Evolution of methods applied for assessing harmful engine deposits caused by gasoline combustion

Abstract

The article describes the threat posed by deposits harmful to the proper functioning of spark ignition engines. The areas of indirect and direct injection engines where the most dangerous deposits form are indicated. The factors having significant influence on the occurrence of this unfavourable phenomenon were collected and analyzed. Consequently, a simplified classification of factors influencing the formation of harmful deposits in direct and indirect injection spark ignition engines was made. In the research part of the project, a comparative study of the tendency of gasolines of different composition and physicochemical properties to form deposits was carried out. The criterion for evaluating the detergent properties of gasolines was the tendency to form deposits on intake valves in the case of indirect injection engine and on the injector in the case of direct injection engine. For this purpose, the previously widely used test procedure CEC F-05-93 relating to deposits formed on intake valves in SI indirect injection engines and the latest test procedure CEC F-113-KC relating to the most harmful deposits formed in injectors of DISI (Direct Injection Spark Ignition) engines were used. The purpose of the comparative study conducted was to determine if there was any relatively simple, identifiable relationship between the results of gasoline detergent property evaluations obtained at engine test sites differing in test engine generations, methods of conducting the evaluations, and type of engine deposits formed. As a result, no correlations were found between the testable engine sludge tendency results obtained from tests using the CEC F-05-93 and CEC F-113-KC procedures. Therefore, knowing the evaluation of gasoline conducted according to one of the above mentioned test procedures, one cannot conclude, predict or estimate the evaluation that will be obtained according to the other test procedure. Therefore, the results obtained according to one of the procedures do not allow extrapolation and evaluation of gasoline in terms of tendency to form harmful engine deposits according to the other procedure.