CRXdan

every honda ive owned has had a strange whirring noise coming from the engine area, it almost sounds like an intake noise but i know its not because it will do it even under good vacuum, just wondering if anyone knows what this sound is? its most apparent at 3-4000rpm. On my last motor (minime) it was very noticable, I just finihsed breaking in my vitara z6 motor and the noise is starting to become apparent. Anything I shoudl worry about or is it a normal honda sound.