Where and what oil catch can for my scooby?

[fai17]

As above where i can get one at good money?

[ANDYJDMSTI]

VTA and save yourself afew quid!!

[bigdavie]

and how is this achieved andy ?? piccies would be good !!!!

[MY94]

Breather system

The original PCV (Positive Crankcase Ventilation)system does indeed do some good for the engine by ensuring the corrosive gasses are removed from the crankcase and replaced by fresh filtered air.

The Subaru system has two main phases depending on manifold pressure/vacuum.

Under manifold vacuum conditions (probably 99% of the engines life) there is a non return valve under the throttle body, which allows the 'blow by' vapours to be drawn into the manifold. The vapours are replaced from the vents on the cam covers, supplied from the inlet duct. This provides the circulation of air through the engine, prevents condensation, oil contamination and internal corrosion.

This is indeed a good thing and there is a strong case to retain this system if the car is a daily driver.

Under positive manifold boost conditions, the non return valve under the throttle body closes and the hot 'blow by' gasses (Note - 'blow by' tends to be a cool vapour at low power but a hot gas at high power) are re-routed via a 't' piece to the intake duct for reconsumption by the engine. The cam cover vents may also vent out during this phase.

This is where you can get oil suspended in the gasses finding its way into the induction system......this is a bad thing ! The oil coats the intercooler, reducing efficiency and causes premature det due to lowering the octane of the fuel.

It is possible to 'catch' the suspended oil in a 'catch can' This is a reservoir deigned to reduce the velocity of the gasses, allowing the oil to fall out of suspension. The oil collects in the bottom of the can and the oil free gasses carry on to be either reconsumed by the engine or vented to atmosphere. The catch can will ideally intercept all 3 vent lines although the main culprit on the Subaru would appear to be the central crankcase vent.

The return of gasses from the catch can is also the subject of some debate. If the gasses are reintroduced to the intake system then you are asking the engine to burn an oxygen free mix ! ie you are reducing slightly the amount of oxygen fed into the engine, this can only mean less power. I personally prefer to vent to atmosphere and block off the return to the intake system. There are concerns that this is not very 'green' however the vented gasses are just of the same constitution as your exhaust gasses (assuming you have a decat exhaust)

TAKEN FROM ANDY F'S WEBSITE!!

[bigdavie]

aaaaaannnndddd if someone could put that into a how 2 !!!!

that would be great !!!

lol

[fai17]

Ok...probably go VTA way

[ANDYJDMSTI]

Can't show any pics as the car is still in a comatosed state getting worked on, and i am not in the country.

Squirrel has done it on his classic and Gumball did it with his too.

[coulty]

anyone want to see it can come to KH on sat and see it already done on my car. I will be on the sidc stand with me mota!

[Gumball]

I gave my catchcan away Peter as greers vented it all to the road using hoses.

That way you spend 10quid rather than 100 or whatever for the catchcan.

The catchcan looks good though

[wilky]

Okay,

In laymans terms venting the breathers for your two cam covers and crank will stop the nasty gases being returned into your induction tract (The pipework that sooks in the air from your filter to the turbo that has mad pipework going into it, the mad pipework is your breathers, the sooking of the air means that it will also sook the nasty gasses out of your breather, but it will go back into your engine, and that air is nae use because its been used already and is full of nasty gases)

A catch can on a subaru ideally needs 3 pipes going in and one coming out, and gives a "can" to collect any oil that is present. the 3 pipes going are from the two cam covers  and the crank. Its hard to find a catch can with 3 ideal inlets and one outlet. I had to modify the cusco one I got off gumball to do this and its still not ideal, so I will be venting to atmosphere. I will be doing this because my outlet on the catch can isnt big enough to allow all the gas to bugger off under full load despite all my fettling. Andy F pointed this out.

Venting to Atmosphere is quite easy, and gets rid of alot of the naff subaru pipework.

Look at the top of your rocker covers and you will see in the center of each a hose coming off, take the hose off and you will see the black stubs the pipes fit onto.

Now look at the back of the engine, under the intercooler but on the turbo side and if you follow the pipework that all joins up and goes to the inlet from the cam covers eventually one will lead to the back of the engine at the tubo side and go into the block, pull that hose off and you will see what looks like a bit of plumbers copper pipe coming out of the block. That is your crank breather. take all the pipework and valves in the pipework off the car. You will have to block the holes left in your induction pipe I originally used araldite and plumbers bungs. Now look at the bore of the stubs on the cam covers and crank breather, go to pirtex and buy oil hosing, or if you want clear garden hosing so you can look for oil in it. You are going to need enough hosing to come from each stub individually , go to the bulkhead then down to the road wherever you decide to attach it. Attach the hosing with jubilee clips, and have it coming up, then down to the road, so that oil can run back in should it so desire, and to avoid kinks.

Coulty has his pipes going onto his strut brake and down, attached with plastic ties, this is a good idea. But remember you want it running free with no kinks.

Many people plastic tie it onto the suspension arms, I would personally keep it away from the exhaust side, if you do get oil coming out (Nothing to worry about!) it may hit the exhaust.

When high power cars lauch they get oil out of the crank breather and onto bottom of the car almost all the time, thats life.

Have alook at a car with it done and you will see what I am talking about.

Hope this helped

Callum

[coulty]

"Coulty has his pipes going onto his strut brake and down, attached with plastic ties, this is a good idea. But remember you want it running free with no kinks."

I used to have it tied up there but have since had it hidden under the inlet manifold when i had it off. You need to make sure you run all three pipes (that is crank and the 2 cam breathers) seperately and have them running away from the turbo side down to the passenger side where you can stick them behind the brake lines.

I will be able to show this to anyone who wants to see it on saturday. Mine is the white classic btw.

[st3ph3n]

Interested in a nerdy geeky would like to know EVERYTHING way.