Hey guys I just installed a CFM Valve Cover breather on my 03 Cobra. I figured it would be a great idea to add it to the car. It looks good and helps relieve some crank case pressure. Take a look at the video below if you would like.
CFM Valve Cover Breather
- Thread starter MrAjsTech
- Start date
You still have the PCV system hooked up (on both valve covers nonetheless), you don't have any crankcase pressure to begin with.
The guys who need to run breathers are the ones who do not have the PCV system hooked up anymore.
--Joe
The guys who need to run breathers are the ones who do not have the PCV system hooked up anymore.
--Joe
You're introducing unmetered air into the car. Under idle and normal driving air is being sucked out of the crankcase via the hose attached to the PCV valve on the driver's side cover. Now instead of pulling metered air (pulled in from the passenger's side hose) you are pulling in air from the atmosphere. Either delete the whole system and run breathers or leave it stock.
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What would be the benefit to deleting the system and running straight breathers?
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Ah, my mistake didn't see that. Just read the product page. Really no harm then. Never saw one of these before.
Same result could be had with a catch can on the driver's side. I personally just run pre-filters on both sides. Retaining the PCV is usually a good idea. Keeps the oil cleaner for longer by removing crank gas vapors. This filter actually seems like a good idea... You get to retain the PCV system while giving any crankcase pressure an exit.
Prefilters don't do anything. The oil still gets through the media.
You do realize the purpose of the PCV system is to "give any crankcase pressure an exit" right? If you keep the PCV system, there is no need to replace your oil cap with that filter.
--Joe
So from the diagram it looks like a three-way T with PCV hose, blower vaccum, and lower intake manifold. So under boost with some crankcase pressure... is it flowing from PCV -> blower vaccum? Is it also going out through the passenger's side cover?
Since the stock positive crankcase ventilation system only works with vacuum at idle and part throttle, there really is no escape for the pressure when you are driving hard. This is from the CFM tech review on SVTPerformance.com.
The breather is designed to work with the stock PCV system. It is also a good idea to work in combination with a catch can setup like I have on my car tucked away in the corner as well as a pre-filter.
These come with a one-way check ball to eliminate unmetered air.
This is a little explanation I found:
"The factory PCV system on your vehicle was designed to perform as intended on a STOCK engine. As you start making modifications to increase horsepower you also start increasing positive crankcase pressure and now the PCV system becomes less effective in its ability to vent it. This increase in pressure is a result of additional blowby caused from increase in cylinder pressure and normal engine wear. This decrease in efficiency from the factory PCV system will lead to negative effects such as loss in power and leaking seals."
These come with a one-way check ball to eliminate unmetered air.
This is a little explanation I found:
"The factory PCV system on your vehicle was designed to perform as intended on a STOCK engine. As you start making modifications to increase horsepower you also start increasing positive crankcase pressure and now the PCV system becomes less effective in its ability to vent it. This increase in pressure is a result of additional blowby caused from increase in cylinder pressure and normal engine wear. This decrease in efficiency from the factory PCV system will lead to negative effects such as loss in power and leaking seals."
Yeah they are saying pressure isn't being released on a stock system under boost, so this part seems useful for this. I'm actually about to order one myself.
I don't know if I agree with that.
As others have said the CFM breather has a check valve so it prevents air from escaping during normal driving. The filter will only vent when there is more pressure in the crank case than what the intake system can suck in through the pass side valve cover.
I installed one of these breathers on my car and the filter just pushes onto the aluminum neck. I could go out and drive the car for miles on end with the filter staying firmly in place if I stayed out of boost. I began to notice that if I took the car out and went into boost the filter would raise up on the aluminum neck until it caught the lip on the neck. I could push the filter down and after the next trip into boost the filter would be raised up again.
Now a person could take this as the force of 22 psi of boost was enough rearward force to cause the filter to be pulled from the neck but I choose to believe its the pressure in the crankcase being released. The force of acceleration should be a more rearward force than an upward force. I've since installed a small black hose clamp on the filter and it stays down all the time now.
One must remember that the drivers side PVC valve doesn't work in boost as the pressure from the blower is keeping it closed and excess boost is being routed back into the top of the blower to be recirculated again. The only source of crank case pressure to get out is from the pass side.
I also like the look of the filter after I powdercoated the cap TVS black.
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The pcv on the driver side is a check valve, when the car hits boost the valve is forced shut, the passenger side enters the tube where it's always under vacuum. The crankcase is always being evacuated and burnt. The problem arises when your guides and rings start getting more blow by, your engine will produce more oil vapor in the inlet of the blower so that's the first best place for a catch can, the hose from the drivers side goes into the bottom of the blower and oil vapor will build up and become oil in the lower intake, that oil is on the outlet side of the blower so it's not terrible but a catch can there is fine as well. Adding the oil cap filter/check valve might be a mute installation because if the engine crankcase is always under vacuum the check valve will always remain closed. I've seen catch cans collect both valve covers and connect the the bottom intake connection this cap filter / check valve would be the proper product for that type of installation.
I just plugged the intake tube and the lower intake then run 2 8an houses from both sides to breather tank.
I think it's the best way to avoid oil condensate in intake and unmetered air issues plus The car idles smother
I've seen lots of setups like this on different platforms, but what I don't understand is how gases are being evacuated. There is not vacuum pulling the gasses out of the crank case, so I never understood what running both valve covers to a tank actually does (besides allow positive pressure to have some kind of escape).
The gases don't need vacuum to be evacuated from the case it's just build up and escape from the easiest way.
and this the point "(besides allow positive pressure to have some kind of escape)."
In my mind PCV does two things. It releases positive pressure, but it also constantly replaces crankcase gas with fresh filtered air. I would think that there would be instances where there are crankcase gasses present without positive pressure. The constant flow of fresh air displacing crankcase gasses would be best in my opinion.
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