A Bench Technique for Evaluating the Induction System Deposit Tendencies of Motor Gasolines

A technique for determining induction system deposit (ISD) tendencies of a gasoline is described. The technique uses a bench apparatus, designed to simulate the valve and port area of an engine intake system, which provides deposit data correlative to real engines. The apparatus is compact, requires a minimal fuel sample, uses a retainable metal tube as the deposit collecting surface, and has good repeatability. Design of the equipment eliminates the possibility of deposit contamination by dirt, rust and lead precipitate, and both solvent-washed and unwashed data may be obtained. ASTM Gum, engine intake deposit weights, and ISD technique data are compared to illustrate the capabilities of this new technique.