5-111.bk Page 16 Monday, July 10, 2006 2:26 PM ENGINE DESIGN FEATURES For linehaul operations covered by the CH and CX models, the AC engine lineup provides the optimum in economy and performance with reduced NOx emissions. Included are both Econodyne ® and Maxicruise ® . (ASET™ AC ENGINES) In the fall of 2002, Mack Trucks introduced two new engines that comply with changes in governmental laws regulating engine emissions. Both engines evolved from the E7 E-Tech™ and continue with the electronic unit pump (EUP) fuel injection system and the V-MAC ® III electronic control system.
The core change in the design of the two new engines, however, is the use of exhaust gas recirculation to lower combustion temperatures for control of nitrogen oxides (NOx). Two different methods are used to accomplish this control. The methods are: ASET™ AC ENGINE APPLICATIONS Internal Exhaust Gas Recirculation (IEGR) — AI/AMI engine Cooled Exhaust Gas Recirculation (CEGR) — AC engine This manual covers only the ASET™ AC engine’s CEGR design, in which a portion of the exhaust gas is “cooled” externally before it is recirculated through the combustion chambers. The ASET™ AI engine’s IEGR design receives complete service coverage in ASET™ AI/AMI Engines Service Manual 5-110.
Regardless of the method used, CEGR or IEGR, both designs are improvements based on changes in several design features of the E7 E-Tech™ current controlled rate shaping (CCRS) engine. The changes are more extensive and visible for the AC engine which is used in linehaul applications at lower governed speeds, than the AI engine which is used in vocational applications at higher governed speeds. The MACK PowerLeash™ engine brake was introduced on ASET™ engines during mid-2003. The PowerLeash™ brake is integrated into the rocker shaft assemblies and uses the standard height cylinder head cover.
Compared to add-on engine brakes, the PowerLeash™ brake has lighter weight, increased braking output, improved response and more consistent operation. Page 16 DESCRIPTION AND OPERATION Engine Chassis ASET™ AC MAXICRUISE® AC-310/330 CH, CX AC-330/350 CH, CX AC-355/380 CH, CX AC-380/410 CH, CX ASET™ AC ECONODYNE® AC-350 CH, CX AC-400 CH, CX AC-427 CH, CX AC-460 (E) CH, CX AC-460 (P) CH, CX