PCV AND VC BREATHERS?

[wbzautocustomiz]

Want to know how a cars pcv system should be plumbed? Breathers that are on VC do let opil seep out is there a stop to this? Know stuff about cars and never really knew how the pcv system worked. Thanks in Advace TB family

 

[PSID6]

On a stock vehicle the crankcase fumes pass through the PCV Valve which are drawn into the intake track by vacuum. These fumes are then introduced with the incoming air and fuel mixture and then burnt in the combustion process. As for a performance standpoint you want to eliminate the mist of oil going inside your intake. As for the valve cover breathers the engine can breathe without introducing that fine mist into the combustion process. As for eliminating the mist altogether you would have to plumb your breathers into a catch can or into your exhaust system which is not ideal in either. Plumbing the valve covers to a catch can i believe is the best method. Which you would have to drain periodically.

 

[Paul Lohr]

Vacuum side of the PCV system: upper part of the crankcase > PCV valve > air / oil separator > intake vacuum source.

Filtered air side of the PCV system: upper part of the crankcase > filter > atmosphere

The upper part of the crankcase could be the intake manifold valley or valve cover. The Buick V6 has its PCV valve in the intake manifold valley.

OEMs usually shield the bottom of the PCV valve so oil does not splash on it. They also draw air into the crankcase from the filtered side of the air cleaner.

Edward Obert's book, Internal Combustion Engines, states that burning lubricants with the air / fuel mixture can increase deposit formation in the combustion chamber. Also, rich mixtures increase deposits left after combustion. Deposits can glow during combustion and sometimes encourage detonation. Not sure about this, but maybe alcohol reduces deposits?

The oil fumes don't need to be in the combustion chamber. Those fumes not being there takes away one more variable.

Higher end vehicles such as BMW have air / oil separators in the PCV system. Some BMWs return the separated oil to the pan.

Most of the aftermarket separators are drained before the oil level gets too high (rather than returning oil to the pan).

Here is a more expensive, probably well built air / oil separator:
http://www.moroso.com/catalog/categorydisplay.asp?catcode=18549

Here is a cheaper one:
http://prosportgauges.com/oil-catch-can-.aspx

This one probably returns the oil to the pan since there is no tank (but it is intended for a Subaru):
http://www.grimmspeed.com/catalog/product_info.php?cPath=91&products_id=191

I've seen separators intended for air compressor systems used as well. They are pretty inexpensive.

Paul Lohr