Read as many thread as I could find, but still am not sure about this with a daily car.

Would you need vacuum to properly vent the crankcase at idle/decel?
Eliminating the PCV, and got a great catch can setup with -6 fittings.

Is it okay to keep the system vta at atmospheric pressure (without vacuum)
or do you think keeping the can under vacuum (with a check valve of course) would be better?

Tried a few things with a friends 1G and he burned an insane amount of oil when hitting boost. Until the can was under vacuum.
(I'm thinking when it was not under vacuum that it was his valve cover ports that werent large enough to handle the volume of the blow by)

 

Bought my Evo brand new. At 7K miles or so I went "vent to atmosphere". At 48k miles before I sold my Evo I had excellent even compression in all cylinders. The intake manifold, pipes and intercooler were all bone dry without any grease or oil residue.

Two things I wish I could have done differently:
1. Vent to atmosphere the second I bought the car.
2. Blocked EGR port and remove completely the day after instead of waiting till 30k miles. But back in April 2007 tuning capabilities were not as advanced as I wanted it to be and or as my knowledge of it.

So my response to you is, you should have done it when you first bought your Evo. I have done a lot of reading on this my conclusion is its only there for emissions purpose. On stock clearance your ok for crank pressure relief. Built motors or I should say "loosely" built motors may need to drill larger vents or multiple vents to satisfy their application. I never had oil dip stick pop out issues.

 

Yes this! I hate that I know I am gumming up my intercooler and everything else

Yea I have seen you in about every thread about this ha
Makes sense to me,
Thanks alot for the info!

 

Great discussion going on right now in the Motorsports section. Go through a couple of pages and everyone starts sharing their tricks on catch can setup ups. From using the exhaust to create a suction under boost to proper hose routing. FWIW it's a good read.

https://www.evolutionm.net/forums/mo...catch-can.html

 

good info there thanks!