Oil Catch Can return to sump: below or above oil level?

[~SlideWays~]

I've had problems with my 4age smallport turbo, on the race track it fills up the catch can pretty quickly.

I've searched a bit online and according to a few sites, the smallports still suffer form this issue even when left NA. (even though it has the external drain from the head)

What I plan to do is have the oil draining from the Catch Can to the sump, I do change the oil very regularly so I don't see contamination becoming a problem.

What I'm not sure about is whether the drain should be plumbed into the sump above or below the oil level?

The turbo drain is above, but according to a site I've seen it says that the catch can one should drain back below the oil level. I assume this is because it could be forced back by crank case pressure? Would this not be the same with the turbo one then?



Cheers.

[bluemaumau]

if this is a good idea, how about just blocking the return on the block and running it from the factory head return to the sump.

thats what im doing (smallport head, silvertop block)

but i was thinking of running a catch can setup aswell

[ChaosAD]

same level as factory external oil return I would have thought

[sxymr2]

i would say above the sump as it is in turbo cars

[matt dunn]

i would say above the sump as it is in turbo cars

A guy down here with an E3 race car had a problem with the ctach can that came back in above th oil level,

The pressure in the sump can blow the oil vapour up and out the catch can vent and it was leaving an oil trail up the screen,

I think they put a one way valve in it to fix it.
Not all cars have that problem though.

We used to run drain back sysytem in our old celica and I think it's in the focus too, but not too sure where they plumb in.

[~SlideWays~]

Well I think I'll try it with the can draining to below the sump oil level, that way there is no crank case pressure pushing oil back up the drain line, much like what matt described.

This is probably the main reason for oil not draining back from the head fast enough in 16v 4ages anyway.

If it doesn't work I'll just try it the other way around with another sump

[barryogen]

Well I think I'll try it with the can draining to below the sump oil level, that way there is no crank case pressure pushing oil back up the drain line, much like what matt described.

Correct me if I'm wrong, but if the crank case is under pressure, the oil thats in it will be too.

So putting the drain below the oil line will mean that rather than vapor being pushed up the return line, you will have oil pushed up there instead.

right?

[Crucible]

Well I think I'll try it with the can draining to below the sump oil level, that way there is no crank case pressure pushing oil back up the drain line, much like what matt described.

Correct me if I'm wrong, but if the crank case is under pressure, the oil thats in it will be too.

So putting the drain below the oil line will mean that rather than vapor being pushed up the return line, you will have oil pushed up there instead.

right?

Ive been thinking about how Im going to do mine also as I have the same problem as Slideways.

how about just using a ball valve on the drain back from the can?, then it wont matter if its above or below the oil line in the sump.

then when your in the pits and the engine isnt running, all youll have to do is open the valve, no pressure, no blowback.

close the valve again, sump is isolated from the can, and away you go. You could even weld a bleed valve to the top of the can to allow the can to drain faster when the ball valve is open, a bit like taking off the fuel cap when draining a fuel tank I suppose.

thats what I had in mind anyway...

[barryogen]

how about just using a ball valve on the drain back from the can?, then it wont matter if its above or below the oil line in the sump.

hmm, if you had a light enough ball in the ball valve you could have it mounted upside down so that if there was pressure from below(ie:the sump), the valve would be closed, and when no pressure, it would open. :)

[Crucible]

how about just using a ball valve on the drain back from the can?, then it wont matter if its above or below the oil line in the sump.

hmm, if you had a light enough ball in the ball valve you could have it mounted upside down so that if there was pressure from below(ie:the sump), the valve would be closed, and when no pressure, it would open.

yeah thats a good idea!

The one I was referring to was like a LPG type ball valve with a handle ontop to open and close.

http://www.northernbrewer.com/pics/full ... lve-ss.jpg

They have a ball with a hollow slot that twists inside the housing, used on lpg gas lines etc. Some guys use them for linelockers too.

[matt dunn]

Well I think I'll try it with the can draining to below the sump oil level, that way there is no crank case pressure pushing oil back up the drain line, much like what matt described.

Correct me if I'm wrong, but if the crank case is under pressure, the oil thats in it will be too.

So putting the drain below the oil line will mean that rather than vapor being pushed up the return line, you will have oil pushed up there instead.

right?

Could be right.

Another high spec race car i looked at today was definatly in above the oil level, the same return as the turbo feed.

[jondee86]

If the drain is above the oil level in the sump, crankcase pressure will
vent out the drain tube. If the drain is below the oil level, the oil will seal
the end of the tube, and prevent the tube acting as a vent. Oil from the
catch can will then drain normally.

Cheers... jondee86

[~SlideWays~]

If the drain is above the oil level in the sump, crankcase pressure will
vent out the drain tube. If the drain is below the oil level, the oil will seal
the end of the tube, and prevent the tube acting as a vent. Oil from the
catch can will then drain normally.

Cheers... jondee86

Thanks for the info jondee86. Thats basically what I was needing confirmation of.

Here is a site which has some info:
http://www.fusionfabrication.fsnet.co.u ... design.htm

[Crucible]

good thread and some good info.

the theory makes sense, I thought about where I would need to run the return, I just thought there may of been a chance oil will travel up the return as suggested above, thats how we used to transfer oil between drums at work, pressure ontop to force it out a submerged hose into another drum.

I think I too will run it below the oil level as it makes more sense than above, but may use a ballvalve aswell just to be certain.

Hey Slideways, you said your can was filling up about a litre, was that after a whole days racing or just after a few laps???

[~SlideWays~]

Hey Slideways, you said your can was filling up about a litre, was that after a whole days racing or just after a few laps???

Tank is 800ml and that was over flowing after less than 10minutes on the track eh, I thought I'd blown something! That was when running 17psi and lots of revs all the time.

What about yours? Was it more or less, interested to see if your breathers have much effect (with the baffling you said it still needed).

My sump is getting welded as we speak, cross fingers it works. Im just going to run a pipe straight from the drain hole in the catch can (have a threaded fitting for it now) and see how well it works. If it works well I'll get another catch can made up to suit (bigger too).

[bluemaumau]

so . . . is this what everyones thinking?

turbo returns = above oil level
head/catchcan returns = below oil return (with ball valve?)

[flygt4]

Hey Slideways, you said your can was filling up about a litre, was that after a whole days racing or just after a few laps???

Tank is 800ml and that was over flowing after less than 10minutes on the track eh, I thought I'd blown something! That was when running 17psi and lots of revs all the time.

What about yours? Was it more or less, interested to see if your breathers have much effect (with the baffling you said it still needed).

My sump is getting welded as we speak, cross fingers it works. Im just going to run a pipe straight from the drain hole in the catch can (have a threaded fitting for it now) and see how well it works. If it works well I'll get another catch can made up to suit (bigger too).

i was barely able to get enough oil in the can to be measured with a dipstick that was ~8laps at a time and working the engine petty hard. i even checked the oil level to make sure there was some in there

[gepsk8]

yea, its the 16valve oil drains aren't as 20valves

[~SlideWays~]

i was barely able to get enough oil in the can to be measured with a dipstick that was ~8laps at a time and working the engine petty hard. i even checked the oil level to make sure there was some in there

Yeah, the 20v heads have never had a problem with filling with oil though eh, was mainly with bigport 16v's then toyota added the external oil drain in smallports to try fix it. But once the 20v head was release there was no need for the external drain anymore.

Its really common in 16v's. Bout the only reason you'd want to go for a 20v actually! Lol

[Crucible]

Hey Slideways, you said your can was filling up about a litre, was that after a whole days racing or just after a few laps???

Tank is 800ml and that was over flowing after less than 10minutes on the track eh, I thought I'd blown something! That was when running 17psi and lots of revs all the time.

What about yours? Was it more or less, interested to see if your breathers have much effect (with the baffling you said it still needed).

My sump is getting welded as we speak, cross fingers it works. Im just going to run a pipe straight from the drain hole in the catch can (have a threaded fitting for it now) and see how well it works. If it works well I'll get another catch can made up to suit (bigger too).

10 mins...ferk!!!

Didnt really load the car up too much on the weekend as was more driver training so oil consumption into the CCan was low apart from my smoky turbo

Will take note and see how much goes into the can though at Megameet so will let you know. I havnt done anything to the breathers since, but will no doubt pack the R/Covers with steelwool aswell sometime.

will be keen to see how your new drain setup goes aswell, im pretty busy at the mo so mine prob wont be done before then.