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man i found a catch can that someone was selling i beleive and now i cant find it. he had a picture of the catch can against the fire wall. it had a breater filter on it and it was kinda long. I beleive it was silver but you could get it in black.
 

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Option #1 does nothing for you. You need to use Option #2 or #3. I plan to do this :

- using moroso catch
- putting a few feet of chain link from home depot/lowes in the bottom of the can to act as additional baffling
- my catch can only has the following connections: drain plug on bottom, one inlet on side, port on top for breather filter.

- plug breather filter opening with a rubber plug
- place a generic pcv in the rubber plug
- remove pcv on block
- put a fitting in the block to take pcv's place
- route block -> inlet on can
- route pcv mountd in can -> intake manifold

I just need to find a good place to mount the can.
Can you please tell me the exact size of the fitting I need to get to replace the PCV valve? I know the barb will be 3/8'' but what about the actual thread size that will go into the block?
 

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I'm planning on running an open system. I've read all the pages in the thread and just need some clarification.

This is how i plan to run the system (I'm N/A)

- Replace the OEM PCV with a barbed fitting
- Run a line from the barbed fitting to the catch can
- Run a line from the valve cover to the catch can

So basically like this...

Barbed fitting ---> Vented CC <--- Valve cover

The catch can will be baffled with a breather on top. Will this setup work? (i don't care if its not emissions friendly)
 

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here is a pic of my set up... two catch cans + a radiator reservoir

Your setup appears to be the 100% right way to do it. I have gutted stock PCV on block (basically a hose barb now)>CC>generic PCV>IM and the valve cover is still routed to the intake hose. I have an oil slick coming from the nipple on the intake hose and going into the throttle body. So, I'm going to go with the dual can setup so everything functions right. Do you run a PCV on your setup? Where do you have it? Thanks in advance!!
 

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PCV/breather/catch can threads are always amusing b/c of how people love to ignore some simple basic facts.

1) Think about under what conditions the PCV opens. When there is positive crankcase pressure. This occurs when highly pressurized combustion gasses make their way past the rings.

2) Think about what the breather port does. Obviously, it is always open. It is a passage to the airspace under the valve cover. But guess what, the airspace under the valve cover is also linked to the airspace in the crankcase by virtue of the oil drain holes and the air space for the timing chain. It is all connected.

3) Think about the conditions in the intake pipe/manifold. Typically, there is vacuum in the intake manifold/intake pipe. At WOT, you can get close to neutral pressure if not a slight amount of positive pressure.

Now, you have to tie all those conditions together bearing in mind that you want:

a) neutral pressure or slight vacuum in the crankcase, you do not want excessive vacuum as it will create more blowby.

b) vacuum under the valve cover, this keeps excessive oil from seeping past valve stem seals.

c) you do not want oil to enter into the intake air.


To address concern a), you NEED the PCV valve in place if you are connecting the crankcase to a vacuum source. Because of how the PCV is sized, I would not recommend simply going to an open port to allow passive venting of crankcase pressure. Without the aid of vacuum, positive crankcase pressure may not be relieved quickly enough. In short, the PCV should be retained and it should be hooked up to a vacuum source. Unless you are planning to enlarge the PCV hole to allow for sufficient passive ventilation of the crankcase to atmosphere, don't mess with the PCV system.

To address concern b), you need to have the breather port on the valve cover hooked up to vacuum all the time. The closest you can get to that is to hook it up to the intake. Note the size of the breather port. It is fairly large because it is the PRIMARY way of controlling crankcase pressure. The PCV is essentially an assist to ensure pressure in the crankcase has a more direct outlet if needed. The breather indirectly vents crankcase pressure via the oil passages & air space around the timing chain.

To address concern c), you need a catch can to collect the oil vapor in the crankcase fumes. The catch can should have two inlets and one outlet with some type of baffling/filtration inbetween. Connect the outlet to the intake. Connect the PCV and Breather to the inlets. Make sure your ports are sized accordingly! If you have tiny little ports on your catch can and you hook up the 3/4" valve cover breather to it, you are severely affecting the vacuum applied to the air space in the crank case.

Now, what I've presented above isn't a complete discussion. To complete your understanding, you have to consider one more thing. What if you are engine braking? Then there is just massive vacuum in the cylinders. This happens because the throttle plate is closed and very little air can be drawn in via the idle air passages. This vacuum in the cylinders creates vacuum in the crank case b/c ring seal is not perfect and the valve stem seal is not perfect. In that specific situation, air flow will reverse through the breather because there is more vacuum in the crank case than there is in the intake pipe. Air will be drawn into the crank case via the breather. Surprise, surprise, this is why there is no one way valve on the breather like there is on the PCV. Airflow through the breather is bi-directional.

More or less, there is no need to re-work the stock system for 99% of all cars, stock or modded. The most beneficial thing you can do is add a catch can to capture oil vapors without altering the routing of airflow of the stock system.
 

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there certainly is alot of information
and the thread is quite old so im guessing thru trial and error there would be a wealth of knowledge

so can we simplify it if possible

if i do not care bout emissions, what is the best system?

and if i do care bout emissions, what is the best system?

pictures or diagrams would be much appreciated
 

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PCV/breather/catch can threads are always amusing b/c of how people love to ignore some simple basic facts.

1) Think about under what conditions the PCV opens. When there is positive crankcase pressure. This occurs when highly pressurized combustion gasses make their way past the rings.

2) Think about what the breather port does. Obviously, it is always open. It is a passage to the airspace under the valve cover. But guess what, the airspace under the valve cover is also linked to the airspace in the crankcase by virtue of the oil drain holes and the air space for the timing chain. It is all connected.

3) Think about the conditions in the intake pipe/manifold. Typically, there is vacuum in the intake manifold/intake pipe. At WOT, you can get close to neutral pressure if not a slight amount of positive pressure.

Now, you have to tie all those conditions together bearing in mind that you want:

a) neutral pressure or slight vacuum in the crankcase, you do not want excessive vacuum as it will create more blowby.

b) vacuum under the valve cover, this keeps excessive oil from seeping past valve stem seals.

c) you do not want oil to enter into the intake air.


To address concern a), you NEED the PCV valve in place if you are connecting the crankcase to a vacuum source. Because of how the PCV is sized, I would not recommend simply going to an open port to allow passive venting of crankcase pressure. Without the aid of vacuum, positive crankcase pressure may not be relieved quickly enough. In short, the PCV should be retained and it should be hooked up to a vacuum source. Unless you are planning to enlarge the PCV hole to allow for sufficient passive ventilation of the crankcase to atmosphere, don't mess with the PCV system.

To address concern b), you need to have the breather port on the valve cover hooked up to vacuum all the time. The closest you can get to that is to hook it up to the intake. Note the size of the breather port. It is fairly large because it is the PRIMARY way of controlling crankcase pressure. The PCV is essentially an assist to ensure pressure in the crankcase has a more direct outlet if needed. The breather indirectly vents crankcase pressure via the oil passages & air space around the timing chain.

To address concern c), you need a catch can to collect the oil vapor in the crankcase fumes. The catch can should have two inlets and one outlet with some type of baffling/filtration inbetween. Connect the outlet to the intake. Connect the PCV and Breather to the inlets. Make sure your ports are sized accordingly! If you have tiny little ports on your catch can and you hook up the 3/4" valve cover breather to it, you are severely affecting the vacuum applied to the air space in the crank case.

Now, what I've presented above isn't a complete discussion. To complete your understanding, you have to consider one more thing. What if you are engine braking? Then there is just massive vacuum in the cylinders. This happens because the throttle plate is closed and very little air can be drawn in via the idle air passages. This vacuum in the cylinders creates vacuum in the crank case b/c ring seal is not perfect and the valve stem seal is not perfect. In that specific situation, air flow will reverse through the breather because there is more vacuum in the crank case than there is in the intake pipe. Air will be drawn into the crank case via the breather. Surprise, surprise, this is why there is no one way valve on the breather like there is on the PCV. Airflow through the breather is bi-directional.

More or less, there is no need to re-work the stock system for 99% of all cars, stock or modded. The most beneficial thing you can do is add a catch can to capture oil vapors without altering the routing of airflow of the stock system.
Ok, this all sounds right to me but I have one question. When you say to tie the breather and pcv together onto the catch can and hook it to the intake, you mean the manifold, not the intake pipe, right?
 

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PCV/breather/catch can threads are always amusing b/c of how people love to ignore some simple basic facts.

1) Think about under what conditions the PCV opens. When there is positive crankcase pressure. This occurs when highly pressurized combustion gasses make their way past the rings.

2) Think about what the breather port does. Obviously, it is always open. It is a passage to the airspace under the valve cover. But guess what, the airspace under the valve cover is also linked to the airspace in the crankcase by virtue of the oil drain holes and the air space for the timing chain. It is all connected.

3) Think about the conditions in the intake pipe/manifold. Typically, there is vacuum in the intake manifold/intake pipe. At WOT, you can get close to neutral pressure if not a slight amount of positive pressure.

Now, you have to tie all those conditions together bearing in mind that you want:

a) neutral pressure or slight vacuum in the crankcase, you do not want excessive vacuum as it will create more blowby.

b) vacuum under the valve cover, this keeps excessive oil from seeping past valve stem seals.

c) you do not want oil to enter into the intake air.


To address concern a), you NEED the PCV valve in place if you are connecting the crankcase to a vacuum source. Because of how the PCV is sized, I would not recommend simply going to an open port to allow passive venting of crankcase pressure. Without the aid of vacuum, positive crankcase pressure may not be relieved quickly enough. In short, the PCV should be retained and it should be hooked up to a vacuum source. Unless you are planning to enlarge the PCV hole to allow for sufficient passive ventilation of the crankcase to atmosphere, don't mess with the PCV system.

To address concern b), you need to have the breather port on the valve cover hooked up to vacuum all the time. The closest you can get to that is to hook it up to the intake. Note the size of the breather port. It is fairly large because it is the PRIMARY way of controlling crankcase pressure. The PCV is essentially an assist to ensure pressure in the crankcase has a more direct outlet if needed. The breather indirectly vents crankcase pressure via the oil passages & air space around the timing chain.

To address concern c), you need a catch can to collect the oil vapor in the crankcase fumes. The catch can should have two inlets and one outlet with some type of baffling/filtration inbetween. Connect the outlet to the intake. Connect the PCV and Breather to the inlets. Make sure your ports are sized accordingly! If you have tiny little ports on your catch can and you hook up the 3/4" valve cover breather to it, you are severely affecting the vacuum applied to the air space in the crank case.

Now, what I've presented above isn't a complete discussion. To complete your understanding, you have to consider one more thing. What if you are engine braking? Then there is just massive vacuum in the cylinders. This happens because the throttle plate is closed and very little air can be drawn in via the idle air passages. This vacuum in the cylinders creates vacuum in the crank case b/c ring seal is not perfect and the valve stem seal is not perfect. In that specific situation, air flow will reverse through the breather because there is more vacuum in the crank case than there is in the intake pipe. Air will be drawn into the crank case via the breather. Surprise, surprise, this is why there is no one way valve on the breather like there is on the PCV. Airflow through the breather is bi-directional.

More or less, there is no need to re-work the stock system for 99% of all cars, stock or modded. The most beneficial thing you can do is add a catch can to capture oil vapors without altering the routing of airflow of the stock system.
Awesome post - I've read the rest of the thread and have got terminally confused and this seemed to make so much sense :) The only question I have is about the 2 inputs and one output. I was expecting to have a set up rather more like 6sp_ek - i.e. keeping all the pressures and flows the same by just placing the catch tanks in the original pathways (Vent -> Inlet and PCV -> IM)

I'm also a little confused why the PCV moves around in some people's set up - why does it not just stay in it's original location?

Many thanks

Miles
 
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