Catch can return line?

[merc-blue]

Guys, i have been looking at the idea of doing somthing about catch cans having to be emptyed (after a mates filled up with some pretty bad effects)
instead of having to empty it every now and then is it possible to run a line form the bottom of the can into one of the feed line of a remotly mounted oil filter? or am i gonna find it will just fill up the catch can?
any help would be great, im just lazy also another thing less to have to maintain is good
Cheers
Rohan

[mic*]

I am thinking oil pressure will be a problem - fill up the can.

What about a return to sump?

Im not too sure really but its interesting in the interest of laziness.

[merc-blue]

yeah i was thinking that but im not keen on drilling a new line into the sump. (if i bought a moroso or somthing i would do it, use one of there existing lines)

also when the can is empty will i just end up pumping air into the sump and building pressure?

[jonra23]

Been thinking a way around the same problem, looking at a small line (10mm) teeing into dipstick tube with even smaller hole in bottom of catch can (2mm) should drain down when engine is stopped.
recon it will work?

[mic*]

Unless the ATM pressure (should be plumbed back to pre TB) outlet of the catch can became blocked, i could not see the blowby pressurising anything. Esp. if the new drain hole was 2mm per say, and the outlet is 10mm tube or the likes.

I like the dipstick Tee idea.

I reckon itd drain down more or less as it condenses.

[Munki]

I would guess that you would create a closed breather system and pressurise the motor causing oil to escape elsewhere, you might also find that connecting it to your filter (pressurised) it could push oil up into the can and cause funny things to happen with the oil pressure.

so i would just empty it

Daniel

[merc-blue]

yeah im liking the idea, i have a few dipstick tubes i might try welding a little boss thing in.
im running a custom ITB setup so im not 100% sure what im going to be venting the pressure to

[jonra23]

The catch can is fully pressure balanced to the rocker cover already, so shouldnt be any pressure difference between it and sump, unless motor has a huge amount of blowby that cant get into rocker cover quick enough in which case motor needs more than catch can.

Most people seem to vent catch cans to atmosphere, but if catch can is doing the job and stripping oil should be no reason that cant plumb back in on an MAP system, would still be a bit nervous about running it through an AFM, could lead to pain.

[WDE_BDY]

The basic setup is line from rocker cover and crankcase into can, can hooked back to vacuum side of intake (pre turbo on a turbo motor) so that any fumes/pressure from crankcase and rocker cover are sucked through engine and burnt. There should be no problems with the can pressurising with this setup. The only reason to plumb back is emissions, otherwise just vent the can. DO NOT run a drain back to the sump, the crap thats gets collected in the catch can is not good for the engine, if you are concerned about it filling up with oil and then being sucked through the engine then run a bigger catch can or put a sight level on it and empty it more often. Some race cars do run drain back due to excessive blowby under race conditions or inadequate drainage in the head causing low oil levels. There are much better (but not as cheap) options to overcome this.

Callum

[LeeRoy]

Callum, why would the oil from the rocker covers be dirtier than anywhere else? just assume you are working with a new motor here with little positive crankcase pressure - although then you wouldnt need a catch can would you.

- LeeRoy

[ed]

http://www.v-eight.com/tech_forum/viewtopic.php?t=38

[jonra23]

Catch cans are often run on turbo motors running reasonably high boost / high revs as rings can have trouble dealing with pressures etc, this volume of air going up to rocker cover area via oil return galleries will keep more oil in rocker cover area. With more oil in rocker cover and more air going out breather will get oil suspended as a mist whch is what catch can is trying to capture.
Agree with Leeroy that oil should be no dirtier.

[WDE_BDY]

Callum, why would the oil from the rocker covers be dirtier than anywhere else? just assume you are working with a new motor here with little positive crankcase pressure - although then you wouldnt need a catch can would you.

- LeeRoy

What collects in the catch can is all the impurities that have been burnt off from the engine oil. Mainly moisture that gets condensed as it cools in the catch can. Rememeber most of what is collected is fumes, you don't get big quantities of oil pumping straight into your catch can except under pretty harsh race conditions.

Callum

[Thomas]

There is no reason why you shouldn't return the excess back to the sump. That's how stock setups are configured. The dipstick tee is a good idea.

[WDE_BDY]

Stock setups don't usually run a catch can, they simly feed the fumes/blowby through the intake.

Callum