The problem with catch cans and the 350Z
05-19-2012, 04:23 PM
#22
Injected Performance fabricated products are tried and true and tested on their 8 second Z. A breather on the catch can or elsewhere in the setup is a must for FI. With MAP based tuning air metering is irrelevant. With MAF based setups you might not want unmetered air in the plenum, but that's easy to work around. Rather than relying on internet gossip, just find a quality can such as the Injected one linked to above and go with one of the proven methods from users who have it installed successfully (see one of the large threads in the FI section).
Also, PCV operation under FI is annoyingly different, due to the extra positive pressure, you end up with oil blowing both ways, it demands a more complicated setup, usually with two cans and some valves in order to be properly effective.
05-19-2012, 06:46 PM
#23
Sounds good, I was ready to pull the trigger on this one:
http://www.eliteengineeringusa.com/Catch_Cans.html
05-19-2012, 06:53 PM
#24
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Sounds good, I was ready to pull the trigger on this one:
http://www.eliteengineeringusa.com/Catch_Cans.html
http://www.eliteengineeringusa.com/Catch_Cans.html
05-19-2012, 07:33 PM
#25
Yeah, they've come up a few times in my searches, they're good cans, though, looking at the inlet/outlet, i'm not sure how it's routed exactly. They're still very expensive.
Hoping this one shows up this next week, pics/guide etc and if all ok, i'll give the go ahead and people can order straight from Saikou as a kit for the 350.
Hoping this one shows up this next week, pics/guide etc and if all ok, i'll give the go ahead and people can order straight from Saikou as a kit for the 350.
05-19-2012, 08:42 PM
#26
you have no idea how a pcv system actually works or its purpose do you? its called positive crankcase ventilation becaume the crankcase is where the positive pressure is not the intake, unless your boosted which the vast majority of cars are not, you will NEVER have positive pressure in the in the intake only a vacuum. air going into the crank case is a horrible idea and increases pumping losses from the windage and is impossible to do on a non boosted vehicle without a air pump. go take a look at the history of the pcv system, it originally was just a tube that led outside the engine compartment, they began connecting it to the intake in the 60's on cars because i was found that 50% or more of the emissions produced on a vehicle came from the old tube style pcv system so they hooked it to the intake to reduce smell and lower emissions. hell you will find a large number of 4 cylinder pcv systems only have a single connection point on the valve covers completely blowing your theory out the window. also considering that a pcv valve is just a one way check valve that only lets air out of the crankcase not in i dont think i need to say more.
It's called the Positive Crankcase Ventilation system. It means positive pressure from the intake, is fed into (in our case) the drivers side of the engine.
This pushes fresh filtered air into the crank, taking the carbolic and corrosive gasses with it.
This is then pushed & pulled out of the passenger side head via the PCV valve.
After the valve, is the pipe that leads back into the plenum and the air/gas mix is fed into the engine to be re-burnt.
If you have a pipe coming from the top of both sides, that hit the can and then vent to atmosphere, how much of the PCV system do you think will still be running?
If you have it 'vent' to the plenum again, it will work partially, but you don't have a fully effective positive pressure system.
This pushes fresh filtered air into the crank, taking the carbolic and corrosive gasses with it.
This is then pushed & pulled out of the passenger side head via the PCV valve.
After the valve, is the pipe that leads back into the plenum and the air/gas mix is fed into the engine to be re-burnt.
If you have a pipe coming from the top of both sides, that hit the can and then vent to atmosphere, how much of the PCV system do you think will still be running?
If you have it 'vent' to the plenum again, it will work partially, but you don't have a fully effective positive pressure system.
05-19-2012, 09:02 PM
#28
just looked at the fsm and see why you think it works that way, but i promise you it dosnt work. theres no positive pressure in the intake its all vacuum. since theres no check valve on the back port the air is going to flow in the direction of least resistance. which is going to be out of the crankcase and into the intake any time the engine is running because theres a vacuum sucking air out of the crankcase, and blow by and windage is helping push it out.
theres nothing on a stock engine to produce a positive pressure to push air into the pcv system, not sure what dude made that diagram at nissan but he needs to be fired because he obviously dint get with anyone else when the car was designed to see if that would even work that way. my guess is they had the janitor make the drawing for how the pcv system works.
in fact i simply had that back port open after i installed my turbo kit and at idle where i was seeing average vaccum and should be the least amount of blow by i definitly had positive pressure coming from both that port and the pcv valve. only thing i had hooked to my intake was brakes, and then the smaller port on my kinetix was connected to boost guage, bov, and fpr. since vacuum is the absence of pressue no way you can turn the vacuum in the intake into pressure that will overcome the pressure trying to escape from that back port.
i know its illegal to run it vented to atmosphere but look how many people we have running no cats and thats illegal too, same for 02 sims or 02 sensor unhooked lol gona have to really **** off the epa for them to hunt you down for it.
theres nothing on a stock engine to produce a positive pressure to push air into the pcv system, not sure what dude made that diagram at nissan but he needs to be fired because he obviously dint get with anyone else when the car was designed to see if that would even work that way. my guess is they had the janitor make the drawing for how the pcv system works.
in fact i simply had that back port open after i installed my turbo kit and at idle where i was seeing average vaccum and should be the least amount of blow by i definitly had positive pressure coming from both that port and the pcv valve. only thing i had hooked to my intake was brakes, and then the smaller port on my kinetix was connected to boost guage, bov, and fpr. since vacuum is the absence of pressue no way you can turn the vacuum in the intake into pressure that will overcome the pressure trying to escape from that back port.
i know its illegal to run it vented to atmosphere but look how many people we have running no cats and thats illegal too, same for 02 sims or 02 sensor unhooked lol gona have to really **** off the epa for them to hunt you down for it.
Last edited by jerryd87; 05-19-2012 at 09:11 PM.
05-19-2012, 09:49 PM
#30
you have no idea how a pcv system actually works or its purpose do you? its called positive crankcase ventilation becaume the crankcase is where the positive pressure is not the intake, unless your boosted which the vast majority of cars are not, you will NEVER have positive pressure in the in the intake only a vacuum...
...go take a look at the history of the pcv system, it originally was just a tube that led outside the engine compartment, they began connecting it to the intake in the 60's on cars because i was found that 50% or more of the emissions produced on a vehicle came from the old tube style pcv system so they hooked it to the intake to reduce smell and lower emissions...
They're not just one way check valves, but that's one of their functions. Please read up on PCV valves.
05-19-2012, 09:57 PM
#31
...since theres no check valve on the back port the air is going to flow in the direction of least resistance. which is going to be out of the crankcase and into the intake any time the engine is running because theres a vacuum sucking air out of the crankcase, and blow by and windage is helping push it out.
sorry.PCV valves do not allow full flow of that vacuum at all times.
...theres nothing on a stock engine to produce a positive pressure to push air into the pcv system, not sure what dude made that diagram at nissan but he needs to be fired because he obviously dint get with anyone else when the car was designed to see if that would even work that way. my guess is they had the janitor make the drawing for how the pcv system works.
...in fact i simply had that back port open after i installed my turbo kit and at idle where i was seeing average vaccum and should be the least amount of blow by i definitly had positive pressure coming from both that port and the pcv valve. only thing i had hooked to my intake was brakes, and then the smaller port on my kinetix was connected to boost guage, bov, and fpr. since vacuum is the absence of pressue no way you can turn the vacuum in the intake into pressure that will overcome the pressure trying to escape from that back port.
05-19-2012, 10:32 PM
#32
they are indeed just one way check valves i have one in my brake vaccum line where the vacuum pump T's in because those are the only plastic ones available that large blow in one side it flows blow in the other it closes and you cant. my wifes focus for one, slightly different because there are two ports on the valve cover but they T togeather and go to a single port on the intake. it can make huge differences for pumping losses ive seen as much as 75 hp in super high power cars going to 5 stage dry sump systems.(which also reduces crank case windage since its sucking from so many places, yah primary function is to recover oil better and faster but it also reduces windage.)
Yup, no argument here.
Really not sure how much difference this would ever make, and air going in there on a non boosted vehicle is absolutely possible, that's the connection from the air intake tube.
Yup, know all this, referred to it in my previous posts.
Really? which ones?
They're not just one way check valves, but that's one of their functions. Please read up on PCV valves.
Really not sure how much difference this would ever make, and air going in there on a non boosted vehicle is absolutely possible, that's the connection from the air intake tube.
Yup, know all this, referred to it in my previous posts.
Really? which ones?
They're not just one way check valves, but that's one of their functions. Please read up on PCV valves.
05-19-2012, 10:41 PM
#33
my biggest thing isnt to insult you but honestly if you have pressure from inside the crank case trying to get out and you have a intake thats a vacuum theres no way air is going to flow into the engine. for the air to actually behave like that diagram shows it would have to overcome the pressure already there with a higher pressure, which since the intake is a vacuum there is no higher pressure just lower. the air acts just like a fluid it is going to follow the path of least resistance, which on the stock engine no matter what the rpm is going to be out of the crankcase and into the intake. by check valve and back port what i was trying to say is only way air could flow into it would be a check valve allowing air in and not out, but it would still have to overcome the positive pressure in the crankcase.
the back port is the port on the back of the driver side valve cover, thats the one the diagram shows as flowing air in. i might be referencing a turbo setup but its going to behave identical to a stock system at idle, my turbo dosnt even hit 0 pressure until 4k rpms, and i dont see positive pressure(which actually would allow this to work sort of air would be able to flow in but the pcv valve would shut not allowing air out.) until around 4200 rpms, i had conservative timing since i was running the bigger turbo and never fully tuned it before pulling the old engine.
the only way for this to work would be a wall of some sort in the intake for the air to hit so it created a high pressure zone, like a windshield. but it would have to be directly in the airflow not below it like the pcv port on the intake, i know i dont have any sort of wall in the stock intake i have sitting on a shelf to create a high pressure zone. ill even go look again tomarrow no way im gona be able to unbury it tonight i have a paper due =/
the back port is the port on the back of the driver side valve cover, thats the one the diagram shows as flowing air in. i might be referencing a turbo setup but its going to behave identical to a stock system at idle, my turbo dosnt even hit 0 pressure until 4k rpms, and i dont see positive pressure(which actually would allow this to work sort of air would be able to flow in but the pcv valve would shut not allowing air out.) until around 4200 rpms, i had conservative timing since i was running the bigger turbo and never fully tuned it before pulling the old engine.
the only way for this to work would be a wall of some sort in the intake for the air to hit so it created a high pressure zone, like a windshield. but it would have to be directly in the airflow not below it like the pcv port on the intake, i know i dont have any sort of wall in the stock intake i have sitting on a shelf to create a high pressure zone. ill even go look again tomarrow no way im gona be able to unbury it tonight i have a paper due =/
It shows the air flow, if i referred to pressure on the front side of the system, i'm sorry, that's probably not correct.
Not sure what you're meaning about check valve and back port sorry.
PCV valves do not allow full flow of that vacuum at all times.
Haha, maybe, but it doesn't show positive pressure, just direction of flow, i'm guessing aided by the vacuum from the PCV valve side of the system. Honda show it the same way.
Sorry, again i don't know what you mean by back port. You're also referencing a turbo setup....
Yeah, i know this, you know this, most of us would never admit to doing something so wrong..
Not sure what you're meaning about check valve and back port
sorry.PCV valves do not allow full flow of that vacuum at all times.
Haha, maybe, but it doesn't show positive pressure, just direction of flow, i'm guessing aided by the vacuum from the PCV valve side of the system. Honda show it the same way.
Sorry, again i don't know what you mean by back port. You're also referencing a turbo setup....
Yeah, i know this, you know this, most of us would never admit to doing something so wrong..
Last edited by jerryd87; 05-19-2012 at 10:44 PM.
05-19-2012, 10:47 PM
#34
also props to you for trying to find a cheaper source but honestly the system will work 100% fine without being hooked to any vacuum source and work well. if vented to atmosphere you will get smell but *shrug* dont need vacuum and if you vented it with it hooked to a vaccum source the issue you would run into is slightly leaner(hardly noticeable) from extra air being sucked in, not slightly richer like letting metered air escape.
05-19-2012, 11:25 PM
#35
Might be called the valve cover breather tube, but there is an inlet from th intake tube to the top of the valve cover on the focus.
Top right of valve cover in pic.
PCV valve, i can't find the professional info PDF i used to have on them, but this is a very basic version.
I can see windage/pumping losses on super high hp engines, but not what we're talking about.
You don't always have blowby and pressure inside the crankcase, it's not always getting it from there. Fresh air needs in, there is the connection to the intake tubing to allow it to pull air through that way. And again, you're right, there is no real pressure from the intake side, it's just allowed through.
The operation of a PCV valve and times when vacuum is higher/lower will dictate how much flow is out of the crank and into the intake, but that's where it will be, yes.
Ahh, thank you for explaining the back port, yes, that's the intake as you say, in some conditions, especially turbo, you'll get crankcase gasses going back to the intake there. It's very rare in NA, but happens.
I don't agree that the system (NA at least) will work 100% fine, but it will work, otherwise there would be no good reason to have the intake able to feed air into the crank. Either way, the system is designed to flow in one direction, and, 95% of the time, it does, that's why there is a PCV valve on one side. If you run the two lines into the same catch can that vents to atmosphere, you'll end up with just an evap system.
The PCV valve wouldn't be too happy either as it's designed to respond to the vacuum from the plenum.
I wanted to find a good catch can for the 350, so i'm doing that at the moment, maybe help some people out. Either way, even the can suggested is over priced, more than twice the price of another good can and it's debatable baffle system. You referenced gasses taking the easiest route earlier, this is very true, even if you enter an OCC into the mix. It will by pass the can as much as it can and find the shortest route to the exit. Another reason why i like a decent baffle system.
Top right of valve cover in pic.
PCV valve, i can't find the professional info PDF i used to have on them, but this is a very basic version.
I can see windage/pumping losses on super high hp engines, but not what we're talking about.
You don't always have blowby and pressure inside the crankcase, it's not always getting it from there. Fresh air needs in, there is the connection to the intake tubing to allow it to pull air through that way. And again, you're right, there is no real pressure from the intake side, it's just allowed through.
The operation of a PCV valve and times when vacuum is higher/lower will dictate how much flow is out of the crank and into the intake, but that's where it will be, yes.
Ahh, thank you for explaining the back port, yes, that's the intake as you say, in some conditions, especially turbo, you'll get crankcase gasses going back to the intake there. It's very rare in NA, but happens.
I don't agree that the system (NA at least) will work 100% fine, but it will work, otherwise there would be no good reason to have the intake able to feed air into the crank. Either way, the system is designed to flow in one direction, and, 95% of the time, it does, that's why there is a PCV valve on one side. If you run the two lines into the same catch can that vents to atmosphere, you'll end up with just an evap system.
The PCV valve wouldn't be too happy either as it's designed to respond to the vacuum from the plenum.
I wanted to find a good catch can for the 350, so i'm doing that at the moment, maybe help some people out. Either way, even the can suggested is over priced, more than twice the price of another good can and it's debatable baffle system. You referenced gasses taking the easiest route earlier, this is very true, even if you enter an OCC into the mix. It will by pass the can as much as it can and find the shortest route to the exit. Another reason why i like a decent baffle system.
05-19-2012, 11:28 PM
#36
Aha, i've jsut found reference to open PCV systems and closed PCV systems.
I'll be honest, i've only ever dealt with closed systems, it's What Honda's and the 350Z has. Hence the clean air flow through the system.
What i read on the following link, shows what you've been describing, as an open PCV system, everything you've been saying now makes sense.
Forgive me, i've not read the accompanying text, just the titles and diagrams.
http://what-when-how.com/automobile/...ol-automobile/
I'll be honest, i've only ever dealt with closed systems, it's What Honda's and the 350Z has. Hence the clean air flow through the system.
What i read on the following link, shows what you've been describing, as an open PCV system, everything you've been saying now makes sense.
Forgive me, i've not read the accompanying text, just the titles and diagrams.
http://what-when-how.com/automobile/...ol-automobile/
Last edited by F2CMaDMaXX; 05-19-2012 at 11:30 PM.
05-20-2012, 12:03 AM
#37
what year is that? my wifes has a port on the top right like that but he hose is only about 3 or 4 inchs long and connects to a T, then there is a long hose on the bottom left side that runs and connects to the middle leg on the T and then the top leg goes to the intake, theres a pcv valve in both ports on the valve covers. 2010 focus SE i havnt modified it at all, hell havnt even changed the oil in it myself to be completely honest. im guessing that one is a bit older though based on the cable throttle body, wifes is dbw and if i remember correctly(i could be wrong on this one but the others im sure on.) is hers is also maf only, dont remember seeing a map sensor as well like that one has. im guessing the pcv valve i have for my brakes definitly does not work like that the plunger is 100% solid you can blow in one way not the other admittedly i have no idea what it came off i just asked for the biggest one they had, all the regular check valves they had where 1/4 inch or smaller, both my 84 camaros and 00 camaro where the same way as well could blow in one side but not the other completely solid plunger as was my 93 civic four door beater.
the reason i know this is i dont trust parts stores and have gotten bad new parts, always change pcv valve with a tune up(pcv, fuel filter, air filter, plugs, oil change is what i would do about once a year. granted oil changes where more frequent.) so i would always check em.
you might not always have blowby but you will have windage from the internals moving which will create pressure. even at idle you can generate 1 psi or so on the hose, granted once it hits the intake its not gona be a big enough volume to do anything.
evap system has a charcoal canister to purify fumes though =P
again im not doubting you for trying to find a cheaper or better solution for your instance and mayby other, just that diagram they have in the fsm is just dead wrong, i cant possibly see any way for the air to flow that way it just dosnt work that way
edit: crap just saw the very bottom of the valve cover, ztec yah that is a oldie they havnt had those in awhile lol wife has a duratec so def a different engine i thought that one said duratec as well at first lol
the reason i know this is i dont trust parts stores and have gotten bad new parts, always change pcv valve with a tune up(pcv, fuel filter, air filter, plugs, oil change is what i would do about once a year. granted oil changes where more frequent.) so i would always check em.
you might not always have blowby but you will have windage from the internals moving which will create pressure. even at idle you can generate 1 psi or so on the hose, granted once it hits the intake its not gona be a big enough volume to do anything.
evap system has a charcoal canister to purify fumes though =P
again im not doubting you for trying to find a cheaper or better solution for your instance and mayby other, just that diagram they have in the fsm is just dead wrong, i cant possibly see any way for the air to flow that way it just dosnt work that way
edit: crap just saw the very bottom of the valve cover, ztec yah that is a oldie they havnt had those in awhile lol wife has a duratec so def a different engine i thought that one said duratec as well at first lol
Might be called the valve cover breather tube, but there is an inlet from th intake tube to the top of the valve cover on the focus.
Top right of valve cover in pic.
PCV valve, i can't find the professional info PDF i used to have on them, but this is a very basic version.
I can see windage/pumping losses on super high hp engines, but not what we're talking about.
You don't always have blowby and pressure inside the crankcase, it's not always getting it from there. Fresh air needs in, there is the connection to the intake tubing to allow it to pull air through that way. And again, you're right, there is no real pressure from the intake side, it's just allowed through.
The operation of a PCV valve and times when vacuum is higher/lower will dictate how much flow is out of the crank and into the intake, but that's where it will be, yes.
Ahh, thank you for explaining the back port, yes, that's the intake as you say, in some conditions, especially turbo, you'll get crankcase gasses going back to the intake there. It's very rare in NA, but happens.
I don't agree that the system (NA at least) will work 100% fine, but it will work, otherwise there would be no good reason to have the intake able to feed air into the crank. Either way, the system is designed to flow in one direction, and, 95% of the time, it does, that's why there is a PCV valve on one side. If you run the two lines into the same catch can that vents to atmosphere, you'll end up with just an evap system.
The PCV valve wouldn't be too happy either as it's designed to respond to the vacuum from the plenum.
I wanted to find a good catch can for the 350, so i'm doing that at the moment, maybe help some people out. Either way, even the can suggested is over priced, more than twice the price of another good can and it's debatable baffle system. You referenced gasses taking the easiest route earlier, this is very true, even if you enter an OCC into the mix. It will by pass the can as much as it can and find the shortest route to the exit. Another reason why i like a decent baffle system.
Top right of valve cover in pic.
PCV valve, i can't find the professional info PDF i used to have on them, but this is a very basic version.
I can see windage/pumping losses on super high hp engines, but not what we're talking about.
You don't always have blowby and pressure inside the crankcase, it's not always getting it from there. Fresh air needs in, there is the connection to the intake tubing to allow it to pull air through that way. And again, you're right, there is no real pressure from the intake side, it's just allowed through.
The operation of a PCV valve and times when vacuum is higher/lower will dictate how much flow is out of the crank and into the intake, but that's where it will be, yes.
Ahh, thank you for explaining the back port, yes, that's the intake as you say, in some conditions, especially turbo, you'll get crankcase gasses going back to the intake there. It's very rare in NA, but happens.
I don't agree that the system (NA at least) will work 100% fine, but it will work, otherwise there would be no good reason to have the intake able to feed air into the crank. Either way, the system is designed to flow in one direction, and, 95% of the time, it does, that's why there is a PCV valve on one side. If you run the two lines into the same catch can that vents to atmosphere, you'll end up with just an evap system.
The PCV valve wouldn't be too happy either as it's designed to respond to the vacuum from the plenum.
I wanted to find a good catch can for the 350, so i'm doing that at the moment, maybe help some people out. Either way, even the can suggested is over priced, more than twice the price of another good can and it's debatable baffle system. You referenced gasses taking the easiest route earlier, this is very true, even if you enter an OCC into the mix. It will by pass the can as much as it can and find the shortest route to the exit. Another reason why i like a decent baffle system.
Last edited by jerryd87; 05-20-2012 at 12:09 AM.
05-20-2012, 12:07 AM
#38
yah draft tube was the original i was talking about, and trust me if you ever ride in a old car with it you can smell it lol. buddys 57 chevy had that system dumped into the fenderwell iirc and smelled horrid he also dint know how to tune a carb which made it worse. ill admit i have never had the 350z pcv valve out, but all the ones ive every experience have been like the one dipicted in that link and only allows flow one way.
Aha, i've jsut found reference to open PCV systems and closed PCV systems.
I'll be honest, i've only ever dealt with closed systems, it's What Honda's and the 350Z has. Hence the clean air flow through the system.
What i read on the following link, shows what you've been describing, as an open PCV system, everything you've been saying now makes sense.
Forgive me, i've not read the accompanying text, just the titles and diagrams.
http://what-when-how.com/automobile/...ol-automobile/
I'll be honest, i've only ever dealt with closed systems, it's What Honda's and the 350Z has. Hence the clean air flow through the system.
What i read on the following link, shows what you've been describing, as an open PCV system, everything you've been saying now makes sense.
Forgive me, i've not read the accompanying text, just the titles and diagrams.
http://what-when-how.com/automobile/...ol-automobile/
05-20-2012, 10:03 AM
#39
Yup, draft tubes are (as we both said, old) very uncommon these days, though my Dad's GT6 has one at the moment. I skimmed over the last link i sent you and it does a fair job of noting out the way each of the systems run.
Basically, if the PCV system is a closed one (most are these days) then it does need the vacuum from the intake in order for everything to flush effectively. I'm not saying that gasses won't escape without it, but it will be considerably less effective if that vacuum is disconnected.
Even on the draft system, it literally used physics on the pipe to create a vacuum, they knew it needed one. I think that relying on what might be produced by windage, isn't worth taking a chance on, personally.
I also want to note that, the longer i look at the PCV valve op, they're clearly a one way valve, as you said, but they're not *just* a one way valve, they're slightly more complicated, at least on Japanese/modern systems.
I too have come across a lot of parts from the stores where they come damaged or just not as designed, it's pretty useful to know what you're doing if you're going to do it yourself (obvious point is obvious)
Yeah, i think that's an early 2000's focus engine, the zetec was a nice little engine from what i knew at the time. By your description, it sounds like the engine has two separate points (via that T piece) for the intake air to get in, and then the PCV valve connected to the plenum, extracts it.
Anyway, given that the link, showing the operation of PCV systems, shows the flow of air moving that way, that the FSM's for my previous cars and for this car, show it moving that way, i'd say that it *does* work that way.
I think the only way that it *can* work that way (taking your arguments into account) is that the vacuum from the plenum, outweighs the blowby/windage under nominal conditions.
The engine is essentially a sealed system, windage will obviously generate disturbance, but it can't create pressure from anywhere, the air is already in there. The blowby gasses are the only pressure increasers, but these are comparatively minimal by design (so obviously a worn engine/rings will increase it)
Draft engines and open PCV system engines, all had vents in the oil cap to allow air intake, letting the sealed system take air in, in order for the draft tube or PCV valve to let air/gasses out.
Closed PCV systems are all sealed, oil filler cap, dipstick, all sealed, so it needs the opening from (in most cases, the intake) to take air from, to replace that which is sucked out by the plenum connection to the PCV valve.
Basically, if the PCV system is a closed one (most are these days) then it does need the vacuum from the intake in order for everything to flush effectively. I'm not saying that gasses won't escape without it, but it will be considerably less effective if that vacuum is disconnected.
Even on the draft system, it literally used physics on the pipe to create a vacuum, they knew it needed one. I think that relying on what might be produced by windage, isn't worth taking a chance on, personally.
I also want to note that, the longer i look at the PCV valve op, they're clearly a one way valve, as you said, but they're not *just* a one way valve, they're slightly more complicated, at least on Japanese/modern systems.
I too have come across a lot of parts from the stores where they come damaged or just not as designed, it's pretty useful to know what you're doing if you're going to do it yourself (obvious point is obvious)
Yeah, i think that's an early 2000's focus engine, the zetec was a nice little engine from what i knew at the time. By your description, it sounds like the engine has two separate points (via that T piece) for the intake air to get in, and then the PCV valve connected to the plenum, extracts it.
Anyway, given that the link, showing the operation of PCV systems, shows the flow of air moving that way, that the FSM's for my previous cars and for this car, show it moving that way, i'd say that it *does* work that way.
I think the only way that it *can* work that way (taking your arguments into account) is that the vacuum from the plenum, outweighs the blowby/windage under nominal conditions.
The engine is essentially a sealed system, windage will obviously generate disturbance, but it can't create pressure from anywhere, the air is already in there. The blowby gasses are the only pressure increasers, but these are comparatively minimal by design (so obviously a worn engine/rings will increase it)
Draft engines and open PCV system engines, all had vents in the oil cap to allow air intake, letting the sealed system take air in, in order for the draft tube or PCV valve to let air/gasses out.
Closed PCV systems are all sealed, oil filler cap, dipstick, all sealed, so it needs the opening from (in most cases, the intake) to take air from, to replace that which is sucked out by the plenum connection to the PCV valve.
Last edited by F2CMaDMaXX; 05-20-2012 at 10:06 AM.
05-27-2012, 08:50 AM
#40
any updates?
good info here
http://www.ls1tech.com/forums/genera...outing-ok.html
under $100
http://catchcans.com/can1.html
good info here
http://www.ls1tech.com/forums/genera...outing-ok.html
under $100
http://catchcans.com/can1.html
Last edited by mw9; 05-27-2012 at 02:29 PM.