Effect of unequal Y-pipes on sound propagation in the exhaust system of V-engines

The crossover or the Y-pipe that connects the two banks of a V-engine to a single exhaust duct in vehicles play a significant role in the relative arrival times of the primary pressure pulses in the Y-connector, thereby affecting the tailpipe-outlet sound quality. To quantify this behavior at full as well as part-load, dynamometer experiments are conducted on an even firing General Motors 4.3L V6 engine with two different crossover pipes: one with unequal and the other with equal branch lengths. The instantaneous crank-angle resolved pressure data is acquired simultaneously both inside the exhaust duct and externally at the tailpipe outlet. The in-duct measurements employ a piezoresistive pressure transducer, while the external tailpipe-outlet measurements use a binaural acoustic head. The significant impact of the branch-length inequality is established by examining the in-duct order content and tailpipe-outlet sound quality.