What it does is keep the oil mist from the crank case from being ingested by the turbo inlet wheel. Despite what folks think, that oil film is abrasive on that wheel when it's spinning at the RPM's it spins. The turbo does not need the oil, nor does that intake charge. The crankcase also does not need the small amount of vacuum the intake provides. I've seen zero data on what effect it may or may not have on intake runner coking.
What's NOT good about it, is that it vents raw hydrocarbons directly into the atmosphere. As Clint Eastwood would say, "It's ecologically unsound."
When these engines are installed in the International medium duty trucks, the CCV is routed to atmosphere by the bell housing. Ford is the one who decided to route it into the intake.
CCV mod will also help if you have or will have an intercooler. It will keep the oil from clogging up the intercooler and causing the boots from becoming oily. Oil boots have a tendency to pop off easier.
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