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Oil Catch Can question/opinions

2K views 4 replies 2 participants last post by  blackmica 
#1 ·
Hello,


I'm planing to add an oil catch can to my speed 6, I want to merge the valve cover and crankcase fumes into one OCC and then split the clean air back into the two inlets. What do you guys think of my setup (t-fittings, PCV valves, check valves, etc.)? Is it any good? Too complicated? I'm better off with two OCCs? Please chime in.



http://i1277.photobucket.com/albums/y484/Average_Joe7/PCV setup_zpssnpeev9q.png~original


Thanks :)
P.S. I kinda don't want to vent to atmosphere
 

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#2 ·
Would you mind explaining the difference between your setup and how an oil catch-can would typically work?

If you won't be venting into the atmosphere, where will it go? Making sure your engine is in good shape, not burning oil or running rich, cats are in good shape, refraining from revving the engine hard all the time are all more effective ways to help the enviroment.

Now, what I do know about having an oil-catch can is that using a thicker oil/ one that is resistant to oil consumption really helps lower blow-by. I would suggest taking a look at Motul 5W40, it is a very good oil. Pricey but worth every penny.
 
#3 ·
No, I wouldn't, well, if you're gonna be venting the crankcase you'll have a PCV valve that only lets oil vapours out and not in (already there from Mazda), then the hose will go to the OCC where it gets filtered (provided it's a proper OCC and not just an empty can) and then out from the OCC to a check valve or a PCV valve that would let air (now filtered) go into the intake manifold but not back to the OCC (hence the one-way check valve) because you don't wanna pressurize the OCC and you don't wanna lose boost. That's one way to properly do it as far I understand. Feel free to correct me.


It will go back into the engine (where it now goes) but it will be clean air instead of oil vapors. My engine has just been rebuilt, so everything is to factory spec. Cats are excellent and I'm not revving it all the time, I mostly drive normal with the occasional overtake or spirited driving on the local mountains. And I don't care that much about the environment anyway, but I'd prefer not to pollute it if it's possible. Also, venting to atmosphere is OK as far as I know, because the oil vapors mostly stay in the can, only a very small percentage leak out through the little filter (as far as I know).


I'm already using 5W-40 oil, but it's Liqui Moly. I have tried Motul in the past on my Honda but it's just too expensive for me. The Liqui Moly is good enough, I think.








The point where I get lost is when you combine the crank case vapors with the valve cover vapors, because in the crank case there's more pressure than in the valve cover, so I was guessing that I'll either need a check valve so that crank case vapors don't go to the valve cover or add a second OCC with its own loop. But I don't really want to have two OCCs in the engine bay so that's why I wanted to merge the crank case vapors and valve cover vapors (or blow-by, whatever) into one OCC, but I just wasn't sure if I'm missing something. Seeing as basically every line will have it's own check valve (two PCV valves in the case of the crank case - HA!), I think that it should be OK, but I just wasn't sure.


How do you guys vent the valve cover? You have two OCCs or you just don't vent it?
 
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