Catch can vacuum

[Aproductions]

I am looking at a new catch can setup and was told that it would have too much vacuum during boost which is also bad. Basically it would be a pcv delete and 2 lines from valve cover into the can and then 1 line to the intake. The reason I was told too much vacuum was because from the factory during boost the pcv line closes and you just have 1 line pulling vacuum not 2. Any thoughts on this? I really don't want to run 2 cans

 

[Tyeler18]

Whoever told you this is wrong, you'd have 2 lines to the catch can and one line pre-turbo pulling vacuum. No different than factory under boost really. It'll only draw as much as the single vacuum line can, which even then, is minimal when it's pre-turbo.

Edit- Are you saying intake, as in intake manifold, or intake pipe?

 

[boostdawd]

This by many users is the best way to run a catch can. 2 lines from the cover and 1 to pre turbo intake. There won't be a problem with vacuum. Iv e ran my setup for this for over 2 years on a evo 3 16g @ 24psi with no issues. I also plan on running this setup on my hx35 build.

 

[Aproductions]

Tyeler18.. I mean pre turbo intake sorry. This is for my EVO X and I posted it on the forum and that is what I was told. Like I said his reasoning is that during boost the PCV side closes and it is just the 1 hose pulling vacuum vs the 2.

 

[boostdawd]

U did mention u were doing the pcv delete. Without the pcv valve then

 

[19gsx91]

This is for my EVO X

Your best bet would be to ask the Evo x guys.. the technology in those engines and emissions equipment.. is at least 18 years newer then the newest DSM..

It's something akin to asking which springs to put in an HEI dizzy to control timing advance on a SBC. Your not wrong for asking the question.. but you might want to go where you're going to get the most well informed answer. What works on our cars might not be the same for an EVO X. Hell there is no such thing as a "catch can" in the Subaru world and I didn't even know that until I got my FXT

 

[Tyeler18]

Tyeler18.. I mean pre turbo intake sorry. This is for my EVO X and I posted it on the forum and that is what I was told. Like I said his reasoning is that during boost the PCV side closes and it is just the 1 hose pulling vacuum vs the 2.

Again, you're still restricted by the size of the intake breather hose, as well as the amount of vacuum that can be pulled pre-turbo- which is minimal. With 2 vent lines to the can, and one line to the intake pipe you'll have LESS vacuum on the crankcase than factory with the PCV drawing. Manifold vacuum is significantly stronger than vacuum pre turbo.