What affects knock? (what makes a car knock)

[turbotalon1g]

Broad question i know, but i am getting knock in my sweet 16g, E85 car like crazy.

The only thing i can think of is that the DP is touching the T-case and that is why, but no matter what any roll below 4k and it will start to knock.

I usually do pulls from 2k upward.

I have the knock sensor activated after 40% throttle and above 3400rpm.

Thanks

Aaron