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Discussion Starter #1
Im thinking about ditching my catch can for breathers but I saw a thread on another forum where a respected member alleges that using breathers is not good. He says that oil vapors can get into the combustion chamber and it lowers octane and that having breathers lets corrosive chemicals stay in the crankcase and eat away at seals and bearings. Does anyone have any info on this?

Also I see a lot of coyote guys run breathers without problems.


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Insomniac
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Breathers tend to let moisture into the crankcase which means more frequent oil changes and potential excess engine wear. Breather catch cans are probably your best option as crankcase pressure will vent outside of the intake system but still have enough distance from the crankcase to avoid the intake of anything corrosive or damaging. Its also believed that a close pcv system helps maintain pressure on the under side of the piston rings helping them stay seated under load. So do what you feel is best.
 

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Discussion Starter #3
I usually stay on top of my oil changes and change it about every 5k miles. Would that be ok with breathers or do you think 3k would be better?

Ive seem breather tanks too and thought about those as well but I like the simplicity of breathers. Thanks for the info


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I usually stay on top of my oil changes and change it about every 5k miles. Would that be ok with breathers or do you think 3k would be better?
I have breathers on both valve covers and change the oil every 5k miles, but then I live in a hot desert climate where moisture is almost non-existent. If you live in a more humid climate and drive mostly short journeys without enough time for engine warm-up, a 3k mile oil change interval might be adviseable.
 

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What advantages are there for running breathers on a NA car?
 

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Catch cans are your best bet na. They maintain the integrity of the oe design while not allowing the intake charge to become contaminated with oil and lower octane, add sludge to the intake side and clog up the charge motion plates.
 

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Discussion Starter #7
I have breathers on both valve covers and change the oil every 5k miles, but then I live in a hot desert climate where moisture is almost non-existent. If you live in a more humid climate and drive mostly short journeys without enough time for engine warm-up, a 3k mile oil change interval might be adviseable.

I live in southwest florida so its pretty damn humid here lol. Now I live far out and my drive to work is about 21 miles one way so I dont really drive for a couple mins.


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---------- Post added at 12:33 PM ---------- Previous post was at 12:30 PM ----------

Catch cans are your best bet na. They maintain the integrity of the oe design while not allowing the intake charge to become contaminated with oil and lower octane, add sludge to the intake side and clog up the charge motion plates.

I like my catch can but its not stopping everything I dont think. I recently did my steeda charge motion plates and my intake looked really sludged up. Do u think that seafoam will help?


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I had the JLT catch can and even with the brillo pad add in the catch can was a complete waste. It still let all the oil through and did not keep it out of the intake. I run breathers now and have for about 20k miles or so. I change my oil at 3-5k just like I did before, I check my oil often and it always looks fresh.
 

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Discussion Starter #9
I have an sr performance catch can and it helps. It always has oil in it when I check it. Ive heard a lot of bad stuff about jlt honestly but I have nothing bad to say about my sr one


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I might switch back to a catch can if one really does catch some oil. My only issue is the smells that come from breathers. I am fine with them, but I have a 6 month old and not sure about him and the smells.
 

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What advantages are there for running breathers on a NA car?
The big advantage is that you completely isolate the crankcase from the intake system so there's no chance of oil vapors contaminating the intake tract and lowering the octane rating of the air/fuel mixture. The biggest problem with the stock PCV system is that the CMCVs quickly become coked up (you'd be shocked at how they look even on a low mileage engine), and deposits accumulate between the throttle body blade and bore causing low idle or erratic idle issues.
I deleted the CMCVs anyway so I don't have the former issue, and I clean the throttle body at each service interval to prevent the latter. I do find that the TB doesn't become as dirty as before so it needs less cleaning. I also clean the breather filters at the same time and there's minimal oil smell underhood.
 

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Discussion Starter #14
The amount of oil to get into the chamber and lower octane levels is nothing you will likely see without a huge problem with the motor fyi.

Ok, I reread the artical I keep talking about (http://mustangboards.com/modular-4-6l-tech/21902-putting-breather-filters-valve-covers.html) and realized the op is fi. Now R3dn3ck is very adament that you need the pcv system on na and fi motors and says things about lowering the octane, lean condition, etc. Is there truth to what this guy says or is he saying like oh well this CAN happen if you run breathers and dont change your oil etc?


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Two filters on the passenger cover.








And one on the driver's side cover. Now this one is pretty much useless unless you dig out the PCV valve in the cam cover. If you leave this in it just sits there closed unless you build up an enormous amount of crankcase pressure which means you have bigger problems.





Anyways, you guys got the gist of it. It's a trade off. If you wanna run clean air through your motor you run breathers. If you don't wanna run breathers you have to get a catch can. And you have to remember that you still don't get clean air with a catch can. A good one should remove most of the oil mist but nothing is 100%. So the rest of the exhaust that sneaks by the rings and such still runs through your motor. This displaces clean air so you can't burn as much fuel and you don't make max power. Not that it is a noticable difference for most. Boosted applications tend to have more blow by just because they attain higher cylinder head pressures during both compression and combustion. It is true that you get contaminents built up more quickly but that is just a matter of changing your oil more often.
So it's a trade off. Personal preference. Run a catch can or run breathers and Chang your oil more often.
 

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Just make sure if you do run a catch can that its hooked up using vaccum line. I ordered a moroso catch can from AM and it was supplied with lines that weren't vaccum line. At idle it looks fine but under any load it sucks closed. Not really a big pain but sucks I couldn't use the lines that were already cut to length.
 

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Discussion Starter #18
I had to cut my stock hard plastic lines for my sr performance catch can and honestly its a nice piece but eventually Im going to swap to breathers to keep all the oil out of my intake.

And boss, thanks for posting. I think Ill swap to breathers in the future. I change my oil at 5k miles and Im always on top of it so I think Ill be ok. Plus I drive a minimum of about 10 miles just to get to the grocery store so I think Ill be fine with the amount of driving I do. Thanks fellas


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I run breathers cause my bung in my cai broke off so I plugged it and switched to breathers. No problems that I have observed. I change breathers every few months just to make sure I'm not sucking in contaminants but other than that I haven't had to do much different than when I ran a catch can
 

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Like A Boss
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I had the JLT catch can and even with the brillo pad add in the catch can was a complete waste. It still let all the oil through and did not keep it out of the intake. I run breathers now and have for about 20k miles or so. I change my oil at 3-5k just like I did before, I check my oil often and it always looks fresh.
I have to empty my jlt every time I get gas. That alone proves to me that it works. I honestly don't know how oil consumption isn't a bigger issue with the 3v.
 
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