SG Motorsports Air Oil Separator

[Stoffa]

I\'ve just installed a SG Motorsport AOS form Tuningworx in Aussie as I was losing alot of oil on my forged engine after a rebuild. I had a baffled catch can breathing to atmosphere and it was catching all the condiensation but most of the oil vapour was getting blown past the baffles and soaking the filter on the catch can and spraying on my fire wall. I got sick of that pretty quick also the smell did my head in.

sample pic

It may be all in my head but it feels more responsive with it hooked back to the intake. Im running clear hoses so I can see how well its working

Ive got a V5 type R running a Link G4 ECU with no MAF so no metered air drama\'s. I\'ve connected the crank breather and the head breather together and into the AOS and then back to the intake, its running clear hoses so I can see how well it works. Im not running a PCV valve so just using the intake vacuum to suck everything out. My car is running a custom 18G VF hybrid turbo at 1.4bar so not sure if this much power will effect how well the AOS works.

Should I be concerned about the condensation going milky in my filler tube and inside the AOS?

Does anyone else running this type of AOS have similar problems?

I can see condensation inside the hoses after the car has been turned off and its nice and clear, only milky in the AOS and filler tube.

From what I read most condensation that gets into the oil ends up getting burnt off when the oil is up to temp.

Is my problem possibly caused from not running a PCV valve?

Are there any engine builders out there that know exactly when blow by is at its worst?

Im thinking I\'ll try a PCV again, if blow by is worse under boost the PCV valve will be closed and the intake will suck the oil vapor through my air oil separator, and when its under vacuum the blow by wont be as bad and the PCV will suck all "bad stuff" hopefully not much oil vapor straight into the intake.

As the engine spends most of its time in vacuum im hoping all the condensation will get pulled into the intake and stop the AOS getting milky.

I know not many people use this type of AOS in NZ, its widely used in aussie and the US and is proven to work

[Guest]

Vacuum in crank case makes engine quicker but I wouldnt\'ve thought you would notice it I thought it was just one of those little things. Ichi did have a post somewhere iirc.

no help at all lol.

[PhatRS]

All the carp that ends up in my catch can is milky if that helps so sounds normal to me. I dont bother putting it all back in the engine tho, just pipe the vapour out the back and drain the can once a year

[Stoffa]

Ive used over 3 litres of oil in 5000kms. probably partly due to it still running in. It has slowed alot over the last few weeks though

[PhatRS]

That sounds like attrocious blowby, I had about 500mls in my can after a nearly a year including a track day.

Rings should be bedded in in the first 20-30 mins, is the majority coming from the crank breather???

[Stoffa]

Not really sure, the engine builder didnt seem too concerend by it.

From my research it just happens on forged engines, some more than others.

[soopersubaru]

Ive said it before an i will state it again. Put waste down the waste pipe!.

Catch cans are a WOFT... A correctly designed exhaust venturi breather system will dispose of this waste milky gunk/oil without dripping out the exhaust or causing excessive or visible smoke!

Even on the track or at hillclimbs I have not been advised of an issue.

Only time I have ever had smoke was when the sump was approx 200ml overfull then i took a long tightening 50kph corner at a considerably higher speed...Then it was like a blown turbo smoking...Cleared very quickly!

One other chap mentioned that there was a slight blue whisper of blue smoke from my exhaust on a hillclimb one day.

During normal/highway daily use there is nothing at all!

My forged motor (40,000km) uses/loses around 500ml per 1000km travelled... That\'s sweet F*#*#* all !!

[rex-leggy]

is that system even legal? more details please i need to sort something for mine also im not a fan of catch can\'s at all anymore after this weekend.

[soopersubaru]

 rex-leggy said:

is that system even legal? more details please i need to sort something for mine also im not a fan of catch can\'s at all anymore after this weekend.

have a read here. Yes can sort one out for you.

http://www.clubsub.org.nz/forum/index.php/topic,27376.0.html

Not been told its illegal...don\'t think the VINZ guy has even noticed it yet alone seen it...V8 boys been doing it for years!

[Stoffa]

its illegal but if scruiteneers saw it they wouldn\'t let you on the track.

scored a PCV, thanks Pollick Marine, see how that goes

[soopersubaru]

 Stoffa said:

its illegal but if scruiteneers saw it they wouldn\'t let you on the track.

scored a PCV, thanks Pollick Marine, see how that goes

Who said it\'s illegal? as above no fumes or visible smoke or drips? Whats the problem?...bet a scrutineer would not even know! Even if it was of concern!! which it is not!

If asked where is your catch can?...just say its (breathers) piped back!...now that\'s not lying either!

[Stoffa]

sorry I ment its LEGAL, but not on the track, the possibility of sucking a crapload of oil and dropping it all over the track.

after all my reading I\'ll be running a PCV as people that dont run them seem to have oil loss problems, I guess its the lack of vacuum helping the rings seal properly. So using a venturi setup in the exhaust or a proper vacuum pump would end up having similar results.

I may also look at doing what Tony has done, welding 2 extra breathers on my V5 rocker covers and connecting them to the capped crankcase breather (v7 sti block) and plumbing those 3 together the same as AVCS equipped cars. It\'s ment to equalise crankcase pressure, also a path of less resistance when hard cornering so its more likely the oil goes up this new pipe instead of into the intake.

[Eight_dollar]

there\'s a limit to the vac level you can safely use in crankcase-

too much and the rings will run dry due to excessive blow by ( washed dry by fuel ) and the 2nd ring can be "pulled" off the bore face

But yes a vac in the crankcase does increase eng performance

Ichi ran a cross over set up and dual catch cans - apparently only a trace of oil in the cans after a full track day

[Stoffa]

I have no doubt I could get a catch can set up to work well, but the smell does my head in having vent to atmosphere, personally im after a maintenance free setup that stops me needing so much extra oil.

who knows, maybe I have a leaking valve seal or something, but I\'ll try the PCV first, if I still have excessive oil consumption I\'ll try compression and leakdown tests. but my engine was built by a well known builder so im sure its fine.

[Stoffa]

OK PCV valve is back on and plumbed in, got an oil change due in a few weeks so I\'ll keep an eye on it over the next 5000kms and see how much oil im using.

I did notice the blocked off unbaffled breather (v7 sti block) has oil seeping out of the bung so there must be a bit of pressure in there.

[ADIKT]

Subaru maintenance free? Yea right

[Stoffa]

Its early days but my PCV going back in has given me more vacuum in the manifold and is pulling all the condensation out of the crank case so no more milky stuff in the AOS. Pretty sure its stopped using oil oil as well.

After speaking with my engine builder he said the lack of vacuum in the crankcase causes a pressure build up between the first and second ring which ends up letting oil past and into the cylinder.

So my theory is that im not sucking all the oil into the intake manifold because the vacuum in the crank case is helping the rings seal properly so its no longer burning it.

As for how well the AOS works at seperating the oil vapor on boost, only time will tell, I need to wait till the clear hoses have been coated in vapor, hopefully just the one hose will be dirty

[soopersubaru]

Just remember this:- The exhaust venturi system maintains crankcase vacuum at all throttle openings...In fact higher vacuum is achieved at higher powers!

[Stoffa]

I love the way you try to get everyone to follow your way of thinking. haha

[petrolheadjman]

And I assume in your signature you mean high? no hi?

trololol

[soopersubaru]

 Stoffa said:

I love the way you try to get everyone to follow your way of thinking. haha

Always promote what works well!...Just as others promote their own ...Blah Blah !

[Stoffa]

Fair enough....personally I run a wideband full time and dont want oil vapor all over it. also probably not a good idea to pull too much vacuum is it?

At least my setup only pulls what a factory setup pulls, maybe less with the crank and breathers on one line to the intake pipe.

Also may setup is easy enough for most people to do it themselves.

[soopersubaru]

 Stoffa said:

Fair enough....personally I run a wideband full time and dont want oil vapor all over it. also probably not a good idea to pull too much vacuum is it?

At least my setup only pulls what a factory setup pulls, maybe less with the crank and breathers on one line to the intake pipe.

Also may setup is easy enough for most people to do it themselves.

No problem to run a O2 sensor...Venturi downstream of sensor

Max Vacuum is around -100 mllibar...Thats around 3"wg

The standard breather PCV system pulls far more than that when you back off and raise intake vacuum to around 20" or more

[Stoffa]

My sensor is mounted 2/3 of the way down the downpipe so I would have to run it quite a way down

Ok maybe your way does sound like a good option, unless its the opposite is true and it wont pull enough vacuum, but if your not using oil I guess its fine.

[soopersubaru]

Stoffa...Yes mine uses oil too..Possibly loses it..Forged motors do this..Mine is around 1/2 litre for 2500 km..however this depends on if its being driven hard or not...harder driving,uses more oil. Has now done 40,000km.

See what you mean on sensor location, Why so far down the pipe? Venturi is fitted on the first bend after turbo on the downpipe where it turns towards the rear of the car. That\'s below the "cat" if one is fitted. (probably not in your case)