1991-05-01

Noise and Vibration Refinement of the Ford 3.8 Liter Powertrain 911073

Continuous improvement of the NVH performance of current production powertrains is a necessary goal of domestic auto makers. In order to maintain a competitive product, it is necessary to re-evaluate proven hardware against demanding NVH performance targets established by the competition. This paper describes an NVH investigation of component modifications to the Ford 3.8 liter powertrain. The hardware investigated includes: ribbed and isolated rocker covers, drop-in roller fulcrums, forged steel and cast iron crankshafts, crankshaft bending damper, full skirt girdle, one piece bearing cap (bearing beam), reduced weight pistons and rods, ribbed sump, and alternate crank pulleys and water pump. At the conclusion of these investigations, a complete powertrain was assembled based on the recommendations generated in this project. The NVH features included in this “quiet” 3.8 liter engine and the rationale behind the decisions are described. NVH improvements include sound power reductions of 4.9 dBA at 1000 RPM in neutral, 3.8 dBA at 3000 RPM under a drive load, and significantly improved vibration characteristics. As a result, the NVH performance criteria established by this “quiet” 3.8 liter engine can serve as realistically attainable targets for further production level design refinement.

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