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A compact, lightweight compression-ignition engine designed for high fuel economy and low emissions was developed by ISUZU for the GM PNGV vehicle. This engine was the key component in the selected parallel hybrid vehicle powertrain for the 80 mpg fuel economy target. The base hardware was derived from a 1.7 Liter, 4-cylinder engine, and a three-cylinder version was created for the PNGV application. To achieve the required high efficiency, the engine used lightweight components thus minimizing weight and friction. To reduce exhaust emissions, electromechanical actuators were used for EGR, intake throttle, and turbocharger. Through careful application of these devices and combustion development, stringent engine out exhaust emission targets were also met.

The newly developed Duramax 6600 V8 Diesel engine has incorporated a lot of the latest technologies to achieve better fuel economy and lower exhaust emissions. It will provide the GMC Sierra and Chevrolet Silverado with a Diesel engine to satisfy a multitude of major customer requirements such as higher output, lower fuel consumption, comfortable V8 sound, high reliability and good driveability. An optimized combustion system coupled with a four-valve per cylinder configuration, high pressure common rail fuel injection system, new design combustion chamber and valve covered orifice (VCO) nozzle enables to meet 1998 U. S. Environmental Protection Agency (EPA) emission standards for heavy-duty diesel engines without exhaust gas recirculation (EGR) and aftertreatment.

A new concept of highly efficient and sulfur tolerant NOx reduction catalyst for diesel engines has been demonstrated. This catalyst has a double-layer construction and is composed of Pt and Rh as the precious metals, oxygen storage materials and some other catalytic components. Periodic lean/rich operation similar to the Lean NOx Trap catalyst was found to improve the highly efficient NOx reduction activity in a laboratory reactor test. As a result, this catalyst has the feature of high NOx reduction in a temperature window from 15°C to 35°C, and of high oxidation activity even in a lower temperature condition for HC and CO. Sulfur poisoning characteristics were also evaluated in a laboratory reactor test. The results showed that the proper desulfation procedure with a relatively low temperature environment enabled the stored sulfur to be reomved, and to maintain the NOx reduction efficiency for asignificantly long time period.