A Study of Carburetion Effects on Power, Emissions, Lean Misfire Limit, and EGR Tolerance of a Single-Cylinder Engine

The influence of carburetor characteristics on power, emissions, lean misfire limit and EGR tolerance has been investigated using a single-cylinder engine. The results, which are based on the use of a conventional carburetor and a modified version of the same carburetor, indicate that the lean limit and EGR tolerance are extended when time variations in fuel flow (“spiking” of A/F) are reduced and the mixture is made more homogeneous. The amount of extension varies with engine load, being largest at the lighter loads studied. Power, CO and NO_x emissions of the engine are insensitive to the carburetion effects at common values of engine air flow rate and A/F. The HC emissions are affected at all but the richest A/F values investigated.