Abstract
Air cleaners in all of the automotive engines have been used for decades. In the early 1920's the oil bath type was the popular shape of air cleaners. The air cleaners of the oil wetted bath type were introduced in 1940's. The shape of the dry pleated paper type media was introduced in the 1950's. This trend still continues with new and innovative media being introduced. Engine air cleaners should have effectively removed and reduced harmful contaminants being ingested into engines. This studies show that both, the ingested contaminant size and concentration need to be controlled. This paper com pare and analyze the characteristics over the economics, engine performances and reduction of noises of power-plus air filters with wet paper which were sticked to heavy duty diesel engine.