Vented oil cap question.
Intermediate
Joined: May 2006
Posts: 32
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Originally Posted by SleeperC5
O2 sensors have been deleted because I was getting the CEL and the code for the passenger side rear O2 sensor. The wires look fine.
If I'm being a newbie, just tell me so and I'll go away
Thread Starter
Le Mans Master
Joined: Aug 2003
Posts: 9,298
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From: American Canyon Lethal Injection
Originally Posted by Glacial
Wait, the rear O2s, or ALL O2s? Wouldn't no O2s lead to strange fuel trims and PE?
If I'm being a newbie, just tell me so and I'll go away
If I'm being a newbie, just tell me so and I'll go away
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
Originally Posted by AMERICAN_HP
But at over 1,000 bucks, its not in line with other remedies on the market.
I was just pointing out that some do this for better performance and less oil consumption.
DH
Team Owner
Joined: May 2004
Posts: 26,345
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From: SoCal
Originally Posted by SleeperC5
Thanks for your input.
I have removed the breather oil cap and replaced it with the sealed oil cap. As you see this is a controversial subject, others believe there is no harm or degrading the performance with a breather oil cap and a catch can.
The car had a street tune after the headers and the FAST intake were installed.
O2 sensors have been deleted because I was getting the CEL and the code for the passenger side rear O2 sensor. The wires look fine.
No vacuum leaks were reported by the tuner or installer, but there is a whistle from the FAST and I was told "they" all do that.
The dyno tuner told me that I don't have large enough cam to run the FAST, not enough duration on the stock 02 ZO6 cam. I'll be taking the FAST off and putting back my LS6 intake along with 1.8 rockers, longer hardened push rods and 918 springs before taking it back for another dyno and tune.
My dyno numbers went from 349 rwhp to 339 rwhp. the rwtq went from 351 to 350 rwtq. Both were done on a DynoJet and the first was done in 20 degree warmer weather.
I'm sure other will still chime in with their thoughts.
Very nice Corvette you have.
BTW, how does 801 rwhp feel?
SLPRC5
I have removed the breather oil cap and replaced it with the sealed oil cap. As you see this is a controversial subject, others believe there is no harm or degrading the performance with a breather oil cap and a catch can.
The car had a street tune after the headers and the FAST intake were installed.
O2 sensors have been deleted because I was getting the CEL and the code for the passenger side rear O2 sensor. The wires look fine.
No vacuum leaks were reported by the tuner or installer, but there is a whistle from the FAST and I was told "they" all do that.
The dyno tuner told me that I don't have large enough cam to run the FAST, not enough duration on the stock 02 ZO6 cam. I'll be taking the FAST off and putting back my LS6 intake along with 1.8 rockers, longer hardened push rods and 918 springs before taking it back for another dyno and tune.
My dyno numbers went from 349 rwhp to 339 rwhp. the rwtq went from 351 to 350 rwtq. Both were done on a DynoJet and the first was done in 20 degree warmer weather.
I'm sure other will still chime in with their thoughts.
Very nice Corvette you have.
BTW, how does 801 rwhp feel?
SLPRC5
DH
Team Owner
Joined: May 2004
Posts: 26,345
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From: SoCal
Originally Posted by Warp Factor
Your setup as pictured is fine. As long as you still have the PCV valve (I can't tell from the picture) there will be nothing wrong with the metering. It's the PCV valve that controls the metering, not the valve cover breather.
As pictured, you have two sources of air to the crankcase. One is the breather, the other is the normal supply fitting at the throttle body. If you want, you could cap the throttle body fitting and remove the small filter and hoses, and also cap the valve cover fitting on the other end just to clean up the engine compartment, if you put the breather back on.
The only time crankcase fumes might come out the breather is at full throttle. As long as there's manifold vacuum and you don't have excessive blowby, air flow will always be in the other direction.
As pictured, you have two sources of air to the crankcase. One is the breather, the other is the normal supply fitting at the throttle body. If you want, you could cap the throttle body fitting and remove the small filter and hoses, and also cap the valve cover fitting on the other end just to clean up the engine compartment, if you put the breather back on.
The only time crankcase fumes might come out the breather is at full throttle. As long as there's manifold vacuum and you don't have excessive blowby, air flow will always be in the other direction.
DH
Le Mans Master
Joined: Oct 2005
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From: Metro Detroit Michigan
Originally Posted by Dirty Howie
What about late model 2004 ..... there is no PCV valve .... just baffling in the valley. Do you think unmetered air would still NOT be an issue??
DH
DH
Chevrolet lists a PCV valve for the 2004..............
Former Vendor
Joined: Feb 2004
Posts: 10,876
Likes: 8
From: Las Vegas NV
St. Jude Donor '06 & '12
Honestly it doesnt matter what year it is..
This setup is a MASSIVE vaccum leak.
Look at the picture... The vaccum from the motor pulls the air through the filter, then through the valve cover, and directly into the intake manifold (Behind the MAF sensor) This air is unmetered by the MAF.. That affects the performance of the motor. It is ingesting air that the MAF is unable to adjust for. The ONLY way it wouldnt matter is if the car is tuned in SD.
This setup is a MASSIVE vaccum leak.
Look at the picture... The vaccum from the motor pulls the air through the filter, then through the valve cover, and directly into the intake manifold (Behind the MAF sensor) This air is unmetered by the MAF.. That affects the performance of the motor. It is ingesting air that the MAF is unable to adjust for. The ONLY way it wouldnt matter is if the car is tuned in SD.
Originally Posted by Dirty Howie
What about late model 2004 ..... there is no PCV valve .... just baffling in the valley. Do you think unmetered air would still NOT be an issue??
DH
DH
Last edited by Jeff @ TPE; Nov 16, 2006 at 07:21 PM.
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
Originally Posted by Warp Factor
I don't know. His is a '97. Mine's a 2000.
Chevrolet lists a PCV valve for the 2004..............
Chevrolet lists a PCV valve for the 2004..............
Also if you check the Elite catch can out. They have the PCV setups for all the different years in their install instructions (found online)...no PCV vollve on 2004!!!
DH
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Team Owner
Joined: May 2004
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From: SoCal
Originally Posted by AMERICAN_HP
Honestly it doesnt matter what year it is..
This setup is a MASSIVE vaccum leak.
Look at the picture... The vaccum from the motor pulls the air through the filter, then through the valve cover, and directly into the intake manifold (Behind the MAF sensor) This air is unmetered by the MAF.. That affects the performance of the motor. It is ingesting air that the MAF is unable to adjust for. The ONLY way it wouldnt matter is if the car is tuned in SD.
This setup is a MASSIVE vaccum leak.
Look at the picture... The vaccum from the motor pulls the air through the filter, then through the valve cover, and directly into the intake manifold (Behind the MAF sensor) This air is unmetered by the MAF.. That affects the performance of the motor. It is ingesting air that the MAF is unable to adjust for. The ONLY way it wouldnt matter is if the car is tuned in SD.
I know nothing of the motor internals compared to you so I am listening closely. So I am assuming you are correct when you state this air is going into the intake manifold and not just replacing air into the engine crank case. In any event you are suggesting a lean condition would occur, correct ??
I do understand your point about the SD. Some of us have SD but still have the MAF for WOT.
DH
Pro
Joined: Aug 2004
Posts: 575
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From: Richmond Hill Ontario
Put everything back to it's original setup before going on the dyno. I'm seeing more guys use the see through 'fuel filter' for trying to catch the oil vapours and don't understand why you would use a filter that's designed for filtering liquids, not air. If the filter is acting as a restriction the vapour pressure that should be getting pulled from the crankcase by the throttle body is not enough and the ring sealing is not what it should be. If you're going to run a catch can it needs to be made with a filter that will trap vapours but allow the free flow of air back to the intake system. I personally don't have one on my car and have seen many different kinds on the forum and internet. Don't know which one I would use at this point but I'd want something with baffles in it to separate the oil from the vapour.
Thread Starter
Le Mans Master
Joined: Aug 2003
Posts: 9,298
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From: American Canyon Lethal Injection
Originally Posted by vetpet
Put everything back to it's original setup before going on the dyno. I'm seeing more guys use the see through 'fuel filter' for trying to catch the oil vapours and don't understand why you would use a filter that's designed for filtering liquids, not air. If the filter is acting as a restriction the vapour pressure that should be getting pulled from the crankcase by the throttle body is not enough and the ring sealing is not what it should be. If you're going to run a catch can it needs to be made with a filter that will trap vapours but allow the free flow of air back to the intake system. I personally don't have one on my car and have seen many different kinds on the forum and internet. Don't know which one I would use at this point but I'd want something with baffles in it to separate the oil from the vapour.
Thread Starter
Le Mans Master
Joined: Aug 2003
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From: American Canyon Lethal Injection
Originally Posted by Dirty Howie
HP
I know nothing of the motor internals compared to you so I am listening closely. So I am assuming you are correct when you state this air is going into the intake manifold and not just replacing air into the engine crank case. In any event you are suggesting a lean condition would occur, correct ??
I do understand your point about the SD. Some of us have SD but still have the MAF for WOT.
DH
I know nothing of the motor internals compared to you so I am listening closely. So I am assuming you are correct when you state this air is going into the intake manifold and not just replacing air into the engine crank case. In any event you are suggesting a lean condition would occur, correct ??
I do understand your point about the SD. Some of us have SD but still have the MAF for WOT.
DH
"
Both of his Dyno runs were on a Dyno jet and I have not seen Dyno Jets that would vary enough to warrant a loss when adding longtubes and a fast intake. He should have picked up with a fast intake on a bone stock motor even if it was only 5rwp. I think that a dyno tune and working on your pcv system would help you out ALOT your car was rich on the dyno at WOT and I am sure there is alot of work that could be done on the timing curve#.
Le Mans Master
Joined: Oct 2005
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From: Metro Detroit Michigan
Originally Posted by AMERICAN_HP
Honestly it doesnt matter what year it is..
This setup is a MASSIVE vaccum leak.
Look at the picture... The vaccum from the motor pulls the air through the filter, then through the valve cover, and directly into the intake manifold (Behind the MAF sensor) This air is unmetered by the MAF.. That affects the performance of the motor. It is ingesting air that the MAF is unable to adjust for. The ONLY way it wouldnt matter is if the car is tuned in SD.
This setup is a MASSIVE vaccum leak.
Look at the picture... The vaccum from the motor pulls the air through the filter, then through the valve cover, and directly into the intake manifold (Behind the MAF sensor) This air is unmetered by the MAF.. That affects the performance of the motor. It is ingesting air that the MAF is unable to adjust for. The ONLY way it wouldnt matter is if the car is tuned in SD.
The metering takes place at the PCV valve.
It's kind of a neat device. Try blowing through one. Have a few beers first. The harder you blow, the more restriction there is. It automatically adjusts to the level of manifold vacuum and only allows a small amount of air through whether vacuum is low or high.
But none of this matters anyway when it comes to his dyno results.
At full throttle, there's almost no vacuum in the intake manifold..........nothing to suck air in from the crankcase ventilation system. It would take massive vacuum to produce massive air flow through a 3/8 inch tube, and he doesn't have this at full throttle.
Team Owner
Joined: May 2004
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From: SoCal
Originally Posted by Warp Factor
Dude, the breather doesn't make much difference. Air is supplied to the crankcase pretty much the same way, whether with a breather or the factory air supply off the throttle body.
The metering takes place at the PCV valve.
It's kind of a neat device. Try blowing through one. Have a few beers first. The harder you blow, the more restriction there is. It automatically adjusts to the level of manifold vacuum and only allows a small amount of air through whether vacuum is low or high.
But none of this matters anyway when it comes to his dyno results.
At full throttle, there's almost no vacuum in the intake manifold..........nothing to suck air in from the crankcase ventilation system. It would take massive vacuum to produce massive air flow through a 3/8 inch tube, and he doesn't have this at full throttle.
The metering takes place at the PCV valve.
It's kind of a neat device. Try blowing through one. Have a few beers first. The harder you blow, the more restriction there is. It automatically adjusts to the level of manifold vacuum and only allows a small amount of air through whether vacuum is low or high.
But none of this matters anyway when it comes to his dyno results.
At full throttle, there's almost no vacuum in the intake manifold..........nothing to suck air in from the crankcase ventilation system. It would take massive vacuum to produce massive air flow through a 3/8 inch tube, and he doesn't have this at full throttle.
I believe by "metered air" he means air that is accounted for by the MAF. And that with an open breather air can be sucked thru it into the intake manifold thus bypassing the MAF and causing tuning issues.
DH
Former Vendor
Joined: Feb 2004
Posts: 10,876
Likes: 8
From: Las Vegas NV
St. Jude Donor '06 & '12
Dude- Look at the picture..
Theres 2 points to this post..
1) Look at the photo. Do you see a PCV valve? He's clearly running a LS1 PCV system. And you can see that it goes directly from the tube above the valve cover, to the catch can, and directly into the manifold.
If there is one, I cant see it. So thats one whole issue in and of its self. And as far as the hose on the TB's concerned, its a recirculated line. As you can see in the photo, it comes from the front of the valve cover back into the TB.
But in all honesty, NONE of this is what I am talking about. As Howie said, I am NOT talking about the metering of the PCV valve (Which it doesnt look like he has)
2) I am talking about the metering of air from the MAF sensor. If ANY air gets throught the system that the MAF is not making the necessary adjustments for, you can run into issues.
Example: Take the band clamp "After" the MAF sensor and make it really loose. Dont take it off. Just make it loose. Watch how fast your car runs like ****. Its not alot of air, but its enough..
Dude.....
Theres 2 points to this post..
1) Look at the photo. Do you see a PCV valve? He's clearly running a LS1 PCV system. And you can see that it goes directly from the tube above the valve cover, to the catch can, and directly into the manifold.
If there is one, I cant see it. So thats one whole issue in and of its self. And as far as the hose on the TB's concerned, its a recirculated line. As you can see in the photo, it comes from the front of the valve cover back into the TB.
But in all honesty, NONE of this is what I am talking about. As Howie said, I am NOT talking about the metering of the PCV valve (Which it doesnt look like he has)
2) I am talking about the metering of air from the MAF sensor. If ANY air gets throught the system that the MAF is not making the necessary adjustments for, you can run into issues.
Example: Take the band clamp "After" the MAF sensor and make it really loose. Dont take it off. Just make it loose. Watch how fast your car runs like ****. Its not alot of air, but its enough..
Dude.....
Originally Posted by Warp Factor
Dude, the breather doesn't make much difference. Air is supplied to the crankcase pretty much the same way, whether with a breather or the factory air supply off the throttle body.
The metering takes place at the PCV valve.
It's kind of a neat device. Try blowing through one. Have a few beers first. The harder you blow, the more restriction there is. It automatically adjusts to the level of manifold vacuum and only allows a small amount of air through whether vacuum is low or high.
But none of this matters anyway when it comes to his dyno results.
At full throttle, there's almost no vacuum in the intake manifold..........nothing to suck air in from the crankcase ventilation system. It would take massive vacuum to produce massive air flow through a 3/8 inch tube, and he doesn't have this at full throttle.
The metering takes place at the PCV valve.
It's kind of a neat device. Try blowing through one. Have a few beers first. The harder you blow, the more restriction there is. It automatically adjusts to the level of manifold vacuum and only allows a small amount of air through whether vacuum is low or high.
But none of this matters anyway when it comes to his dyno results.
At full throttle, there's almost no vacuum in the intake manifold..........nothing to suck air in from the crankcase ventilation system. It would take massive vacuum to produce massive air flow through a 3/8 inch tube, and he doesn't have this at full throttle.
Thread Starter
Le Mans Master
Joined: Aug 2003
Posts: 9,298
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From: American Canyon Lethal Injection
Originally Posted by mvvette97
Hmm, maybe I should take the breather off my oil cap on my ta as well
Le Mans Master
Joined: Oct 2005
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From: Metro Detroit Michigan
Originally Posted by Dirty Howie
Warp
I believe by "metered air" he means air that is accounted for by the MAF. And that with an open breather air can be sucked thru it into the intake manifold thus bypassing the MAF and causing tuning issues.
DH
I believe by "metered air" he means air that is accounted for by the MAF. And that with an open breather air can be sucked thru it into the intake manifold thus bypassing the MAF and causing tuning issues.
DH
At full throttle, almost no fresh air is being supplied to the crankcase. There's almost no manifold vacuum to produce flow through those small hoses. What is pulled into the intake from the crankcase is mostly blowby, which doesn't have much oxygen content to mess up the f/a ratio.
I've run my car with the fresh air source coming from the air filter, from a breather, and from both. No change.
The only thing I haven't done is switch from either of these air sources to the throttle body source (air which has been metered) without a tuning change.
But he was in the process of getting a tune anyway, right?
Last edited by Warp Factor; Nov 17, 2006 at 11:15 AM.