Abstract: Fluctuating pressure filtering in Motycka method of predicting maximum instantanneous distortion is modified by instantaneous distortion filtering. Comparisonand analysis of the statistical properties of the instantaneous distortion and its maximum value with different filtering position are carried out. Relationships between the results obtained by the mentioned methods are established. It is shown that fluctuating pressure filtering in Motycka method can be modified by instantaneous distortion filtering to predict the maximum instantaneous distortion values and computing time can be greatly reduced.