knock detectors on Stage blocks

[Tom Shea]

I'm curious if there is any way to determine the value of trying to use a detector on stage blocks. If they have a thicker and heavier casting, and are made out of a higher nickle content cast iron, does that make the sonic signal somehow different? Does the detector become less sensetive? Is there a more appropriate part for this application? Should I bother to even try to use a detector for any input at this level? They do seem to alert, but I'm wondering if it's only on severe detonation and or spurious noises, (false knock).

[CTX-SLPR]

The material velocity will be different and the internal geometry would mess with a guided wave but I'm pretty sure it won't effect the actual function of the sensor since its just a piezoelectric microphone coupled the to block which works like a big resonator. Put it in the same spot as stock and I don't think you'd see a difference but I'll let Bruce or one of the other EFI electronic gurus give you the definative answer. All of my stuff is based off of my experience with ultrasonic testing equipment which uses a piezoelectric transducer to put a guided wave into the part.

[Tom Shea]

I seem to be haveing some unreported detonation. I have some black specs on the plugs. The detector does go off but it seems like it should be doing it more or sooner or earlier. I seem to be able to run more boost and timing than I thought would set it off. Both of my stage cars have operating detectors but they seem to work well when alerting to non detonation noises (False knock), and maybe less well when I suspect detonation might be occurring. Jay C. told me years ago that there would be issues with trying to use the detector with my stage motor, but I thought he was mostly referring to my roller cam. I should have asked more questions then.

[JayC]

I was refering more to the cam than the block however I do believe the overall combination causes the sensor to be overly sensitive. Personally, anything with a roller cam, I think youre wasting your time running a knock sensor.