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Flow-through diesel oxidation catalysts (DOC's) have been shown to be an effective means of reducing emissions from diesel engines. In this work, the further development of diesel oxidation catalysts for the control of emissions from heavy duty engines is illustrated. Laboratory reactor and engine dynamometer data obtained from engine-based accelerated poisoning and aging studies demonstrate that HC, CO and SO2 oxidation by DOC's can be modified by adjusting platinum and vanadium loadings in alumina-based Pt/V catalyst formulations. The performance and durability of this type of catalyst system are demonstrated with several aging cycles on heavy-duty engines. The fresh performance of two catalyst systems was determined on both US Heavy Duty Transient and ECE-R49 Test cycles with a 1991 calibration Perkins Phaser 6.0 L engine. Gas phase emissions were reduced by a similar amount for both catalysts over both cycles (HC: 60-70%, CO: 45-75%).

Turbocharging of a basic engine type to suit different ratings and applications poses many problems. Careful design of components, choice of turbocharger match and supporting equipment are all critical in obtaining the optimum solution. The addition of turbocharging to an engine type permits it to leave behind some of the restraints of its naturally aspirated form. However other factors are encountered which set limits rather than offer advantages. The successful optimisation of all these factors within one engine type permits the benefits of component and configuration rationalisation to be realised while still retaining the performance diversity and flexibility necessary to meet the needs of the market place.