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With swelling gasoline prices, automotive OEMs have taken different approaches to improve vehicle fuel economy. One trend is to down-size the engine and to add turbo charging. One of the challenges in utilizing the turbocharger in passenger cars is to control the added NVH issues associated with this hardware, especially for the North American market where turbocharger use is scarce in gasoline engines. In this paper, the authors review an investigation on turbocharger related “whoosh” noise on a V6 engine. The whoosh noise, also called surge noise, is caused by the compressor working at or near surge conditions. Whoosh noise is a broad frequency band flow noise typically found during throttle tip-in conditions, but sometimes found even at steady state driving conditions. The root cause of whoosh noise and the detection methods are discussed in this paper. The countermeasures to reduce whoosh noises are also discussed.

Vehicle idle quality has become an increasing quality concern for car manufacturers because of its impact on customer satisfaction. To get better fuel economy the overall trend is to reduce idle speed at both drive and neutral idles. This typically has adverse impact on vehicle idle quality. Lowering the idle rpm generally degrades the engine combustion stability and also makes the engine driving forces more likely to align with vehicle sensitivities (Powertrain rigid body modes, body modes, etc.). To better understand the contribution to the idle quality from different factors and carry out well-planned improvement measures, a quick and easy way to assess engine combustion stability is required.

Vehicle idle quality has become an increasing quality concern for automobile manufacturers because of its impact on customer satisfaction. As demand for better fuel economy increases, automobile manufacturers are continuously looking for any benefits from different driving conditions. One area is lowering the idle speed at both drive and neutral idles. This typically has adverse impact on vehicle idle quality for the two reasons. First, lowering the idle speed generally degrades the engine combustion stability, which typically increases the excitation forces (0.5th, 1.0th, 1.5th, etc combustion torques). Second, lowering idle speed will cause modal alignment issues (i.e. combustion and inertia forces align with Powertrain rigid body modes, body modes, etc.).