More stupid AOS talk...

[NewArt]

So this week I changed out my AOS (again) because last week I had a smoke bomb/flashing CEL at the track. The motor-sport AOS is on my wish list and probably, if I could make the proper decisions, I could have spent less and solved my problem.
So, I cut open the old AOS which had been pumping oil through my intake and causing mayhem, only to find that the diaphragm was like new, no other obvious physical problems whatsoever.
Okay, on the track I'm fairly new (2nd season), I'm running street tires (Mich sport PS2s), I'm not pulling big lateral G's on the corners as if I were on sticky R comps. Is the stock AOS really that bad???
Question: How many of you share this experience, pulling off the hose between the AOS and the intake plenum, to find it bathed in oil?
I've got a sport oil sump baffle coming in from Pelican next week with some other necessities and am hoping it will help! I've heard talk about a catch can, but the jury seems to be still out.
Talk to me.

[JFP in PA]

Assuming that your AOS is working (max of 5 inches or water steady vacuum at the oil filler cap), you are always going to find the hose from the AOS to the intake coated in oil, that is simply a fact of life. Adding a catch can will only coat that as well.

The AOS is designed to reduce the amount of liquid oil pulled into the intake system, but not to eliminate it completely. The problem is that oil is being transferred as vapor when the engine is running hot, and that vapor accumulates on everything it touches. That also happens with the motor sport version as well.

If you are smoking badly at the track, and the AOS is working properly, the problem lies elsewhere, as in the AOS system pulling liquid oil out of the cam covers.

[NewArt]

Originally Posted by JFP in PA

If you are smoking badly at the track, and the AOS is working properly, the problem lies elsewhere, as in the AOS system pulling liquid oil out of the cam covers.

How does this happen?
p.s. It's not smoking badly. This is only the second time that it has happened.

[JFP in PA]

Originally Posted by NewArt

How does this happen?
p.s. It's not smoking badly. This is only the second time that it has happened.

At speed, your cam covers have a lot of oil in them; add G=loads in corners and some of that liquid oil can get sucked into the AOS system (which has a vacuum line running to each cam cover). While the AOS can handle some level of liquid oil, it cannot deal with a flood, and more than normal vapor gets sucked into the intake.

Porsche had been aware of this for a long time, and actually produced an exotic and hyper expensive kit (read $10K+) for the heavily tracked 996's to help limit it. Amongst other things, the kit contains a "north west passage" oil recovery system which consists of additional oil scavenging pumps in the cylinder heads with lines to run the oil back to the sump. Unfortunately, this kit was never made available to fit in a Boxster.

[Gelbster]

Originally Posted by JFP in PA

At speed, your cam covers have a lot of oil in them; add G=loads in corners and some of that liquid oil can get sucked into the AOS system (which has a vacuum line running to each cam cover). While the AOS can handle some level of liquid oil, it cannot deal with a flood, and more than normal vapor gets sucked into the intake.

Porsche had been aware of this for a long time, and actually produced an exotic and hyper expensive kit (read $10K+) for the heavily tracked 996's to help limit it. Amongst other things, the kit contains a "north west passage" oil recovery system which consists of additional oil scavenging pumps in the cylinder heads with lines to run the oil back to the sump. Unfortunately, this kit was never made available to fit in a Boxster.

" Adding a catch can will only coat that as well."
I had hoped that someone(Stelan?) would publish a diy catch can solution by placing a Catch Can ahead of the AOS to divert liquid oil direct to the sump. From what JFP and Porsche R&D have discovered it seems unlikely that a cheap,simple catch can would be effective?
see post #8 in this link to a previous discussion:
http://986forum.com/forums/general-discussions/60203-new-aos-failing.html
So time to investigate other contributory factors like lack of anti-foam additives in the engine oil?

[stelan]

Originally Posted by Gelbster

" Adding a catch can will only coat that as well."
I had hoped that someone(Stelan?) would publish a diy catch can solution by placing a Catch Can ahead of the AOS to divert liquid oil direct to the sump. From what JFP and Porsche R&D have discovered it seems unlikely that a cheap,simple catch can would be effective?
see post #8 in this link to a previous discussion:
http://986forum.com/forums/general-discussions/60203-new-aos-failing.html
So time to investigate other contributory factors like lack of anti-foam additives in the engine oil?

I will try to get the time to write a good diy on my custom AOS
I have been all over the place due to work but will try to find the time
Steve

[Racer Boy]

I've had the extreme smoke bomb action on my '02 at the track recently as well. I've ordered a new AOS, special oil pan baffles, and "deep sump" kit to lower the oil pan 1/4". Based on what I've read, that commonly solves the problem.

I'm really hoping it does!

[NewArt]

And, unfortunately, I don't have a spare $10K+ even if it were available!
Oh, and thanks for that explanation!

[Gelbster]

Suggest you read up threads about installing the deep sump and baffles. If you put the horizontal plate-baffle in the wrong place, if the 'windows' jam open ,if the pick-up tubes aren't the right ones - it will be sub-optimal.
It seems the cheaper sump spacer+baffle kits work but only with intelligent fitting & fiddling . The deep sump kits (Mantis/Brey Krause?) seem to work better out-of-the-box.
Need to check your vac system too. An inexpensive paint-can smoker works well.

[JFP in PA]

Problem is that the AOS system draws vacuum on both cam covers and thereby the sump. Even at only 5 inches of water, hot oil is going to give off some level of oil vapor, as well as other vapors (we will get back to that in a moment). To limit the vapor transmission to the intake hose (read vacuum source), the catch can device needs to be cooled to condense this vapor back to a liquid. This presents a couple of issues: Where to put the two devices (one of each bank, otherwise you would need one larger unit), how to cool them and keep them cool in proximity to a hot engine, and how to get the condensed vapor separated (some of it is oil, some is water, some is fuel) so that only the oil portion is returned to the sump. You would also need to figure out how to dispose of the non oil components from the cans as well because you do not want them returning to the oil system. (currently, they are sucked as vapor into the intake and burned).

Add in conditions where there is an overly large amount of liquid oil being thrown about the inside of the cam covers (high RPM and g loads in the corners at the track), and now you have some liquid oil entering the catch can system as well. This also has to be handled at the separation stage.

None of this is insurmountable, but it would take some very intricate engineering (read expensive) to make it all work.

[Jake Raby]

AOS units simply are not lasting these days. The latest run from Mann has proven to have issues, as I have experienced them several times in the last couple of months.

We've been testing a product for a while thats almost far enough along to pitch to distributors. If they accept it, the AOS problems will be over.

[Gilles]

Originally Posted by Jake Raby

We've been testing a product for a while thats almost far enough along to pitch to distributors. If they accept it, the AOS problems will be over.

Hello Jake,
Sounds very interesting, are you talking about a new AOS design, or new internals for the existing AOS..?
Regards,
Gilles

[Gelbster]

Good luck with the new product Jake !
I am surprised a diy system using a small,brushless 12v vac pump + adjustable pcv+catch can +check valve has not been tried.
That would allow an AOS delete.
Some hot rod/race guys do this.
http://www.hobbyexpress.com/power_25_bl_outrunner_motor_1250kv_1036351_prd1.ht m
http://grannys.tripod.com/evac.html
http://mewagner.com/

[steved0x]

Originally Posted by Jake Raby

AOS units simply are not lasting these days. The latest run from Mann has proven to have issues, as I have experienced them several times in the last couple of months.

We've been testing a product for a while thats almost far enough along to pitch to distributors. If they accept it, the AOS problems will be over.

Please let it be yes, if you want an additional tester I volunteer

[stelan]

Here you go, sorry about the missinformation as the pcv is not from a vr6 but a 1.8turbo vw. vr6 one will work but the 1.8t is a little lower profile and has only two ports
also there are a couple of things I do not remember exactly like the size of the barbed fitting that I use with orings and rtv into the small engine block oil return, perhaps if someone does this we can update some of those details in the drawing, all 3 ports where there are oil vapors need to be at the bottom, so all fumes go thru the ss media and condense oil into liquid to be returned back to the block, on top it should only be the pcv port with clean air/vapors
this drawing also includes a coouple of corrections and changes as the large hose is actually not 1" but a little larger in diameter and as not everybody has access to a lathe turn the small fitting is updated with a double barbed fitting, also this shows the bulkhead bottom fittings with nuts and rubber washers ahas not every one has a tig welder to weld bungs

[Gelbster]

1. The PCV is from a 2003 VW Passat 1.8l turbo(??)
The generic part is BECK/ARNLEY 0450392 from Rock Auto $23 minus their usual 5% discount.
2003 VOLKSWAGEN PASSAT 1.8L L4 Turbocharged PCV (Positive Crankcase Ventilation) Valve | RockAuto
2. the 'catch can' - I am assuming that a generic EBay can 500 to 750ml & made of aluminum is the best choice. A design with an un-screwable cap is easiest for fabrication? Most have inconveniently positioned fittings that require modification or plugging:
Universal Silver Round Aluminum Racing Oil Catch Tank Can | eBay
The Mishimoto & Moroso cans seem too expensive for an experiment?
3.The various barbed fittings : - I prefer using brass & source from "Fast Fittings" because I can usually find everything I need on their site:
https://fastfittings.com/
For this application, here is a good place to start because it gives the actual(not just nominal dimensions of the fittings:
https://fastfittings.com/collections/brass-hose-barb-fittings

4.The stainless steel wool (coarse) is here in abundance & made in USA!
1 lb Stainless Steel Wool Roll Coarse Great Forexhaust Muffler Repacking | eBay

What we also need is a specification and source for the absolute best vacuum lines - both the hard line and the softer grade.The OEM items usually become brittle.Any improved AOS is only as good as the next weak link!
I prefer to avoid using what is described merely as "plastic" tube and try to find a specific high performance polymer to avoid deterioration and leaks in future.Tygon tube i one candidate ? I tried finding something better than SAE J30R7. 30R9 is too stiff & thick?
I hope this info and some of the ideas help move this project along for others who will follow.

[NewArt]

So now we need a track rat who's willing to build this and try it out!

[Gelbster]

I'm still apprehensive because if something as simple & inexpensive as Stelan's AOS is effective ,why didn't Porsche do it this way? And why haven't other talented enthusiasts done this years ago?
Some other mad guy proposed a system with an electric vacuum pump but that was way more complicated than Stelan's AOS.

[Smallblock454]

Hello,

does anybody know the inner diameter of the vacuum lines needed?

In general these hoses have to be fuel and oil resistant. So i would think more something like fabric reinforced fuel lines. Also had the idea of silicone lines, but silicone seems not to be oil and fuel stable. Also it has to be ethanol stable.

Regards, Markus

[Gelbster]

Great suggestion Markus.
Silicone hose in the larger diameters for connection to a pcv tends to collapse when warm and under high vacuum at idle.Bends will kink. For that reason it will fail the Smog Test here if a tech sees the vivid color of aftermarket silicone hose.

You are correct, here is a fiber wall reinforced version but that helps with pressure ,not vacuum.
One solution may be to select thick wall/heavy wall silicone.It is so much easier to work with than the stock "plastic". I found some with a 3mm i.d. and 8mm o.d. Turbosmart TS-HV0303-BK
3m Pack-6mm Vacuum Tube Reinforced - Black
Normal wall thickness would be 1.5mm.This item is 2.5mm.Should help??
One complication is that silicone is very elastic so you usually buy it 1mm smaller i.d. than the 'plastic' OEM style tube.
Note that the silicone hose manufacturers seldom specify a wall thickness and tend to use hyperbole like "turbo" ,'platinum cured' ,so it can be difficult to find a truly premium product.