Salvia, Ketamine, and LSD have all produced incredible time dilation for me. In the case of Salvia, it isn't so much time-dilation, as a complete restructuring of the temporal laws of the universe. It's like I exit the flow of time in the vector I usually perceive it, and am able to perceive it's shape and direction from a distant perspective. Salvia time is probably one of the most bizarre forms of psychedelic time distortion I have experienced.
Ketamine time distortion is immense. I can be existing in all possible temporal locations "simultaneously" (if that word can apply here). In the deepest of K-holes, I have been there forever and always.
LSD time is quite interseting in itself. Again, I have found that it is not a simple case of linear time stretched out. With high doses there is a sense of experiencing the end of the trip before the beginning interspliced with bits in the middle. Space also factors heavily in to this with LSD, so that actual spacial events in time can be perceived to be effecting each other from seemingly incongruous parts of the temporal spectrum. As if you are zooming out and seeing the folds in space time which connect up with each other "behind" the normal percieved linearity of space time.
Shrooms have flat out stretched time to the point where it becomes almost unbearable. It is during the shroom peak at which it feels like you are coasting in to a void of reality where the passage of time has ground to a halt, even though events still appear to continue. I have had weird time 'loops' on shrooms, where the very same event appears to play out again and again.