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Want to make a homemade catch can. The a/c system is removed and I got a stainless steel water bottle that will fit perfectly where the a/c drier goes. My only concerns is the water bottle has a thick hard plastic screw on cap. I'm gonna replace the o-ring with one that's capable of handle some heat.
My question is, how hot will this catch can get? I can't see it getting too hot, I'm just concerned that I'll have issue with the cap. Anybody have any input?

Under hood temps could reach 200 deg F. It may not be like that all the time. Also, the turbo is in the vicinity so it will put out some radient heat.

Honestly, you're likely to have issues with the o-ring not being able to deal with the oil vapors and it could swell or degrade. The plastic cap should be ok for a while, but may also get brittle due to the heat and oil vapors.

And there are 1000's of them on Ebay for $45 or so.

But I am one that will not use a catch can. Condensation causes milky smudge. I have always made a oil/air separator. There are some on Ebay too.

Dave_J wrote:But I am one that will not use a catch can. Condensation causes milky smudge. I have always made a oil/air separator. There are some on Ebay too.

Do you have one that you can recommend?

On my Mustang Turbo build I used a Porsche 944 unit. The oil mixed air would come from two PVC ports and enter the top and swirl around and the oil would drip down and the mostly oil free air got sucked back under the carb in the turbo manifold intake. This was a draw threw "Wet" turbo system without intercooling.

That type should still work.

I am going to try using a GrimmSpeed oil/air seperator.

Assuming that the catch can is simply emptied and not recycled back into the oil supply, what's the harm in it forming a sludge?

James614 wrote:Assuming that the catch can is simply emptied and not recycled back into the oil supply, what's the harm in it forming a sludge?

I guess remembering to simply empty it. Its old school that still works but what a mess to deal with.

Almost got this thing in use. Read up a bunch on it. I took the stock o ring off the water bottle and put a bead of the pink subaru silicone sealant instead. Figure that should seal and hold up longer than the plastic cap. I also read up about people running into issues with freezing. I figure this will be an issue for me (northern canada!?!) so by keeping it mounted in the a/c drier location I'm thinking the radiant heat from the turbo should help as well. I also used very large hose that I pruchased at a hydraulic supplier store so it'll withstand the oil residue. By using the larger hose (5/8, 3/4) if there is any freezing I doubt it'll block the whole line. Mounted the brass outlets on the stainless steel bottle with jb weld and silicone, also gonna stuff a steel dish cleaning pad in there to help soak up the junk. This get up doesn't exactly look the hottest but I figure it should work. Gonna check the set up after a week and see how it's doing.
And ya Dave I seen those ones on ebay and such but the shipping is like $75 to get it up here. Just a little steep for a bottle with some fittings on it. Like I said I'm gonna monitor this and if it's not panning out I'll probably take the hit and order something online.

You will still probably see freezing in the bottle, not necessarily the lines, even with it being in that location. But give it a shot and see how it works. You may be able to insulate it to help the condensation/freezing issue.

Ya I figured some freezing would happen in the bottle so I mounted the hose flanges half way up and the vacuum on top of that.
I'm still waiting for the silicone to fully cure and I was staring at the engine bay and some spare parts and came up with another idea to ponder. There's another post iirc Davej made about high performance engines apply vacuum to the crank case to help remove restrictions. I don't think my application would have huge power benefits but I really like the idea of using a vacuum source other than the intake port apres maf and pre turbo. Just want to avoid getting the gunk in the intake as much as possible. I was thinking about taking a look at some fishing bait aerators and a buddy had an extra fish tank air pumps to possible wire up. But when I was looking at the random parts I ripped out I took a good look at the cruise control air pump and wondered how it would hold up to being in use constant. I think there might be some issues with oil residue but the residue might actually aid lubing the pump. I guess it would freeze as well but I think my main concern is could it stay running for up to 8 hours without burning out. I gotta commute the beast to races a few times a year so it would get worked pretty hard.

I'm not sure the cruise pump would give you the volume of flow that you need to pull a vacuum on the crankcase. It's meant for much smaller volumes.

I have a buddy that has a old chevy nova with a built 350 in it who took the factory smog pump and applied vacuum to his crank case. Dyno proven to gain 7 hp. But that is with more cylinders and surface area to act on. The gains versus time and money i think would be negligable for our smaller aplications. But it does work.

To pull a vacuum it has to overcome the blow-by. On a race car you will spend over $250 for a set of piston rings, another $80 per cylinder to super fine hone them with a torque plate. All to limit the blow-by. A multy stage Dry sump/Vacuum pump will set you back another $2000-$5000. This is not a street feasible idea. On a 1500 HP small block, HELL YEAH.

For our Suby's a simple blow-by catch can is a cheap way to remove oil from the intake tract but becomes another maintenance item that must be emptyed and cleaned.

A oil/air separator works better and never needs emptying but new ones start at $200 up, Used are around $35. The GrimmSpeed unit is almost $300. I think I spent $125 back years ago for the used Porsche 944 unit.

So its decided that a oil/air seperator is the ideal application for our subies. Not a catch can..

Dillon it depends on your situation.. if u got the dough go with an aos! i don't have that much to spend on it so I got this for 17$ shipped and will just empty it when it fills up

I didnt read all of this, but in regards to the oil seperater. I have heard of people not having pleasing results with Grimmspeeds AOS.

So far the only positive AOS i have heard is the Crawford. I have a co-worker (and long time friend) who just got done doing a full build on his STi. He almost bought the Grimmspeed unit, but heard it doesnt work the best. and i think the crawford is not too much more in price.

I ran a catch can on my old swapped RS.. i ran it for about 15k miles and didnt notice the yellow "vaseline" type sludge. BUT my 04 STi had no catch can or AOS and it had the yellow sludge.

Thats my 2 cents.. i hope i have helped..