Tests on the PCV system - How Honda intended it -
12-05-2003, 07:10 AM
#1
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Tests on the PCV system - How Honda intended it -
Over the years i have read much controversy over the stock PCV system and placing breather filters on the valve over. I have always wanted to test a stock Integra to get the facts straight and I finally got the opportunity to test this on a friends car.
Here is a picture from the helms manual so you can see the how the stock PCV system is supposed to work -
As you can see the airflow flows from the intake to the valve cover to supply fresh air. While the intake manifold supplies a source of vacuum to help evacuate the crankcase.
When designing a PCV system on cars their is 3 considerations which are taken in
1) Performance
2) Emissions standards
3) Reliability
Performance
It is well known that performance gains can be had if the crankcase is under a slight source of vacumm which helps reduce crankcase windage losses. Many domestic users have seen decent gains by using either an electric or mechanical pump to help evacuate the pressure generated in the crankcase and even generate a vacuum present. Regaining lost power through the introduction of vacuum pressure evacuating the crankcase will not be as noticable on a small displacement 4 cylinder as compared to a larger displacement 8cyl domestic. Despite this, it should still be of importance to explore the various configurations and attempt to "free-up" any power hidden in our engines which can easily be tested on a dyno.
Emmisions Standards and Reliabilty
In order to comply with US emission standards honda had to use a closed PCV sytem which eliminated oil vapor from escaping into the atmosphere either from the valve cover or the crankcase breather. Oil vapors being introduced into our cylinders hurts performance and increases the probability of detonation occuring. The stock PCV system allows for the introduction of oil vapors into our intake manifold which hurts performance and reliabilty(a stock intake manifold is usually caked with collected oil and soot over the years). Is the stock PCV system designed with reliabilty in mind or merely to meet emission standards? Can we make our cars more reliable when we ignore emission standards and neglect the environment?
Many attempt to trap some of the oil vapors being introduced into the engine by using either a catch can inline between the crankcase and intake manifold, a catch can inline between the valve cover breather and the intake, or both.
I sometimes find it odd how people on the web will go on for years argueing and theorizing about the way in which the stock PCV functions and the intentions Honda engineers had when designing it. Knowledge and progress can only be obtained through keen observation and constant empirical tests... anything else is just wastefull.
All these tests were conducted to measure the pressure differentiation between the valve cover and the stock air intake. It is already very well know the directional flow of from the "Crankcase-Crankcase breather-PCV valve- Intake manifold" path. The PCV valve acts as a check valve only allowing air to flow out of the crankcase and not in reverse. In a Naturally aspirated car the intake manifold provides a constant source of vacumm to pull air out of the crankcase. What we still need to tests is the pressure differentiation between the intake and the valve cover and how it behaves as a part in the system.
Here we go with the tests:
Car: 3 gen obd1 integra
Engine:
B18C1
Modifications:
DC4-1 header, exhaust, (Stock Air intake!)
The car was in great working order with good compression test + leakdown test #s.
Testing tools:
Calibrated Dewyer Magnehelic Pressure Gauge
0-5 psi range // Accuracy +-2% ///
**************** Test 1 ***********************
Tests were conducted in the driveway with the car in a nuetral gear with little to no load placed on the car.
Testing methodology:
The Magnehelic guage has a high and low pressure port to allow one to test pressure differences between two locations in real time. In the first test the low pressure port was connected to the Valve cover breather and the other port was connected directly to a stock intake as normally. In the second test I connected the low pressure port to the valve cover and the second port to a valve cover breather filter. In the tests data was recorded when the car was warming up and also recored at various different rpm levels when driving. The length of the hose was kept to a minimum to and from the guage. The length of the hose has no effect on the accuracy of the pressure readings and only effects the response quickness of the measurement.
Results:
The results for both trials were identical so the data will be shown together.
idle warm up: 0.9 psi drawn into the valve cover
idle operating temp: 0.8 psi drawn into the valve cover
2000 rpm: 0.75 psi drawn into the valve cover
5000 rpm: 0.70 psi drawn into the valve cover
8000 rpm: 0.65 psi drawn into the valve cover
Analysis of the results:
-At no load, you can see that the helms manual diagram is correct and their is a constant source of vacuum being drawn into the valve cover.
-The pressure being drawn into the valve cover tends to drop slightly at WOT and higher rev ranges.
-Using a valve cover breather did not impeed the breathing ability of the valve cover or change the results.
-The stock Intake does not have a slash cut tube inside the intake for assistance of pulling air into the valve cover. It sits flush. Because it sits flush, the bernoulli effect attempts to pull air out of the valve cover, yet the vacuum source in the Valve cover overcomes this and still draws the air into the valvecover.
Now for the more important test --- Load presented in a real life driving example and pressure datalogged.
************ Test 2*******************
Testing conditions: Car was warmed up to normal operating temperature. Vacuum tubes were thread through the firewall hole into the cabin where i could monitor the pressure difference while driving between the valve cover and intake.
Idle - 2K rpm... .75 to .8 psi vacuum into the valve cover.
whenever I place any amount of load on my car the vacuum pressure dropped down quickly.
2nd gear pull to 4K rpm the vacuum pressure quickly dropped to .5 psi vacuum drawn into the valve cover.
In 4th or 5th gear at 3-4K rpms I would quickly remove all vacuum present and noticed my needle went past 0 psi.
Out of curiousity I then reversed the vacuum ports to read any pressure comming out of the Valve cover under load.
Tests indicate that under load the pressure would shoot up to a maximum of .45 to .5 psi being pushed out of the valve cover.
Even at half throttle at 3500 rpm in 4th gear the flow reverses blowing air out of the valve cover into the intake... this is not just an issue at WOT or high speeds... This is an issue when any fair amount of load is placed on the sytem.
I conducted these tests over 30 minutes of driving in all gears. Unfortnately for safety reasons I was unable to rev past 5.5K rpm in any of the tests.
///////////////////////////////////////////////////////////////////////////////////
Conclusions:
- Engine Load effects the pressures in the PCV system.
- The diagram in the helms manual is correct only at idle and low load conditions.
- Load placed on the engine forces air to flow both out of the valve cover and out of the crankcase into the intake manifold. Thus the flow reverses from vacuum being drawn into the intake manifold to pressure forced out.
Before I give my opinion on the implications of the results on:
1) Valve cover breather Filter- helpful or harmful?
2) Stock Honda PCV system- designed for reliabilty, emmisions, or performance?
3) In terms of reliability and performance how should a NA PCV system be setup?
4) In terms of reliability and performance how should a FI PCV system be setup?
I welcome everyone else to first share their thoughts on these matters before I give my opinions.
I welcome any discussion or critism of my tests but please criticize the testing methodology or my analysis of data in a logical manner since I carefully spent the time to gather these results.
PS- stay tuned! when I have time I'm going to run several tests on the advantages/disadvantages of various different PCV systems on a Turbo car and test the results with the Dewyer gauge and test any performace gains which can be obtained(tested on a dyno).
Modified by dasher at 12:03 AM 12/6/2003
Here is a picture from the helms manual so you can see the how the stock PCV system is supposed to work -
As you can see the airflow flows from the intake to the valve cover to supply fresh air. While the intake manifold supplies a source of vacuum to help evacuate the crankcase.
When designing a PCV system on cars their is 3 considerations which are taken in
1) Performance
2) Emissions standards
3) Reliability
Performance
It is well known that performance gains can be had if the crankcase is under a slight source of vacumm which helps reduce crankcase windage losses. Many domestic users have seen decent gains by using either an electric or mechanical pump to help evacuate the pressure generated in the crankcase and even generate a vacuum present. Regaining lost power through the introduction of vacuum pressure evacuating the crankcase will not be as noticable on a small displacement 4 cylinder as compared to a larger displacement 8cyl domestic. Despite this, it should still be of importance to explore the various configurations and attempt to "free-up" any power hidden in our engines which can easily be tested on a dyno.
Emmisions Standards and Reliabilty
In order to comply with US emission standards honda had to use a closed PCV sytem which eliminated oil vapor from escaping into the atmosphere either from the valve cover or the crankcase breather. Oil vapors being introduced into our cylinders hurts performance and increases the probability of detonation occuring. The stock PCV system allows for the introduction of oil vapors into our intake manifold which hurts performance and reliabilty(a stock intake manifold is usually caked with collected oil and soot over the years). Is the stock PCV system designed with reliabilty in mind or merely to meet emission standards? Can we make our cars more reliable when we ignore emission standards and neglect the environment?
Many attempt to trap some of the oil vapors being introduced into the engine by using either a catch can inline between the crankcase and intake manifold, a catch can inline between the valve cover breather and the intake, or both.
I sometimes find it odd how people on the web will go on for years argueing and theorizing about the way in which the stock PCV functions and the intentions Honda engineers had when designing it. Knowledge and progress can only be obtained through keen observation and constant empirical tests... anything else is just wastefull.
All these tests were conducted to measure the pressure differentiation between the valve cover and the stock air intake. It is already very well know the directional flow of from the "Crankcase-Crankcase breather-PCV valve- Intake manifold" path. The PCV valve acts as a check valve only allowing air to flow out of the crankcase and not in reverse. In a Naturally aspirated car the intake manifold provides a constant source of vacumm to pull air out of the crankcase. What we still need to tests is the pressure differentiation between the intake and the valve cover and how it behaves as a part in the system.
Here we go with the tests:
Car: 3 gen obd1 integra
Engine:
B18C1
Modifications:
DC4-1 header, exhaust, (Stock Air intake!)
The car was in great working order with good compression test + leakdown test #s.
Testing tools:
Calibrated Dewyer Magnehelic Pressure Gauge
0-5 psi range // Accuracy +-2% ///
**************** Test 1 ***********************
Tests were conducted in the driveway with the car in a nuetral gear with little to no load placed on the car.
Testing methodology:
The Magnehelic guage has a high and low pressure port to allow one to test pressure differences between two locations in real time. In the first test the low pressure port was connected to the Valve cover breather and the other port was connected directly to a stock intake as normally. In the second test I connected the low pressure port to the valve cover and the second port to a valve cover breather filter. In the tests data was recorded when the car was warming up and also recored at various different rpm levels when driving. The length of the hose was kept to a minimum to and from the guage. The length of the hose has no effect on the accuracy of the pressure readings and only effects the response quickness of the measurement.
Results:
The results for both trials were identical so the data will be shown together.
idle warm up: 0.9 psi drawn into the valve cover
idle operating temp: 0.8 psi drawn into the valve cover
2000 rpm: 0.75 psi drawn into the valve cover
5000 rpm: 0.70 psi drawn into the valve cover
8000 rpm: 0.65 psi drawn into the valve cover
Analysis of the results:
-At no load, you can see that the helms manual diagram is correct and their is a constant source of vacuum being drawn into the valve cover.
-The pressure being drawn into the valve cover tends to drop slightly at WOT and higher rev ranges.
-Using a valve cover breather did not impeed the breathing ability of the valve cover or change the results.
-The stock Intake does not have a slash cut tube inside the intake for assistance of pulling air into the valve cover. It sits flush. Because it sits flush, the bernoulli effect attempts to pull air out of the valve cover, yet the vacuum source in the Valve cover overcomes this and still draws the air into the valvecover.
Now for the more important test --- Load presented in a real life driving example and pressure datalogged.
************ Test 2*******************
Testing conditions: Car was warmed up to normal operating temperature. Vacuum tubes were thread through the firewall hole into the cabin where i could monitor the pressure difference while driving between the valve cover and intake.
Idle - 2K rpm... .75 to .8 psi vacuum into the valve cover.
whenever I place any amount of load on my car the vacuum pressure dropped down quickly.
2nd gear pull to 4K rpm the vacuum pressure quickly dropped to .5 psi vacuum drawn into the valve cover.
In 4th or 5th gear at 3-4K rpms I would quickly remove all vacuum present and noticed my needle went past 0 psi.
Out of curiousity I then reversed the vacuum ports to read any pressure comming out of the Valve cover under load.
Tests indicate that under load the pressure would shoot up to a maximum of .45 to .5 psi being pushed out of the valve cover.
Even at half throttle at 3500 rpm in 4th gear the flow reverses blowing air out of the valve cover into the intake... this is not just an issue at WOT or high speeds... This is an issue when any fair amount of load is placed on the sytem.
I conducted these tests over 30 minutes of driving in all gears. Unfortnately for safety reasons I was unable to rev past 5.5K rpm in any of the tests.
///////////////////////////////////////////////////////////////////////////////////
Conclusions:
- Engine Load effects the pressures in the PCV system.
- The diagram in the helms manual is correct only at idle and low load conditions.
- Load placed on the engine forces air to flow both out of the valve cover and out of the crankcase into the intake manifold. Thus the flow reverses from vacuum being drawn into the intake manifold to pressure forced out.
Before I give my opinion on the implications of the results on:
1) Valve cover breather Filter- helpful or harmful?
2) Stock Honda PCV system- designed for reliabilty, emmisions, or performance?
3) In terms of reliability and performance how should a NA PCV system be setup?
4) In terms of reliability and performance how should a FI PCV system be setup?
I welcome everyone else to first share their thoughts on these matters before I give my opinions.
I welcome any discussion or critism of my tests but please criticize the testing methodology or my analysis of data in a logical manner since I carefully spent the time to gather these results.
PS- stay tuned! when I have time I'm going to run several tests on the advantages/disadvantages of various different PCV systems on a Turbo car and test the results with the Dewyer gauge and test any performace gains which can be obtained(tested on a dyno).
Modified by dasher at 12:03 AM 12/6/2003
12-05-2003, 09:19 AM
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Re: Tests on the PCV system - How Honda intended it - (dasher)
cool test.............i only run the stock PCV system on my B16A........on my Big Block Chevy i just run the breathers on both valve covers......
12-05-2003, 09:47 AM
#3
Re: Tests on the PCV system - How Honda intended it - (dasher)
This is a great post dasher!
Would a slash cut tube in the intake arm allow the pcv to open while under load? Or would the pressure from the valve cover overcome it?
1. As long as its clean it shouldn't matter.
2. emissions at low rpm, performance at high rpm, both reroute oil vapor to the intake mani, which is not good for reliability as defined.
3+4. Need to eliminate rerouting the oil vapor back to the intake mani. Either an external vac source, or open loop.
Would a slash cut tube in the intake arm allow the pcv to open while under load? Or would the pressure from the valve cover overcome it?
1. As long as its clean it shouldn't matter.
2. emissions at low rpm, performance at high rpm, both reroute oil vapor to the intake mani, which is not good for reliability as defined.
3+4. Need to eliminate rerouting the oil vapor back to the intake mani. Either an external vac source, or open loop.
12-05-2003, 12:24 PM
#4
Re: Tests on the PCV system - How Honda intended it - (Sleeper)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sleeper »</TD></TR><TR><TD CLASS="quote">Would a slash cut tube in the intake arm allow the pcv to open while under load? Or would the pressure from the valve cover overcome it?</TD></TR></TABLE>It might help under some borderline conditions, but 1/2*rho*V^2 is going to be a fairly small pressure. Like 0.076psi for air going 100ft/sec in the intake pipe.
This is an interesting test. Now a question for dasher...
When you connected the gauge, did you put it in series with the breather? In other words, did the gauge prevent the air from flowing through the breather? If so, it will influence the position of the PCV valve & then your system isn't in the same configuration as it would be in normal operation.
This is an interesting test. Now a question for dasher...
When you connected the gauge, did you put it in series with the breather? In other words, did the gauge prevent the air from flowing through the breather? If so, it will influence the position of the PCV valve & then your system isn't in the same configuration as it would be in normal operation.
12-05-2003, 01:38 PM
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Re: Tests on the PCV system - How Honda intended it - (JimBlake)
A very timely & interesting thread . . . There's been lots of discussion on this stuff the past few weeks, and very little hard data.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake »</TD></TR><TR><TD CLASS="quote">When you connected the gauge, did you put it in series with the breather? In other words, did the gauge prevent the air from flowing through the breather? If so, it will influence the position of the PCV valve & then your system isn't in the same configuration as it would be in normal operation.
</TD></TR></TABLE>
That's an interesting point . . . . How does your gauge work?
I was a little surprised to see that the PCV valve closes itself at WOT. Is that a known fact? Does vacuum really drop that much at WOT? I would think it would be at it's highest . . . .
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake »</TD></TR><TR><TD CLASS="quote">When you connected the gauge, did you put it in series with the breather? In other words, did the gauge prevent the air from flowing through the breather? If so, it will influence the position of the PCV valve & then your system isn't in the same configuration as it would be in normal operation.
</TD></TR></TABLE>
That's an interesting point . . . . How does your gauge work?
I was a little surprised to see that the PCV valve closes itself at WOT. Is that a known fact? Does vacuum really drop that much at WOT? I would think it would be at it's highest . . . .
12-05-2003, 04:00 PM
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Re: Tests on the PCV system - How Honda intended it - (Daemione)
Well, I hooked up my system to function like my motorcycle, because my motorcycle (At the time of it's manufacture) was not mandated to have a PVC System at all.
And considering the HP wars between the manufactures, they would not waste 1 HP on emissions that wasn't required by the Gov't.
So..
The hose from my PVC Valve runs nowhere, it's ty-rapped* to the back of the block, open-ended.
(As you said, it's a check valve and can only let pressure escape, nothing gets drawn in)
This hose has remained "Bone-Dry" (No oily residue on the open end) over thousands upon thousands of miles.
And on my valve cover:
I have a long hose attached running to the bottom of the car that sits flush with the tow hook.
This hose always drops nasty muck, (Water & Oil mix I guess) not much, but I sure as hell do not want it going into my intake manifold.
So, being all the crap is being drawn out the bottom of the car, and my intake only sucks dry, clean air, I'm pleased at it's operation.
Yes, I'm not doing everything I can to save the planet.
[EDIT]
How'd I do?
[/EDIT]
And considering the HP wars between the manufactures, they would not waste 1 HP on emissions that wasn't required by the Gov't.
So..
The hose from my PVC Valve runs nowhere, it's ty-rapped* to the back of the block, open-ended.
(As you said, it's a check valve and can only let pressure escape, nothing gets drawn in)
This hose has remained "Bone-Dry" (No oily residue on the open end) over thousands upon thousands of miles.
And on my valve cover:
I have a long hose attached running to the bottom of the car that sits flush with the tow hook.
This hose always drops nasty muck, (Water & Oil mix I guess) not much, but I sure as hell do not want it going into my intake manifold.
So, being all the crap is being drawn out the bottom of the car, and my intake only sucks dry, clean air, I'm pleased at it's operation.
Yes, I'm not doing everything I can to save the planet.
[EDIT]
How'd I do?
[/EDIT]
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12-05-2003, 04:44 PM
#8
Re: Tests on the PCV system - How Honda intended it - (7PSI CRX)
great post dasher 
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 7PSI CRX »</TD></TR><TR><TD CLASS="quote">This hose always drops nasty muck, (Water & Oil mix I guess) not much, but I sure as hell do not want it going into my intake manifold.</TD></TR></TABLE>
I'd be curious how much of the water dripping out of there is just picked up road filth and how much is coming out of your motor.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 7PSI CRX »</TD></TR><TR><TD CLASS="quote">This hose always drops nasty muck, (Water & Oil mix I guess) not much, but I sure as hell do not want it going into my intake manifold.</TD></TR></TABLE>
I'd be curious how much of the water dripping out of there is just picked up road filth and how much is coming out of your motor.
12-05-2003, 07:17 PM
#10
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Thread Starter
Re: Tests on the PCV system - How Honda intended it -
Ok guys lets go through some basics.
Purpose of the PCV system
During each compression stroke a small amount of gas seeps past the piston rings. These gasses comprise of an unburnt fuel/air mixture which contaiminates your engine oil and corrodes your internal parts. The purpose of the PCV system is to remove these gasses while maintaining emissions standards.
The PCV valve tested is known as a variable-flow PCV valve. This valve allows the crankcase to evacuate gasses into the intake manifold even at high load conditions.
The problem Honda engineers had was the following:
They needed to find a vacuum source which provides a variable vacuum with less draw at idle and more vacuum pressure pulling gasses out at high load (WOT) conditions. The dilemma is that at Idle and low load conditions the vacuum present inside the Intake manifold is the greatest and at WOT the vacuum in the intake manifold is the lowest(almost none). This is the exact opposite of what is needed because their is more blowby gasses needed to evacuate at WOT (high load) then at Idle!
So they designed a special spring loaded pintle valve(PCV valve) which does the following:
Idle, Low load--- high vacuum pressures fully retract the pintle causing only a small vacuum draw on the crankcase.
Mild load conditions--- vacuum present in the intake manifold is not as strong so the pintle sits in the middle of the pcv valve allowing more vacuum to evacuate the crankcase.
High load + WOT conditions--- their is almost no vacuum present and the pintle is almost completely extended allowing the most amount of gasses to be drawn into the intake manifold.
Engine backfire--- the pintle fully extends and seals to eliminate any gasses from flowing from the intake manifold to the crankcase.
Under acceleration and high load situations blowby is extremely high and consequently the PCV valve/purge hose cannot supply enough vacuum to remove all the gasses needed. This is when the flow reverses from the valve cover to the intake. Their is so much blowby present that both the PCV valve/purge hose and the Valve cover breather/hose have to both vent excess pressures created. The PCV is working at its best but can't keep up with the demanding pressures created.
Purpose of the PCV system
During each compression stroke a small amount of gas seeps past the piston rings. These gasses comprise of an unburnt fuel/air mixture which contaiminates your engine oil and corrodes your internal parts. The purpose of the PCV system is to remove these gasses while maintaining emissions standards.
The PCV valve tested is known as a variable-flow PCV valve. This valve allows the crankcase to evacuate gasses into the intake manifold even at high load conditions.
The problem Honda engineers had was the following:
They needed to find a vacuum source which provides a variable vacuum with less draw at idle and more vacuum pressure pulling gasses out at high load (WOT) conditions. The dilemma is that at Idle and low load conditions the vacuum present inside the Intake manifold is the greatest and at WOT the vacuum in the intake manifold is the lowest(almost none). This is the exact opposite of what is needed because their is more blowby gasses needed to evacuate at WOT (high load) then at Idle!
So they designed a special spring loaded pintle valve(PCV valve) which does the following:
Idle, Low load--- high vacuum pressures fully retract the pintle causing only a small vacuum draw on the crankcase.
Mild load conditions--- vacuum present in the intake manifold is not as strong so the pintle sits in the middle of the pcv valve allowing more vacuum to evacuate the crankcase.
High load + WOT conditions--- their is almost no vacuum present and the pintle is almost completely extended allowing the most amount of gasses to be drawn into the intake manifold.
Engine backfire--- the pintle fully extends and seals to eliminate any gasses from flowing from the intake manifold to the crankcase.
Under acceleration and high load situations blowby is extremely high and consequently the PCV valve/purge hose cannot supply enough vacuum to remove all the gasses needed. This is when the flow reverses from the valve cover to the intake. Their is so much blowby present that both the PCV valve/purge hose and the Valve cover breather/hose have to both vent excess pressures created. The PCV is working at its best but can't keep up with the demanding pressures created.
12-05-2003, 07:27 PM
#11
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Re: Tests on the PCV system - How Honda intended it - (Sleeper)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sleeper »</TD></TR><TR><TD CLASS="quote">Would a slash cut tube in the intake arm allow the pcv to open while under load? Or would the pressure from the valve cover overcome it? </TD></TR></TABLE>
a slashcut tube in the intake arm will have no effect on wether the intake will open under load because the pintle location in the pcv valve is solely dictated by the pressure differentiation between the Intake manifold and the crankcase and a slashcut tube(in the intake) will not effect the pressure seen(in the Intake Manifold) at various load conditions.
a slashcut tube in the intake arm will have no effect on wether the intake will open under load because the pintle location in the pcv valve is solely dictated by the pressure differentiation between the Intake manifold and the crankcase and a slashcut tube(in the intake) will not effect the pressure seen(in the Intake Manifold) at various load conditions.
12-05-2003, 07:48 PM
#12
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Thread Starter
Re: Tests on the PCV system - How Honda intended it - (JimBlake)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake »</TD></TR><TR><TD CLASS="quote">
This is an interesting test. Now a question for dasher...
When you connected the gauge, did you put it in series with the breather? In other words, did the gauge prevent the air from flowing through the breather? If so, it will influence the position of the PCV valve & then your system isn't in the same configuration as it would be in normal operation.
</TD></TR></TABLE>
The Dewyer gauge was place inline with one port connected to the valve cover and the other port connected to the intake. This setup does block the flow of gasses from the Valve cover to the intake tract. It has no influence upon the pintle position inside the pcv valve(see above posts for explanation). However the numbers recorded do not accurately represent the pressures seen inside the valve cover because the gauge restricts flow and consequently will build higher pressures(in the valve cover) than would normally be seen in a stock system.
In order to accurately measure the pressure seen in the valve cover one would simply connect the breather hose as normally to the intake and tap another hole in the valve cover to rune a 1 hose to either the high/low pressure port on the Gauge while the other port be left open to atmosphere. This would accurately measure the pressure or vacuum in the valve cover and keep the stock PCV system intact.
The purpose of these tests were not to measure the pressures/vacuum seen in the valve cover but merely to measure the pressure differentiation between the stock intake and the valve cover breather outlet. Flow direction can thus be obtained from the analysis of the pressure differences between both points and this is what we are after. Was the Helms diagram correct? Is blowby so great under load that the stock pcv valve/purge line becomes overcome and the pressures have to escape out of the valve cover breather? These are the questions which were accurately answered by the tests.
This is an interesting test. Now a question for dasher...
When you connected the gauge, did you put it in series with the breather? In other words, did the gauge prevent the air from flowing through the breather? If so, it will influence the position of the PCV valve & then your system isn't in the same configuration as it would be in normal operation.
</TD></TR></TABLE>
The Dewyer gauge was place inline with one port connected to the valve cover and the other port connected to the intake. This setup does block the flow of gasses from the Valve cover to the intake tract. It has no influence upon the pintle position inside the pcv valve(see above posts for explanation). However the numbers recorded do not accurately represent the pressures seen inside the valve cover because the gauge restricts flow and consequently will build higher pressures(in the valve cover) than would normally be seen in a stock system.
In order to accurately measure the pressure seen in the valve cover one would simply connect the breather hose as normally to the intake and tap another hole in the valve cover to rune a 1 hose to either the high/low pressure port on the Gauge while the other port be left open to atmosphere. This would accurately measure the pressure or vacuum in the valve cover and keep the stock PCV system intact.
The purpose of these tests were not to measure the pressures/vacuum seen in the valve cover but merely to measure the pressure differentiation between the stock intake and the valve cover breather outlet. Flow direction can thus be obtained from the analysis of the pressure differences between both points and this is what we are after. Was the Helms diagram correct? Is blowby so great under load that the stock pcv valve/purge line becomes overcome and the pressures have to escape out of the valve cover breather? These are the questions which were accurately answered by the tests.
12-05-2003, 07:53 PM
#13
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Thread Starter
Re: Tests on the PCV system - How Honda intended it - (Daemione)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Daemione »</TD></TR><TR><TD CLASS="quote">I was a little surprised to see that the PCV valve closes itself at WOT. Is that a known fact? Does vacuum really drop that much at WOT? I would think it would be at it's highest . . . . </TD></TR></TABLE>
You did catch one mistake i made (and corrected)... I was right the first time when I explained that at WOT their are very little(almost none) vacuum present... however the PCV valve actually opens up greater at WOT .... yet it cannot keep up with the demanding blowby gasses created.
You did catch one mistake i made (and corrected)... I was right the first time when I explained that at WOT their are very little(almost none) vacuum present... however the PCV valve actually opens up greater at WOT .... yet it cannot keep up with the demanding blowby gasses created.
12-05-2003, 08:00 PM
#14
Member
Thread Starter
Re: Tests on the PCV system - How Honda intended it - (7PSI CRX)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 7PSI CRX »</TD></TR><TR><TD CLASS="quote">
Yes, I'm not doing everything I can to save the planet.
[EDIT]
How'd I do?
[/EDIT]</TD></TR></TABLE>
I would have to agree with your sentiments; most people on this board probably have little to no concern about their car polluting the environment or maintaining emissions(except those people in Cali.).... although I consider myself somewhat concerned with keeping our planet clean , the oil vapors escaping through an open pcv system are so small that It is the last of my worries when designing a modified PCV system.
Yes, I'm not doing everything I can to save the planet.
[EDIT]
How'd I do?
[/EDIT]</TD></TR></TABLE>
I would have to agree with your sentiments; most people on this board probably have little to no concern about their car polluting the environment or maintaining emissions(except those people in Cali.).... although I consider myself somewhat concerned with keeping our planet clean , the oil vapors escaping through an open pcv system are so small that It is the last of my worries when designing a modified PCV system.
12-05-2003, 09:43 PM
#15
Honda-Tech Member
Re: Tests on the PCV system - How Honda intended it - (dasher)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dasher »</TD></TR><TR><TD CLASS="quote">
High load + WOT conditions--- their is almost no vacuum present and the pintle is almost completely extended allowing the most amount of gasses to be drawn into the intake manifold.
</TD></TR></TABLE>
Under high loads, (no vacuum) wouldn't the PCV valve be pushed closed by the internal spring. It would be as if it had the same presure on either side of it, as it would in it's rest possition if it was disconnected and you were holding it in your hand. Or am I missing something?
12-05-2003, 09:47 PM
#16
Honda-Tech Member
Re: Tests on the PCV system - How Honda intended it - (dasher)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dasher »</TD></TR><TR><TD CLASS="quote">
the oil vapors escaping through an open pcv system are so small that It is the last of my worries when designing a modified PCV system.</TD></TR></TABLE>
Actually it's a pretty large chunk of hc the system keeps under control.
the oil vapors escaping through an open pcv system are so small that It is the last of my worries when designing a modified PCV system.</TD></TR></TABLE>
Actually it's a pretty large chunk of hc the system keeps under control.
12-05-2003, 10:05 PM
#17
Member
Thread Starter
Re: Tests on the PCV system - How Honda intended it - (Chiovnidca)
"Large" relative to the engine ... but I was speaking in the context of the amount of pollution being emited to the atmosphere in a open PCV system system versus
1)Someone with a leaky oil pan
2)Someone with a bad cat
3)Someone driving around with a smoking exhaust because of bad piston rings
People running an open pcv system are not polluting the environment anywhere near what these people are and their are a ton of them out their.
1)Someone with a leaky oil pan
2)Someone with a bad cat
3)Someone driving around with a smoking exhaust because of bad piston rings
People running an open pcv system are not polluting the environment anywhere near what these people are and their are a ton of them out their.
12-05-2003, 10:09 PM
#18
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Thread Starter
Re: Tests on the PCV system - How Honda intended it - (Chiovnidca)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chiovnidca »</TD></TR><TR><TD CLASS="quote">
Under high loads, (no vacuum) wouldn't the PCV valve be pushed closed by the internal spring. It would be as if it had the same presure on either side of it, as it would in it's rest possition if it was disconnected and you were holding it in your hand. Or am I missing something?
</TD></TR></TABLE>
Under high loads(Very slight vacuum) the PCV valve is not closed . Emailed you a pdf with some pictures and diagrams of how a pcv valve works and the position of the pintle in various different stages .
Under high loads, (no vacuum) wouldn't the PCV valve be pushed closed by the internal spring. It would be as if it had the same presure on either side of it, as it would in it's rest possition if it was disconnected and you were holding it in your hand. Or am I missing something?
</TD></TR></TABLE>
Under high loads(Very slight vacuum) the PCV valve is not closed . Emailed you a pdf with some pictures and diagrams of how a pcv valve works and the position of the pintle in various different stages .
12-05-2003, 11:16 PM
#19
Honda-Tech Member
Re: Tests on the PCV system - How Honda intended it - (dasher)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dasher »</TD></TR><TR><TD CLASS="quote">
Under high loads(Very slight vacuum) the PCV valve is not closed . </TD></TR></TABLE>
What about at wide open throttle, no vacuum?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dasher »</TD></TR><TR><TD CLASS="quote">
Emailed you a pdf with some pictures and diagrams of how a pcv valve works and the position of the pintle in various different stages .</TD></TR></TABLE>
That's similar to what Honda has in there training module. But remember, Toyotas PCV system sucks compared to Hondas. They are having all kinds of trouble with sludge buildup. They are not all created equal.
Any idea how long PCV systems have been around?
Under high loads(Very slight vacuum) the PCV valve is not closed . </TD></TR></TABLE>
What about at wide open throttle, no vacuum?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dasher »</TD></TR><TR><TD CLASS="quote">
Emailed you a pdf with some pictures and diagrams of how a pcv valve works and the position of the pintle in various different stages .</TD></TR></TABLE>
That's similar to what Honda has in there training module. But remember, Toyotas PCV system sucks compared to Hondas. They are having all kinds of trouble with sludge buildup. They are not all created equal.
Any idea how long PCV systems have been around?
12-05-2003, 11:48 PM
#20
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Re: Tests on the PCV system - How Honda intended it - (dasher)
simply put, theoretically, would it hurt or help hp with just having the factory pcv system setup but running a valve cover breather filter as opposed to hose to intake pipe? My brain is already fried!
12-06-2003, 04:52 AM
#21
Member
Thread Starter
Re: Tests on the PCV system - How Honda intended it - (Chiovnidca)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chiovnidca »</TD></TR><TR><TD CLASS="quote">
What about at wide open throttle, no vacuum? </TD></TR></TABLE>
If their is no vacuum then the PCV valve will close... Ive always have been able to test a slight amount of vacuum at WOT in the Intake manifold... If the PCV valve is operating correctly it should be open during WOT... their is a fine line however when you look at the diagrams before it being fully open and closed.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chiovnidca »</TD></TR><TR><TD CLASS="quote">
That's similar to what Honda has in there training module. But remember, Toyotas PCV system sucks compared to Hondas. They are having all kinds of trouble with sludge buildup. They are not all created equal. </TD></TR></TABLE>
Hondas PCV valves may be superior but the principles behind the way a variable flow PCV valve function are the same between the two. I was not trying to say that toyota's build superior PCV valves ... i merely was pulling up a picture to show how modern pcv valves function.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chiovnidca »</TD></TR><TR><TD CLASS="quote">Any idea how long PCV systems have been around? </TD></TR></TABLE>
I don't see how this exactly fits in the scope of the discussion... but I guess it always interesting to throw in a "fun fact" every now and then ....
The earliest I can remember a PCV system being used was in a 1926 Cadillac V8... which at that time was did not use a variable PCv valve and was a open system. In 1963 they introduced a closed PCv system.
What about at wide open throttle, no vacuum? </TD></TR></TABLE>
If their is no vacuum then the PCV valve will close... Ive always have been able to test a slight amount of vacuum at WOT in the Intake manifold... If the PCV valve is operating correctly it should be open during WOT... their is a fine line however when you look at the diagrams before it being fully open and closed.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chiovnidca »</TD></TR><TR><TD CLASS="quote">
That's similar to what Honda has in there training module. But remember, Toyotas PCV system sucks compared to Hondas. They are having all kinds of trouble with sludge buildup. They are not all created equal. </TD></TR></TABLE>
Hondas PCV valves may be superior but the principles behind the way a variable flow PCV valve function are the same between the two. I was not trying to say that toyota's build superior PCV valves ... i merely was pulling up a picture to show how modern pcv valves function.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chiovnidca »</TD></TR><TR><TD CLASS="quote">Any idea how long PCV systems have been around? </TD></TR></TABLE>
I don't see how this exactly fits in the scope of the discussion... but I guess it always interesting to throw in a "fun fact" every now and then ....
The earliest I can remember a PCV system being used was in a 1926 Cadillac V8... which at that time was did not use a variable PCv valve and was a open system. In 1963 they introduced a closed PCv system.
12-06-2003, 05:19 AM
#22
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Thread Starter
Re: Tests on the PCV system - How Honda intended it - (VtecDA9)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by VtecDA9 »</TD></TR><TR><TD CLASS="quote">simply put, theoretically, would it hurt or help hp with just having the factory pcv system setup but running a valve cover breather filter as opposed to hose to intake pipe? My brain is already fried!</TD></TR></TABLE>
Its no fun to just giving the answers away
ok ... here is my opinion on keeping the PCV valve/purge line stock while slapping on one of the cheap breather filters on the valve cover breather:
-- Honda reroutes the excess oil vapor/unburnt air-fuel pressures to be purged through the valve cover(Only to be ingested by the engine through the intake) to keep the PCV system closed and meet emission standards.
--- If you don't care about emissions and you keep the breather filter cleaned then it could only help by removing these gases from re-entering the incoming air to be ingested.
--- The bernoulli effect of a the flush opening in the intake has negligable benefits in assisting the pull of the excess gasses thats build up in the valve cover under load.
--- The bernoulli effect works against the vacuum at low load/idle situations and some people have noticed that an introduction of a slash-cut tube facing airflow to assist (rather then resist in the flush setup) in the vacuum drawn into the valve cover has some benefits in helping the piston rings seat better.
Its no fun to just giving the answers away
ok ... here is my opinion on keeping the PCV valve/purge line stock while slapping on one of the cheap breather filters on the valve cover breather:
-- Honda reroutes the excess oil vapor/unburnt air-fuel pressures to be purged through the valve cover(Only to be ingested by the engine through the intake) to keep the PCV system closed and meet emission standards.
--- If you don't care about emissions and you keep the breather filter cleaned then it could only help by removing these gases from re-entering the incoming air to be ingested.
--- The bernoulli effect of a the flush opening in the intake has negligable benefits in assisting the pull of the excess gasses thats build up in the valve cover under load.
--- The bernoulli effect works against the vacuum at low load/idle situations and some people have noticed that an introduction of a slash-cut tube facing airflow to assist (rather then resist in the flush setup) in the vacuum drawn into the valve cover has some benefits in helping the piston rings seat better.
12-06-2003, 05:49 AM
#23
Honda-Tech Member
Re: Tests on the PCV system - How Honda intended it - (dasher)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dasher »</TD></TR><TR><TD CLASS="quote">
High load + WOT conditions--- their is almost no vacuum present and the pintle is almost completely extended allowing the most amount of gasses to be drawn into the intake manifold.
</TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dasher »</TD></TR><TR><TD CLASS="quote">
If their is no vacuum then the PCV valve will close... Ive always have been able to test a slight amount of vacuum at WOT in the Intake manifold... If the PCV valve is operating correctly it should be open during WOT... their is a fine line however when you look at the diagrams before it being fully open and closed.
</TD></TR></TABLE>
What i'm trying to get at is that if there is little presure difference, there isn't going to be much flow. Right? It seems to me that the highest flow through the PCV valve would be during light load cruise conditions.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dasher »</TD></TR><TR><TD CLASS="quote">
I don't see how this exactly fits in the scope of the discussion... but I guess it always interesting to throw in a "fun fact" every now and then ....
The earliest I can remember a PCV system being used was in a 1926 Cadillac V8... which at that time was did not use a variable PCv valve and was a open system. In 1963 they introduced a closed PCv system. </TD></TR></TABLE>
I was just curious on this. They made alot of advancements on autos in the 1920s, doesn't surprise me at all.
In the early 1960, PCV systems were mandated for autos sold in California, to help control hydrocarbon emissions. I think that makes it the first required emission control system for autos.
12-06-2003, 06:38 AM
#24
Member
Thread Starter
Re: Tests on the PCV system - How Honda intended it - (Chiovnidca)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chiovnidca »</TD></TR><TR><TD CLASS="quote">
What i'm trying to get at is that if there is little presure difference, there isn't going to be much flow. Right? It seems to me that the highest flow through the PCV valve would be during light load cruise conditions.
</TD></TR></TABLE>
if you study the PCV diagrams you will notice that slight vacuum(under WOT) will cause the PCV valve to open fully and at backfire or no vacuum will close the PCV valve.
A variable PCV valve has the characteristics of the following:
this is a chart to help explain it...
Engine off/backfire --- Low load/Idle --- Medium Load/cruising --- High load/WOT
0 /positive pressure---Highest Vacuum--- Moderate Vacuum ---- Slight Vacuum
PCV Valve closed ---- PCV open slightly-- Valve opens more --- Open all the way
What i'm trying to get at is that if there is little presure difference, there isn't going to be much flow. Right? It seems to me that the highest flow through the PCV valve would be during light load cruise conditions.
</TD></TR></TABLE>
if you study the PCV diagrams you will notice that slight vacuum(under WOT) will cause the PCV valve to open fully and at backfire or no vacuum will close the PCV valve.
A variable PCV valve has the characteristics of the following:
this is a chart to help explain it...
Engine off/backfire --- Low load/Idle --- Medium Load/cruising --- High load/WOT
0 /positive pressure---Highest Vacuum--- Moderate Vacuum ---- Slight Vacuum
PCV Valve closed ---- PCV open slightly-- Valve opens more --- Open all the way
12-06-2003, 06:55 AM
#25
Honda-Tech Member
Re: Tests on the PCV system - How Honda intended it - (dasher)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dasher »</TD></TR><TR><TD CLASS="quote">
if you study the PCV diagrams you will notice that slight vacuum(under WOT) will cause the PCV valve to open fully and at backfire or no vacuum will close the PCV valve.
A variable PCV valve has the characteristics of the following:
this is a chart to help explain it...
Engine off/backfire --- Low load/Idle --- Medium Load/cruising --- High load/WOT
0 /positive pressure---Highest Vacuum--- Moderate Vacuum ---- Slight Vacuum
PCV Valve closed ---- PCV open slightly-- Valve opens more --- Open all the way</TD></TR></TABLE>
I'm still not getting across my question: Even if the valve is fully open, if there is very little presure difference from one side to the other, there will be little flow, right?
if you study the PCV diagrams you will notice that slight vacuum(under WOT) will cause the PCV valve to open fully and at backfire or no vacuum will close the PCV valve.
A variable PCV valve has the characteristics of the following:
this is a chart to help explain it...
Engine off/backfire --- Low load/Idle --- Medium Load/cruising --- High load/WOT
0 /positive pressure---Highest Vacuum--- Moderate Vacuum ---- Slight Vacuum
PCV Valve closed ---- PCV open slightly-- Valve opens more --- Open all the way</TD></TR></TABLE>
I'm still not getting across my question: Even if the valve is fully open, if there is very little presure difference from one side to the other, there will be little flow, right?