Smoking: catching oil from PCV line on a 408 Magnum

Good moves.
There's always some crankcase pressure because no engine seals 100% of the combustion pressure. As rpms rise the number of firing events per second go up, so more compression leakage per second, while the path for that pressure to escape stays the same. Eventually the top ring gets pushed off the ring land by gasses below it and that's where things really get ugly and seal is lost. That's why vacuum pumps are good to have on race engines. It increases ring seal and raises the rpm capability. Sometimes the PCV is not enough but in most decent engines it's more than enough. You see race cars losing the PCV to reduce oil contamination and leaning out of certain cylinders that can come with it.