Car seems to be down on power...500rwhp car only runing 11.5s at 121 3600lbs race weight. anyways heres what happend only 2 time at the track. I made my run as im slowing down u hear this very loud knocking sound so i look rite at my oil psi and its at 40psi at a hot idel i bump my car in netural after the traps.... befor i can even get back to my trailer it went away and was fine for the rest of the night....same thing happend about a month ago. i pulled the valve covers and all the rockers and springs seem ok maybe a broken inner spring? collapsed lifter?.......

 

Are you sure that it's coming from the engine?