PCV breather filter in the modern hemi

[RIDEW/ME]

I need some help / opinions on the use of PCV breathers in the modern hemi. Those with BT catch cans seem to be collecting lots of gunk. Seems to me these breathers would let the air out, and keep the gunk in... wherever that is. I can see the benefits of keeping the gunk out of the intake, whether it be with a catch can or breather... I just don't know if there is any harm in not letting the gunk out by using a breather. Is there any harm in the use of these breathers??? Please drop any and all knowledge on me. I know nothing on this topic.

[joey]

I would think venting the PCV line anywhere but back into the intake manifold would be illegal in most states.
Also, I would think a hose from the PCV valve would have to be routed to below the engine bay to the road to avoid oil vapor from dirtying up the engine bay.

[Rambit]

By law it has to be a closed system. It always strikes me as funny that so many have CAI's with filters that allow more airflow, which in turn allows more crap in the intake are so worried about the small amount of oil that gets in there. Then there's the oil charged filters these CAI's use that probably let oil in the intake as well.

Think about it, jeez we have a guy who's obsessed with counting the pleats on every oil filter on the market, yet for all I know he has a CAI that allows more contaminates in with a larger micron air filter. That crap gets into the engine. Then we have those who get their oil analysed looking for all sorts of trace elements, most of which probably came from the environment through the CAI.

Bernie

[joey]

There are also air filters, which are called breather filters as shown in the first pic. But the air flow is going into the crankcase through this filter. The PCV valve is on the opposite side of the engine and is for expelling blow by gases.
On our stock cars, there is a hose from the air intake to the crankcase inlet.

On the second pic, the red arrow shows where the breather filter goes, and the blue arrow where the Catch Can goes.

Some folks have said that gases/oil can occasionally back-up from the crank case breather hose and actually reverse flow back into the air intake/CAI.
I have looked at my stock air box where the crank case hose is connected and there is no oil at all inside my air box after 34k miles of driving.

[AlexDestructive]

the only thing you're doing by turning your PCV into a road draft tube is increasing your emissions by %50, you get zero performance gain and add smog.

explanation: the PCV valve just lets blowby (unburned hydrocarbons) back into the intake to be reburned. opening that up just causes an increase in emissions as the blowby is stuff that would otherwise be reburned for no performance loss.

[stevesrt8]

Pcv is a one way valve. If installed correctly there is no backflow at all.

[AlexDestructive]

Originally Posted by stevesrt8

Pcv is a one way valve. If installed correctly there is no backflow at all.

correct, hence "positive crankcase ventilation"

it only flows one way, out and into the intake.

[stevesrt8]

Originally Posted by joey

folks have said that gases/oil can occasionally back-up from the crank case breather hose and actually reverse flow back into the air intake/CAI.
I have looked at my stock air box where the crank case hose is connected and there is no oil at all inside my air box after 34k miles of driving.

This is the reason for my comment