Killer D

Ok, so I have mine routed this way:

I've been getting nothing but greif from some people on other forums saying that I can't have the valve cover breather Tee'd into the vent hose from the gutted PCV valve, because thats where air gets drawn into the crankcase...BUT, this setup always has vacuum applied to the crankcase, In and out of throttle.

When your on the gas, boost will kick in, lock up the one check valve and vacuum created by the slashcut fitting in my exhaust will vent the crankcase.

When your at idle, vacuum from the Intake Manifold locks up the slashcut check valve, and vents the crankcase back into the manifold, mimicking the stock PCV system.

All I need to know is if it is absolutely necessary to have the valvecover bringing in open air?

HiProfile

Well if you look at many baller setups with 2-4 braided SS lines going to the catch can, they have no breather left on the valve cover, but they're looking for max power, not longevity. For a street setup, I'd leave the breather in place, since your crankcase will be filled only with blowby gasses after anything besides a short trip w/o a breather. The blowby is basicly intake gases (unburn fuel) and exhaust gases (burnt fuel/carbon), which both contain corrosive particles.

If you really wanted to get the most suction from your catch can lines, just restrict the breather opening. I'd also recommend a pcv valve between the catch can and the check valve on the line going to the manifold, so low-load vacuum won't be sucking too much through that line during idle/cruising.

Killer D

Thanks for the Info.

What you're saying makes sense...But If theres always vacuum pulling the gases from the valvecover/crankcase, wouldnt the blowby be evacuated?

Killer D

Wow this site isn't very helpful.