Can the mean effective pressure ever theoretically be lower than atmospheric pressure? I'm stumped

Seems unlikely to me, because how would then the compression phase take place? But on the otheer hand MEP is an average, so I can't exclude it.

What if you're trying to put pressure on someone meaner than you? >:3

>>1
It is indeed possible, you can lower the mean effective pressure in the piston by sucking out the gas and then putting it back so that it reverts back to the original state.