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Valvetrain ticking noise is one of the key failure modes in noise vibration harshness (NVH) evaluation at idle. It affects customer satisfaction inversely. In this paper, the root cause of the valvetrain ticking noise and key parameters that impact ticking noise will be presented. A physics based math model has been developed and integrated into a parameterized multi-body dynamic model. The analytical prediction has been correlated with testing data. Valvetrain ticking noise control is discussed.

In the recent times, the reduction of process variability has become very important for delivering cost-effective product. As per Taguchi's Loss Function, higher variability means higher cost also. The quantification of variability is a tremendous challenge to NVH engineers. To understand the NVH characteristics of an engine, measurements at various locations are needed. Moreover, each measurement is also a function of engine speed. In order to capture the process variability, multiple engines need to be measured. Thus, the final data is a function of engine, location, and speed. The objective of this paper is to define the various types of variability associated with the NVH data and to develop a procedure to estimate them. This paper contains the examples from the test data.