why do some catch cans have a breather
 

i dont get this, im looking into making a somewhat functional pcv system and making my own catch can

wouldnt this just make no suction on the pcv? unless theres a good reason to have one i was just gona make a sealed container with steel wool in it and a in from my drilled out pcv valve and out to my slash cut barb fitting in my pre-turbo intake

Re: why do some catch cans have a breather
 

the pcv system vents positive crank case pressure. So by having a breather on your catch can you are providing a path for the pressure to escape to atmosphere. If you want to further increase the suction, you can put a slash cut outlet in your downpipe facing backwards, this will draw out the gasses using the suction created by passing exhaust gas. Putting a ball valve in the line to the outlet prevents exhaust venting into the crank case.

Re: why do some catch cans have a breather
 

ya but wouldnt putting a breather on the catch can make hooking up a vac source to it kinda worthless? the vac source would just pull air in through the breather id think

Re: why do some catch cans have a breather
 

its just a good pluss on the jdm ricer scale

Re: why do some catch cans have a breather
 

cool

Re: why do some catch cans have a breather
 

I meant you can use one or the other, not both. Atmospheric pressure is lower then crank case pressure so it'll vent either way, but if you want suction venting to exhaust works.

Re: why do some catch cans have a breather
 

ya i forgot about the exhaust way, i should do that

Re: why do some catch cans have a breather
 

just wondering, does a n/a car's manifold always see vac? or is it at 0 when when the throttle is open like my turbo car before boost

Re: why do some catch cans have a breather
 

n/a engines show about 10inhg at wot so there is a slight vaccume

Re: why do some catch cans have a breather
 

would this work, i think it might work more like a stock system

Attachment 30153

maybe?

Re: why do some catch cans have a breather
 

Exactly, thats the setup I have with 2 pcv valves. I just gutted the stock pcv and bored it running to the lines for the system. Works with both vaccum as would a stock system and vents when under boost.

I have two catch cans (one going to each locaton) just to be safe so oil problems dont happen.

Re: why do some catch cans have a breather
 

so you have 2 pcv's and your stock one is drilled out? right now i have my stock one drilled out but just a catchcan going to my pre turbo intake, which makes some suction not alot, almost none at idle, and i figure the stock system is pulling on the pcv at like 20+ psi at idle thats why i thought of this

Re: why do some catch cans have a breather
 

not unless your throttle body is about 20mm or you're using a crankcase breather filter for an air filter...

Seriously, there's no vacuum left when the throttle plate is wide open in a N/A honda. I can post a video if you guys need it. Long story short, I installed the boost/vacuum gauge before the turbo setup, and now I'm broke, so the setup is very slowly coming together, lol.

Further proof of vacuum @ wot is in CROME. Look at the headings of the columns, and you'll see where WOT is.
-josh-

Re: why do some catch cans have a breather
 

so the pcv doesnt have suction except at idle? i thought wot is when your engine makes the most pressure in the crank case, i guess its just not a big deal or they would have a better way to suck it out or have some pump that would suc it out

pretty much i dont like the smell that comes out of my valve cover filter it comes in through the vents if there on fresh air so i think a one way valve to the manifold on the catchcan would keep it flowing the right way, at least at stops, anyone tried this? what does a stock turbo car use for the pcv system anyways?

Re: why do some catch cans have a breather
 

it won't work. I've tested that like an year and a half ago .. and guess what, the valves don't seal perfect, so at the end you get pressure in the oil pan area, and you oil dip stick starts popin out :)