The foundation for Mack’s EPA ‘02 vocational solution is a new platform of diesel engines, known as the Application Specific Engine Technology (ASET) family. All ASET engines rely on exhaust gas recirculation EGR technology as the basis for emission reductions.
The main component of the ASET vocational application emissions breakthrough is the use of internal exhaust gas recirculation (I-EGR), a technology that allows a percentage of exhaust gases to remain in the cylinders of the engine from one combustion cycle to another. This approach provides a consistent level of emissions benefits and performance in the varying and often harsh environments in which vocational trucks operate, according to Mack.
Mack vehicles that will feature I-EGR engines as of October 1 include the Mack Granite Series and the Mack RD6, MR, LE, DM and RB models. Seven engines will be available with varying horsepower ratings, including three Maxidyne models (a 300-horsepower, and new 335- and 370- horsepower versions) and four Econodyne (350-, 400-, 427-, and 460E- horsepower) models.
Mack said it developed I-EGR after studying the typical operation of a vocational vehicle that often performs in a stop-and-go manner over shorter distances, and where operational hours are a more important concern than miles traveled. Vocational vehicles also travel in much harsher environments than over-the-road highway vehicles.
For ASET engines ticketed for vocational applications, the Mack I-EGR approach centers on optimizing the flow of exhaust gases through the system, to make it possible to retain a precise amount of gases in the cylinders for further combustion. That was accomplished through a new camshaft, advancements to the valve system, and precision machining of the exhaust ports to maximize aerodynamic flow.
“We don't believe that one EPA ‘02 solution is the answer for all trucking applications,” said Mack executive vp of Class 8 programs Steve Homcha. “Our vocational customers wanted a simplified approach, and one that is optimized for their operational environment, and that’s what we are going to give them.”
Homcha reiterated that for Mack highway application customers, the ASET solution will be cooled exhaust gas recirculation (C-EGR), in which exhaust gases are diverted from the exhaust system, sent through a cooling apparatus and then carefully remixed with air entering the engine for combustion.