Buick's 1972 Exhaust Gas Recirculation System

In 1972 models for sale in California, Buick first employed programmed-metered exhaust gas dilution of the engine intake charge as the major means of reducing Oxides of Nitrogen (NOx) emission levels.

With more stringent NOx emission standards applicable nationally to 1973 light duty vehicles, it is probable that similar systems will be more widely used.

The major considerations in the decision to use this means of reducing NOx emissions, the design details of the total system, and the field experience to date is discussed.

The author concludes with some thought on the limit of usefulness of Exhaust Gas Recirculation for NOx reduction, and further refinements needed to approach that limit.