says it’s ACERT again for EPA ‘07

LOUISVILLE, KY. Here at the Mid-America Trucking show today, Caterpillar announced it will use its ACERT technology as “the foundation” to comply with the 2007 Environmental Protection Agency (EPA) emission regulations for diesel engines.

"We developed ACERT Technology with the goal of meeting all current and future emissions regulations, while continuing to provide the overall value on-highway vehicle owners need to operate profitably," said Greg Gauger, director, on-highway power systems.

Gauger explained that the EPA ’07 requirements will impact on-highway engine design in five areas:

Particulate matter (PM) will require a ten-fold reduction from .10 to .01 grams per horsepower per hour. To meet this requirement, engine makers will need to add a diesel particulate filter.

  1. Cat engines will move from 2.5g/hphr NOx + HC to 1.2g/hphr NOx. This 1.2 figure is based on a phase-in provision allowed by the EPA. The actual requirement is to reduce NOx emissions to .20 by 2010.
  2. Crankcase emissions will be regulated as exhaust emissions.
  3. Engine manufacturers will have to monitor the performance of the engine's emissions system. This industry standard is called Engine Manufacturer Diagnostics (EMD) and will detect issues within the emissions control system.
  4. The ‘07 standard will regulate the useful life of the engine’s emission system, which has been set at 435,000 miles for heavy-duty and transit bus and 185,000 miles for mid-range vehicles.

According to Gauger, for ’07 compliance, Cat will use existing ACERT technology, which includes series turbochargers, variable valve control, a high-pressure multiple injection fuel system, Cat electronic control systems and an oxidation catalyst. In addition, to meet the ’07 regs, all Cat ACERT engines will have: an enhanced combustion process called Clean Gas Induction (CGI); a closed crankcase ventilation system; and a diesel particulate filter system with active regeneration.

Mid-range engine compliance will also be built on ACERT technology. These engines, Gauger noted, will feature a high-pressure injection system along with the closed crankcase ventilation and a variable turbine geometry turbocharger.

The Cat diesel particulate filter uses a wall-flow filter technology. Regeneration is necessary to activate a process of oxidation that eliminates the soot that collects along the inlet walls of the filter. To aid the regeneration process, Gauger stated, the exhaust gas is heated by auxiliary means. Regeneration only takes place when needed, which optimizes fuel economy. Engines producing 500 hp or less will require one diesel particulate filter; engines with 550 or more hp will require dual filters. The filter system also provides sound attenuation and will be serviced by the Caterpillar dealers and authorized truck dealers.

Gauger said the “primary process for achieving additional NOx reduction includes the elements of ACERT technology with Clean Gas Induction (CGI). CGI draws clean inert gas from downstream of the particulate filter and then puts this clean gas into the intake air system.”

He explained that a key advantage of CGI is the intake charge is soot-free. This “clean gas” does not induce the engine wear that cooled-EGR produces, according to Gauger. In addition, CGI's low intake manifold gas temperature contributes to the engine's low NOx emissions.

"We expect our heavy-duty engines with ACERT technology for 2007 will maintain the same fuel economy as today's engines, and our mid-range products will improve by approximately 4%," Gauger said.

For more information, go to

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.