Emission Control With Lean Mixtures

Nitrogen oxide emissions can be controlled through engine operation with lean homogeneous air/fuel mixtures. This emission control approach precludes the need for exhaust gas recirculation (EGR) and secondary air injection systems. The Lean Mixture concept results in similar emissions, fuel economy, and driveability when compared to EGR systems tailored to similar emission levels with similar aftertreatment systems. A Lean Mixture-Manifold Reactor emission control system was used to evaluate the effect of compression ratio and leaded fuel on vehicle emissions and fuel economy. System durability is shown for a Lean Mixture-Catalytic Converter system with lead-free fuel and for a Lean Mixture system without aftertreatment with leaded fuel. /GMRL/