BR's dyno testing and new parts development continues...
Jun 27, 2008, 03:18 AM
#76
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PCV = needs vaccum
No PCV = Vaccum not needed
Jun 27, 2008, 03:31 AM
#77
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In stock form, under manifold vacuum, these gases are mixed with fresh air (from the breater vent) and into the IM. Your way completely reverses this, so it's taking a much longer path to be burnt and also using a very weak vacuum source, risking more contamination, such as the water vapor that you mentioned a couple posts up. It is this contamination that the PVC system is designed to remove, using the greatest vacuum source (IM) and the shortest path to the cylinders (IM).
So I don't agree with the idea of keeping a factory setup to help clean the vapors under the valve cover due to fresh air. Where would the fresh air come from?
Vent the breather and vent/disable the PCV. Your engine, intercooler, intake mainfold, ect.... will love you for it.
Last edited by meltdown; Jun 27, 2008 at 03:35 AM.
Jun 27, 2008, 06:24 AM
#78
When the PCV valve opens due to vaccum in the IM that means there is vaccum in the turbo intake pipe as well, which is connected to the breather vent, which would help pull excess gases/vent pressure into the intake pipe. That's why you see oil in the IC. Also think of it that the valve cover is venting pressure through the PCV, it can't have pressure to vent and vaccum to suck in fresh air at the same time.
You see oil in the IC because the breather hose, under boost, is now the only vent the valve cover has to vent any blow-by, etc, that occurs during during a boosted run. If you have excessive blow-by, then you get effects like blowing out dipsticks. The oil vapor that condenses in the IC is from this.
If you don't understand how contaminants like water vapor and fuel vapor can hurt your oil and engine over time, then that's your issue to deal with. If you think that all of this can easily escape the crankcase and valve cover from the tiny amount of pressure that may be there during low-boost cruising and idle, again, I can't change your mind.
My major point to all of this is that a properly running PCV system needs a large vacuum source to properly function. The IM is the logical choice, unless you start running external sources, such as some kind of pump.
Last edited by l2r99gst; Jun 27, 2008 at 06:31 AM.
Jun 27, 2008, 06:42 AM
#79
Meltdown, while wikipedia isn't the best source in the world, it does have a good explanation on how PCV works, so just to help you out, here is the quote from the article:
If you read through all of my posts, you will see that I am describing the same exact thing.
Maybe this will help you understand where the fresh air is coming from and the function of the breather hose while the IM is under vacuum.
The PCV valve is only one part of the PCV system, which is essentially a variable and calibrated air leak, whereby the engine returns its crankcase combustion gases. Instead of the gases being vented to the atmosphere, gases are fed back into the intake manifold, to re-enter the combustion chamber as part of a fresh charge of air and fuel. The PCV system is not a classical "vacuum leak." Remember that all the air collected by the air cleaner (and metered by the mass air flow sensor, on a fuel injected engine) goes through the intake manifold anyway. The PCV system just diverts a small percentage of this air via the breather to the crankcase before allowing it to be drawn back in to the intake tract again. It is an "open system" in that fresh exterior air is continuously used to flush contaminants from the crankcase and into the combustion chamber.
The system relies on the fact that, while the engine is running, the intake manifold's air pressure is always less than crankcase air pressure. The lower pressure of the intake manifold draws air towards it, pulling air from the breather through the crankcase (where it dilutes and mixes with combustion gases), through the PCV valve, and into the intake manifold.
The PCV system consists of the breather tube and the PCV valve. The breather tube connects the crankcase to a clean source of fresh air, such as the air cleaner body. Usually, clean air from the air cleaner flows in to this tube and in to the engine after passing through a screen, baffle, or other simple system to arrest a flame front, to prevent a potentially explosive atmosphere within the engine crank case from being ignited from a back-fire in to the intake manifold. The baffle, filter, or screen also traps oil mist, and keeps it inside the engine.
Once inside the engine, the air circulates around the interior of the engine, picking up and clearing away combustion byproduct gases, including a large amount of water vapor, then exits through a simple baffle, screen or mesh to trap oil droplets before being drawn out through the PCV valve, and into the intake manifold.
The system relies on the fact that, while the engine is running, the intake manifold's air pressure is always less than crankcase air pressure. The lower pressure of the intake manifold draws air towards it, pulling air from the breather through the crankcase (where it dilutes and mixes with combustion gases), through the PCV valve, and into the intake manifold.
The PCV system consists of the breather tube and the PCV valve. The breather tube connects the crankcase to a clean source of fresh air, such as the air cleaner body. Usually, clean air from the air cleaner flows in to this tube and in to the engine after passing through a screen, baffle, or other simple system to arrest a flame front, to prevent a potentially explosive atmosphere within the engine crank case from being ignited from a back-fire in to the intake manifold. The baffle, filter, or screen also traps oil mist, and keeps it inside the engine.
Once inside the engine, the air circulates around the interior of the engine, picking up and clearing away combustion byproduct gases, including a large amount of water vapor, then exits through a simple baffle, screen or mesh to trap oil droplets before being drawn out through the PCV valve, and into the intake manifold.
Maybe this will help you understand where the fresh air is coming from and the function of the breather hose while the IM is under vacuum.
Jun 27, 2008, 11:49 AM
#81
Click on the image to open the putfile site for a larger image.
Hope this helps.
Sorry David I hope you dont mind me posting this so that it can benefit all of us. Hopefully people can understand the stock pcv to get a better understanding of the topic as well as the recirculating catch can.
Hope this helps.
Sorry David I hope you dont mind me posting this so that it can benefit all of us. Hopefully people can understand the stock pcv to get a better understanding of the topic as well as the recirculating catch can.
Jun 27, 2008, 12:53 PM
#84
what ? No one likes my pdf ?
... I don't want this thread to turn into a theory based piece but here is a great link that you guys should read
http://www.honda-tech.com/zerothread?id=1199935
some very interesing stuff in there ,,,, enjoy
... I don't want this thread to turn into a theory based piece but here is a great link that you guys should read http://www.honda-tech.com/zerothread?id=1199935
some very interesing stuff in there ,,,, enjoy
Jun 27, 2008, 01:22 PM
#85
No you said something crazy about vacuum in the intake pipe
Here's what happens:
Under manifold vacuum, fresh air gets sucked into the valve cover from the intake pipe and goes into the mani thru PCV with all the gases from the crankcase.
Under boost crank case pressure builds and pushes the gases and blowby out and into the intake pipe. PCV is closed.
You got it a bit mixed up.
Here's what happens:
Under manifold vacuum, fresh air gets sucked into the valve cover from the intake pipe and goes into the mani thru PCV with all the gases from the crankcase.
Under boost crank case pressure builds and pushes the gases and blowby out and into the intake pipe. PCV is closed.
You got it a bit mixed up.
Jun 27, 2008, 07:15 PM
#86
I have been venting thousands of 4g63's to atmosphere through both valve cover ports for atleast 10 years. I believe that these contaminents and water vapors are text book problems to be dead honest. That is my opinion and if anyone disagrees, that's fine but I don't wish to argue about it, that's for sure as it is just an opinion. We are talking about high performance engines that really shouldn't be going 7500 miles on an oil change. I don't recommend over 3,000 miles when we are dealing with cars over 300 whp on our dyno.
Just venting the hoses to atmosphere has worked perfectly for us, it is just messy and I'd like a way to recover the oil. That is the point of this, I am going to use it, produce it and sell it.
The PCV does not need vacuum to open actually as the engines have enough pressure to push the valve open. If you unhook the hose from the intake and let it lay there you will see it vents without vacuum. The PCV is there so intake pressure (boost) doesn't pressurize the crankcase.
The valve cover breather, I do not believe it sucks fresh air from the turbo inlet into the valve cover, atleast not enough to "cleanse" the area under the valve cover. The engine has too much pressure in it, even a good engine and I do not believe there is ever enough pull from the intake manifold/PCV is high enough to actually pull through the breather hose.
I'd like to test this actually, it would be easy for me to test, I can through a MAP sensor on the breather hose and hook up the PCV to the intake and log it.
Slorice, not sure your example of your Subaru getting oil back in the intake is a good one
That car was always a problem! haha
Blow by on an engine with no boost or stock levels of boost, no matter how good the engine is will be less than an engine running 30+ psi.
We run the two factory vents on our black car and it seems to work well, they just go to a catch can, the car runs 50+ psi of boost.
Just venting the hoses to atmosphere has worked perfectly for us, it is just messy and I'd like a way to recover the oil. That is the point of this, I am going to use it, produce it and sell it.
The PCV does not need vacuum to open actually as the engines have enough pressure to push the valve open. If you unhook the hose from the intake and let it lay there you will see it vents without vacuum. The PCV is there so intake pressure (boost) doesn't pressurize the crankcase.
The valve cover breather, I do not believe it sucks fresh air from the turbo inlet into the valve cover, atleast not enough to "cleanse" the area under the valve cover. The engine has too much pressure in it, even a good engine and I do not believe there is ever enough pull from the intake manifold/PCV is high enough to actually pull through the breather hose.
I'd like to test this actually, it would be easy for me to test, I can through a MAP sensor on the breather hose and hook up the PCV to the intake and log it.
Slorice, not sure your example of your Subaru getting oil back in the intake is a good one
That car was always a problem! hahaBlow by on an engine with no boost or stock levels of boost, no matter how good the engine is will be less than an engine running 30+ psi.
We run the two factory vents on our black car and it seems to work well, they just go to a catch can, the car runs 50+ psi of boost.
Jun 27, 2008, 09:14 PM
#87
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I was always under the impression vaccum was needed to pull the pressure out. But now that I think about it, if the vents are open, there would be no way for pressure to build, really. It would be like trying to fill a bag with a hole in it with water.
I'm thinking now about just VTAing my PCV and breather. I can deal with the mess. There are just so many different opinions on PCV theory about why VTAing is bad and others that say VTAing doesn't do any harm. I just want a 100% for sure answer But thinking about it, I'm not sure how the crankcase would build pressure if there are two open ports. They're really just recirculated for emissions regulations.
Wow. I thought it was mentioned in order to just VTA, you'll need to remove the PCV. I guess if this is the case, it really doesn't matter if it's there or not.
When do you predict these going on sale, Dave? I'm interested in purchasing one That is once the underside of my car is covered with oil from the vent tubes 
I'm thinking now about just VTAing my PCV and breather. I can deal with the mess. There are just so many different opinions on PCV theory about why VTAing is bad and others that say VTAing doesn't do any harm. I just want a 100% for sure answer
But thinking about it, I'm not sure how the crankcase would build pressure if there are two open ports. They're really just recirculated for emissions regulations. When do you predict these going on sale, Dave? I'm interested in purchasing one
That is once the underside of my car is covered with oil from the vent tubes
Jun 28, 2008, 12:54 AM
#90
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The T1(Tony1) catch can system.
Most effective sytem for the Hondas. Works very good on that high rpm/boost pressure application.
It consist of four lines to the valve cover and two returns to the block when there is no crankcase pressure..
Most effective sytem for the Hondas. Works very good on that high rpm/boost pressure application.
It consist of four lines to the valve cover and two returns to the block when there is no crankcase pressure..