EddScott

As heading really, whats it do and what are the benefits of having one?

Are they universal or vehicle specific?

Thanks in advance.

96turbz

i think sum of the pipes in your breather system are routed bak in2 the intake and it causes the pipes 2 get oiled up.if u route the pipes in2 a bottle or a can of sumkind it will catch the oil instead of it goin in2 the boost pipes

stevem2k

The catch can collects oil vapour that builds up from crankcase pressure. The vapour is returned to the intake tract normally. It's more pronounced in turbocharged cars. The oil is bad because it builds up in the IC and diminishes it's efficiency.

FB Tuning

iTrader: (30)

Just a thought....

Surely it's not all bad, because the oil vapours that are recirculating back through the intake are helping to lubricate turbo and valve stems / seats etc.

I stand to be corrected though!

dnb

The oil mist can cause a certain amount of detonation. Oil has a very much lower octane rating than even NUL.

Mark A

iTrader: (1)

Its recirculated into the intake and deposits in the turbo,IC and throttle body and then burnt in the engine. This can cause problems with combustion and I'm possibly altered fueling etc .

More useful on older or high output cars with higher crank case pressures. I also think that this is done by manufactors due to emission laws.

My understanding anyway.

Mark A

EddScott

So would it be worth investing in one for a MY00 Impreza running 270BHP?

Mark A

iTrader: (1)

I would wait, unless you've got a good deal. In which case fit it anyway, I'm sure it won't cause any harm.

Mark A

StanS

iTrader: (3)

IIRC the breathers from the cam covers are at slight negative pressure so you could fit the mini air filters (like you use for the idle control valve intake) on a short pipe to them i.e they dont need to go to the catch tank, but the crank case is at + pressure so needs to go to a catch tank to condense the oil vapour then "clean" (!) air goes out to atmosphere.
I hope someone who knows for sure can confirm/correct this, as I am about to change my breathers which currently all go to the catch tank to the above routing !
Stan

AlanG

On a healthy engine, then yes the heads will be in a slight *vacuum* condition as you say, but if it's a tired/worn engine, then +ve pressure can be seen in this area, so still a good idea to vent them into a tank IMO.

96turbz

wat would be the best thing 2 use as the catch can or can u buy a proper kit?

chrome

demon tweeks do cans IIRC

EddScott

I was looking at a Greddy one on Ebay in Aus. Worked out to about £70. Sounds a bit complicated to fit properly? wouldn't want to get the pipes mixed up

dowser

I paid ~100 quid for a Cusco one Next time I use a plastic coke bottle

Richard

AlanG

Not complicated.
One pipe from crankcase breather to tank and join the two heads into one pipe and join that on to catchtank. Then vent to atmos.