Catch Can

[SLAPS]

do u go into the exhaust side or the inlet side. from what you ^^^ have said it sounds like u done exhaust side

Either way it really doesn't matter.

[DCIEVE]

Something to consider is the oil from your catch can will foul up the oil in the sump. I'd only do it on the track and even then only if your pushing litres of oil into the can (enough to drop the level in the sump).

[SLAPS]

Why would it foul the oil in the sump??

The trickle if any oil returning to the sump from the catch can will be much cleaner than the turbo's frothy air rated oil.

Edited February 11, 2009 by TheRogue

[Bliksem]

The blow by will be partially burnt oil, another reason to fit a filter between the catch can drain and the sump.

[Snowman]

We run a Y piece off the dip-stick tube and feed back into that.

[Cjmartz2k]

Dude, blow by is anything that makes it past the rings i.e. oil, unburnt fuel, carbon, etc. That would be HORRIBLE for you oil. There is no reason what so ever to do this, other than hating your engine.

[shaund]

Dude, blow by is anything that makes it past the rings i.e. oil, unburnt fuel, carbon, etc. That would be HORRIBLE for you oil. There is no reason what so ever to do this, other than hating your engine.

Agreed... also, if you're getting that much blow by that a catch can gets full in more than a months worth of street driving or 3-4 track days, your engine is well and truly shagged and/or you're pushing it too hard (too much boost perhaps?)

[SLAPS]

Dude, blow by is anything that makes it past the rings i.e. oil, unburnt fuel, carbon, etc. That would be HORRIBLE for you oil. There is no reason what so ever to do this, other than hating your engine.

Vent the catch can.

The combustion gasses that push past the rings push up the oil return feeds while oil is attempting to run in the opposite direction and then out of your breathers.

Vent that sump and your problem is mostly solved.

Mine breathes zero; catch can is always clean. On the dyno the cans breather is clean running 1.6bar.

Setup the heads oil restriction correctly, vent the sump and you'll have no issues. providing the motor has been built well.

I've seen some 'well' built motors piss crap out of the cans breather.

Edited February 12, 2009 by TheRogue

[DCIEVE]

If your catch can runs dry there's no need for the return to the sump then is there?...

For a street car with 5k service intervals this is a bad idea - if your racing the car and doing regular changes (ie after every track day) then its not a problem.

I find my catch can runs bone dry when drag racing and cruising around on the street but as soon as a corner is thrown in the can fills up. Apparently the mines baffles will help but otherwise I'l have to run a drain for track days etc.

[SLAPS]

Your missing the point.

Its primary purpose is to VENT the sump not return oil. Vent the sump and you won't have to worry about the pressure from the sump picking up oil and blowing it in to your catch can.

If your can starts filling with track use mines baffles are a bandaid/waste of $$.

Fix the problem properly; restrict the oil flowing to the head 'slightly' and vent the sump. Problem solved, or at the very minimum vent the sump it will make a world of difference.

Have a good think 'WHY' your catch can is filling.....

Sump pressurises due to combustion gasses leaking past the rings at WOT

Where is that pressure going to vent?

Its going to push up the heads oil return galley in to the cam covers.

On its way it passes oil going in the opposite direction picking up a little, heating and slowing the oil return.

As it slows the oil return more oil stays in the head excasabating the problem of too much oil in the head.

Combine that with constant RPM and you have oil pooling in the top end; the pressure blows out your breathers and starts to fill the catch can.

As I said; vent the sump to the catch can; run a nice 3/4" hose and you won't have issues. Make sure the catch can has baffles/steel wool etc to prevent any oil vapor soiling the cans vent and possibly having scrutineers pull you up on it if its bad enough.

The sump return as you put it is not a oil return; think of it as a sump vent.

The cam cover breathers will then do very minimal work if any as all the pressure will be released from the sump and not from the cam covers.

Edited February 12, 2009 by TheRogue