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2018 Kia Optima
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929 Posts
Notwithstanding that the PCV in our cars (or in the 2.0T) is a one-way valve--wouldn't the fact that at WOT there is very little to no vacuum in the intake manifold a bigger factor in which port blowby evacuates from the valve cover? I mean, blowby isn't evacuating throught the PCV if there is no vacuum from the intake manifold regardless of whether the PCV is open or closed (or, whether it's a one-way or two-way valve)...no?
 

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Premium Member
2012 Kia Optima SX-T
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1,454 Posts
Notwithstanding that the PCV in our cars (or in the 2.0T) is a one-way valve--wouldn't the fact that at WOT there is very little to no vacuum in the intake manifold a bigger factor in which port blowby evacuates from the valve cover? I mean, blowby isn't evacuating throught the PCV if there is no vacuum from the intake manifold regardless of whether the PCV is open or closed (or, whether it's a one-way or two-way valve)...no?
My understanding is that under significant boost, the PCV circuit is basically stopped due to the PCV valve. There is no flow. So in the OEM case with the "fresh air" side of the valve cover being hooked to the turbo upstream side near the air filter and it is getting some vacuum from the turbo sucking in air, that blow-by from the valve cover can vent back into the clean air side - just where you don't want it - and coating your turbo and intercooler with that oily mist. That was why there was a second OCC on this side of that route as well as one on the PCV side. That was the theory anyway for the product I purchased made for my car (see signature line). My observation is that while I get ~2oz of gunkly fluid (heavy smell of gas) in the PCV side OCC between OCIs, I have NEVER gotten anything on the "clean" air side nor have I ever seen any oily residue in my Injen Short-ram that has this connection to the "clean" side route. Hence, why I don't recommend spending the money on that type of system.
 

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2018 Kia Optima
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929 Posts
So have you (since) removed the OCC on the air intake side (your sig says you're running a two-OCC setup), given your observations?
 

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Premium Member
2012 Kia Optima SX-T
Joined
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1,454 Posts
So have you (since) removed the OCC on the air intake side (your sig says you're running a two-OCC setup), given your observations?
No, I've kept it on since I paid for it and installed it several years back. I just know it really won't pick anything up but "just in case"...

Cool thing was when my engine was replaced by Kia in Dec 2018 under warranty, they correctly moved all my aftermarket parts over for me. I'm just leaving it be.
 
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