Combustion-Chamber Deposition and Power Loss 520257

THIS paper describes the important factors that must be considered in a study of engine power loss due to combustion-chamber deposits. Dafa are presented to show the effects of fuel composition, sulfur and lead concentration, and lubricant composition, engine design, and operating conditions on deposit power loss.
The influence of engine operating conditions existent during the accumulation of deposits, and the importance of the engine conditions selected to evaluate the magnitude of the deposit power loss are illustrated. It is indicated that deposits cause power loss by thermal and physical restriction of the intake charge, and by reduction of thermal efficiency.
It is concluded that differences in effect among the majority of commercial fuels and lubricants are probably small although relatively large differences may exist in certain critical engine applications. The engine operating conditions under which the deposits are accumulated are a major factor in deposit power loss. Constant-speed, constant-load operation represents the most adverse condition.
Engine design is indicated as the principal means of alleviating the problem where it does exist, and several design features which will minimize deposit power loss are discussed.


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