Please help me identify the chatterring noise my motor is making. Firstly, it is an 87 NA with 89 internals. It has been streetported and runs on a Microtech LT10. It makes over 190whp. When under load and rpm's above 6k, it will make this horrible metal chattering noise. The sound is what you would hear if you put a pack of marbles in a plastic box and shook it. And how do I fix it? I've tried switching to 93 octane but this does not help.

 

Your suspicion that it’s detonation is probably correct.
Detonation is VERY BAD for a rotary engine.

Keep the power low until you can get it to your tuner.
Check sensors, fuel pressure, injectors, timing, etc.

It could be something simple like a loose secondary injector plug, or a clogged fuel filter, or a loose vac line to the FPR.