It has been shown within the catalyst industry that the emission performance with higher cell density technology and therefore with higher specific geometric area is improved. The focus of this study was to compare the overall performance of high cell density catalysts, up to 1600cpsi, using a MY 2001 production vehicle with a 4.7ltr.V8 engine. The substrates were configured to be on the edge of the design capability. The goal was to develop cost optimized systems with similar emission and back pressure performance, which meet physical and production requirements. This paper will present the results of a preliminary computer simulation study and the final emission testing of a production vehicle. For the pre-evaluation a numerical simulation model was used to compare the light-off performance of different substrate designs in the cold start portion of the FTP test cycle. Four sets of converters were aged for 72 hours at 1025°C on an engine dynamometer stand, which is equivalent to 50k mile road driving condition. The emission performance of the catalysts was tested according the FTP75 driving cycle in close coupled and toe board position. In addition emission testing, back pressure tests before and after aging were also carried out.

The Environmental Protection Agency (EPA) and California Air Resources Board (CARB) requirements for high mileage durability of emission components make it necessary to ensure the mechanical robustness of metallic catalytic converters. In addition, the robustness of design features must be assessed in the early design development phase without resorting to vehicle fleet testing. By following established reliability methods, a new approach for time and cost efficient accelerated durability testing was developed, which can account for the combined effects of critical stressors of a metallic catalytic converter. This paper describes the methodology used to determine the critical stressors and their levels in actual operating conditions which were determined by analyzing a broad range of vehicle test information. This information was used to develop a temperature profile and a high vibration load profile for the new life test method. Finally, this paper describes the combination and superimposed introduction of all stressors in a hot vibration/ thermal cycling component bench test. The new time and cost efficient highly accelerated test method can reproduce metallic converter failure modes and can be used to develop the robustness o f mechanical designs for metallic catalytic converters.