Catch can setup.

I just redid my catch can setup and I think it's fine. But for some reason I have this nagging voice in the back of my head to have someone double check me.

OLD SETUP:

PCV Valve -> factory setup.
Breather Vent -> to catch can which was vented to atmosphere through a breather filter.

NEW SETUP:

Both PCV Valve and Breather Vent -> to the same catch can which is ported back into the intake tract between the AFM and the supercharger. Added some plastic pot scrubber medium to the catch can to help condense oil and water vapors from the vented gasses.

Why? After the ECR toy run my car started spewing oil out the valve cover gasket. It was an old gasket that I had reused....twice. (Don't judge me) I had a sneaking suspicion that the PCV valve was also letting boost past and into the valve cover/crank case (bad). So I figured I'd do like I've done on other boosted cars and just point all that crap back to a catch can. I replaced the valve cover gasket and PCV valve, too.

Vented it back to the intake so that the vacuum would help scavenge gasses and recapture metered air.

Of course I capped the port on the intake manifold that used to hook up to the PCV valve.

So...any reason this setup is a bad idea? I think it's fine but I need someone else to tell the nagging voice to shut up.

Seems logical to me and I believe I had mine plumbed that way at one time. I ended up removing the vacuum line going back to the manifold, but I can't remember why.

if you didn't replace the PCV valve with the 323GTX one, then your symptoms won't change.

How so? The PCV system is no longer exposed to any boost. Only vacuum. I would say that drastically changes how the PCV system behaves regardless of the valve used.

John is right, been there, done that. There is a reason Mazda engineered a special valve for the 323 and MSM, they didn't do it for fun.

Quote:

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Originally Posted by mk2tmr2

How so? The PCV system is no longer exposed to any boost. Only vacuum. I would say that drastically changes how the PCV system behaves regardless of the valve used.

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There is significantly more pressure in the intake pipes than negative pressure at the open/atmostphere blower inlet.
http://theory.uwinnipeg.ca/mod_tech/node68.html
specifically:
http://theory.uwinnipeg.ca/mod_tech/img111.gif
The PCV side needs the 323/MSM valve for this reason because the pick-up orifices lies at the back of the head. Any time you're on the gas or especially on the gas and turning left oil is pooling around that pick-up and you're puking oil.

My solution was to plug the intakes side of the valve cover and run a -10 line from the stock hot-side location to a catch can. It works very well. If I didn't make the mistake of welding up the PCV port, I'd still have it with the MSM valve.

You guys rock. Thanks for the detail. Makes perfect sense.

My catch can has been dry since the day the supercharger was installed. Sounds like I'll have to keep an eye on it from now on.

With the way he has it set up couldn't he just install a check valve in the line from the catch can to the intake to prevent any boost from entering the engine through the catch can? Not saying to not use the better PCV as well but I can see how boost could still enter the engine through the port on cam cover on the drivers side.

Quote:

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Originally Posted by Flyin96M

With the way he has it set up couldn't he just install a check valve in the line from the catch can to the intake to prevent any boost from entering the engine through the catch can? Not saying to not use the better PCV as well but I can see how boost could still enter the engine through the port on cam cover on the drivers side.

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I don't see why not, but the MSM valve is cheap and easy. The port on the driver's side is routed to the catch can, I don't see the need for vacuum anywhere sans-dry-sump glory in lieu of the PCV engine eater emissions stuff.

Quote:

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Originally Posted by Flyin96M

With the way he has it set up couldn't he just install a check valve in the line from the catch can to the intake to prevent any boost from entering the engine through the catch can? Not saying to not use the better PCV as well but I can see how boost could still enter the engine through the port on cam cover on the drivers side.

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I don't see how this is possible. With the way it's set up now, my prior issue of boost making its way into the cam cover/crank case is not possible.

I think the issue Wags and brg are referring to is the stock '99 Miata PCV valve allowing too much oil to pass through to the catch can due to the persistent vacuum that it will be subjected to.

Quote:

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Originally Posted by mk2tmr2

I think the issue Wags and brg are referring to is the stock '99 Miata PCV valve allowing too much oil to pass through to the catch can due to the persistent vacuum that it will be subjected to.

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I'd rather not put oil-vapor through the engine because it will cause detonation, ask the Evo guys. You're right, when the valve opens, and you're on the gas, especially in a left-turn, oil will pass through the valve and flood the can. There is a reason Mazda put a valve on one side and not on the other. I learned this the hard way.

So just to be clear, because I sometimes need to have things explained to me as if I'm 12, the MSM PCV valve should make my setup livable, yeah?

And perhaps I need to invest in a larger catch can. I was looking at Gary's setup at ECR and it looks like he can hold about 2 quarts in his :-P

Quote:

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Originally Posted by mk2tmr2

So just to be clear, because I sometimes need to have things explained to me as if I'm 12, the MSM PCV valve should make my setup livable, yeah?

And perhaps I need to invest in a larger catch can. I was looking at Gary's setup at ECR and it looks like he can hold about 2 quarts in his :-P

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I think this is right btu I have not seen your set-up to provide my erudite, revered opinion.

Gary's set-up is nice. I run a -10 line to a Jeg's "oil breather tank" and it works pretty good, holds 7-ounces, and after "fixing" it I only drained about 1-ounce of cappuccino from all day at ECR.

OK I went back to your first post and you are right you don't need a check valve with your set up. For some reason I thought you were getting vacuum from the intake manifold which would see boost.

Gary's setup works is because he removed the metal nipples from the valve cover, tapped the orifice and put -8 lines. He ran the lines above the engine across the firewall and then vented the furthest catch.