A TEST METHOD FOR RATING THE THROTTLE ICING TENDENCIES OF GASOLINES 600109
Carburetor icing is considered as a twofold problem consisting of cold-stalling during the warmup period, and throttle restriction due to ice formation at highway cruise conditions. A simple engine test method is described whereby test or reference fuel samples are continuously metered upstream from the throttle plate. Through suitable interpretation of time-rate-of-rise of induction vacuum, conclusions are drawn regarding the resistance of fuel compositions and gasoline additives to both forms of carburetor icing.
These conclusions are based entirely upon equivalent concentrations of a reference alcohol mixture in a gasoline of known throttle-icing characteristics. The characteristics of alcohol as a carburetor icing inhibitor are discussed, and typical data are presented to illustrate the effects of a surface-active type gasoline additive on carburetor icing. In each case, an evaluation of the important influence of atmospheric humidity on test ratings is included. A survey of the throttle-icing characteristics of a group of commercial winter gasolines provides an estimate of the utility of anti-icing additives in current marketing practice.