vladj

<span style="color:Red">MOD EDIT PLEASE DONT QUOTE POST ABOVE YOURS</span>

/\ i think it works perfectly. and yes it is the breather and it doesnt spray oil anywhere

zoned019

^^ Please don't quote the post directly above yours.

I meant, what is that breather filter going to?

Does the can still catch a lot being in that location?

vladj

just for you dude i went outside and took more pics:







the line from the breather goes the the one closer to the you in the pic. and yes it filters alot even that is so far

REDZMAN

Zoned, check your PM's.

radu_rd2

<div class='quotetop'>QUOTE (SOCKS @ Aug 1 2007, 01:53 PM) <{POST_SNAPBACK}></div><div class='quotemain'>pcv: catch can, line to atmos.
valve cover: breather filter.

that setup worked like shit.. breather spewed oil all over inside of bay.</div>

I think the big problem with hooking the PCV line to the intake (when you're turboing) is that there will be positive pressure in the intake, and that will blow air through the PCV INTO the engine rather than OUT of the engine. That is why in the setup above the breather would spew oil. This is not how the PCV system was designed, and there are probably some boost losses because of this. There should be a valve on that line that blocks the air when there is boost.

And I have no idea if this would work, but how about adding a PCV valve but mounted in reverse? As I see it, the PCV valve blocks the pathway when there is too little pressure in the intake (otherwise there would be way too much air at idle); so it blocks when the pressure difference is too much. It would still allow a little bit of air travel into the engine when the boost pressure is low (intake pressure slightly above atmosphere), but it would close up when boost gets significant. What do you think?

In any case, in a good setup, the breather should always only draw air into the crankcase, so there would be no need for an oil catch can on that side, the breather could just draw directly from the atmosphere (again, you don't want boost going through the crankcase, so it shouldn't be connected to the positive pressure in the intake)


Edit: By the way, DTN - I think you're wrong; I think the spring in the PCV valve blocks the valve when there is too much negative pressure on the intake side, rather than the other way around. So I think it would still allow the gases to vent if you disconnected the PCV line from the intake, but obviously not as good since there is no neg. pressure to draw them out..

JonGTR

There's NO reason to even touch the PCV or its line! You're not dumping a whole lot of oil in your manifold, and if anything, it helps lubricate your cylinders. Leave it alone.

It's the breather line you want to modify. Run a line from the valve cover to a catchcan, then vent to atmosphere with a filter on it.

This works for both NA and FI systems.

You cannot run a line to the bottom of the car to let the oil drip. There always needs to be either a catchcan, or a line to your intake. If not, a tech will not pass you at the track because you are dropping oil and causing a possible hazzard.

radu_rd2

But then at negative pressure in the intake the air is going breather->crankcase->PCV, and at boost it's going PCV->crankcase->breather.. Don't really know if this is a problem, so you might be right, but the breathing system was designed only for the first direction of air travel..

And wasn't the whole idea of a oil catch can to keep your intake clean of oil (that gets through the PCV) ?

JonGTR

You will NOT get pressure during boost. That is the whole function of the PCV valve. It only allows for one direction of air, and that is TO the manifold during vacuum.

The reason why you want a catchcan is to keep oil out of your intake pipes. Your manifold doesn't matter.

radu_rd2

I don't get that. Why would there be a PCV valve in the first place then? Stock engine is N/A, which means there will always be negative pressure in the manifold (or at best 0 pressure, which would mean no air flow through the line). The PCV valve blocks the flow when there is too much negative pressure in the manifold (actually, it only limits the flow, it doesn't block it completely). Try to disconnect the line from the PCV valve while the engine is idleing, and the engine will die (too much air/too little fuel).

If the PCV valve wouldn't allow air to go in, how do you figure SOCKS' first setup resulting in the breather spewing oil? And why would you ever have an oil catch can on the breather? If what you're saying is true, the air will NEVER go OUT the breather, only in (and out the PCV line).


From wikipedia:

The PCV valve connects the crankcase to the intake manifold from a location more-or-less opposite the breather connection. Typical locations include the opposite valve cover that the breather tube connects to on a V engine. A typical location is the valve cover(s), although some engines place the valve in locations far from the valve cover. The valve is simple, but actually performs a complicated control function. An internal restrictor (generally a cone or ball) is held in "normal" (engine off, zero vacuum) position with a light spring, exposing the full size of the PCV opening to the intake manifold. With the engine running, the tapered end of the cone is drawn towards the opening in the PCV valve, restricting the opening proportionate to the level of engine vacuum vs. spring tension. At idle, the intake manifold vacuum is near maximum. It is at this time the least amount of blow by is actually occurring, so the PCV valve provides the largest amount of (but not complete) restriction. As engine load increases, vacuum on the valve decreases proportionally and blow by increases proportionally. Sensing a lower level of vacuum, the spring returns the cone to the "open" position to allow more air flow. At full throttle, there is nearly zero vacuum. At this point the PCV valve is nearly useless, and most combustion gases escape via the "breather tube" where they are then drawn in to the engine's intake manifold anyway.

zoned019

I finished this a long time ago and took pics, but then the site went down, and I forgot about it.

Not sure about all the boost discussion going on, but I do know that for N/A it is DEFINITELY worth it to have something between the PCV and IM to catch stuff. I have caught so much junk there it is amazing. Look for Larrs' topic about catch cans, his is basically the same setup as mine.

Also, the only way for this to work properly is to have the catch can IN LINE between the PCV and IM. Meaning that the output on the can has to go to the IM, that way you get the vacuum you need. If you don't hook it up, you will be spraying oil all over your bay, and not catching as much.

After about 2 months, I still see nothing more than a drop or two of oil in the can that sits inline before the intake elbow.