So.. my understanding is that it helps vent crankcase preasure. But what I dont understand is what it actually does to help the motor, and at what kind of level of modding would this be beneficial? I heard someone say it would be usefull for someone with a 2.7 and 60's, would it even beneficial if I just have stage 2 and bolt-ons? I'm not some kind of noob thinking this is gonna make my car faster, I'm just wondering if it will do anything to make my engine run better/smoother/more efficiently in any way or if its just there to look cool? lol, so sorry if this a noob question, but I couldnt find a suffcient answer with search.

 

oil cap breather? not sure what you're talking about.

 

some people have either a replaced oil fil cap with a filter on it, or have drilled a hope into their normal oil fil cap and attached a breather to it.

 

Your probably talking about the line that goes into your air intake off the valve cover right?

 

Only use one if you are pushing higher boost on stock rings and have crankcase pressure problems.

Its an uncontrolled air induction leak, don't run it unless necesssary. Also won't pass any type of state inspection/emissions.

 

I believe this is what he is talking about.

 

I doubt your pushing enough boost for one of these, only tvs and turbo guys need one or twincharge.

 

^^Yeah thats it.

Stock PCV system and that will open the intake pipe up to straight air. Even if you cap the intake pipe it will still draw/push air from the intake manifold PCV hole.

 

I just got into a discussion with this and a local friend the other day. I didnt think our balts needed additional breathing (at my level of mods). I told him if he really wanted to be different to run a vacuum pump like the guys with dry sumps/low tension rings.

 

at 15 lbs of boost and the front crankcase vent covered up by the early version of hahns intake manifold I was blowing the dipstick literally across the garage on dyno runs. I was also getting oil pushed back up by the rings into the combustion chamber after dyno runs from the increased crankcase pressure. But by running a large hose to the oil cap cover these problems stopped.

The top vent by itself was not enough.

 

I run stock rings on higher comp pistons and can blow it out as well. 18+ psi of boost will do it. Each cylinder holds 200psi during a compression check.

The big thing you have to watch for is ambient temperature swings throwing off the MAF calibration. Mine swings about 5% in either direction WOT while using one of these breathers.

 

those aren't used for "extra air" pcv systems main use is for emissions. blow by from the rings that goes into the crank case needs to go somewhere, so they plumb a hose from some area that sees the pressure of the blow by, back into the intake which goes back into the engine. (this is a crude description of it)

a breather filter put in place to remove the pcv system allows the air to go into atmosphere which will cause you to fail emissions test if your state does a visual inspection. the reason the guys running higher boost use them is because the oem pcv system recirculates air that has already seen ignition and the more boost they run, the more blow by they see and the more contaminated air goes back in to be refired ( another crude explanation) and you need as much fresh air as possible in the combustion chamber. if people are blowing out dipsticks, there's an issue with your rings or your pcv system needs cleaned.

i run a breather filter at the track, but for every day driving i leave the pcv system on.

 

I've been getting crankcase pressure problems since I was BONE stock. My dip stick has contiunally popped up since the first month I bought it. So I'll be doing this mod especially since I am throwing a 2.9 pulley on now.

 

I was just looking at it beacuse its pretty cheap and easy to do and sounded like it'd give me something to do on my day off with a quick trip to the hardware store,lol. Now you guys running breathers, are you just using the oil cap one similar to post #6(or a homemade version of it) or are you chopping off the line going from the valvecover to the intake and putting a breather on it and plugging the hole in the intake? Where I am there are no emissions tests and I've been pulled over a few times here, and maybe 7-10x(usually nothing, they'll stop you if you LOOK like you might be speeding,lol) where I used to be from and no cop has ever looked under my hood. So I dunno if I should put the breather in the oil cap and just put a catch-can(midas well keep the s/c clean and its another cheap diy) on the line going from the valvecover to the intake, or am I better off running the breather off that line?

Also, even though someone told me its probably related to the valvecover not being torqued down properly, but could adding a breather help with whatever is causing me to blow valvecover seals? Its blown again for the 2end time, only springs a slow leak and both times its the exact same spot on the left side of the block, near the back, around the little black plug thats on the seal. The little plack plug theres 4 of them, 2 on eash side, and it seems that their on the ends of the block where the shape of the seal dips down slightly in a U shape where the cams would be inside. I usually dont drive hard day to day, but atleast 2 or 3 times a week, I go out and usually do 2 or 3, sometimes a few more consecutive wot pulls 2end and 3rd gear to redline.

**edit** Ok, so I understand how the pcv system is venting out blowby thats going into the crankcase and feeding it into the intkae just before the throtlebody... what I dont understand is how someone said that adding a breather is going to affect maf calibration. Also, how much of the air coming out of there is fuel? Would outright disconnecting the pcv line and putting in a breather lean me out slightly? Would is affect fuel economy at all? Emissions I dont really care that much about... just wondering the pros/cons of keeping either:
A) not adding any breathers and only if anything putting a catch-can to keep my s/c clean.
B) Adding a breather to the oil cap but still leaving the pcv line connected to the intake(again, with a catch can probably)
or C) cutting the pcv line and putting a breather on the end of it, and plugging the hole in the intake...

 

it will not have any effect whatsoever on the maf readings. for that to happen, there would have to be a maf on the pcv system measuring air as it goes out and back into the intake. there's really not a large amount of air going through the pcv system unless you're rings are not within specs.

none of it would be fuel, it would be air that has already burnt after ignition and slips through the rings. there will be oil in it though and the oil is combustible

i could go on explaining but just check out the wikipedia page, it explains everything.

http://en.wikipedia.org/wiki/PCV_valve

don't plug up the hole on the valve cover though, make sure you put a filter on that part

 

It's not going to break anything but it's not going to make your idle better or engine smoother or quieter. Actually it's probably only going to affect the pressure in the top part of the head and do nothing like reduce boost or cause oil leaks. Do it if you want...it's just not necessary.

 

I know its not gonna make my engine smoother or quieter, I just wanted to know if it'd be better for my motor. I mean oil in the pcv system thats getting misted back through the supercharger doesnt sound very good for the supercharger,lol. So what I'm just wondering... if I put a breather filter and cap off the pcv, will it be too much oil that it'll clog up the filter? should I run a catch-can before the filter if I want to use a breather? And does it work out basically the same as running the filter/breather over the oil cap? Is it redundant to do both or does the stock vent for the pcv not vent enough pressure and it'd be better to do both? Does better ventilation free up a little power by reducing the resistance your pistons have to push agains even slightly? I mean even if it only picks up 1 or 2 whp to put both vents, its still worth it for a $15 hardware store mod. I dunno the effect on our cars but a buddy of mine said when they built big V8 all-motor engines at the shop he worked at they saw gains with better crankcase ventilation, would it basically be the same but just on a smaller scale with our motors? I dunnp if this seems like a noob question or not, but its definatly not your standard bolt-on, lol. Even if there isnt alot to it and I'm overthinking this, its still a good topic for discussion I think.

 

if you run a catch can you need to plumb it back into the intake

 

so back to my last questions...
1) Is it redundant to put the breather where the pcv line should be AND put on an oil cap breather? If running both is not gonna vent better than 1, which one is best to run?
2) Will too much oil in the vented gasses plug up the filter? If so, would a small catch-can before the filter make sense or should I just clean the filter often?

 

1) only do one or the other

2) yes, but if your filter gets clogged up within 5000 miles, you've got some internal problems. i clean the filters on my supra when i clean the air filter, not because they need it, but it just makes it easier

 

I just did a bit of researching and even though none of these people drive cobalts, they did say that
a) they had oil ripping from the filter they put on the pcv line, and running a catch can, with a filter on the opposite side of the catch-can eliminated the oil dripage problem.
b) since its not using the vacume of the intake to vent out the gasses and only relying on the pressure in the crankcase, it might not allways vent as effectivly.

From that, it seems it might be a good idea to do both, even if its not completly nessesary now, it wouldnt hurt. More effective ventilation isnt a negative thing... it would also be nice to allready have in place for once I do turn the boost up to where it'll be making more of a difference. Basically, the pcv delete will be more just to keep dirty oily air from getting into my intake, which sounds beneficial to me. If theres problems with no getting enough ventilation through the stock pcv system, an oil cap breather would still be beneficial ( and from ralli's post about popping out the dipstick while still bone stock, it sure sounds like this is the case)

 

Isn't it mandatory to get rid of the pcv line for turbo-swapped guys?