The mist will eventually saturate the breather and drip oil on shit.

This is my catch can. My vacuum is pulled from that ugly top fitting. I would put it in a different spot next time. If you really wanted a atmosphere only section, I could do that too.https://www.miataturbo.net/attachmen...ine=1461878908

Got it. Like your setup, what kind of can is that?

Also, taking it a step further as has been mentioned here, what would the added benefit be of running that can to the intake tube, and at that point would it still use a vented setup or be closed?

This is working pretty well. It's the stock setup with a catch can on each circuit:
https://www.miataturbo.net/attachmen...ine=1461304011
Hey look its even emissions legal!
https://www.miataturbo.net/attachmen...ine=1461304011
Driver's side is an attempt to make a 2 way can so that it can catch oil in boost and breathe air in vac.
It is working well for now, we'll have to see how it does on the track. If I see oil getting to the compressor, I'll devise something to vent to atmosphere for offroad stuff.
https://www.miataturbo.net/attachmen...ine=1461304011

https://www.miataturbo.net/attachmen...ine=1461304011

https://lh3.googleusercontent.com/-P...419_193935.jpg

https://www.miataturbo.net/attachmen...ine=1461304011

https://www.miataturbo.net/attachmen...ine=1461304011

https://www.miataturbo.net/attachmen...ine=1461880446

Talking to me? If so, it's my can. I make them. Should have added the pic of my intake venturi.

https://www.miataturbo.net/attachmen...ine=1461880293

You are required to plum the crank vent back to the intake post-maf for the same reasons you need a recirc BOV, any air going into the engine needs to be metered, even if it passes through the block to get there. If you run speed density there's really no benefit other than the chance of burning oil unnecessarily.

Whatever intake plumbing vacuum you might generate probably isn't going to do much in assisting venting the block, that'd be the only real reason to plumb it back.

I'm not sure about that. But maybe. All I know is that when I blew a shop Vac past my venturi, I was picking shit up off the floor with it.

I think you were posting at the same time I was, I hadn't considered a venturi. An open ended hose barb was more what I was thinking.

No, that was for the guy I quoted. Just trying to figure out the driver's side

So a friend of a friend who also does track (although in an awesome S2000), was making a heat shield for my turbo today and was having a hard time understanding how this system works. He says (and it makes sense) that under boost, the system is doing nothing because it is closed, and forcing air out through the exhaust side vent. Here is my setup for reference, it has been done numerous times here. His suggestion was to gut the PCV, and run both sides of the valve cover to a catch can with a breather on it and call it a day. I did have it set up that way before, oil came back with higher than desired fuel content, although not terribly high. The flashpoint was also off, and this is oil that was not used on the track. He says the reason my can is usually empty is because under boost, it's not actually catching anything, only at idle, decal, out of boost, etc.

https://www.miataturbo.net/attachmen...ine=1462328508System uses a working PCV, into the can, then connected back to intake manifold

He is wrong. Gutting the PCV is the last thing you want. That pressurizes the crank case and does a whole bunch of other junk. The purpose of a PCV is to pull clean air in when it should, and stop pressurized air going in when it shouldn't.

If your catch can isn't catching much then that is a good sign. You don't have a lot of blowby, and maybe you don't have a lot of crank pressure.

Understood, so what about the people who ARE running both sides of the valve cover to a vented can? Are they messing with the baffles inside the cover to correct some of this?

Try it and report back after a track day ...

The definitive "How do I catch can?" thread.
 

I am running both sides to a catch can directly with no valves. I have only had as much is half a pint of oil after a track day. Not very much. I am currently changing over to larger fittings and hoses between the valve cover and catch can to reduce the speed of the air through the hoses so that less oil will be carried to the catch can. I'm using a weld in bung like the one that Ryan G used on his valve cover. I will look up the part and post it here later when I get a chance.

Thank you shooter! The understanding that i have is that you can run the setup you have, or dual cans, and achieve a similar effect. From what I read here, my friend was right about the intake side system closing off under boost, so if I understand correctly I can either run the setup like you (both sides of cover to can) or like me (one can between PCV and IM and one can with a breather for the exhaust side).

Seems like my setup may be more emissions friendly as I heard the setup you have is not as friendly to oil. I don't particularly care about changing oil since I run cheap t6 anyaway, but I don't want to run fouled oil which won't protect my bearings as well.

Sorry if I'm beating a dead horse here guys but this is probably one of the most confusing things I've set up so far and there is clearly more than one way that works.

Yes, those really are your two options. I came from the muscle car world into this and everyone there ran breathers on both valve covers and no PCV ever. The problem I have always had with PCV valves has been the oil that gets into the intake manifold. I have seen enough of the crusty orange-brown trails along the insides of intake manifolds where the PCV hose attaches. I know that oil and oil vapor have a significantly lower octane rating than gasoline. I also know that the deposits from the burned oil leave carbon crust on pistons and valves which create hot spots and promote detonation. I have heard the argument that the PCV valve only allows vapor to enter the intake manifold when the vehicle is decelerating but I don't believe that the oil trail inside the manifold and intake ports magically disperses once the throttle is opened. I know that the carbon crust within the combustion chamber certainly does not disappear with the application of the throttle.

I understand that some here have submitted the argument that the purpose of the PCV is to bring fresh air into the engine, but I propose that the on throttle blow by events generate far more gas volume than the PCV is capable of consuming and occur when the PCV valve is designed to be closed. The PCV valve is an emissions device designed to reduce hydrocarbon release from the crankcase during idle and part throttle cruise events. It does not aid us at all when we are in positive manifold pressure or are neutral with atmospheric pressure.

It is definitely important to allow the pressure within the crankcase to escape so as not to push out the oil seals and gaskets. It is also important for the combustion by-product gases to escape as well as moisture in the form of water vapor. It is my opinion is that it is not the purpose of the PCV system to introduce fresh air to the crankcase for any other reason than to allow the extraction of gases harmful to the environment. I do not believe that the system is designed to introduce fresh air to the crankcase for any specific reason related to the proper operation of the crankcase, especially with the large volume of gasses attempting to escape the crankcase when operational.

Both valve covers to catch can that is vented. Worked well on my 700whp stang.

Ive just build 25 of these, USD is pretty damned strong compared to ours (75 cents), do you reckon anyone here would be interested?

https://scontent-lax3-1.xx.fbcdn.net...25&oe=5800FAF3

https://scontent-lax3-1.xx.fbcdn.net...25&oe=5808B9DD

https://fbcdn-sphotos-e-a.akamaihd.n...f069a452f07ed0

https://fbcdn-sphotos-e-a.akamaihd.n...a3ccf452f6d123

https://scontent-lax3-1.xx.fbcdn.net...78&oe=57FFBD6E

https://fbcdn-sphotos-g-a.akamaihd.n...ce97dee81d5d3d

https://scontent-lax3-1.xx.fbcdn.net...65&oe=57E9DD27

What does the inside look like? Does it have any baffles or false floor for drip collection? Filter media?

The outside looks really nice. Sweet welding.

Yeah, 3 separated chambers and packed with steel wool.

Here is the spiel I posted on the aussie groups.

Included in the package:
-Catch can with 3 baffled chambers with steel wool filling and dash -06 AN weld on fittings, bracket to bolt it to the OEM thread as pictured.
-Drain valve, with 1m silicone hose and P clamp to secure drain hose under car.
-Double sided foam tape block (5mm thick) applied to the bottom for secure mounting.
-Mounting bracket to suit OEM 8mm thread on body (check the last pic).
-Breather filter, silver in colour, polished, hose clamp to suit.
-Raceworks AN pushlock fittings, 2x 45*, 1x straight, 1x 90* female junction, 2m E85 ready -06 hose to suit.
-Zipties, 3x small, 3x medium, to secure hoses.
-Vacuum bung to seal the now unused intake manifold port.
-NitroDann Sticker (20x200mm).