On the PFC what is a safe knock level

 

Tough question, suggest you search and read all the threads on the topic and make your own conclusions.

 

I don't trust the knock reading on the PFC at all. Mine's hit 180 before and my engine is just fine. Everytime I get in my car my reading hits at least 50.

 

Azaka is right, it really depends on the car. I usually get into the 40's on every drive, I'm still tuning my car with datalogit slowly and my AFR is in the 10's with timing pulled back until I get the AFR cleaned up.. still get an occasional 50. I've seen a couple weird ones above 100 and the motor is still fine, the noise it is picking up seems to be coming from another source.

 

it matters what mods you have

 

Under boost with no gear changing my knock levels are signal digits to 20s. But as soon as I shift gears even under normal driving, my knock can go over 100.


So my answer is not over 40 under constant load in the same gear.