Question about VC breathers and vacuum

[CManT1914]

The breather I have now works just fine, but it doesn't have a nipple to connect it to the inlet tube on my C&L. I have heard that it is better to run a non-breather setup with a hose so as to avoid vacuum issues. Any truth to this? Basically, will having only a breather, and no hose running to the intake pipe cause any problems? It looks cleaner without a hose sticking out there.

 

[95strokerPSU]

I don't have a hose anymore and I haven't experienced any problems. But I'd be interested to hear a response from someone that actually knows what their talking about.

 

[VibrantRedGT]

Actually the vacuum line removed and air escaping out of the valve cover nipple is a vacuum leak. Use the Moroso or FRPP breather and vacuum hose hooked up to the air intake and valve cover nipple.

 

[S/CBlack95GT]

I just slapped the breather on the valve cover in place of the regular oil cap. Then I simply plugged the nipple. My PowerPipe doesnt have a provision for the factory hose so placing a cap on the nipple has worked fine for me.

 

[95strokerPSU]

Actually the vacuum line removed and air escaping out of the valve cover nipple is a vacuum leak. Use the Moroso or FRPP breather and vacuum hose hooked up to the air intake and valve cover nipple.

As long as the VC nipple and the air intake nipple are plugged properly and air isn't escaping, then there wouldn't be a vac leak, right? And using the FRPP breather cap.

 

[CManT1914]

Actually the vacuum line removed and air escaping out of the valve cover nipple is a vacuum leak. Use the Moroso or FRPP breather and vacuum hose hooked up to the air intake and valve cover nipple.

Joe, mine is just a breather, no nipple for the hose. My C&L inlet DOES have a nipple for it, but I capped it off. So I shouldn't be experiencing any vacuum leaks like this?

 

[18mustangs]

As long as the VC nipple and the air intake nipple are plugged properly and air isn't escaping, then there wouldn't be a vac leak, right? And using the FRPP breather cap.

Under load the PVC system draws vapor laden air from the crank case into the intake stream to be burned. If one has a filtered breather cap that does not rely on the tube to draw in metered air there is a vacuum as the tube is bidrectional allowing fresh metered air to enter the crank case after the PCV draws out air from the crank case. It is important for this air to be metered as not to lean out the air\fuel ratio as the exact amount of air entering the crank case after the MAF is the same as the amount of air that went through the PCV valve. If a filtered breather is run the PCV is drawing in air from the crank case in addition to all of the metered air from the intake (none was diverted to the crank case for the 1:1 swap) so you can run lean and possible detonate. This is possible whether or not the oil filler nipple was plugged running the breather cap.
On another note, one should also not just leave the stock cap in place and remove the filler neck hose capping off the nipple if oil is found in the air inlet as some people have done. With the PCV still operating and no source for clean air to enter the crankcase it is possible to create a vacuum or at least severely hamper the crank case ventilation system.
This is the cap that Chris should be running with his valve covers in order to have his PCV system operate properly:
http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=482

 

[RIO5.0]

This is the FRPP one I use....M6766-G302 (push in style)...I tied the line on the u/side of my CAI...I ran it with a vented breather like your for 2 yrs and really didn't see any ill affects....I decided with the VC swap to hook it back up again to help vent things...