John Deere achieved impressive fuel-economy gains in 2005 when the company applied cooled exhaust gas recirculation (EGR) and variable geometry turbochargers (VGT) to meet Tier 3 diesel-engine emissions limits. Deere expects PowerTech for Tier 4 Interim to retain their fuel efficiency advantage or improve up to 5 percent. Updated versions of the cylinder head, fuel system, cooled EGR, VGT and air-to-air aftercooling systems, with the addition of exhaust aftertreatment, bring the PowerTech line into Tier 4i compliance. Some engines will use series turbochargers in lieu of VGT. Deere’s Phoenix Int’l business unit has doubled the RAM and processing speed and quadrupled the program memory of the PowerTech electronic control module for ratings over 174 horsepower to facilitate more-advanced control. Deere will also use EGR and an exhaust filter in 75-to-174-horsepower engines. These 4.5L and 6.8L models will feature full-authority electronic controls, a four-valve cylinder head, air-to-air aftercooling, a high-pressure common-rail fuel system and a wastegate or variable geometry turbocharger.
