yaya

so whats the point of having your pcv hooked to your im ? why cant it just vent into the air? im asking cuz i have gotten into a debate with some people.....

why would you want to suck up oil vapor?

im not talking about an oil catch can, leave that topic alone. just having the pcv valve open to the atmosphere seems like it would be better than sucking up your oil vapor into the cylinders


right?

RHD_BB4T

From "what I've heard," the fumes that get sucked up into the IM through the PCV system are somewhat "toxic" to the engine internals. These get sucked up into your engine, burned, and get turned into something else that your CAT can handle, turning them into something a little more atmosphericly friendly rather than just "dumping" them into the air. Also, I've heard that having negative pressure in the crank case caused by the suction of the intake also makes the engine run a little bit more efficiently, gaining a little more power.

Don't quote ME on that, though... I have not scientific proof on all that stuff. Just throughing out things I've heard so that others might respond for or against it...

Have Fun!!

Dan P.

EFb18b

oh no it starts again....

Check this thread out https://honda-tech.com/zerothread?id=394876

StyleTEG

From what I understand, the crankcase is designed to run under a vaccum. Running with just a filter causes the crankcase not to have a vaccum, and apparently you will get lots of blowby.

3gdude

Actually the reason for PCV is basically for emissions. And there is no vacuum inside the crankcase. Try connecting your vacuum gauge to the dip stick hole with motor running. On a good system, there is no pressure or vacuum.... Combustion gases that find there way into the crankcase could easily be vented to atmosphere, providing you can separate the liquid oil from these gases. That is what a baffle or oil separator is used for. It does also help rid your motor of unburnt fuel (hydrocarbons) that get past the rings and can dilute the motor oil that you are trying to get 3K miles out of. As far as engine performance goes, it makes no difference.

StyleTEG

Sorry I was mistaken, its not vaccum, it has to be pressurized

_Endless_

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StyleTEG &raquo;</TD></TR><TR><TD CLASS="quote">Sorry I was mistaken, its not vaccum, it has to be pressurized





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don't mean to hijack your thread but since we are on this issue, i'm have something to ask and i believe everyone may learn something about it.

what i don't understand about that diagram is this:

the breather tube from the valve cover takes in fresh air as indicated by the diagram, but why is that during idling that tube blows out air instead of sucking in fresh air??? that's what confusing me.

i recently changed my engine oil, i let the engine run while i took the oil filler cap off, it's blowing out air. i put the cap back and took off my breather filter off and the tube was also blowing out air and not sucking. so how can fresh air come in if the tube is blowing out air?

maybe someone who got an idea to please chime in.

3gdude

When you have your oil cap off and engine running you can easily be fooled, as your feeling pulses. The ones coming out, you feel. The ones going in you dont. Heres how to test your PCV system on a good engine. Pull your dipstick out and put vacuum gauge tightly into dipstick hole. Start engine and let it idle. Block fresh air hose (from air cleaner). It should pull a slight vacuum (1 to 3 inches in 10 seconds). If it doesn't, either your vacuum supply to PCV is restricted, the valve is bad or you have excessive blow-by (rings shot). Dont do this for long as crankcase vacuum over 5 inches can suck oil seals into motor......3gdude

StyleTEG

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
The honda crankcase breather is a POSITIVE pressure ventilation system.The air from the intake blows into the valve cover. It is NOT a negative pressure ventilation system...it does NOT suck air from the valvecover to the intake.

Breathers remove the source of positive ventilation that repressurizes the POSTIVE CRANKCASE VENTILATION (PCV) valve.

There is less pressure in the crank when you add a breather at the valve cover. The consequence of this is you get more positive blow-by from the combustion chamber past the piston rings and into the crankcase. More blow-by means less cylinder pressure...less cylinder pressure means the burn is slower and less complete...the result is more emissions and less power.

If you want to do this right and remove oil vapor from the circulating crankcase before it goes into the intake valve then, get an oilcatch can and put a breather on the catch can. Then place the catch can in between the valve cover breather and the PCV valve.

Disconnecting the breather tube, which blows fresh intake air into the valve cover, and placing a breather on the valve cover just creates more blow-by and emissions. Eventually you have so much blow-by, you lose power.
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My guess is that with the breather filter, you don't have any source of positive ventilation, so instead the crankcase vents from the valve cover instead of is pressurized by it.

3gdude

Style Teg, exactly who are you quoting..not me...I dont beleive any of this...the intake does not blow air into the valve cover... Oh wait..I think someone just threw me a forced induction curve...but that is the only way this could happen....3gdude

jhwage

Where is the PCV valve located on a 1996 Honda Civic EX

94dxt

intake manifold, under the fuel rail

if you have a FI set up it doesn't seem to me that you should use a pcv sys. as it would create compressed air to the valve

StyleTEG

I am quoting micheal delaney (tuan) specificly.

That diagram is from the helms manual

And Larry from Endyn has experessed the same idea on his web board as well.

So you are saying that the crankcase blows air out of the valve cover nipple and into the intake? If that is the case, why is it that the section closest to the throttle body does not get covered in carbon? (I have checked at least 6-7 intake tubes for this).

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
if you have a FI set up it doesn't seem to me that you should use a pcv sys. as it would create compressed air to the valve
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When you have a turbo, you want the line to run before the actual turbo. That way it gets fresh air, but it is not pressurized. You can keep the same location with a supercharger.

94dxt

When you have a turbo, you want the line to run before the actual turbo. That way it gets fresh air, but it is not pressurized. You can keep the same location with a supercharger


are you talking about the pcv or the valve cover breather?

3gdude

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StyleTEG &raquo;</TD></TR><TR><TD CLASS="quote">

So you are saying that the crankcase blows air out of the valve cover nipple and into the intake? If that is the case, why is it that the section closest to the throttle body does not get covered in carbon? (I have checked at least 6-7 intake tubes for this).

</TD></TR></TABLE> No thats not it. The diagram is correct. The fresh air from intake tube goes into valve cover and mixes with the blow-by gases and then is pulled from engine by vacuum from intake manifold via the PCV valve. If you block this fresh air supply with motor idling, the PCV will pull a vacuum on the crankcase...3gdude

94dxt

my valve cover blows out air @ least @ idle, it doesn't suck

Dgr8wun

there are pro's and con's about the pvc. but its mainly there for smog purposes.
the bad thing is it dilutes your gas air mixture giving you less power but also keeping you combustion chambers cooler cuz your moisture isn't as potent. the other thing is it takes air off the crack case, the more air you have in there the more drag you'll have on your pistons on the power stroke... its been proven to help your 1/4 time and hp by putting an external vacuum pump on your crank case to get the pressure out but the only problem is it also takes out some oil...

methred_92

yeah, so why isn't there a PCV valve at the valve cover?

Do we rely on gravity to pull down the heavy stuff for the block breather tank to catch and we burn the *light stuff* that gets fed out of the valve cover and into your intake?

According to the diagram there is supposed to be clean air being sucked into the valve cover. Is this air *sucked in* or is it blown in when the air pressure in the intake tubing overcomes the pressure coming out of the valve cover? If there is pressure in the in the crankcase and the block breather tank is not dealing with all this pressure, then it goes to the head where it comes out of the valve cover vent. I know I have had an oily film coating in my intake tubing and throttle body before.

The diagram only applies when the engine is under load, and not when at idle?

2k1_ITR_0736

holy jeez, you guys jump around pretty seriously.

i run a breather filter. i run a 12.683 1/4 on an all motor setup.

**** all that pcv ****. the simpler the better.

soo all in all. vacuum, positive pressure. who gives a damn. b series have very lil blowby, buy a h22a, then you can talk about that ****. ask POSlude97 he'll tell you about how his lude would suck downa quart every 600mi. had no clue where ti went. but anyway. damn you guy corn-fused me.

methred_92

*sigh*
Yeah, that's it. We should all be using a b-series motors and drag racing.

StyleTEG

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94dxt &raquo;</TD></TR><TR><TD CLASS="quote">my valve cover blows out air @ least @ idle, it doesn't suck</TD></TR></TABLE>

er.. thats because the crankcase is not run under a vaccum, it is pressurized. So it shouldn't suck. You disconnect the line from the intake to the valve cover and its no longer pressurized so I am not surprised that it blows out air.

It is not *just* for emissions reasons.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">originally stated by micheal delaney
We have a PCV system designed as a closed system though. When attached to the intake, the breather hose actually generates more pressure gradient to push fresh air down into the crankcase via the valve cover breather from the intake at higher engine speeds! When you use only 1 breather in an open system, not enough fresh air coming through the breather filter gets down to the crankcase.

The crankcase has less pressure inside. This opens the door for more blow-by. Without the positive pressure in the crankcase to offer some resistance to blow-by past the piston ring, you get crap going down. The other problem with less fresh air entering is, as was said before, the circulation flow out to the PCV valve is decreased. So more crap stays in the crankcase. It becomes a vicious cycle.

If you insist on using an open PCV system then drill a second hole and mount a second breather tube in the valvecover. Using 2 breather filters will deliver enough fresh air down to the crankcase. This is what the AEBS boys did with their race B18C1 that ran in the 10's all motor:



Now the other smart move would be to use an oil catch can that is baffled so that it captures or intercepts the oil in the vapor leaving the crankcase before it reached the PCV valve and enters the IM. Now you have more fresh air entering the IM instead of oil vapor.

If you plan to use an open system, add more breathers. If you use a closed system or an open system, use an oil catch can.

The good oil catch cans have baffles and drain the captured oil back to the oil pan without you having to empty them periodically. </TD></TR></TABLE>

Just because you have an engine generating a lot of HP doesn't mean its done correctly. Sure you may be freeing up some HP because you are not recycling the blowby gases, but you in turn are giving your motor a beating.

94dxt

so what is the safest setup???? oem? filter on valve cover w/ pcv? filter on valve cover and no pcv(open atmosphere)?

StyleTEG

Oil catch can between the PCV and the IM. No breathers.

If you don't want to have to deal with draining the blowby, you can always run a hose from the drain of the catch can to the oil pan. The endyn setup does this.

2k1_ITR_0736

im not saying that its a drag only as a matter of fact i hate drag i just use it for a power perspective for everyone. actually i am a autoX kinda guy

94dxt

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StyleTEG &raquo;</TD></TR><TR><TD CLASS="quote">Oil catch can between the PCV and the IM. No breathers.

If you don't want to have to deal with draining the blowby, you can always run a hose from the drain of the catch can to the oil pan. The endyn setup does this.</TD></TR></TABLE>

what about the valve cover?