why not to remove that rear rocker breather and pipework
- Thread starter Dooie Pop Pop
- Start date
In my experience of the 1 way valve,it is only open at idle and was intened to lower the CO2 emissions for the MOT.If you blip the revs whilst inspecting the valve,as soon as they start to rise the valve closes,but the revs have to settle to near tickover for it to open again.So i have to agree with Blob errrrr i mean Rob.LOL.
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tro||
Guest
the point of the pcv valve is to allow the crankcase blowby gases, which are mainly made up of unburned fuel to return to the combustion chamber. The fuel vapour can if its not recirclated from the crankcase have a detrimental effect on the quality of the oil, causing it to dilute and decrease its lubrication abilities and contribute to sludge build up. At high engine speeds, blow-by gases can cause oil seals to fail.
how does it work ?
the gtir has a variable flow pcv valve.
The system use manifold vacuam to draw the blowby gases into the intake manifold. Obviously blow by gases are at the highest at high engine speeds and at their lightest at low load situations (idle, deceleration). The manifold vacuam does not match the requirements for proper crankcase ventilation. The pcv valve is used to regulate blowby flow back into the inlet manifold.
at idle, deceleration blowby gases are low, but vacuam is high. The valve will basically close, although a small passage remains allowing the low amounts of blowby to flow into the inlet and into the combustion chamber.
during low load cruising the valve opens slightly and allows a moderate amount of blowby into the inlet and the combustion chamber.
during high load situations (WOT) blowby gases are high, the valve fully opens allowing a large amount of blowby into the inlet and into the combustion chamber. However, during extremely high loads the amount of blowby gases can be more than the pcv valve can flow, the excess blowby will then flow through the breather hose, oil seperator and be drawn back into the combustion chamber through the air inlet.
When the engine is off or backfires spring tension in the valve causes it to close completely preventing the release of blowby into the intake and during a backfire to prevent the flame from travelling into the crankcase where it could ignite the fuel vapours.
The pcv valves operation is taken into account as part of the ecus proper feedback control, problems with the pcv valve can have an effect on the air fuel ratios. A blocked pcv valve will prevent the normal flow of blowby gases and can cause a richer than normal afr. A blocked crankcase breather may cause the engine to use oil due to the increased levels of crankcase pressure. A fooked valve or restricted breather/vacuam hose can cause oil to contaminate the intake.
in relation to emissions if the crankcase oil gets diluted with fuel, and that vapour is then drawn through as it should be, carbon monoxide levels can increase as the pcv system is now allowing the fuel/oil vapour into the combustion chamber.
to conclude, nissan put it there for a reason, the fact some have trouble with oil contamination in the intake is due to age and condition of the engine. Removing it will probably cause a standard ecu'd car to run ever so slightly rich as there oxygen that is left in the crankcase gases is not being recirculated, no bigdeal, but removing it may cause problems with crankcase pressures causing blown oilseals if the breather system is not adequate.
i'd say for most this is not a problem and removing the pcv/breather system has the better effect on old engines due to the oil contamination problems, most cant be arsed to clean, replace the parts and on an old engine it wont take long for the problem to return. On a fresh build there shouldn't be any problem with this as the engine is basically new
The cooling affect mentioned at the start of this thread is not due to carbon dioxide but the fuel vapour being recirculated, again not harmful but probably not that harmful if you didn't have it as lots of people have removed it all over the world, i highly doubt it would contribute to any detonation if you didn't have it
lesson of today..
your all wrong and the tro||s more than just an occasional nuscience...lol
how does it work ?
the gtir has a variable flow pcv valve.
The system use manifold vacuam to draw the blowby gases into the intake manifold. Obviously blow by gases are at the highest at high engine speeds and at their lightest at low load situations (idle, deceleration). The manifold vacuam does not match the requirements for proper crankcase ventilation. The pcv valve is used to regulate blowby flow back into the inlet manifold.
at idle, deceleration blowby gases are low, but vacuam is high. The valve will basically close, although a small passage remains allowing the low amounts of blowby to flow into the inlet and into the combustion chamber.
during low load cruising the valve opens slightly and allows a moderate amount of blowby into the inlet and the combustion chamber.
during high load situations (WOT) blowby gases are high, the valve fully opens allowing a large amount of blowby into the inlet and into the combustion chamber. However, during extremely high loads the amount of blowby gases can be more than the pcv valve can flow, the excess blowby will then flow through the breather hose, oil seperator and be drawn back into the combustion chamber through the air inlet.
When the engine is off or backfires spring tension in the valve causes it to close completely preventing the release of blowby into the intake and during a backfire to prevent the flame from travelling into the crankcase where it could ignite the fuel vapours.
The pcv valves operation is taken into account as part of the ecus proper feedback control, problems with the pcv valve can have an effect on the air fuel ratios. A blocked pcv valve will prevent the normal flow of blowby gases and can cause a richer than normal afr. A blocked crankcase breather may cause the engine to use oil due to the increased levels of crankcase pressure. A fooked valve or restricted breather/vacuam hose can cause oil to contaminate the intake.
in relation to emissions if the crankcase oil gets diluted with fuel, and that vapour is then drawn through as it should be, carbon monoxide levels can increase as the pcv system is now allowing the fuel/oil vapour into the combustion chamber.
to conclude, nissan put it there for a reason, the fact some have trouble with oil contamination in the intake is due to age and condition of the engine. Removing it will probably cause a standard ecu'd car to run ever so slightly rich as there oxygen that is left in the crankcase gases is not being recirculated, no bigdeal, but removing it may cause problems with crankcase pressures causing blown oilseals if the breather system is not adequate.
i'd say for most this is not a problem and removing the pcv/breather system has the better effect on old engines due to the oil contamination problems, most cant be arsed to clean, replace the parts and on an old engine it wont take long for the problem to return. On a fresh build there shouldn't be any problem with this as the engine is basically new
The cooling affect mentioned at the start of this thread is not due to carbon dioxide but the fuel vapour being recirculated, again not harmful but probably not that harmful if you didn't have it as lots of people have removed it all over the world, i highly doubt it would contribute to any detonation if you didn't have it
lesson of today..
your all wrong and the tro||s more than just an occasional nuscience...lol
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tro||
Guest
make the most of that cause its not often i can be arsed to post anything of any use...lol
Dooie Pop Pop
New Member
Troll: im damn sure i guessed you right;-)
glad i started ths thread now the section was getting a little stale
glad i started ths thread now the section was getting a little stale
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GTI-R Kid
Guest
Anyone have photos to accompany all this information for the less technically minded of us?
Ohh lurvley.................we could have a game of name the person, who has a bumhole like this :lol:tro|| said:
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GTI-R Kid
Guest
Ah, such a shame.:doh:tro|| said:
After a very educating and informative post things get dragged straight back down the gutter.:?
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tro||
Guest
the carbon canister is there to collect fuel vapour from the tank to reduce hydrocarbons that would otherwise be aborbed into the atmosphere. The vapour is stored in the canister and through a small constantly open hole is constantly drawn into the inlet when the engine is running, as revs increase another valve opens and more vapour is drawn into the engine. Its not directly related to emissions from the exhaustjpward said:
The oil seperator, funnily enough, seperates any oil in the crankcase blowby gases.
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tro||
Guest
blah, blah, blah
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GTI-R Kid
Guest
Sometimes the optimistic side of me overloads and I give someone (even the troll) the benefit of the doubt.:lol:stumo said:
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tro||
Guest
the blowby gases get back into the combustion chamber with the throttle shut as they are drawn into the inlet after the butterfliesDooie Pop Pop said:
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tro||
Guest
from an air chamber on the back of the inlet manifoldjpward said:
CruiseGTi-R
Member
Troll rocks.
The only fun I ever had with crankcase breathing was my old car which would blow the oil dipstick out.
Quite good fun opening the bonnet and searching for the stick, and eer cleaning the whole engine bay of oil.
The only fun I ever had with crankcase breathing was my old car which would blow the oil dipstick out.
Quite good fun opening the bonnet and searching for the stick, and eer cleaning the whole engine bay of oil.
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Fusion Ed
Guest
To stir this up again Crankcase gases are not unburnt fuel. Crank case gases are simply piston blow by gases that happen mainly during the burn stage. A tiny - and i mean tiny, amount may pass unburnt during the compression stage but its almost irrelevent compared to the latter half of the combustion cycle where the extreme pressures are present, after the mixture has been fired. To prove this point the carbon deposits that form around the piston skirts below the rings due to blow by wouldnt form if it was unburnt fuel.
Popping on over run is due to a LEAN mixture not a rich one. Nissan ECCS cuts the fuel on over run, but when balencing in overrun/very light load can casue the popping by the ecu firing the injectors where there is not enough mixture to ignite, this builds up in the exhaust and causes the pops/bangs etc. I can demonstrate this point on an e-manage for example and remove fuel on light over run load cells and depending on the car can result in extreme pops and bangs.
My thoughts on the emissions on the GTi-R is that they are not necessary, unless you plan to save the planet - in which case you wouldn't own a pulsar anyway.
My preference would be to compleatly seperate the crank case from anything to do with the inlet pipework, and have just one vent with an oil seperator or catch tank to keep the oil and crank case gasses seperate. There is no performance benefit in leaving them on.
Crankcase gases are not unburnt fuel. Crank case gases are simply piston blow by gases that happen mainly during the burn stage. A tiny - and i mean tiny, amount may pass unburnt during the compression stage but its almost irrelevent compared to the latter half of the combustion cycle where the extreme pressures are present, after the mixture has been fired. To prove this point the carbon deposits that form around the piston skirts below the rings due to blow by wouldnt form if it was unburnt fuel.Popping on over run is due to a LEAN mixture not a rich one. Nissan ECCS cuts the fuel on over run, but when balencing in overrun/very light load can casue the popping by the ecu firing the injectors where there is not enough mixture to ignite, this builds up in the exhaust and causes the pops/bangs etc. I can demonstrate this point on an e-manage for example and remove fuel on light over run load cells and depending on the car can result in extreme pops and bangs.
My thoughts on the emissions on the GTi-R is that they are not necessary, unless you plan to save the planet - in which case you wouldn't own a pulsar anyway.
My preference would be to compleatly seperate the crank case from anything to do with the inlet pipework, and have just one vent with an oil seperator or catch tank to keep the oil and crank case gasses seperate. There is no performance benefit in leaving them on.
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tro||
Guest
Positive Crankcase Ventilation (PCV) was one of the first techniques employed to reduce unburned VOC emissions from petrol powered vehicles. It was required initially on Californian vehicles in the 60's. Because the gases in the combustion chamber are under high pressure while combustion is taking place, a small fraction leaks past the rings that seal the gap between the piston and the cylinder wall. These blow-by gases end up in the crankcase. They are a mixture of unburned fuel, air and combustion products. As the blow-by gases accumulate in the crankcase, they must be vented to avoid pressurizing the crankcase, which would force oil out of the engine. PCV systems consist of tubing and a control valve that meters the flow of the blow-by gases from the crankcase back into the engine's intake air system, from which they are drawn into the cylinders and burned. Prior to the use of PCV,blow-by was vented to the atmosphere, providing a significant source of VOCs.
A goodlink for those of you that are interested
emission control
A goodlink for those of you that are interested
emission control
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AJ4
Guest
The whole system is a pile of crap. Most blow by gases are burnt fuel, very little is unburnt fuel. Any of this going in the intake will dilute the intake charge and its not metered either as it hasn't come through the AFM.
The only purpose of the PCV is to stop pressure building up in the crankcase. Venting it to atmosphere is a lot better than feeding it back into the intake ( unless your a green loony ).
The only advantage of running the crankcase in vacuum is to lower windage losses, and that stupid little valve isn't even man enough to have any effect on that.
Personal opinion, all I want in my engine is cold, finely metered fuel and air, not uncontrollable random oil fumes and burnt exhaust gases. I mean, you spend a fortune on pulse tuning some lovely extractor manifold to get as much exhaust out as possible at the end of each stroke, and then you feed it back in with that emissions system ? :lol::lol:
At the end of the day, its an emissions device that hurts power. Bin it !
Don't listen to Troll, he has shares in a PCV manufacturer :lol:
The only purpose of the PCV is to stop pressure building up in the crankcase. Venting it to atmosphere is a lot better than feeding it back into the intake ( unless your a green loony
).The only advantage of running the crankcase in vacuum is to lower windage losses, and that stupid little valve isn't even man enough to have any effect on that.
Personal opinion, all I want in my engine is cold, finely metered fuel and air, not uncontrollable random oil fumes and burnt exhaust gases. I mean, you spend a fortune on pulse tuning some lovely extractor manifold to get as much exhaust out as possible at the end of each stroke, and then you feed it back in with that emissions system ? :lol::lol:
At the end of the day, its an emissions device that hurts power. Bin it !
Don't listen to Troll, he has shares in a PCV manufacturer :lol:
"Personal opinion, all I want in my engine is cold, finely metered fuel and air, not uncontrollable random oil fumes and burnt exhaust gases. I mean, you spend a fortune on pulse tuning some lovely extractor manifold to get as much exhaust out as possible at the end of each stroke, and then you feed it back in with that emissions system ? "
You only feed it back in on idle as the one way valve shuts the instant you make positive pressure (hee hee)
You only feed it back in on idle as the one way valve shuts the instant you make positive pressure (hee hee)
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AJ4
Guest
lol, good point But thats only if your 15 year old oil-manked valve is still actually working and not just a big hole in your inlet
I still dont want to feed in sloppy seconds air thats already been burnt once, no matter what rpm
But thats only if your 15 year old oil-manked valve is still actually working and not just a big hole in your inlet I still dont want to feed in sloppy seconds air thats already been burnt once, no matter what rpm