OK, tnx very much. Here is one obstacle: I take data in 2 crank degree increments in order to get fine detail for computation of lifter velocity, etc. With a symmetrical lobe, and same lobe for IN and EX, that is still something in the range of 60 to 80 data points, not 5-7 points like for head flow. With assymetric lobes and different IN and EX, now we are talking 250-300+ data points. It might work OK with fewer data points.