It won't cause damage necessarily, but there won't be clean air to cycle blowby gasses out of the crank case. It can contaminate the oil (by my understanding) but that's easily remedied by more frequent oil changes.

An oil catch can in conjunction with a breather filter would be the proper way of doing it. Personally, I don't see the point other than engine bay bling. The amount of oil sucked into the intake is so minimal that you won't notice any difference in power.

 

Yeah by running that open, that PCV breather is gonna suck unfiltered air into your crankcase. Now sure, it's not being combusted in any way but it is coming in direct contact with your engine oil and everything outside the cylinders.

If you pay for synthetic oil and good oil filters and air filters and so on, to me it would make sense to add this additional protection to your engine so you're filtering it at all entry points.

For an RSX I think you need a 0.75" ID one, like:
https://www.kseriesparts.com/VIB-2164.html
https://www.kseriesparts.com/KN-62-1360.html

 

Yea I ordered one of those..I may sound stupid but when I turned on the car it was pushing air out of the hole not sucking in

 

Here's an idea.

 

I don't claim to fully understand it, but, the PCV loop is using that port as an intake during the conditions that incur blow-by, which is during WOT (at least). So during idle, yes, apparently the vacuum isn't present and thus there is air coming out, but that is not the path of the oil vapors (it's in through the port over by the alternator that runs to the intake manifold).

 

3.5" velocity stack filter combos sound amazing compaired to cookie cutter standard sri and cai straw with filter design. IMO, most cai's are actually too long.

 

I think your right about the off the shelf cai piping being too long. From my experience and just going based off of how the car feels, it responds well to short piping. I think the key is keeping the piping and the air filter as level as possible with the throttle body.

 

Another view, our pleniums are small in comparison to others. At high rpm's, if there isnt enough air stored in the oem plenium there is less piping to the velocity stack I am using to fill it back up. To me keypoint is sri intake with ram air is king

 

Back to the OP's original post. If you have a spare valvecover laying around notice the breather is isolated in it's own cavity inside the VC. There is a small vent into the rest of valvecover on the opposite side of the breather's positioning. So when I see VC's all drilled out with extra hoses coming off to a breather tank, I question did they tap into the isolated cavity? And is air correctly being drawn into the engine like Honda designed it?

You guys want me to post a pic of this cavity I speak of?

 

Sure! Yes, please, since most of us don't have one lying around, and especially since this thread is turning to gold real quick :thumbsup:

I had lots of aspirations to explore ram air methods or at least feed an air box with velocity stack inside, etc., but then I found an Injen CAI for next to nothing on CL so I just had to go with it

 

I have a AEM cai and then I tried out sri, I would rather have a 3.5" velocity stack sri filter combo. I am still fabricating ram-air airbox, the SRI still has HP available
.

 

Valvecover breather cavity ( inward directional flow )

Opposite side of breather attatchment, the exit port is shaped with a 45 degree angle lip to mimic "venturi vacuum assistance" I am guessing. The additional 2 exit ports opposed from venturi port are there to allow more air in once velocity gets going.

After studying this more and more, it is not just so simple to drill holes in a valvecover, weld a thread-o-let on, and hook up hoses plumbed to a square breather box. Honda put the 45 degree venturi lip for a reason. Leading to if the thread-o-let does not enter into this cavity by ( piping ) with fillet welds at/on the VC & at least fillet welded @ the cavity wall, the newly added vent hoses may not work as planned. IMO, even if this is done correctly, I would want to add an in-line vaccum block b/t breather tank and valvecover, that is venturi assisted.

If someone feels I am overthinking this or wrong please correct me. Still I would ask them did they know the valvecover cavity exists and how can they prove just by adding breather hoses and breather tank set-up functions properly. I would rather follow Honda's footsteps and add on from there.