This leads back to my original question: Is the valve cover positive pressure (blowing the oil out) or is the intake tube negative pressure (sucking the oil in)?

If the former I will very quickly have a breather filter clogged with oil. If the latter I would be fine with a filter and capping the intake port.

 

If you take off both the PCV at the valve cover and the hose to the front breather, you'll discover that there is pressure coming OUT of both even when you rev the engine. When everything is connected and there is heavy manifold vacuum like during deceleration, that vacuum will draw the under valve cover atmosphere OUT via the PCV. I believe that it is this time that there is a strong possibility that fresh air will be drawn IN from the front breather (if manifold vacuum can produce a vacuum under the valve cover). During acceleration, I think that any under valve cover pressure can and does escape through the front breather as well as through the PVC but since the front breather is a bigger passageway and the PCV valve is quite narrow and has that little "stopper" in it, most of the pressure will exit via the front breather.

 

Righty-ho then it's catch can on the front breather time!

 

this is kinda along the same lines..

you guys with the Comptech supercharged S's experiencing extreme loss of oil?..What is normal evaporation of oil from the engine, if i drive it hard all the time.

 

Mine doesn't seem to use much oil.