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 Post subject: Re: oil catch can problem
PostPosted: Thu Dec 16, 2010 8:43 pm 
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PCV method

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 Post subject: Re: oil catch can problem
PostPosted: Thu Dec 16, 2010 8:52 pm 
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FC purge valve method

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 Post subject: Re: oil catch can problem
PostPosted: Thu Dec 16, 2010 8:56 pm 
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KE13BT wrote:
ok so if i'm right this should do the job.

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This setup defeats the catch can as you have the fumes sucked straight back into the inlet.
The second one is better.


Basically, you need vacuum in the catch can.
To do this you hook it up to the inlet after the TB, with a one way valve (i use a brake booster valve) to stop it getting pressurised.

Top of the can to the inlet.
Bottom of the can to the lower oil filler (to act as oil drain)
Thats the minimum.
If you want another line, you can add one to the crankcase vent.

Just make sure you have a sealed oil system, or you will introduce a rather large air leak!!!
This can be a real bastard of a job to do, sealing the dipstick can be an issue - but O-rings fix all kinda things (BMW do it from the factory, just in case you ever need to know that)

If you go for the sealed crankcase route, you shouldn't EVER have a moisture issue - BUT, honestly, i haven't seen this tried on a rotary first hand ... i cant see why it shouldn't work tho.

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 Post subject: Re: oil catch can problem
PostPosted: Thu Dec 16, 2010 10:08 pm 
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bumpstart wrote:
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PCV method



ok looks like this is the way i'll go. just one more question tho, under boost the pcv will close so the blow by and oil film will be going into the catch can. wont this still want to find it's way out of the filter on the catch can?


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 Post subject: Re: oil catch can problem
PostPosted: Thu Dec 16, 2010 10:12 pm 
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you wont be pressurising the can, and once your back into vacuum it will suck the can clear of fumes.

The method i listed is basically the diagram bumpstart has posted up.
For it to work, you cant have a filter on the can, it must be sealed, or you will just have a massive vacuum leak

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 Post subject: Re: oil catch can problem
PostPosted: Fri Dec 17, 2010 12:41 am 
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KE13BT wrote:
bumpstart wrote:
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PCV method



ok looks like this is the way i'll go. just one more question tho, under boost the pcv will close so the blow by and oil film will be going into the catch can. wont this still want to find it's way out of the filter on the catch can?

the PCV isnt technically a one way valve,, rather a valve shaped to flow less under high vacuum than when there is minimal pressure drop across it
think of it as a funnel with grooves ,, with a ball in it ,, the harder it sucks,, the ball closes the funnel
( but not the groove )
if you are wary of this amounting to a boost leak towards your can
a supplementry one way valve ( like brake booster unit) would be used inline with the PCV

when pressure differential between the motor side of TB and the crankcase is re-established crankcase vapours will to flow towards the TB



below i show this system superimposed onto the FD schematic
- the vent on the can purely replaces the line from the air cleaner
and so the low speed/ load/ non WOT function of this can system and the FD one is the same
--however,, at WOT and boost the FD OEM system will flow like the FC one , amounting to a high speed/load circuit that runs towards the air-cleaner

catch cans with a remote filter will instead breath out via the filter


Image

now maybe you can see why i prefer the full time suck towards the air cleaner and recommended that one straight up
( emulating the high speed/load circuit )

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 Post subject: Re: oil catch can problem
PostPosted: Fri Dec 17, 2010 8:33 am 
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yes i understand what you mean. i'm not worried about the fumes it's the oil finding it's way out of the filter i want to get around. my setup is very neat. fd engine with single turbs and all braided lines. i dont want to be running lines all over the place. tlmitf said he runs a sealed catch can with no filter. just the feed from the filler neck, then a one way valve to the manifold and a drain. can you see a problem with this? from what i understand the one way valve to the manifold will close under boost. wont this pretty much make it same as having the filler neck blocked off since the can is sealed there is no escape for the blow by from the sump under boost?


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 Post subject: Re: oil catch can problem
PostPosted: Fri Dec 17, 2010 11:31 am 
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so you have a one way valve from the catch can going towards the manifold in order to vent the gases
& dont attach a breathing system for the catch can
where is the manifold hook up point? pre turbo or post turbo?

effects;
pre turbo = will suck everything from your catch can & anything thats connected to it (attaching a breather valve would be required or you will end up making a huge vaccum in your catch can etc)

post turbo = probably wont vent the gases too well as your manifold will be positively pressurised

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 Post subject: Re: oil catch can problem
PostPosted: Fri Dec 17, 2010 11:51 am 
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na not me i was refering to what tlmitf said on previous page.


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 Post subject: Re: oil catch can problem
PostPosted: Fri Dec 24, 2010 10:01 pm 
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Hate admiting when im wrong ... but i think i got it wrong.

What your saying about pressurizing the sump under boost is quite right - this setup was really only used on N/A.
If you were to put a one way valve on the vent of the catch can to allow the pressure to escape, it should work.

So you hookup things like this:

2 hookups to the crankcase, one to the oil filler breather and another low down to act as a oil drain.

1 hookup to the inlet post throttle body. This one will need a one way valve to stop the boost from filling the catch can.

and a vent line that has a pressure valve to vent pressure while under boost.
If it holds a couple of pound thats not an issue, but it MUST seal under light vacuum or you will have a vacuum leak.



The design of the can is quite important with this setup.
A simple can will not work.
It needs to be an oil separator.

Im sure bumpstart has a few ideas on oil separators, but the design i work with is a couple of baffles to make the airflow bend around a bit between the various inlets and outlets - and then fill the bugger with stainless steel wool.
The wool helps to condense the oil mist.


The vent pipe can be run under the car, back into the inlet (pre TB) or you can just stick one of those stupid little filters on it (which do dick btw)
If you run the vent back into the intake, your doing your best to keep it legal - but i think the fact your modding the emissions screws that idea right away ....
Venting to atmosphere is fine in my eyes, but try and dump it away from hot things, or things you dont want getting an oily film over...

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 Post subject: Re: oil catch can problem
PostPosted: Sun Jan 02, 2011 4:59 pm 
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the filter is also illegal. epa will jump on that..

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 Post subject: Re: oil catch can problem
PostPosted: Thu May 24, 2012 10:03 pm 
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Questions on my setup which is a 12a turbo running low boost (6psi) drawing through a carb.

Ignoring all emissions regulations, as here in nz on old cars there are none so long as its not smokey, is there any reason why could I not just vent my crankcase to atmosphere? I realise that it will be a total lose setup with oil being lost to the underside of my car.

Is it strictly necessary to involve vacuum?

I presume you can't just run a baffled catch can with a filtered vent but no vacuum because it would then fill with volatile fumes which could be a hazard?

My current setup just involves a hose leaving the vent halfway up the filler tube being sucked into the inlet manifold after the turbo. The manifold has a one way valve.
There is also a small hole in the centre plate facing backwards about where the big Mazda writing is on the rear housing. This is open to atmosphere and hence after hard driving or long trips I have to clean the area under the oil filter of oily mess. This I want to stop...

Is that vent hole on the centre plate just venting the same circuit as the filler vent (basically the sump) or is it linked to some other area like the air gap around e shaft?
Can I just block that hole and just use the one vent on the filler tube?

I would rather not be burning oil into the manifold and would like to stop the above mess so I was going to install a simple catch can that once in a while I would just empty back into sump. Bad idea??

Plus I like the idea that by keeping the sump venting and oil vapours separate to the inlet side of the engine I completely rule out any worries of vacuum leaks and oil burning upsetting my wideband readouts and general tuning of the carb etc.


Yet more i am needing to learn. Another schoolday for me...

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 Post subject: Re: oil catch can problem
PostPosted: Thu May 24, 2012 10:16 pm 
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open venting works fine on NA stock engines,,but does not on anything with a turbo or high oil temps

i will say it loud and clear ( once again ) ,,,
sure -----------re-invent the wheel all you like with your catch can / extra sump / mist seperator
( depending on how much of an arse you made of the install )

but unless it has a vacuum on it , dont come on here wasting everybodies time asking why your engine puffs smoke and why your turbos and oil control seals dont last long
the answer is simple ,, cause you failed to hook up a vacuum, dont pass go, dont collect $200

BLOCKING THE VENTS OR LEAVING THEM OPEN VENT WITHOUT A VACUUM IS THE SINGLE BIGGEST RORT I HAVE SEEN DONE BY SHOPS AND INDIVIDUALS WHO SHOULD KNOW BETTER
it will invariably bring the customer back soon cause of smokey exhaust , and they scam a turbo, then an engine build out of it ,,, seen it umpteen times

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 Post subject: Re: oil catch can problem
PostPosted: Fri May 25, 2012 12:50 am 
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Post so I can find later.....

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 Post subject: Re: oil catch can problem
PostPosted: Fri May 25, 2012 6:29 am 
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Ok so I need the vacuum. But why? If blow by from the turbo forcing more past the oil control rings etc is pressurising the sump then surely just an open vent to atmosphere will stop the sump pressurising?

The reason I figure the vacuum is needed is to 'pull' the unburnt petrol fumes out from the sump and other voids. If these were left then over time they will mix with the sump oil and generally degrade it, plus being a potential volatile hazard?

My problem with my current system is that the vent pipe is drawn through a one way valve, into the manifold after the turbo. This works fine at low revs under a light load when the manifold is a vacuum. But when the turbo is boosting, and producing the most crankcase pressure, the manifold is under pressure- so shutting the one way valve which means that sump pressure can go no where.

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