Question about WRX V11 knock frequency. Please check the knock setting of the basemap for V11 and let me ask you a question. The frequency is 8 kHz, but I was worried because it was far from the value calculated by the general formula. 1800 / (3.14 × piston diameter [mm]) I thought it was around 6khz for EJ20?
I initially tried 6KHz and wasnt getting reliable knock detection, so I done a frequency analysis and you can see why...
Frequency is the Y axis on this spectrograph, notice at 6KHz you can hardly tell the difference between the area with no knock Vs the heavy knock. The best signal to noise ratio looks to be around 8-8.5KHz, you can see quite a clear difference in sound energy between no knock and heavy knock.