Cooled EGR and a variable-geometry turbo-charger are among the technologies used by John Deere Power Systems, Waterloo, Iowa, in the company’s PowerTech Plus family of Tier 3-compliant engines. PowerTech Plus engines (Circle 930) are available in displacements of 4.5 L (149-185 hp), 6.8 L (180-275 hp), 9.0 L (225-400 hp) and 13.5 L (350-600 hp). Compared with the company’s Tier 2 engines, the Tier 3 engines feature maintained or improved performance characteristics, such as peak power, peak torque, low-speed torque, transient response and cold-weather starting. The PowerTech Plus engines also provide best-in-class fuel economy, according to the company. The PowerTech Plus 4.5-L engines will be available in January 2006, a year before the regulations go into effect for the 100- to 175-hp engine range. With cooled EGR, measured amounts of exhaust gas are cooled and mixed with incoming fresh air to lower peak combustion temperatures, thereby reducing NOx. Unfortunately, reducing NOx emissions tends to increase particulate-matter emissions, so Deere employed several techniques to reduce particulate matter. Using high-pressure common-rail fuel systems and electronic unit injector technology increases fuel-injection pressure.
