wreckleford

iTrader: (2)

Are you returning through the "screwdriver hole" for the balance shaft?

l2r99gst

iTrader: (2)

And water vapor.


Dave - If I am picturing what you are doing correctly, I don't think this is the best idea. Hear me out first before making a comment...I am actually helping here.

The whole point of the PCV system in our cars, or any car for that matter, is to relieve crankcase pressure and to allow clean, fresh air to mix with the oil vapor, water vapor, and fuel vapor (and any other combustion gases that made their way into the crankcase) and be burned again and expelled through the exhaust system.

In stock form, under manifold vacuum, clean air is brought in through the air filter, out through the nipple on the turbo inlet pipe, into the valve cover breather nipple, mixing with the above mentioned gases, then out through the opened PCV valve, into the intake manifold, into the cylinders, and out the exhaust. The whole flow is driven by the amount of vacuum in the intake manifold.

It sounds like to me, and correct me if I am reading your posts wrong, that you are bypassing the IM side of the system, running both hoses from the VC to your catch can, one to the turbo intake pipe for vacuum, and one to drain the oil 'mixture' back to the pan/block, correct?

If so, I see a couple of issues:

You are now introducing any vapors and gases that don't condense in your catch can, back into the system pre-turbo, whereas in stock form it was right into the IM, to be burned and expelled through the exhaust. In your setup, you are potentially allowing fuel vapor, water vapor, and oil vapor (and other potential combustion gases), to now be pulled through the compressor wheel, the IC, all of the IC pipes, and into the IM and cylinders. You are basically reversing the engineered design of the PCV flow.

Now, if you can ensure 100% that your catch can will condense every possible vapor (oil, water, gas) before it has a chance to get back to the intake pipe, then this might work, but I still see an issue.

The turbo intake pipe has very little vacuum compared to the IM. So, it will be difficult to properly scavenge the gases/vapors from under the valve cover with that vaccum as compared to the IM vacuum.

Does any of what I said make sense or am I understanding your design incorrectly?


Eric

crcain

l2r99gst... under boost, the stock PCV system vents all crankcase pressure to the air intake correct? Because the PCV valve is closed. So Dave's proposed system would behave just as the stock system does while under boost.

Also, how sure are you that there is flow of clean air into the crankcase in a situation like idle? There is negative pressure in both intake and air intake, but I guess the intake manifold vacuum is greater than the air intake vacuum?

l2r99gst

iTrader: (2)

Yes, that's correct. My entire explanation above was only during vacuum situations...I didn't talk about the boost side of things.

You already answered your own question there.

MitsuJDM

iTrader: (6)

I've trying to rear and comprehend what is going on, but seriously, I'm a picture person. I'm trying to imagine what the routing is, but I just can't.

I currently use a clear fuel filter from the valve cover to intake pipe and a bigger, metal (so it doesn't blow up) fuel filter, inbetween the PCV and IM.

The fuel filter on the valve cover/intake side works great. I use clear PVC (not to be confused with PCV ) tubing so I can SEE the discoloration of the vapors. The filter works. The tube coming off the valve cover is brown and the tube going into the intake is clear as can be. I change the filter every other oil change, or 7-8k miles. It's $2, so no big deal, really.

I worry about the efficentcy of my set-up on the PCV side. Especially since I don't use the clear PVC tubes and I can't see into the metal filter.

I'd really like to see some pictures of this set-up, Dave. I have a reading comprehension disability. With that said.... PICTURES!!!!!!!!

EDIT: Also, in most of my searching, I've been told by various people and have read about how you need vaccum to pull the pressure from the crankcase. If you leave it a closed system, as I picture you're doing (I re-read your first post), what's happening to the pressure? If vaccum isn't needed, then I see no problem just venting to atmosphere other then I'm not sure that passes tech inspection in SCCA, which of course doesn't affect everyone.

antilag_200

iTrader: (49)

The little Pdf that I drew up was for the exact reason, of keeping the stock ventilation system, but there are lots of us out there that run 30 pounds everyday, the last thing I want is excessive oil going into my intake, The draining back to the engine is great idea, and I am excited to see where exactly it drains back into the engine. Good job dave. ( I think it is in the bolt hole that I mentioned before, where you stick the screw driver in to stop the balance shaft)

David Buschur

iTrader: (53)

I don't mind the questions, I don't have all the answers.

Let's take a brief look at the factory set up.

PCV, this is the small fitting on the back of the valve cover that has vacuum pulled through it and the vapors/oil residue etc. gets sucked into the intake manifold and then burnt in the combustion process. Not ideal as all the crap is not good to burn, I think we can all agree on that. Between the PCV and the EGR they fill the intake with a thick black coating over time, nasty stuff. Agreed?

Valve cover vent. This is the hose on the driver side that originally runs to the turbo inlet pipe. This line typically has oil dripping out of it. Under vacuum if the PCV is hooked to intake manifold there may be some suction drawing air through it, I don't think so though as there is quite a bit of crankcase pressure in the engine and I think it is probably all the PCV can do just to try and keep up with the normal crankcase pressure. In order for the PCV to actually draw air through that valve cover vent it would mean the PCV had so much volume and suction it would produce a vacuum in the engine/head. I do not believe that is going to happen, as a matter of fact, I'll put money on it. Do we agree on that?

(BTW, I am not being a smart *** here, I am actually asking if we all agree or not.)

The valve cover vent that runs to the turbo inlet pipe we all know has oil come out of it, this oil is sucked through the turbo and then passed through the turbo, intercooler, i/c pipes, into the intake and then burned in the combustion process. Along with this oil is all the "bad gases" being mentioned by others.

The only way to get rid of ALL the oil and "bad gases" is to disconnect the PCV valve and the valve cover vent and just vent them to atmosphere, which is what we generally do on every car.

Disconnecting the hoses and letting them vent to atmosphere eliminates any and all oil/vapor from making it into the engine at all, do we agree? I have to say yes on this as my intake manifold/i/c pipes and FMIC on cars with this done stay super clean.

I like just having two hoses coming off the valve cover and routing them down under the car to vent the crankcase. Problem is there is oil pushed out of them and you can get drips occasionally. Depending on how tight the engine is some see a lot of oil, some see hardly any.

On a typical "catch can" the hoses from the valve cover are routed to the catch can and it catches the oil that comes out of them. A catch can has a vent on the top, whether it is a filter or just a hole, it HAS to have that because of the crankcase pressure escaping from the breather lines, you cannot put it into a "closed" can. Something would have to give, typically it will blow seals out of the engine, gaskets or like what happened to me yesterday make enough pressure to push oil past the turbo seals and smoke like mad.

I think looking at how the factory does this we can determine the car is going to burn the oil/vapors etc. either by sucking them back through the turbo or sucking them through the PCV and into the intake, do we all agree?

What I have built is a can that does NOT have a breather on it. It is a closed system. I have two ports entering the can, these two ports are the PCV and valve cover breather. The can is designed to keep the oil seperate from the vapor. The oil settles to the bottom of the can and then drains back to the oil pan. The vapors are sucked/pushed out of the can and drawn back through the turbo inlet pipe and reburned.

The way I see it this is actually how the factory is doing it too, nothing different except the oil is not re-burnt and it doesn't end up coating your i/c pipes, intake and FMIC with oil inside.

I hope this explains it all better.

The Crawford can, as I mentioned briefly in my first post, is like this and it works freaking perfectly on the Subaru's. I ran one on my car and thousands of other people run them on their Subaru. I never saw any signs of contamination in the oil or the oil seeming to break down early.

I think what needs to be thought about here is the vapor/oil is coming from inside the engine in the first place, it's already there, it's not like any of it is being introduced from this new product for the first time to the engine, it is already in there. This is just a way to seperate it all, keep it from dumping on the ground and hopefully scavenge some of the pressure out of the crankcase.

Also, I am not draining it back into the bolt hole for checking the balance shaft. Just be patient, as soon as I have this done and built like I want it, I will post pictures

Hope this explains it further and opens up some thoughts on it all.

Tarmacisback69

iTrader: (4)

+1 nice post david b

David Buschur

iTrader: (53)

One more thing, there is water vapor in the engine already. A lot of it. Anyone who wants to see it, take off your oil cap and look at the back side of it. It is very very typical to have a creamy substance on the back that will make you think you blew a head gasket.

Like I said, there is nothing being introduced to the engine that isn't already there and I believe this is the best/cleanest way of doing it.

I pulled the hose off the can again today, the one going to the air intake, this was after Trent took the car down the road with a customer in it and the dyno work I did yesterday............bone dry. Surprisingly dry actually.

I am going to build a 2nd can when my proper tubing comes in. When it does I plan to run the car on the dyno more and street drive it. If in the end this seems like a flop, I won't sell it.

Right now, it is looking extremely promising.

JC evo1

Dave do you know what the crawford can looks like inside?

BluEVOIX

iTrader: (69)

The way you describe it to be is similar to air oil separators that air planes use.

Regarding PCV systems and venting to atmosphere. From what I have been reading is that ventilation under the valve cover is important. Ventilation as in creating a draft. The ventilation of moving air under the cover removes the blow by gasses replacing them with fresh air. Simply venting to atmosphere just helps in releaving pressure but blow by hydrocarbons/fuel still remain to contaminate the oil.

This is what I concluded from researching. I was thinking in the past to just vent to atmosphere but wasnt too sure of the importance of the ventilation draft created under the valve cover.

Oh and PCV means Positive Crankcase Ventilation, meaning no vacuum. So Dave Buschur is correct that no vacuum is created under the valve cover. If you have vacuum or pressure then something is wrong.

David Buschur

iTrader: (53)

Yes, bluEVOIX, you hit the nail on the head, that is correct, an oil/air seperator is the purpose of this.

Also agree with you on the ventilation under the valve cover, that is why there is a port on this can that goes back to the turbo inlet that draws on the can.

JCEVO, yes.

Indy Evo

iTrader: (41)

vacuum=good, pressure=bad

l2r99gst

iTrader: (2)

This is one of the points that I was trying to make. The intake manifold vacuum is what is pulling the blow-by gases, water vapor, etc, into the IM. If you unhook the PCV hose coming from the backside of the valve cover and don't provide a large enough vacuum, then you risk leaving too many blow-by gases, especially water vapor, which can cause problems in the long run.

It's called positive crankcase ventilation, because it is venting postive pressure from the crankcase (blow-by gases) which work their way under the valve cover from the oiling passages. There is vacuum in the intake manifold, which is pulling the blow-by and vapors into the IM. The fresh air comes from the breather nipple that hooks into the intake pipe. The air is 'clean' air because it is being drawn through the air filter and counted by the MAF first.

l2r99gst

iTrader: (2)

This is exactly one of the points why I was asking about how your system is setup.

You're absoultely right that there is a lot of moisture that can build up under the valve cover and if you get rid of the strong vacuum source from the IM which is providing the pull to expel these gases and vapors, then you are potentially leaving all of that moisture in there.

Moisture removal is actually one of the major benefits of a properly functioning PCV system.