Put the PCV back in....
02-27-2007, 12:30 PM
#21
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The ONLY place you will ever see vacuum on an engine is downstream (after) the throttle. Since the crossover tube is upstream of the TB, it will NEVER see vacuum. Therefore the drivers vent is always at/near atmospheric.
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02-27-2007, 02:28 PM
#25
It all started with environmentalists, not because the car companies wanted to improve the auto. My first many cars just had a big pipe open to atmosphere hanging down to vent the crankcase. When you got a lot of smoke and noise from that one, it was time to do a ring and valve job.:gay:
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02-28-2007, 09:37 AM
#26
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I found a few pics that show the path of air through the system:
2003 Pathfinder
Interga info 1/2 way down
2003 Pathfinder
Interga info 1/2 way down
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02-28-2007, 09:56 AM
#27
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Hmmm, so 'splain this to me:
If the driver's side vent is actually a fresh-air intake, then why is it that connecting it to vacuum cures people's turbo oil drainage problems (that is to say, folks that otherwise are venting that driver's side to atmosphere or even mistakenly to a charge pipe)?
If anything, connecting it to a charge pipe would GREATLY increase the fresh air to it, but you'd be blowing your head gasket in the process
I stand by the fact that PCV stands for positive crankcase ventilation, and part of the system's job is to rid the crankcase of excess pressure caused by blow-by.
If the driver's side vent is actually a fresh-air intake, then why is it that connecting it to vacuum cures people's turbo oil drainage problems (that is to say, folks that otherwise are venting that driver's side to atmosphere or even mistakenly to a charge pipe)?
If anything, connecting it to a charge pipe would GREATLY increase the fresh air to it, but you'd be blowing your head gasket in the process
I stand by the fact that PCV stands for positive crankcase ventilation, and part of the system's job is to rid the crankcase of excess pressure caused by blow-by.
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02-28-2007, 10:19 AM
#28
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The honda crankcase breather is a POSITIVE pressure ventilation system.The air from the intake blows into the valve cover. It is NOT a negative pressure ventilation system...it does NOT suck air from the valvecover to the intake.
so it does happen in other cars, but not on our miatas!
so it does happen in other cars, but not on our miatas!
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02-28-2007, 10:30 AM
#29
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02-28-2007, 02:43 PM
#30
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The honda crankcase breather is a POSITIVE pressure ventilation system.The air from the intake blows into the valve cover. It is NOT a negative pressure ventilation system...it does NOT suck air from the valvecover to the intake.
so it does happen in other cars, but not on our miatas!
so it does happen in other cars, but not on our miatas!
I'm not sure who doesn't support that idea. All I would add is that an additional job is to clear the crankcase of sludge-forming byproducts (water, acids) from combustion blowby.
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02-28-2007, 02:47 PM
#31
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hey i just copied and pasted from the website you provided.
Originally Posted by the website you provided
All you have to learn is how the fresh air cicuit flows (follow the open white arrow) and how the crankcase vapor (with oil vapors in it ) circuit flows (follow the black arrows). Notice which circuit flows to the valve cover (on top of the engine on the left)....it's NOT the crankcase vapors. When you add a breather, you remove the line from the intake to the valve cover.
The honda crankcase breather is a POSITIVE pressure ventilation system.The air from the intake blows into the valve cover. It is NOT a negative pressure ventilation system...it does NOT suck air from the valvecover to the intake.
Breathers remove the source of positive ventilation that repressurizes the POSTIVE CRANKCASE VENTILATION (PCV) valve.
There is less pressure in the crank when you add a breather at the valve cover. The consequence of this is you get more positive blow-by from the combustion chamber past the piston rings and into the crankcase. More blow-by means less cylinder pressure...less cylinder pressure means the burn is slower and less complete...the result is more emissions and less power.
If you want to do this right and remove oil vapor from the circulating crankcase before it goes into the intake valve then, get an oilcatch can and put a breather on the catch can. Then place the catch can in between the valve cover breather and the PCV valve.
Disconnecting the breather tube, which blows fresh intake air into the valve cover, and placing a breather on the valve cover just creates more blow-by and emissions. Eventually you have so much blow-by, you lose power.
The honda crankcase breather is a POSITIVE pressure ventilation system.The air from the intake blows into the valve cover. It is NOT a negative pressure ventilation system...it does NOT suck air from the valvecover to the intake.
Breathers remove the source of positive ventilation that repressurizes the POSTIVE CRANKCASE VENTILATION (PCV) valve.
There is less pressure in the crank when you add a breather at the valve cover. The consequence of this is you get more positive blow-by from the combustion chamber past the piston rings and into the crankcase. More blow-by means less cylinder pressure...less cylinder pressure means the burn is slower and less complete...the result is more emissions and less power.
If you want to do this right and remove oil vapor from the circulating crankcase before it goes into the intake valve then, get an oilcatch can and put a breather on the catch can. Then place the catch can in between the valve cover breather and the PCV valve.
Disconnecting the breather tube, which blows fresh intake air into the valve cover, and placing a breather on the valve cover just creates more blow-by and emissions. Eventually you have so much blow-by, you lose power.
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02-28-2007, 03:10 PM
#34
I'd like to know who you quoted from that thread. The information is only realistic in a 100% stock configuration.
Many many people in the honda camp don't understand the PCV system... its designed for NA cars... not turbo.
(this goes for many of the people asking questions and not understanding the information provided in that tread... not to mention the typical ricer honda)
They can't apply their stock NA, honda designed PCV knowledge.... so yeah... who was that post from?
Many many people in the honda camp don't understand the PCV system... its designed for NA cars... not turbo.
(this goes for many of the people asking questions and not understanding the information provided in that tread... not to mention the typical ricer honda)
They can't apply their stock NA, honda designed PCV knowledge.... so yeah... who was that post from?
Last edited by Splitime; 02-28-2007 at 03:31 PM.
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02-28-2007, 03:43 PM
#36
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Yeah, I was referencing the diagram, not the poster's opinion.
He thinks that lowering the pressure in the crankcase is going to create blow-by. Umm, yeah.
Originally Posted by honda dood
There is less pressure in the crank when you add a breather at the valve cover. The consequence of this is you get more positive blow-by from the combustion chamber past the piston rings and into the crankcase. More blow-by means less cylinder pressure...less cylinder pressure means the burn is slower and less complete...the result is more emissions and less power.
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03-21-2007, 12:49 AM
#37
Pcv?!!
Sorry to bring out an old thead, but Holy Cow!!...I could not believe some of the postings on here by Braineack and Brian.
A PCV system is a PCV system...they pull in fresh air from one side (driver's side) and use vacuum (PCV side) to "burn" the fumes during the combustion process.
Braineack, if you are indeed using vacuum on the vent side, what do you think happens under boost? You would be pressurizing your crankcase...not the way to make power!!
Please guys, stop making stuff up!
Tony
A PCV system is a PCV system...they pull in fresh air from one side (driver's side) and use vacuum (PCV side) to "burn" the fumes during the combustion process.
Braineack, if you are indeed using vacuum on the vent side, what do you think happens under boost? You would be pressurizing your crankcase...not the way to make power!!
Please guys, stop making stuff up!
Tony
Last edited by mrtonyg; 03-21-2007 at 01:01 AM. Reason: clarify
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03-21-2007, 11:58 AM
#38
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Tony, sorry to be the bearer of bad news, but: you're wrong.
A little something to chew on: if the driver's side vent (notice it's called a "vent" not an "inlet") were connected to a charge pipe, then, yes, you'd see boost in the crankcase, which is precisely what you want to avoid. With that "vent" connected to a constant source of vacuum, say, in a pipe that's post-AFM but pre-compressor inlet, it'll always see vacuum...unless your turbo's furbar'd.
A little something to chew on: if the driver's side vent (notice it's called a "vent" not an "inlet") were connected to a charge pipe, then, yes, you'd see boost in the crankcase, which is precisely what you want to avoid. With that "vent" connected to a constant source of vacuum, say, in a pipe that's post-AFM but pre-compressor inlet, it'll always see vacuum...unless your turbo's furbar'd.
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03-21-2007, 12:26 PM
#39
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seriously dude, idle you car and blow into the breather line. watch you dump blue smoke out the tailpipe. now connect that smae port to constant vacuum......maybe it might, i dunno, pull the oil out of the turbo? why? oh i dunno, since the bottom of the oil drain is connected to the oil pan, which intern means that vacuum pulling out of the crankcase breather line will effect the oil drain.
Please guys, stop making stuff up!
IE, no boost ever enters you intake path, only vacuum.
I could not believe some of the postings on here by Braineack and Brian.
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03-21-2007, 04:02 PM
#40
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I KNEW IT!
Caught again eh!
j/k
so heres how I did mine
intake manifold|---(pcv)-|valvecover|----|intake preturbo/post afm
boosted========|====================vacuumed
thats the "correct" yes?
because the air in the crankcase has allready been metered theoretically?
Caught again eh!
j/k
so heres how I did mine
intake manifold|---(pcv)-|valvecover|----|intake preturbo/post afm
boosted========|====================vacuumed
thats the "correct" yes?
because the air in the crankcase has allready been metered theoretically?
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