Using the pre-turbo pipe as a vac. source can be bad because the oil vapors lower the octane rating of your fuel, resulting in detonation.

 

Then which could be a good vac instead of that pre-turbo line

 

Thats why you use a catchcan. I dont understand why you would want a vented catchcan anyway? you're vaccum source would just suck through the vent in the catchcan and lower the vaccum on the crankcase.

 

On my last diagram vac are taken from intake mani before boost, and from pre-turbo intake at boost, then, i was thinking this setup work better for vacuum under boost from pre-turbo intake if i use a non-vented setup, because from pre-turbo it suck air from the catch can (at boost suck air from crank case and intake mani) and if i use a vented setup also is going to suck air from the air filter reducing the vac pressure from pre-turbo.

 

A catchcan won't trap vapors, just liquid oil.

 

Here i attach an image showing what im talking about.

People says crank case must be in vac all the time

On number 1: intake mani suck air from crank case as stock before boost
On number 2: in boost the intake mani becomes presurized, so now we need another vac source, thats the reason we use pre-turbo intake as vacuum

 

Just set it up like that and throw a catch can somewhere in the mix. Otherwise how you have yours setup will end up with a massive vacuum leak out of boost.

 

dude thats one of the cheapest ones i have seen so far

 

i still say this design my buddy and i came up with is the best.



-Luke

 

I ran my BOV line to the old PCV manifold fitting. Then I ran the PCV and valve cover to the catch can which is sealed, and ran a vacuum line from the catch can to the turbo intake. I'll get some pics.