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?