Whats this Motor Knocking?

[DR. EVIL]

Didn't seem to notice any strangeness in how the car was running before, and don't think I noticed any knocking noise before either. I just got an oil change yesterday right at my 3K miles, with synthetic oil. I have the right amount in it.
Today I had the hood popped with the motor on and noticed a loud knocking sound right behind the turbo, seemed to be under the valve cover. The knocking does increase in speed as the motor revs up. I'm not going to drive it until I have an idea of how serious this is.
Before I go blindly to my mechanic, what things could be causing this?
Got about 80K on the motor

 

[DR. EVIL]

ttt

 

[Red Regal T]

Don't go blindly to your mechanic.........look under the valve cover.

 

[87grandnat]

mine was doing that, and i found out all the oil drained out of it due to a leak.

 

[87gninpa]

dont ask me how i know, but just out of curiosity check your coilpack and ign module. my module went just as i started the car after an oil change, i thought the thing was falling the hell apart, ive never seen it run that bad. turn out the middle coil was not firing due to a faulty module. best way to test is with the car running, take off one wire at a time form the coilpack and make sure theres spark. if theres not on two adjacent cylinders, then you know either the coil is bad or the module is. my car was knocking really bad, but it turns out it was only running on 4 cylinders!!!! new module and the car runs as perfect as it did before. also, before ripping off the valve cover, take a long screwdriver and put it up to a few things aorunf the area, valve cover, header, turbo, etc and check for the banging noise. it should give you an idea of where its coming from

 

[DR. EVIL]

well it wouldn't be completely blind, I know it is something in the valvetrain. I'll check for spark on the coilpack, it has been having symptoms like it was before when my plugs were in need of changing and the gap was WAAAY too big (some were as large as .45!) I just replaced these plugs and gapped them at .30 3K miles ago though.
Why would a lack of spark sound like a knock though? I've heard a car knock due to lack of oil and thats what it sounds like, but I just had it changed and I checked and its full

 

[DR. EVIL]

ttt