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Open Breather Ventilation
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This method is adequate for ventilating crankcase gasses in turbocharged/supercharged cars because the extra blow-by will force its way through any filter quite easily. You want to make sure you provide as many sources as possible to allow the pressure to escape with ease.
For H, F, and D series engines you can use the stock PCV line(excluding the PCV valve), Breather Line, and tap an extra 1-2 ports in the valve cover if wanted. You can attach a filter directly to the line or connect them to 1or2 catchcans with a breather filter on top.
You want to place the catchcan in the highest possible location you can locate in your engine bay. This will allow the catchcan to collect blow-by gasses without consuming excessive oil and allow a drainback line to easily flow oil/gas mixture back into the engine(if you choose to use this feature).
The sole purpose of a catchcan in an open breather system is to "trap" oil and blow-by gasses so they do not contaminate your engine bay and the environment. The surface area in the lines and the catchcan facilitate this. Increasing the surface area by using steel wool or other means will certainly help capturing these gasses but will also restrict them from escaping. The best compromise is to use a baffled catchcan such as one Moroso manufactures.
On B series engines it is preferable to ventilate the crankcase gases through 2 ports located on the back of the block. This arrangement can be accomplished by removing the PCV chamber behind the Intake manifold bracket and sealing the stock Crankcase ventilation hole. If you are running the stock Intake manifold you will want to also plug the PCV port on the Intake Manifold as well.
The Crankcase ventilation hole can be sealed with one of these 3 methods:
1) Aluminum Freeze Plug (34.4mm-34.6mm)
2) Aluminum circular plate epoxied with Devcon Liquid Aluminum
http://www.devcon.com/devconfa...id=34
3)
http://www.z10eng.com/ makes a plug.
It is important that you seal this opening with an Aluminum plug and not a rubber one!
Remove the ports with a 14mm Allen(Snap-on) and install these 2 washers and ports as shown below(Honda part numbers shown):
Use reinforced high temp hose 5/8" ID. Their will be a port on the top of your block which normally connects a line to your PVC chamber. You can either seal this or T it off one of your ventilation lines. The last thing to do is place a small filter on your breather port located on your valve cover.
I ran this above setup for approximately 1 year with no problems. My car was daily driven hard boosting 17-18 psi. I tested this setup using the following configurations:
1) Drain-back feature to the one of the original lines
2) Back to the oil pan
3) Without the drainback feature.
When I removed the drainback feature I would fill the catchcan half full every 2-3 weeks. The evacuation lines would dis-color but never suck oil even when I used the stock Honda fittings without an anti-siphon tube. The contents of fluid collected inside the catchcan was mostly unburnt fuel and contaminants with very little oil. If you are experiencing excessive oil consumption in the catchcan I suggest you place your catchcan higher or do a leak-down test.
I suggest manually draining the catchcan instead of using the drainback feature to eliminate gasoline and contaminants from re-introducing themselves to your oil.
Bottom Line
Cost: 20-150 dollars(dependent upon open filter lines or use of catchcan)
Performance: Good(as long as their is enough ventilation)
Reliability: Good.
Environment: Horrible(no catchcan)- poor(Catchcan)
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Intake Manifold Vacuum Assisted Ventilation
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In Turbocharged vehicles the Intake manifold sees both vacuum and boost pressure unlike in naturally aspirated cars. The PCV valve acts as a check valve blocking any pressure in the rare occasion their is backfire in the Intake Manifold. I have heard that some individuals placing a check valve in-line and allowing the Intake manifold to assist in ventilating the crankcase. The check valve insures that boost pressure doesn't enter into the crankcase through this line.
Ideally one would want to induce a gradual amount of vacuum up to 15 in/hg under full load. Connecting the evacuation line to the intake manifold would do the exact opposite of this. On a boosted vehicle the Intake Manifold will read 25in/hg at idle and 20-15in/Hg in low load conditions and quickly disappear when any moderate to high load conditions appear.
In a stock vehicle this is acceptable because the PCV valve meters the vacuum as shown:
Idle, Low load--- high vacuum pressures fully retract the pintle causing only a small vacuum draw on the crankcase.
Mild load conditions--- vacuum present in the intake manifold is not as strong so the pintle sits in the middle of the pcv valve allowing more vacuum to evacuate the crankcase.
High load + WOT conditions--- their is almost no vacuum present and the pintle is almost completely extended allowing the most amount of gasses to be drawn into the intake manifold.
Engine backfire--- the pintle fully extends and seals to eliminate any gasses from flowing from the intake manifold to the crankcase.
Not only are you pulling excessive vacuum at low load conditions you are contaminating the Intake charge with oil and unburnt fuel blow-by.
I cannot recommend this setup to anyone.
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Intake slashcut evacuation
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Using a slashcut tube to create vacuum is an old trick which works on the Bernoulli effect as air rushes past the tube at high velocities. Make sure you place the slash-cut opening in the opposite direction of the airflow.
One method for evacuating the crankcase is to allow the Intake(pre-turbo) to draw out these gasses. In my tests their was a linear load dependent vacuum drawn using this method. None to insignificant amount of vacuum drawn at idle and low load conditions, moderate load created 0.25 psi(0.5") of vacuum, and high load/WOT created a maximum vacuum of 0.5 psi (1") vacuum. One does not need to use a check valve with this approach as their is never any reason for pressure to force its way into the crankcase.
Their is a positive and negative aspect to this approach. The great thing about this method is that it is the only method which allows one to completely eliminate any blow-by gasses from contaminating the environment. The downside is that it contaminates the Intake charge with oil/fuel/contaminants.
Judging from the amount of contaminants I collected in my open breather catchcan every 2-3 weeks it would be absolutely insane to use this method without a sealed(no open breather element) and baffled catchcan in-line between the crankcase /valve cover and the intake. Keep in mind that most of the contaminants will be sucked into the intake as opposed to only some contaminants trapped in an open breather catchcan while the rest pollutes the environment.
Some good news is that the Intercooler piping and intercooler will act as a very large catchcan and trap most of these contaminants before they reach the engine. The bad news is that I suggest you periodically clean the inside of your intercooler and intercooler pipe.
Bottom Line
Cost: 20-150 dollars(dependent use of catchcan and welding)
Performance: Good(as long as the compressor housing/Intercooler are cleaned
periodically and a catchcan is used)
Reliability: Good.
Environment: Excellent(provided that you use no other open breather elements)
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Originally Posted by mb7050
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