SR20DET knocking sound in cylinder head, long description. Please help!

[gdbyyosh1to]

Ok so this started about a week ago right before or as my engine ran out of oil. I have no idea where the oil went... there are no signs of leakage anywhere on the block and there's no blue smoke coming from my exhaust. I had put the specified 3.7 quarts of oil in the engine and checked the level at least twice a week. I had driven about 2,000 miles since this oil change when all the oil disappeared. Previously the car sat in the driveway over the winter (2 months) with relatively fresh oil and no coolant in the system. I do occasionally drive the car hard in the back roads on the weekends but i don't drift so i rarely get it to 7,000rpm.

The sound definitely comes from the cylinder head and sounds like it's only happening on one bank. The speed of the sound increases with engine speed and sounds like a hard definitive knock.

I took off the valve cover to inspect and didnt see any signs of damage except on the last lobe of the intake cam there was a small chip. I have replaced the camshaft and the rocker arm according to the sr20det service manual. Upon installing the replacement intake camshaft i applied new engine oil to all mating surfaces and on every bolt. The camshaft bolts were torqued at 10 lb-ft and the sprocket was torqued onto the cam at 98 lb-ft. The timing is right because the engine runs smooth except for the knocking noise.

At this point the problem is beyond my knowledge so i've come here for help. Thanks for any advice/tips/knowledge you can give me, i love this car and if i can't fix the problem soon i will have to get rid of it and i really dont want to do that.