Leiffi
New member
In Firepunks Youtube video about nitrous they said no one monitors turbo shaft speed because it is too complicated and expensive. Actually it is free if you already own a smartphone. Use Spectrogram or other similar FFT analyzer app to measure sound. Calculate full blades of compressor inducer , measure Hz , divide by full blade count and multiply by 60 to get your turbo rpm. From the screenshot attached, 8 blade HX60: 13000Hz / 8 x 60 = 97500 rpm.