Oil catch can/ Breather

[Talasas]

That is the point I was trying to make above. Re-routing somewhat oil saturated air into the intake plenum still has similar effect than if you have no catch can at all. I would design a catch can to have hoses on EITHER side seperated by some sort of baffle inside to force the air to flow downwards ramming the oil/gas into already settled oil mixture. This would in turn seperate out the oil vapour leaving cleaner air back into the plenum.

http://www.turbophile.com/technical/diy_catch_can.html

Similar to this design but I would have the outlet hose on the other side of the baffle. Having the breather with filter being optional there.

[petespipes]

Oil is heavier than air,we can all agree.So,to allow the oil being carried by air [in suspension] to seperate,we need to slow the air.once the air loses speed [velocity] the oil or water or any liquid in suspension will fall due to gravitational forces being stronger than the high speed air flow in a small diamater pipe.
This is why the catch can needs SIZE.the air cant slow down in a small catch can.Small cans are BULLSHIT.Any can that does not need emptying regularly is also BS.Just because you can buy it and its called a catch can doesnt mean Anything,its required to understand how things work before parting with your hard earned.
Bling is not worth 2 cents here either.It may as well be a 3 litre plastic bottle,provided the fast moving oil laden hot air from your pressurised crank is allowed a place to cool and slow down it will drop its oil content as previously mentioned.

Another factor is the octane level reducing properties of oil mist.

If you consider for a minute the amount of "blow by" that occurs by super hot exhaust gasses escaping past your piston rings thus pressurising the crank.In many older engines you may have noticed the vacuum hoses meant to remove these gasses via vacuum into the inlet become hard and blocked up over time.
This factor then becomes responsible for oil leaks etc as the pressurised gasses will then push past oil seals etc creating all sorts of problems.
The ideal solution is a large catch can hidden inside your gaurd with a one way valve allowing oil collected to find its own way back to the sump via a hose.Definitely much better to have it vacuum assisted.There is nothing clever about polluting and nothing wimpy about doing things properly.Those who disagree should go and have a lovely oil saturated winnie red lol.

[feral4mr2]

Yes you could.
The positive pressure wouldnt go back into the crankcase due to the PCV valve.

4age's and 4agze (and various other engines) dont have a pcv valve.
on a boosted application if you wanted to route the catch can back to a vacum, plumb it before the turbo. i have both my cam covers vented to my catch can, but it's then vented to the atmoshpere (ooohh, naughty me) instead of back before the turbo like it should be by law.....

If you just suck air from the crank case, itll create a vaccum... but the bad gasses will still be in there.
By having a small breather pipe from before the TB to the crankcase, clean air can get in so the dirty air can all be sucked out.

Nearly every factory engine is setup this way.

never seen/or heard of it before in my life. where is this pipe on either of the 4age variants?

[mic*]

HOORAY FOR PETE...

Listen to the man!!!

The reason CAMS reccommends a size based on displacement is coz thats what will determine blowby volume.

Essentially the larger the better coz the gas velocity will slow more and more oil will condense.

I thought that statement would have been comprehensible enough.

[monkeymajik]

4age's and 4agze (and various other engines) dont have a pcv valve.
on a boosted application if you wanted to route the catch can back to a vacum, plumb it before the turbo. i have both my cam covers vented to my catch can, but it's then vented to the atmoshpere (ooohh, naughty me) instead of back before the turbo like it should be by law.....


never seen/or heard of it before in my life. where is this pipe on either of the 4age variants?

Are you running two venting cam covers? Or is there some secret vent I'm unaware of?

I only know of one vent on the 4ag(z)e, on the intake side camcover.

[4agte]

having seen ferals setup before he has a n/a and s/c cam cover fitted so not only does he have 2 breather holes he can fill the oil from 2 place

[feral4mr2]

[Ta2272]

ok here is another question which is relevant to my orignial question,

The Car is a datsun 1600, with an l18 oldshool motor, i have been told most newer motors shoudl have postitive crank case ventilation and therefore you will need a catch can which holds some pressure.

Thought my li8 motor shouldnt have positive crank case ventilation, does this mean i need a breather or will i get away without one.

thanks alot guys

Jason

[Cruiser97_80]

You have to let it breath .... If you don't it will presurize and will find it's own way out i.e. through seals etc. Causing oil leaks.

[roadsailing]

I skipped a bit of that last page, but here are some of my own experiences.

I used to have a breather consisitng of a short length of hose that went from my inlet cam cover to jammed in between two inlet runners.

To fix this i ran a hose from the cam cover breather to a fitting into the inlet manifold (post TB so in the "vacuum bit")

this made my idle jump up by about 500-1000RPM and made the car really annoying to drive.

As far as i can remember, the standard setup has a hose fitting that looks like it goes into the post TB inlet manifold, but it is actually routed to go in front ot the throttle body.

in my opinion, this is a good thing, as that oily mist will lubricate your throttle (mine stcks at the moment)

my current setup is a coke bottle at the end of a length of hose, that grew a crack in the bottom so i dont get worried about excessive blowby.

that probably didn;t help much, so i think i should go sleep.

[Ta2272]

hey, di dyou read what i said about positive crank case ventilation and cars without this.

Jason

[mic*]

Maybe im wrong but every engine must vent blowby or ironically it will eventually blowby the other way and stuff seals.

Back in the day authorities didn give a hoot about a bit of oily air goin to atmo... These days they will pull you over if you've eaten too much maca's and you fart out the window.

Legislation is very difficult to make retrospective thus anything built before the rules changed can still go round blowing as much oil into the air as they like.

Personally id just be a good little greenie and plumb it back anyway, ultimately you get a less greasy engine bay.

[Ta2272]

i think is it is a race car and there really isnt anywere to plumb it back

another question i have asked does anone know why newer cars are positive crank case ventilation (ie u pull the oil filler plug off while running and it will affect the revs)


Thanks

Jason

[mic*]

i think is it is a race car and there really isnt anywere to plumb it back

another question i have asked does anone know why newer cars are positive crank case ventilation (ie u pull the oil filler plug off while running and it will affect the revs)


Thanks

Jason

It because you are creating a vacuum leak on an EFI car. If air is being drawn into the intake after the AFM in/near the air box (typical factory setup) the ECU is metering a different volume to actual volume hence idle probs etc.

If you vent to air & you block the hole/s in your intake you should have no probs except if you get pulled over by the boys in purple or blue.

[Toycrash]

This is why i dont neverever route crank case ventilation to intake..




It should look something like this tho...



Think about it when you route your vent tubes...