The Stovebolt Site Forums The Shop Area Engine Shop Road Draft Tube

If you go with a PCV system you MUST use a filter with a collector and drain.
You can make one yourself but they are also available online.
It works by condensing the heavy crankcase fumes into liquid form inside the filter canister.
It fills up really quick and needs to be drained every few hundred miles.
You have to see for yourself how much nasty stuff the crankcase produces.
You would never introduce this into your intake on purpose.

Despite the filter a pcv system will produce a hard crusty build up inside the combustion chambers after a few thousand miles already, decreasing performance.
Another drawback with these systems is they stop working when the engine produces most of the crankcase vapors - under heavy load or prolonged high rpm.
Without the road draft tube, the increased crankcase pressure in these conditions is hard on the seals and rings, let alone escaping oil vapor makes a constant mess of a clean engine.

I have used a filtered closed PCV system daily for a few years and am now going back to the road draft tube with a dedicated valve cover filter.
I found that crankcase vapors shouldn't be anywhere near the intake of my engine and that increased pressure on the freeway needs to be evacuated.
If the road draft tube can't do this efficiently, I may use the exhaust as the last resort.
There are crankcase evacuation kits available online where the exhaust sucks out the vapor pressure at higher rpm and eases piston travel at the same time.