Modifying PCV system

[Jamo]

How freaky was that!

Surprised your famous PCV diagrams haven't appeared in this thread yet Paul

[S2central.net]

Someone else can find them... SEARCH function !!!!!!!!!!!!

[A80Avant]

Thanks guys!
I had been told before that the catch tank configurations tend to smell badly if not routed somewhere at least towards the bottom of the engine,which is what i plan to do.SO what is a good cyclone tank then?

I wouldnt want to worry too much about putting the oil back to the sump so i guess i will have to check it everynow and then and empty it.

A cyclone then would have one hose connected to it from the cyl.head that use to go to the MAF,and then another hose that would go from the tank towards the bottom of the engine with a filter attached to it.

right?

[A80Avant]

Been looking into the Mocal 1l catch tank. What do they mean by 'breathable cap'? does that mean that even if i fit a filter,it will still vent some fumes out and produce a bad smell?

[A80Avant]

i also read a few things from other posts... it is not as easy as i thought now is it?

from what i understand if i only take the hose that goes to the MAF and connect there the catch tank,that wont work,will it?

[Jamo]

See post 17

[A80Avant]

yes i did find the the pcv diagrams,but that doesnt mean that i understand them fully.I see the pressure control valve and the one way valve as well as the N80 valve,but as i read those old threads i get the impression that i cannot do what im proposing(but noone explains why).

Problem is that most people that go for a catch tank eliminate all PCV system. I dont want that,i want to incorporate that.However after reading Andy Caseys thread,who initially he wanted to do that as well, you Jamo said that he cannot just connect a catch tank to the MAF hose(that comes from the cyl.head that is) for various reasons,one having something to do with the fuel vapours.

Now Paul is suggesting that what i proposed IS actually possible....

SO,.. what is doable then?


PS: before rushing to post 'search is your friend' and 'use search' or 'go to post # xx' understand that even when that is done,sometimes not everyone is able to understand everything that is written here,and may need a bit of more explanation.

cheers
vasilis

[Jamo]

I did because you need a separator and a catch tank.

A catch tank on it's own is different IMO and has been proved so.

A catch tank just collects and stores condensed oil fumes so ideally you want a separator removing the oil mist then the drain at the bottom going to a catch tank and the output from the separator go back to the MAF inlet hose if you want to keep the system closed.

[A80Avant]

that is even a greater idea!!! thanks Jamo,

anyone else tried on something like that? what would a separator look like,and are there any options ready to buy like that?

[S2central.net]

PapVas...

I know how frustrating it is sometimes to get a solution on here - the sheer amount of info and opinions can be daunting when looking for a simple yes or no, so let me try to level this one out for you.

A crankcase has to breath - otherwise all those nasty blow-by gasses will pressurise the crankcase to the point where the engine stops or you burst an oil seal. This positive pressure is where we get the term Positive Crankcase Ventilation (PCV) in the 1st place.

The blow by products are a mixture of unburnt fuel, oil and air - all mushed up together in a nasty smelling vapour with quite a high temperature.

The stock PCV setup on S2 / RS2 is a bit flawed in my opinion as it allows this untreated vapour to return to the inlet side of the engine via the MAF hose on the turbo (this location is always under vacuum and effectively sucks the vapours out of the crankcase all day long)... allowing the engine to suck in some amounts of hot-air... and thats dirty/impure air with the oil vapour and other fumes which can have an impact on mixture... making the engine less resilient to knock as well when carrying this dirtier/warmer air... Finally we get the build of oil at the bottom of our intercoolers - pretty nasty. Its like our intercooler is the catch tank on the S2/RS2.

Audi have used cyclone systems on other engines - like some TDIs for instance - but not here.

The purpose of the cyclone/catch system is to give a way to stop this rubbish being ingested by the engine. See the previous post about baffles in the tank to help separate oil from air. Giving you two choices for treating oil --->

1. Catch it / Store it in the treatment tank and empty on a regular basis - you'll see lots of motorsport catch tanks with 'window pipes' so yo ucan see the level of goo in there. Pretty evil when you have to empty them IMO - but its a good way to see how much is collected.

2. Return it to sump - bit more work, but tidier and hassle free... No more goo to drain manually.

Even on this type of system, that pressurised air has to be vented somewhere... You have three options for that -

1. Let the MAF hose suck in the vented air - the cyclone tank is purging most of the oil content so this is a useful upgrade, but not perfect and only viable with a really efficient cyclone tank.

2. Let the cyclone tank just vent to atmosphere - but its still a bit smelly - and so the best vent location is somewhere low down... somewhere downwind of any cabin intakes. You can fail an MOT for this if you get the wrong guy on the wrong day... I did once fail another car with a very obvious crank vent which was flouting the precious environmental laws.

3. Use the suction from the exhaust system to create vacuum (or an external electrical pump) with cleverly positioned pipework as a way to suck the air out of the cyclone tank. This is quite elaborate but is a nice way to get vacuum without involving the engine intake.


My recommendation to you for what you desire is a good cyclone tank that has a window for the oil level which can be easily seen in the engine bay - and readily accessed for emptying... and easily upgradeable to a drain system when you get bored emptying it. The air outlet of the tank can be tested for oil and heat content on some hot runs if you wish - then you can decide whether to let it vent via a long pipe to underneath the car - or have it returned to the MAF hose (carrying much less oil than before). Note if choosing to feed it back to MAF hose, then think of a means to reduce its temperature content... Top tip - look at the corrugated metal hose on the S2/RS2 for reducing temp of hydraulic fluid en route to the PAS pump.

Howzat ?

[Jamo]

034 sell one

Mine is this one http://www.s2forum.com/forum/showthread.php?t=13254

http://www.s2forum.com/forum/showthread.php?t=12603

[S2central.net]

FFS Jamo - thats twice youve done that to me today

I agree with what you said - but I used SOH many more words than you.......... I could sense some mediterranean tension building there.

[S2central.net]

After all that typing and description... I want to buy one now

[A80Avant]

@ Paul

thanks for taking the time to explain in detail my options.From what it seems i have 2 easy options here.

1) the separator option that Jamo is mentioning,
2) the catch tank option with the hose somewhere at the low area of the car +/- a filter on that.

My question for option No 2 is regurading the setup. Is it as simple as that,as taking the crankcase hose that goes to the MAF and hooking that to an inlet of the cyclone tank + tapping the MAF hose itself and finally adding a second hose to the tank outlet to go under the engine with a filter on it's end?
This will basically leave the rest of the PCV system unaffected. However since there will no longer be a vaccum from the turbo area that was previously sucking all that nasty vapour,will that mean that the crankcase pressure will go up now that it is connected to the atmosphere through the catch/cyclone tank?

thanks again

[A80Avant]

by the way.,
when i type for cyclone tanks on the web i get nothing,i can only find catch tanks but nowhere mentioned if those have inner plates...