What is this sound? (video)

[bmk]

So im driving yesterday accelerating near wot, then all of a sudden a loud noise came out of no where. Ive never really herd anything like it I took a video for all of you to check out. It sound like a bent valve to me but not really sure. Its very metallic sounding and if you rev it up it sounds like a backfire coming from the intake. I can hear it very clearly when I put my ear up to the intake mani vs if I listen through the valve cover. If anyone can lead me in the right direction that would be great.

http://www.youtube.com/watch?v=WgVod...yer_detailpage

[bmwstudent]

yes that sounds like a bent valve, probably an intake valve if you can hear a pressure wave coming back through the intake manifold. Possible jumped timing belt. Sorry.

[bmk]

Yeah this engine ran PERFECT for thousands of miles, im thinking it had to be the timing belt slipping.