What did you do to the exhaust side vent? Did you put a catch can there to?
If you have excessive blow by you will get a lot of oil coming out of it even with your setup, or little to none if the engine is healthy.

I put a breather there and am not getting any oil out of it. Also someone told me via PM that if I had excess blowby I'd notice my dipstick popping out. I set the can as in the photo and spent 2 days doing normal commuting and some boost runs on the highway, just having fun.

Can is empty (dipstick had oil vapors on it) but the can itself has nothing in the bottom, breather is dry, dipstick staying in place. I got my Blackstone results yesterday and the fuel content was 1.5%, they said under 2% is not a concern.

Look like you are in good shape now, just keep an eye on the catch can and empty it if it has anything.

Is the valve cover "mod" in post 118 in any shade effective?

For those with a slash cut. Do you draw vacuum on both sides with the exhaust or do you leave the intake side on the IM to get good vacuum at idle/overrun?

I think that is an either/or proposition.

I was drawing a bit from what Bob ran into with his car. It looks like he ended up just running the exhaust side vent and plugging the intake side. If I do end up doing this I'll try and get some with/without dyno plots since there doesn't seem to be much in the way of evidence (on a BP) of the power claims behind running the crankcase under vacuum at WOT.

https://www.miataturbo.net/general-m...e5/#post717141

Just provoking thought here, but has anyone tried something like this?


https://www.miataturbo.net/attachmen...ine=1439260598

I just made the passenger side pcv vent tube pick up from closer to the roof of the valve cover. in my brain, late at night it made sense. what do you guys think? Im still going to use the driver side too, but i was thinking and had to try this.

I think that is why bob plugged his intake side hole, pouring oil out in long sustained corners.

I can't make mine do it, and I'm not at all surprised Bob can...

I like that, it's cleaner than poking a hole in top like my plan.

Update on my dual catch cans...
I've run the car for approximately 6000 miles (all street) with this setup. One can between the valve cover and intake and the other between the valve cover and pre throttle intake tubing. All of these miles were unboosted. Never got more than oil residue in the can between the valve cover and pre throttle intake.

Now I've been boosted for 200 miles and have accumulated some liquid in the pre throttle side can. This confirmed my suspicions that when boosted, you will get oil out of that side of things.

I had considered just rigging both cans up for two stage separation on pcv side. Now I will certainly keep them separate to keep oil out of the intercooler.

Other notes: I'm running a check valve in tandem with the pcv to be certain no boost is leaking through the (GTX) pcv. I'm pretty certain the GXT valve was still letting boost by.

I just got an e-scavenger bung welded to the exhaust but is capped for now. My driver side vent condenses oil vapor all over the place and I really would love to figure out a solution to this. I was still pulling oil in with a check valve on the PCV but can try again. I just really want to isolate the crank case from the intake and my car is emissions exempt this year.

Has there been a definitive yes/no on what works and doesn't? People seem to go back and fourth to the point where YMMV with any setup regardless of others' experience.

I'm thinking taking the driver side to catch can/vacuum via slashcut/evap then the PCV side to catch can/atmo in effort to avoid Exxon Valdez left corner potential

So my can from the PCV to the intake manifold is working good, but I had a small issue on track yesterday. Not sure what caused it but my second run, my breather which was just dangling somehow fell off and started melting under my exhaust manifold. I then noticed that I had a little oil coming out of the exaust side hole (maybe from all the right hand turns on the track). I don't know if the oil splashes all over the TOP/REAR of the valve cover are from vapors pushing from that side (maybe needs a can like you said) Heat from the turbo is also cooking the valve cover gasket so that will need replacing, as you can see that leaking DOWN.

https://www.miataturbo.net/attachmen...ine=1461876996
Black spot above runner 2 is rubber from breather, not oil from the valve cover. PCV valve in this pic is gutted and was just used as as adapter to fit the larger breather onto the smaller bung.

My question on the exhaust side port is isn't that supposed to be a fresh air source for the crankcase? At idle, I can feel tiny puffs of air coming from it, not sure what it's doing when I'm driving. Never had issues with that side before, but the track I was on has a steep fast 180* right hander that might be pushing oil out that side, but this is only my second track event also, so I'm just speaking theoretically. I don't know if there's blow-by passing the rings, but the car sounded perfect when I started it this morning cold, no knocks, and oil pressure after the track has been spot on (drove 200 miles after to get a hardtop for my car too). Have some mis-fires but I think those are related to plugs, cause I was shooting fireballs all over the track once the car was really hot.

Anyway, my tuner suggested that perhaps a second catch-can between that exhaust side port and the intake tube would be beneficial. I am happy with my intake side can and how it works (collected 1.5oz over 2000 miles and 1 track event). What is the purpose of the exhaust side to intake tube can, and what do you make of the puffs of air im seeing? I never checked before, so it might have been doing them since the engine was built for all I know. Blackstone sample will be sent next week.

I have oil vapor coming out of that filter, it condenses on a lot of things and ends up dripping onto my manifold when it cools. That being said, my PCV just kinda floats and there is no vacuum in the crank case right now

Me too. Thats blowby. It saturated my filter on there.

So i did this

https://www.miataturbo.net/attachmen...ine=1461877433
https://www.miataturbo.net/attachmen...ine=1461877433
https://www.miataturbo.net/attachmen...ine=1461877433

It's a vent for fresh air untill the PCV valve on the intake side closes, then it is the only crankcase vent available to all blowby. The only reason you need a driver's side catch can is if you must hook the vent up to the intake, like with a maf or afm, and you don't want oil in the intake. Otherwise all it does is keep down on oil smells on hard boost pulls. Blowby is inevitable, it's nothing to worry about if it's not pushing seals or massive oil amounts out of the block.

Why do you have what looks like a PCV valve on the driver's side vent, or is that just what's left of the filter?

Looks like a pcv valve to me.

It does more than keep oil smells down. My valve cover and manifold got coated in oil and junk.

The breather I used was too big for that port so I used a gutted PCV as a reducer since it was the only thing I had laying around.

I run two catch cans, you need air going into and out of the exaust side port so you will need to take out that pcv valve and plumb it to a vented catch can

I'd say all you need then is a hose with a filter away from heat, and a catch can if you can't handle the oil mist.

If you want to cut down on the oil mist you'll probably need to pull the valve cover and do some modding to assist oil drainage. You need enough room for blowby to vent, but still enough room that returning oil isn't picked up and carried out with the evacuating blowby.

The PCV is just a reducer, nothing inside it.
So the mist is nothing to worry about? I guess before when I had the breather on it I just never noticed, but once it fell off, there was nothing stopping that mist from going all over.