I'm telling you... did this already myself :th_depressed: ... Its main engine.
Either valvetrain noise (broken lifter, spring, etc...)
or its a chipped piston (doesn't usually happen on a stock pulley, but it could be possible)
or like me, main bearing is gone, going, or something else lower end.
Put the belts back on, put car on ramps, chock the wheels &/or set the parking-brake, leave it running and get under it, if its louder under it and it is above it guess what??? :th_crying1:
If both belts are off and the noise is there, it can NOT be anything but engine, no belt to move anything else so write those off. Unless you have electric parts installed and your being sneaksie.