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Pros & Cons of getting rid of PCV system.....; By just venting blow by gas into the air.
Topic Started: Nov 8 2014, 11:39 PM (3,677 Views)
Rondawg
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Mrbreeze
Nov 11 2014, 10:10 AM
How can I put this, if you are having issues with blow by and or oil consumption you have bigger issues than a PVC valve scavenging vapors...
I don't have any problem with either (blowby or oil consumption ) I'm just trying to do cheap mods that have more benefits than drawbacks. Im primiraly concerned with longevity, reliability, simplicity, MPG & cost. It seemed to me ( at least initially) that eliminating nasty crankcase vapors from flowing endlessly into the intake would meet the afore mentioned criteria.
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snowfish
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Basic GearHead

That's a variation of a catch can. ^o) But it appears to be passive. :news Meaning the PCV is not connected to the circuit. :hmm

The G10 PCV is an odd duck. Grab a new PCV and see what direction the flow is. Yep, it's away from the intake. Not into the intake. Seems weird, but the pulses towards the crank case is what creates the positive flow towards the throttle body. :hmm

Retaining those pulses is necessary to retain the positive flow. Thus the PCV valve.

Posted Image

A little crankcase vapor, or even droplets, is not going to gum up the intake runs. Especially on a fresh build. There's plenty of gasoline to wash everything clean. :thumb

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Mrbreeze


Just went out to the garage and got a PVC valve, doing the blow thru test, it is one way to the intake, hey snowfish, you didn't put yours in upside down did you?? By the way that's a sweet look you got there, very nice, one question thou, why don't you have your PVC teed into your valve cover vent hose? Just curious..
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Rondawg
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snowfish
Nov 11 2014, 10:49 AM
That's a variation of a catch can. ^o) But it appears to be passive. :news Meaning the PCV is not connected to the circuit. :hmm

The G10 PCV is an odd duck. Grab a new PCV and see what direction the flow is. Yep, it's away from the intake. Not into the intake. Seems weird, but the pulses towards the crank case is what creates the positive flow towards the throttle body. :hmm

Retaining those pulses is necessary to retain the positive flow. Thus the PCV valve.

Posted Image

A little crankcase vapor, or even droplets, is not going to gum up the intake runs. Especially on a fresh build. There's plenty of gasoline to wash everything clean. :thumb

Good explanation. If an engine "goes thru"....lets say 1/2 a quart of oil between changes. Assuming there are no leaks, I wonder how much of that raw oil is actually goes thru the intake and is reburned??
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perfesser
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Elite Member - Former Metro owner

Rondawg
Nov 11 2014, 10:34 AM
Mrbreeze
Nov 11 2014, 10:10 AM
How can I put this, if you are having issues with blow by and or oil consumption you have bigger issues than a PVC valve scavenging vapors...
I don't have any problem with either (blowby or oil consumption ) I'm just trying to do cheap mods that have more benefits than drawbacks. Im primiraly concerned with longevity, reliability, simplicity, MPG & cost. It seemed to me ( at least initially) that eliminating nasty crankcase vapors from flowing endlessly into the intake would meet the afore mentioned criteria.


Benefits? I can't think of one, except maybe the warm glow of having done something in the engine room. Drawbacks? As discussed in numerous threads from numerous members. There are better things you could spend your time on that this.

Rondawg
Nov 11 2014, 11:15 AM
]Good explanation. If an engine "goes thru"....lets say 1/2 a quart of oil between changes. Assuming there are no leaks, I wonder how much of that raw oil is actually goes thru the intake and is reburned??


All of it. Even if you use a quart every 3,000 miles, and get 40 mpg, that's one quart of oil and 75 gallons of gasoline. That oil has no chance of building up!
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Old Man


Run my 125,000 mile+ engine for 25,000 miles between cleaning out
the PVC system and air cleaner housing. Don't find anything unusual.
I fully believe that "too many fingers cause more problems than they cure"
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Rondawg
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Carbon clogged pcv: http://geometroforum.com/topic/5621598/1/

Clogged egr, numerous threads on this! http://geometroforum.com/topic/5595238/1/

Plus countless photos of burnt valves, carbon crusted pistons & combustion chambers. I will admit I am not an engine design engineer but where does that carbon buildup come from? I just can't see how REDUCING and \or eliminating the volume of oil being sucked in and re-burned thru the intake could be nothing but good for the top end! Now is this BENEFIT is outweighed by contaminating oil quicker or building up sludge in the bottom end?? I dunno.....that's the big question IMO.
Edited by Rondawg, Nov 11 2014, 01:55 PM.
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perfesser
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Elite Member - Former Metro owner

The most widely used hydrocarbon in the engine is not the oil. It's the gasoline. There is no challenge in finding pictures of carbon buildup, burnt valves, etc. on a forum that enthusiastically covers engines and their problems. Leaping from that to blaming oil cannot be supported by data nor experience.

Running rich is the number #1 cause of carbon buildup. Running lean is the number #1 cause of burnt valves.

Not blowby. Not oil farts. Gasoline!

There is no appreciable benefit to the top end in eliminating the recirculation of blowby gases. There is a huge drawback contaminating your oil with sulfuric acid.

Your choice.
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Rondawg
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So the black coating found in the intake manifold, upstream of the combustion chambers, is from gasoline?
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perfesser
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Elite Member - Former Metro owner

Very often, yes. Just like the film in a coffee cup comes from long use. The manifold is heated, after all, because the gasoline needs to be vaporized before it hits the combustion chamber.
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Rondawg
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Vaporized gas & oil.
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Cobb
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Im sure more clean air would make more power, cause mpg to go down like most mods. I know many say disconnecting the egr doesnt effect performance as its closed during WOT anyway. Well, I disagree as I see more throttle response and less heat soak once Ive been out an hour or so.

My idea using a T and second pcv valve pn the breather tube was to allow the engine to take a vacuum during casual driving and during WOT the gasses can be discharged outside the CAI down a hose to the lower engine compartment. :drivin
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perfesser
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perfesser
Nov 11 2014, 12:55 PM
Even if you use a quart every 3,000 miles, and get 40 mpg, that's one quart of oil and 75 gallons of gasoline. That oil has no chance of building up!


Rondawg
Nov 11 2014, 05:36 PM
Vaporized gas & oil.


If you compare the ratios, the oil's effect fades by comparison.

Some of us have tried to persuade you of the facts relating to your proposal. You're going to do what you want anyway, so why fight it? Seems like you're trying to convince us that we're wrong. (Won't work, y'know!)

When you get it done, post again with your results, but do a true A-B-A. No "butt dyno" evidence, please!
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Rondawg
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perfesser
Nov 11 2014, 08:18 PM
perfesser
Nov 11 2014, 12:55 PM
Even if you use a quart every 3,000 miles, and get 40 mpg, that's one quart of oil and 75 gallons of gasoline. That oil has no chance of building up!


Rondawg
Nov 11 2014, 05:36 PM
Vaporized gas & oil.


If you compare the ratios, the oil's effect fades by comparison.

Some of us have tried to persuade you of the facts relating to your proposal. You're going to do what you want anyway, so why fight it? Seems like you're trying to convince us that we're wrong. (Won't work, y'know!)

When you get it done, post again with your results, but do a true A-B-A. No "butt dyno" evidence, please!
Im not trying to convince you or anybody you are right or wrong. I certainly never mentioned performance gains and got no plans on doing Dyno Runs either. You must really think I am a Dick and/ or misread my posts if you somehow feel I would try dyno runs? I am just trying to learn about these cars & keep mine running for as long and as reliably as possible for as cheap as possible.
Obviously I am having a hard time accepting the fact that sucking up and burning a quart of oil, every 3k miles or so, thru the fuel system, is in no way harmful.
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Rondawg
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Cobb
Nov 11 2014, 06:35 PM
Im sure more clean air would make more power, cause mpg to go down like most mods. I know many say disconnecting the egr doesnt effect performance as its closed during WOT anyway. Well, I disagree as I see more throttle response and less heat soak once Ive been out an hour or so.

My idea using a T and second pcv valve pn the breather tube was to allow the engine to take a vacuum during casual driving and during WOT the gasses can be discharged outside the CAI down a hose to the lower engine compartment. :drivin
WOT? CAI?? This is the kind of info I was looking for.... Something beyond the obvious. I don't know much about the inner details of EFI functions. Maybe that is why I am perhaps overly concerned in regards to keeping the injection/intake system as free of carbon buildup as possible.
Im thinking that an oil catch can in line with a working PCV system might be the best of both worlds.

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