Crankcase Vents - Catch Cans

[NY98M3]

What are you guys using for crankcase vents? Are you dumping to atmosphere? Using a catch can? Im dumping to atmosphere under the car though the stock vent on the OBDII cover. Im finding I need to use a catch can but not too crazy about it. Choosing the right can in key.

Up for suggestions!

[NOTORIOUS VR]

I want to build something eventually as well.. Currently it's just open off the VC in my car... No oil comes out at all, just vapor so once in a while it's a little stinky. I'm probably going to mod the stock outlet to be larger like Chiknhead did in his thread and then go to a catch can and vent to atmosphere somewhere outside of the engine bay. Or maybe route it into the exhaust using the PCV kit from Vibrant.

[someguy2800]

I just have a hose going from the stock obd1 valve cover to a 2 inch round breather filter. I never get any oil in mine.

[NY98M3]

Or maybe route it into the exhaust using the PCV kit from Vibrant.

I have this capped right now on the exhaust...Im concerned about the exhaust going into the crankcase, there is a Moroso check valve but at low pressure (blowing though) I can get air past it....

Never had any blow by til this weekend where I turned up the wick to 31 psi. Low boost (25psi) there is barely any...

[Butters Stoch]

I have this capped right now on the exhaust...Im concerned about the exhaust going into the crankcase, there is a Moroso check valve but at low pressure (blowing though) I can get air past it....

Never had any blow by til this weekend where I turned up the wick to 31 psi. Low boost (25psi) there is barely any...

I get a little bit. I was messing around with different combinations of cheap ways and found my best solution. A walk through the "performance" section of a local pep boys gave me the idea. I found the longer the lines or hose I used, the more I would throw up at 20+#'s. Under 20#'s I'd have nothing. Here is my simple solution to keep it clean.

[pbonsalb]

The single stock valve cover vent is probably inadequate for 4 times factory power. Add a second vent on the valve cover. Maybe a third on the oil pan near the dipstick tube (or use the side stem on an OBD2 tube as a vent). Where they go to is another matter. I have done the open vent, but eventually the discharge area gets oily. Maybe not if you drive 200 miles per year, but certainly if you drive 8000 miles per year. Open vent will also occasionally lead to oil smell inside of car. I also tried a valve cover vent directly to a filter, but the filter clogged up and got oil soaked eventually.

I am now venting to a Burger catch can with internal baffle but instead of returning it to the intake, I have a filter on the outlet side. Ideally, I'd use a can with as many inlets as you have crankcase vents and with internal baffles and with either a filter or a vacuum pull to a filter. I ran the Vibrant exhaust scavenge for several years at the 550 rwhp level and it worked fine, but it did not seem to cope as well beyond that and I am not using it currently. With that, there can obviously be no breather so you are relying entirely on one long hose and a small amount of occasional vacuum.

I'd like to look more into the electric vacuum using the BMW SAP. Some say they work OK and some say they don't. There are also a variety of schemes to plumb them.

[someguy2800]

I use the same kind of filter as butters picture above except I have mine attached with a 3/8 hose and have it mounted vertically near the dipstick. Anyway that's not helpful since you already said its not adequate for you.

I would just get something like this and find a place to put it.

http://www.jegs.com/i/Moroso/710/854...LARRoCnJnw_wcB

[Jaze]

I am tapping the VC for 2 big AN lines, maybe -12 to a filtered catch can that will drain back in to the obd2 dipstick. Seems like the best option, without too much hassle.

[rajicase]

Jaze,
OBD1 or 2 VC? Where you plan to tap?

[Jaze]

OBD2, but OBD1 is the same just have to drill through magnesium. I haven't ironed out exactly where, but I have seen it done a lot in Europe with turbo M5x.

The sandwich style fittings i'd use have just a 10-12mm lip on the back/inside part of the VC, there should be tons of room. The only certain thing is one fitting for each cam/bank of the valve cover.

[jszy25]

I would just get something like this and find a place to put it.

http://www.jegs.com/i/Moroso/710/854...LARRoCnJnw_wcB

I use a black plastic version of this catch can. I run a -10 bulkhead fitting off the obdii valve cover port to pushlok rubber hose to the can. Catch can just has a filter on the top and I do not return it to the dip stick return. I'll just drain it when the time comes.

Finding a good vertical location to mount the can be challenging while trying to keep it clean looking. Mine is behind the driver's headlight and the filter is slightly compressed down (i.e. slightly crushed).

I used to just run the hose to atmosphere below the car but the vapor does eventually form into a drip which is annoying.

[pbonsalb]

The horizontal filter will get oil soaked and drip eventually, especially if on the downhill end of a hose. Vertical is better.

[NY98M3]

Wouldn't it be advisable if you could go with the largest Inlet/outlet for these? Seems the easier it can travel (larger opening), the less likely it is to pressurize other parts of the crankcase.

[chikinhed]

I had fabricated an air/oil separator type catch can for my car a few years back. Most of what ends up in the catch cans is water vapour which condenses in the catch can. Routing the liquid that is in the catch can back to the oil pan is not a good idea as it is highly acidic. I had a drain on the bottom of my catch can that I ended up having to drain on a regular basis. I eventually said screw it and pulled the catch can out and now I just run a 1" ID hose from the modified OBD2 valve cover down to the stock fuel filter location under the car. I park in the same spot everyday and have never had oil drip onto the floor from the hose. I do smell the blow by smell occasionally when stopped at a light and the wind catches it. That's my only complaint really.

Sent from my GTX3582R

[jakermac]

I know you guys can't do this, but maybe a revision of it. I have 2 -8 lines coming off the top of the VC. The OEM port is plugged. The can is home made with the VC going into the sides of the can at the top, then down through 5-6 layers of aluminum window screen, and back up the inside of a 3/4" aluminum tube out the top of the can. There is a drain on the bottom of the can that goes to a 20oz plastic bottle down in the bumper. It collects a lot of water (12-15ozs every couple weeks in the winter time, PNW and all, a lot less in the summer). I originally ran the top of the can with the breather (like photos) but got tired of the oil vapor smell. I then ran a -12 line back to the breather inlet on the bottom of the TB boot (this is the part I know you guys can't do with FI). I have checked that tube at the TB boot many many times now and it is bone dry, not a speck of oil.

[busterhax]

I run mine though a cheap unbaffled ebay catch can then straight to the exhaust (JEGS crankcase evacuation kit). Catch can definitely fills up and no smoking from the exhaust.
Be sure to weld the bung in properly. No instructions are included and I believe 100% of the people who say this method doesn't work just welded the bung in incorrectly.

Up above 1.5k RPM, the exhaust evac sucks hard. I wouldn't run my ccv any other way.

[Jaze]

I know you guys can't do this, but maybe a revision of it. I have 2 -8 lines coming off the top of the VC. The OEM port is plugged. The can is home made with the VC going into the sides of the can at the top, then down through 5-6 layers of aluminum window screen, and back up the inside of a 3/4" aluminum tube out the top of the can. There is a drain on the bottom of the can that goes to a 20oz plastic bottle down in the bumper. It collects a lot of water (12-15ozs every couple weeks in the winter time, PNW and all, a lot less in the summer). I originally ran the top of the can with the breather (like photos) but got tired of the oil vapor smell. I then ran a -12 line back to the breather inlet on the bottom of the TB boot (this is the part I know you guys can't do with FI). I have checked that tube at the TB boot many many times now and it is bone dry, not a speck of oil.

That's exactly what I was planning except now I won't route back to the oil pan, I will just have a relief valve or something similar on the bottom to let the gunk out. Thanks for the tip Chknhed

[bmw328m52]

I know you guys can't do this, but maybe a revision of it. I have 2 -8 lines coming off the top of the VC. The OEM port is plugged. The can is home made with the VC going into the sides of the can at the top, then down through 5-6 layers of aluminum window screen, and back up the inside of a 3/4" aluminum tube out the top of the can. There is a drain on the bottom of the can that goes to a 20oz plastic bottle down in the bumper. It collects a lot of water (12-15ozs every couple weeks in the winter time, PNW and all, a lot less in the summer). I originally ran the top of the can with the breather (like photos) but got tired of the oil vapor smell. I then ran a -12 line back to the breather inlet on the bottom of the TB boot (this is the part I know you guys can't do with FI). I have checked that tube at the TB boot many many times now and it is bone dry, not a speck of oil.

Love this setup.

[jakermac]

Love this setup.

Thanks. This is what it looks like now. I should have use a blue/red AN 90, but it wasn't available from the cheap source I bought the stuff from. Oh well, save a bunch of cash and have a black fitting!! Oh and chikinhed is responsible for the good looking welding on the can!!!

[chikinhed]

I think the requirements for the CC breather change with the higher cylinder pressures of FI running high boosts. Also, AN lines have relatively small ID's. Multiple AN lines help but the total cross sectional area is not that big. A couple of -12's would probably do it. The hose I'm using would probably be the equivalent of an AN-20 hose but I was only able to open up the bottle neck in the VC to about 0.86".

AN-6 = 0.34" hose ID
AN-8 = 0.44" hose ID
AN-10 = 0.56" hose ID
AN-12 = 0.69" hose ID
AN-16 = 0.88" hose ID

Another thing that you will find is that the fitting ID's are even smaller than the hoses so you really get ripped off as far as flow potential.

Sent from my GTX3582R

[dburt86]

I run mine though a cheap unbaffled ebay catch can then straight to the exhaust (JEGS crankcase evacuation kit). Catch can definitely fills up and no smoking from the exhaust.
Be sure to weld the bung in properly. No instructions are included and I believe 100% of the people who say this method doesn't work just welded the bung in incorrectly.

Up above 1.5k RPM, the exhaust evac sucks hard. I wouldn't run my ccv any other way.

Thats good to hear. I've been thinking about doing a setup like that for a while.

if you guys think your cars smell, take a ride in a junk yard turbo LS with .030 ring gaps. Walk into work like you just showered in oil.

[bry195]

SAP to OEM vent. Hobbs switch for 3 psi. Zero problems with venting. If I turn it off my previous journal bearing turbo leaked bad. AS soon as I kick it on no more problems.

Funny thing is its audible at idle if I manually kick it on. You cant hear it when its in auto but some dudes have heard it and I tell them I have a one of those ebay electric turbos that you put put in the intake. Yea, you need to intercool it.

[jszy25]

Looks great man. Is your intake right off the turbo, down low?

[doktor b]

Looks great man. Is your intake right off the turbo, down low?

jakermac has no turbo.

[busterhax]

Looks great man. Is your intake right off the turbo, down low?

Mine is. Sits in front of the passenger fender liner.