Return Flow Catch Can Rb20

[s213b]

I know catch cans have been covered to death, and I have searched a few times and found some results, but not 100% what I'm looking for.

I've got an r32 rb20 with a eBay catch can. The can has two inlet/ outlets at the top, and A drain plug at the bottom.

My plan is to take the hose off the intake (just before afm) and plug it to the catch can, then take the other inlet/outlet and plug it back into the intake to relieve any pressure from crankcase etc (I noticed it makes a fair bit of vacuum)

Then to recirculate the can I'm going to weld on a piece of alloy pipe on the drain at the bottom of the can, and then clamp a hose from that to the port where my dipstick is.

Can anyone see a problem I'm missing? I know the can will catch f**k all, but I like the idea of having it 1) legal and 2) maintenance free. Thanks.

[s213b]

can anyone help me out? is bad to essentially have the dipstick venting to atmo?

surely the oil system couldnt be getting up to much pressure seeing as the dipstick just sits there?

[blind_elk]

In your search, you should have found a thread that had a photo of my setup. It's for a RB25 (in a R32), but the basic principle is the same for a RB20.

[s213b]

Was that the one that was returning to the turbo oil drain?

[bubba]

For a plumbed back setup put the catch can inline with the exh. cam cover and the intake.

i.e. the breathers go intake cover > exhaust cover > catch can > intake pipe (between afm and turbo)

If you want to have it *reasonably* maintenance free then you need to run a 2 stage system with a catch can and then an oil/separator which is then plumbed back to the intake pipe.

[s213b]

For a plumbed back setup put the catch can inline with the exh. cam cover and the intake.

i.e. the breathers go intake cover > exhaust cover > catch can > intake pipe (between afm and turbo)

If you want to have it *reasonably* maintenance free then you need to run a 2 stage system with a catch can and then an oil/separator which is then plumbed back to the intake pipe.

breathers - intake/exh valve covers - catch can - intake pipe. how is this return flow? I dont just want the can 'sealed' i want the oil in the catch can to be put back into the system.

oil seperator? if its plumbing into the intake pipe, thats all well and good, but where can i tap into to allow the oil from the can to drain back into the oil system of the car?

Surely someone out there must have this set up on an rb20... does anyone know if its ok for me to tap back into the sump/oil filler neck? this will effectivley relieve all pressure from the oil system as i have a hose going from the catch can to the intake pipe before turbo.

cheers

[RIPae86]

I was thinking about this too but was worried it may affect oil pressure. There are specific products that do what you want but they are not an empty can.

maybe you can adapt your ebay can.

http://www.cfpfilters.com/downloads/product_info/Mann/provent.pdf

http://www.nismo.co.jp/en/products/competition/engine/rb26dett.html

Some of the ones ive seen use the dipstick as the return to the sump.

[s213b]

I was thinking about this too but was worried it may affect oil pressure. There are specific products that do what you want but they are not an empty can.

maybe you can adapt your ebay can.

http://www.cfpfilter...ann/provent.pdf

http://www.nismo.co....e/rb26dett.html

Some of the ones ive seen use the dipstick as the return to the sump.

thankyou for your help!

yeh, ive heard that you can use your dipstick as a return, but i tried this and my problem was the catch can was under vaccuum, so when i connected it to the dip stick pipe the can had no where to breathe and made the engine give this horrible squeek (sounded bad so i disconnected it straight away)

so now im thinking make a drain at the bottom of the can go to dip stick pipe.

then have the hose taken off the rubber intake pipe and put onto the catch can.

then have another hose going from the other inlet/outlet to the intake pipe for breathing (vaccuum release)

but as you said, ill be essentially venting my oil system to atmosphere, so i dont know how that will go with oil pressure.....

im going to take my dip stick out and start the car and watch the pressure etc, if it sits on 0 theres obviously a problem. But after some research ( my skyline gauge usually reads 4kg cm2 which = 30-40psi or something similar, cant remember exactly) if the dipstick is pressurised to that amount why doesnt it pop off? its only sitting there!? all i can think of is theres some sort of one way valve that as soon as the oil system builds pressure, it blocks entry to the oil system via the dip stick....

this would be ok because it would mean as soon as you turn your car off the oil will drain back, and even in 6-7-8 hours of continous driving (eg long trips) id be confident in saying theres no way my car would fill the can (500ml) + the dip stick pipe.

hope im making sense.....? replies would be great! (maybe mods - mechanics out there?)

[bubba]

Are you venting to atmosphere?

I think you need to do a little more research.. there is many threads on here about this type of thing..

What I was trying to point out to you is that if you want a "maintenance free" system (meaning it automatically drains back to the sump) then you need to run a two stage system if NOT venting to atmo. The first stage is a "catch can" which vents into an "oil/air separator" and then plumbs the vent back into the intake.

The "catch can" can have a drain back to the sump (or via dipstick) but I would be more inclined to put a T and a ball valve in the dipstick line, run one hose to the top of the catch can as a vent and have the valve opening this way normally. Then have a drain from the bottom of the catch can to the ball valve so that when you want to empty the catch can back into the sump you open the valve.

Personally, my setup is atmo with each cam breather and dipstick going to the catch can and I don't drain it back to the sump.

[s213b]

Are you venting to atmosphere?

I think you need to do a little more research.. there is many threads on here about this type of thing..

What I was trying to point out to you is that if you want a "maintenance free" system (meaning it automatically drains back to the sump) then you need to run a two stage system if NOT venting to atmo. The first stage is a "catch can" which vents into an "oil/air separator" and then plumbs the vent back into the intake.

The "catch can" can have a drain back to the sump (or via dipstick) but I would be more inclined to put a T and a ball valve in the dipstick line, run one hose to the top of the catch can as a vent and have the valve opening this way normally. Then have a drain from the bottom of the catch can to the ball valve so that when you want to empty the catch can back into the sump you open the valve.

Personally, my setup is atmo with each cam breather and dipstick going to the catch can and I don't drain it back to the sump.

as written above, one hose going from valve covers, to catch can, the other hose going from catch can to intake pipe.

I can weld on a fitting at the bottom of the catch can to allow for the return, but i have no idea where to get the dip stick return things.....

any problems with oil pressure?