Vaccum assisted Engine Ventilation
10-11-2006, 03:31 AM
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Vaccum assisted Engine Ventilation
I know there are couple different ways to do this. I had a discussion about this and learned something new to me i'd like to understand better.
Lets say you run pcv valve to vaccum source while leaving breather valve open. If breather valve is open (with or without the filter), does that mean you'll never be able to achieve vacuum because one source is open?
In my setup i would leave breather valve open, then connect the pcv valve to IM through check valve so it shuts under boost. but from what i was told, it doesn't matter if i connect pcv valve to vacuum source (IM or compressor housing), as long as i have breather valve exposed to atmosphere, there won't be any vacuum therefore defeating the purpose of connecting pcv valve to anything.
Lets say you run pcv valve to vaccum source while leaving breather valve open. If breather valve is open (with or without the filter), does that mean you'll never be able to achieve vacuum because one source is open?
In my setup i would leave breather valve open, then connect the pcv valve to IM through check valve so it shuts under boost. but from what i was told, it doesn't matter if i connect pcv valve to vacuum source (IM or compressor housing), as long as i have breather valve exposed to atmosphere, there won't be any vacuum therefore defeating the purpose of connecting pcv valve to anything.
10-11-2006, 01:00 PM
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10-11-2006, 01:02 PM
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Re: Vaccum assisted Engine Ventilation (vtec.dc2)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtec.dc2 »</TD></TR><TR><TD CLASS="quote">I know there are couple different ways to do this. I had a discussion about this and learned something new to me i'd like to understand better.
Lets say you run pcv valve to vaccum source while leaving breather valve open. If breather valve is open (with or without the filter), does that mean you'll never be able to achieve vacuum because one source is open?
In my setup i would leave breather valve open, then connect the pcv valve to IM through check valve so it shuts under boost. but from what i was told, it doesn't matter if i connect pcv valve to vacuum source (IM or compressor housing), as long as i have breather valve exposed to atmosphere, there won't be any vacuum therefore defeating the purpose of connecting pcv valve to anything. </TD></TR></TABLE>
i have the same suspicions, i think the vacuum needs a "sealed" area for it to have a solid vacuum.
Lets say you run pcv valve to vaccum source while leaving breather valve open. If breather valve is open (with or without the filter), does that mean you'll never be able to achieve vacuum because one source is open?
In my setup i would leave breather valve open, then connect the pcv valve to IM through check valve so it shuts under boost. but from what i was told, it doesn't matter if i connect pcv valve to vacuum source (IM or compressor housing), as long as i have breather valve exposed to atmosphere, there won't be any vacuum therefore defeating the purpose of connecting pcv valve to anything. </TD></TR></TABLE>
i have the same suspicions, i think the vacuum needs a "sealed" area for it to have a solid vacuum.
10-11-2006, 03:59 PM
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Re: Vaccum assisted Engine Ventilation (igo4bmx)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by igo4bmx »</TD></TR><TR><TD CLASS="quote">
i have the same suspicions, i think the vacuum needs a "sealed" area for it to have a solid vacuum.</TD></TR></TABLE>
with that said, i'm not sure if i'm getting the results i was hoping for. i've been running like that for over 30k miles: open breather valve, then pcv valve connects to IM with 2 inline check valves in between, one supposed to stop boost from going through pcv valve, the other opens under pressure from pcv valve. but i always through i had vacuum under idle.. meanwhile it probably leaned out my A/F under partial throttle..
i have the same suspicions, i think the vacuum needs a "sealed" area for it to have a solid vacuum.</TD></TR></TABLE>
with that said, i'm not sure if i'm getting the results i was hoping for. i've been running like that for over 30k miles: open breather valve, then pcv valve connects to IM with 2 inline check valves in between, one supposed to stop boost from going through pcv valve, the other opens under pressure from pcv valve. but i always through i had vacuum under idle.. meanwhile it probably leaned out my A/F under partial throttle..
10-12-2006, 05:09 PM
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You pcv valve should be a 1 way valve. You shouldn't have to use any check valves with it. The one I am using is old, (1987) but it's made out of metal, and seals perfectly if I try to blow air back through it. Anyway, you're not going to achieve anything like a vacuum in the crankcase under boost unless you either inhale the crankcase air through the turbo (bad) or pull on it using some type of dowpipe evac system, or with some kind of air pump, with a filtered restriction wherever you're letting the air into the crankcase. If you didn't have the filtered restriction, you would pull more vacuum, but your oil would be exposed to a higher amount of blow by, as you wouldn't be diluting it with fresh air.
I don't know of anyone who has actually done this, but the best (not smog legal) system I can come up with would be a setup using a decent pcv valve like I described combined with a one way valved downpipe evac system, with a normal breather filter on the valve cover. Under normal driving, manifold vacuum would pull air into the crankcase and through the pcv valve, the downpipe evac system being closed due to the one way valve. Under boost, the pcv valve would seal, and the higher velocity through the downpipe would create enough of a pressure difference to open the one way valve, pulling air through the filter, through the crankcase, and out the exhaust.
To reiterate what I wrote earlier, I see no worthwhile advantage to running a high vacuum level in the crankcase, vs a lower vacuum level and more fresh filtered air through it. Some people might say you make more power due to slightly better ring seal with more vacuum, but I say do what keeps your oil cleanest.
I don't know of anyone who has actually done this, but the best (not smog legal) system I can come up with would be a setup using a decent pcv valve like I described combined with a one way valved downpipe evac system, with a normal breather filter on the valve cover. Under normal driving, manifold vacuum would pull air into the crankcase and through the pcv valve, the downpipe evac system being closed due to the one way valve. Under boost, the pcv valve would seal, and the higher velocity through the downpipe would create enough of a pressure difference to open the one way valve, pulling air through the filter, through the crankcase, and out the exhaust.
To reiterate what I wrote earlier, I see no worthwhile advantage to running a high vacuum level in the crankcase, vs a lower vacuum level and more fresh filtered air through it. Some people might say you make more power due to slightly better ring seal with more vacuum, but I say do what keeps your oil cleanest.
10-12-2006, 08:10 PM
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Re: (rorik)
doesnt pro-stock use some sort of vacuum box for their ventilation system? im pretty sure they do. i think its like a powered vacuum box, whether it be belt driven or electronically controlled, im not sure.
Modified by redboost10 at 3:24 PM 10/13/2006
Modified by redboost10 at 3:24 PM 10/13/2006
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10-13-2006, 05:37 AM
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Re: Vaccum assisted Engine Ventilation (vtec.dc2)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtec.dc2 »</TD></TR><TR><TD CLASS="quote">I know there are couple different ways to do this. I had a discussion about this and learned something new to me i'd like to understand better.
Lets say you run pcv valve to vaccum source while leaving breather valve open. If breather valve is open (with or without the filter), does that mean you'll never be able to achieve vacuum because one source is open?
In my setup i would leave breather valve open, then connect the pcv valve to IM through check valve so it shuts under boost. but from what i was told, it doesn't matter if i connect pcv valve to vacuum source (IM or compressor housing), as long as i have breather valve exposed to atmosphere, there won't be any vacuum therefore defeating the purpose of connecting pcv valve to anything. </TD></TR></TABLE>
I have the same setup as you, except I am also running the vac from the compressor joined to the vac source from the IM to give my extra vac assist.
Lets say you run pcv valve to vaccum source while leaving breather valve open. If breather valve is open (with or without the filter), does that mean you'll never be able to achieve vacuum because one source is open?
In my setup i would leave breather valve open, then connect the pcv valve to IM through check valve so it shuts under boost. but from what i was told, it doesn't matter if i connect pcv valve to vacuum source (IM or compressor housing), as long as i have breather valve exposed to atmosphere, there won't be any vacuum therefore defeating the purpose of connecting pcv valve to anything. </TD></TR></TABLE>
I have the same setup as you, except I am also running the vac from the compressor joined to the vac source from the IM to give my extra vac assist.
10-14-2006, 12:22 PM
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Re: (rorik)
pcv valves will fail, so you gotta use check valve along side to prevent boost from going in. even some check valves may allow 2-3psi of pressure through
10-14-2006, 12:27 PM
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Re: Vaccum assisted Engine Ventilation
i just rememberd. wheneve i would open drain valve on catch can, idle would raise (catch can would be in bewteen IM and pcv valve), so maybe there is some vacuum going on.. i gotta investigate it a bit more
10-15-2006, 09:56 AM
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I don't see the pcv valve I have failing. When I was building my motor, I bought a new one from napa and it didn't seal at all. It had about the same resistance to airflow in both directions. Plastic piece of junk. So I took one off of an old accord motor, sprayed it a little with brake clean, and checked it out. It seals perfectly, and with it's metal construction, I can tell that it's just a much more expensive, much higher quality valve. In contrast, the valves that come on the integras stock or any valve you can get at the parts store are garbage, they're designed to be disposable, not reusable.
10-15-2006, 10:00 AM
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Re: Vaccum assisted Engine Ventilation (swlabhot)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by swlabhot »</TD></TR><TR><TD CLASS="quote">
I have the same setup as you, except I am also running the vac from the compressor joined to the vac source from the IM to give my extra vac assist.</TD></TR></TABLE>
...? So when you have boost, it gets bled off into the compressor inlet from the intake manifold? And when you have manifold vacuum, the amount of vacuum in the line (in other words the amount that the pcv valve sees) is reduced by air being let into it at the compressor inlet? If so, that is completely counterproductive...am I not understanding what you mean?
I have the same setup as you, except I am also running the vac from the compressor joined to the vac source from the IM to give my extra vac assist.</TD></TR></TABLE>
...? So when you have boost, it gets bled off into the compressor inlet from the intake manifold? And when you have manifold vacuum, the amount of vacuum in the line (in other words the amount that the pcv valve sees) is reduced by air being let into it at the compressor inlet? If so, that is completely counterproductive...am I not understanding what you mean?
10-15-2006, 10:11 AM
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Re: (rorik)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rorik »</TD></TR><TR><TD CLASS="quote">I don't see the pcv valve I have failing. When I was building my motor, I bought a new one from napa and it didn't seal at all. It had about the same resistance to airflow in both directions. Plastic piece of junk. So I took one off of an old accord motor, sprayed it a little with brake clean, and checked it out. It seals perfectly, and with it's metal construction, I can tell that it's just a much more expensive, much higher quality valve. In contrast, the valves that come on the integras stock or any valve you can get at the parts store are garbage, they're designed to be disposable, not reusable.</TD></TR></TABLE>
i can't say from experience what fails or not.. just for extra protection i choose to run inline check valve, even these aren't 100% guaranteed to work.
i can't say from experience what fails or not.. just for extra protection i choose to run inline check valve, even these aren't 100% guaranteed to work.
10-15-2006, 10:19 AM
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Re: Vaccum assisted Engine Ventilation (rorik)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rorik »</TD></TR><TR><TD CLASS="quote">
...? So when you have boost, it gets bled off into the compressor inlet from the intake manifold? And when you have manifold vacuum, the amount of vacuum in the line (in other words the amount that the pcv valve sees) is reduced by air being let into it at the compressor inlet? If so, that is completely counterproductive...am I not understanding what you mean?</TD></TR></TABLE>
if his setup is similar to mine.. then he would T the line after from pcv valve between manifold and compressor with check valve in between.
so my setup will be as follows:
oem pcv valve --> t fitting with check valve to vent to atmosphere under WOT --> sealed catch can --> inline check valve (to prevent boost from going through) --> IM
then i will have open oem breather valve with no filter. and 2 on the front of valve cover (i may run them to catch can with vent if it shoots too much oil, i'll decide once i have it all running)
basically, i'll get as close as possible to stock system while out of boost.. and will vent from crankcase through pcv valve and 3 ports from valve cover.. that shoudl be enough
...? So when you have boost, it gets bled off into the compressor inlet from the intake manifold? And when you have manifold vacuum, the amount of vacuum in the line (in other words the amount that the pcv valve sees) is reduced by air being let into it at the compressor inlet? If so, that is completely counterproductive...am I not understanding what you mean?</TD></TR></TABLE>
if his setup is similar to mine.. then he would T the line after from pcv valve between manifold and compressor with check valve in between.
so my setup will be as follows:
oem pcv valve --> t fitting with check valve to vent to atmosphere under WOT --> sealed catch can --> inline check valve (to prevent boost from going through) --> IM
then i will have open oem breather valve with no filter. and 2 on the front of valve cover (i may run them to catch can with vent if it shoots too much oil, i'll decide once i have it all running)
basically, i'll get as close as possible to stock system while out of boost.. and will vent from crankcase through pcv valve and 3 ports from valve cover.. that shoudl be enough
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