Suppliers have introduced replacement aftermarket catalytic converters which are characterized by design differences from the original equipment converters in the direction of lower costs. The objective of the work reported here was to test a group of nine aftermarket catalysts from three manufacturers for 25,000 miles. Mileage was accumulated on three routes in Maryland and West Virginia characterized by varying degrees of tire wear.
All catalysts were dynamometer tested on the same vehicle at the same laboratory. Catalyst HC and CO conversion efficiencies versus mileage are compared to a goal of 70 percent at 25,000 miles. Baseline conversion efficiency testing of an OEM catalyst at 83,161 miles is also shown for comparison. Steady-state tests were also conducted at speeds of zero (idle), 20, 40, and 60 miles per hour (mph), during which temperatures, pressures, and efficiencies were measured.
The Federal Test Procedure (FTP) and steady-state efficiency tests were based on modal mass emissions of HC, CO, NOx, and CO2. The transient cycle modal results yielded measures of conversion efficiencies and catalyst light-off temperatures.