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Thread: Whats the purpse of a breather and what does it do?

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    Default Whats the purpse of a breather and what does it do?

    What is the purpose of a breather? What does it do? And does it increase performance if i unhook it from my intake and put a breather filter on it?:weak:
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    PittSpeed Legacy Member Array JackdUp's Avatar
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    A breather or breather tube vents pressure from one area to another, either the case is a simple atmospheric breather or pressurized venting in the case of a valve cover to intake tract breather.

    In the case of a valve cover breather, one that routes from the valve cover to the intake allows the vacuum caused by the air ingestion of an N/A motor to remove the pressure from the top of the motor. This allows the pressure to be safely bled off from the top of the head and also allows any unburned oil vapors that come from the valve-train area to be combusted in the cylinder, reducing hydrocarbon emissions.

    Dyingwish had some good reasons why it's a bad idea to NOT run the breather tube into the intake, at least on an N/A Honda motor. I presume these parallel a v6 N/A Pontiac motor as well. One reason is the positive pressure displacement is done much better on an N/A motor when the intake tract pulls (actively) the pressure from the valve-train area rather than venting to atmosphere...the atmosphere pressure differential is less than that of the vacuum in a n/a car's intake tract.

    If you have a boost motor, venting to atmosphere is more efficient because the intake tract is pressurized...which means the effect would be to possibly add more pressure to the top of the head....and that would be bad!
    WTF?

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    Little filter breathers are good for putting oil all over the top of your engine.
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    I have a breather filter on my car. What are the long-term effects?

    Quote Originally Posted by Dominator View Post
    Little filter breathers are good for putting oil all over the top of your engine.
    I don't have that problem. Just a really dirty filter.
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    Lifetime User Array Shaggy's Avatar
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    plug the line and the valve cover, fuck that burnt oil smell.
    Snots

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    Quote Originally Posted by Shaggy View Post
    plug the line and the valve cover, fuck that burnt oil smell.
    The purpose of using catch can setups are two-fold. The primary objective is clean out the oil vapor that is filling the airspace in the head/block BEFORE it's routed back into the intake tract via the PCV system.

    The other major benefit is it can be used to vent the excessive pressure inside the head and block to atmosphere (technically illegal for road-going cars). This helps with crank windage losses and cavitation issues, but more importantly it reduces oil burning from excessive pressures forcing oil past the valve seals into the guides, ring blow-by, etc. The blackish smoke you may be seeing occurs during initial start-up, engine braking, and hard accel? If so you can definately benefit from a PCV cleaning, and catch setup, they're great for NA cars and turbo. I personally run a total of 4 -10AN hoses for my car, two from the head, two from the block.

    Blocking off that line that connects the intake tract and the valve cover is a BAD idea. Without a proper breathing setup all you'll be doing is pressurizing the head/block more than it already is. It is true that blocking it off will cleanse the intake charge of unburned oil, but it then forces the valvetrain/crank to work against oil vapor saturated air under high pressure.

    Justin is correct about the issues with turbo cars....since the intake trat is now pressurized, much moreso than the head. Without a check valve to keep pressure from bleeding the wrong direction, that tube cannot be kept in place. For that circumstance you simply delete that line, and setup a catch can configuration that vents to atmosphere, via the bock and valve cover

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    Lifetime User Array Shaggy's Avatar
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    you didn't see the humor, but thanks for the long response that i barely read
    Snots

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    unless you have a turbo a functioning pcv system is way better than a dumbass breather

    no doubt you'll contaminate your oil a lot faster and have more sludging problems with a breather
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