Originally Posted by faiz23
The knock could be the vtc solenoid it self. Look up vtc solenoid issues with s14,s15 and 300zx. You can ground the solenoid and see if the issue goes away. Also what you could be mistaken for a knock around vtc but it could be a timing chain guide or tensioner. Also just throwing it out there but with rev up the weakness in the engine is piston rings and valve guide seals.
Thanks man. I replaced the offending VTC solenoid yesterday with no change in the problem. It only happens when the engine is warm, near silent at cold. I've tried to trace the passages, seems like 1 goes past cylinder 1, hope it's not a worn bearing. There's multiple noises at once it seems, possibly low oil pressure. The knock just seems extremely loud from the solenoid.