I know video is a few months old.... but, if this is a dedicated track car, venting to atmosphere may be your answer. Your engine bay will be coated with oil despite the filter. If this is a street car, a catch can is your answer. A larger catch can is what you're going to need based on your consumption. It is normal to use that amount of oil on the track. You may want a heavier weight oil for the use on track and changing it when going back to the street. Also, you're seeing water mixed with your oil, the catch can is doing its job. As the oil heats up it is boiling off moisture and going to the can and back to water. At the same time oil mist is carried out of the crank case(with other vapors) to the can which mixes with the water. BTW, nice job detailing your experience on and off track.
Nibiru3064 remove the PCV check and on boost you will pressure the Crank case / sump and blow all the engine seals, and that’s if the motor don’t pop first.
Interesting about how the PCV works for a WRX to a dual can setup for a 2.5 STi Motor . You may be able to use two cans on a WRX by splicing the PCV connection hose from the tree to the manifold and placing the can between the tree and valve. PCV valve to can / to tree then take the crankcase hose from the turbo inlet and unhook the tree to turbo inlet and tee it with the crankcase hose that runs off the intercooler into a can . Then the can to the turbo inlet for fresh air back into the turbo. Just don’t forget to plug the hole left in the turbo inlet from the tree. Let me know if that sounds correct.
The tube that puts the oil in the bottom of the can that they added in video is ridiculous. Why would that tube need to be added to get the oil to the bottom? Does gravity fail to apply inside the catch can? If you are concerned about gaseous oil being sucked straight through, you would need a baffle plate. So you had a good idea to put steel wool in but the tube is moronic. In essence what that tube does is create a siphon as soon as enough oil fills the can to cover the end. The small holes to vent are limited in velocity because they are too small and do nothing to prevent the tube from filling up. Once the tube is full of oil, the oil is sucked out of the crankcase instead of blown out and every turn that puts oil in the valve cover is now being sucked out. Did any CFD get done to prove the vent holes in that tube would actually prevent the scenario I just described? What about a fluid dynamic free body diagram? How long were you on the track? 10 - 15 minutes? That means you would be burning oil at a rate of 2 quarts/hr. You'd be empty in 2 hours. If that were the normal mode of operation, without a catch can, there would be so much particulate and hydrocarbon exhaust that the car would never pass emissions even at a spirited non-track type pace. Common sense guys. Turbo cars run 8, 12, 24 hour races. They aren't all dry sump so how are they keeping oil in their engines? Easy, they aren't siphoning it out with some idiotically modified catch can. Surely, this can't be the basis of your logic.
Thanks for your question. The purpose of this catch can was to simply see how much blow-by was moving out of the PCV. The initial assumption was that the basic catch can which had no filter media at all would not capture much of what oil vapor might make its way through the PCV. Since the overall goal was to see how much fluid was moving through the PCV, I decided to put in the steel wool, and the tube to force the vapor to the bottom of the can. As you say, this is not ideal for sure (though there are some commercially available cans that use something similar), and that is what came out when on the track. But before that, there was basically no oil collected in the can through hundreds of street miles. There is another issue with this catch can which is the plumbing to and from the can. That is at least as problematic, if not worse than the baffling going on in the catch can itself. In short, now knowing what we know, this demonstrates a worst practice for a catch can design, and also a worst case for plumbing a catch can. If you watch any of the other videos, we have learned more from installing an AOS, and I am working on a video to go into detail about all that we learned from the mistakes that were made in this process. Thanks for watching, and Stay Tuned for all the details!
Thanks for the comment! Changes have been happening, and more are on the way. But. The plan is to pick back up on all of the details on that build. Hopefully in the next couple of weeks. Stay Tuned!
I'm wondering what I can do to eliminate oil and other contaminants from going into my intake and building upon the back of my intake valves and turbo blades and I'm sure cylinder portion heads rings and I'm sure the exhaust side as well. Oil separator or catch can. What one would work better in my DGI engine? DGI is a problem for carbon build-up and performance.on a DGI engine.
Thanks for your question. If you aren't using much oil, then definitely start with a catch can. Once you have that in place, see what results you get and go from there. Thanks for watching and Stay Tuned!
always AOS for turbo cars. If you boost a ton you will constantly fill the can and will be too much hassle to maintain. Also if you run E85 some AOS are designed to evaporate the moisture off the oil due to E85 water content.
Doesnt matter if you're running e85 or pump gas theres still water in gas, I run a catch can vented to atmosphere on e85 never had a problem and never will. The heat that the motor generate is enough to evaporate the water from your oil, a AOS is a catch can with a coolant hose. if you haven't checked the lines running to your AOS in a while I bet that coolant line has a a minor leak or will be leaking in the near future.
I recently let my catch can overflow not due to laziness but due to the musturding of the water and oil combination in the catch can. I was emptying my catch can on a very regular basis but didn't realise that every time I emptied it, it was leaving behind a thick substance in the can that I couldn't see in the can that was taking up valuable space. I was simply pouring out the liquid and reinstalling the can. Anyway, it overfilled recently and I also got a ton of smoke suddenly from the tailpipe. Now my car is backing off timing by 9.5 degrees under boost. I've cleaned the intercooler, turbo, intake and throttle body and next is to replace the plugs because they have to be shot! My question to you is, what else do I need to do to get everything back to normal and safe to run? Any help would be appreciated.
Very sorry to hear that. You have definitely cleaned all of the main things I would think of. The only other thing I would check would be your O2 sensor. If there is any oily residue on it, it could be that it got some of the contamination as well?? Beyond that, it could be that the ECU just needs a little bit of time to calibrate? If all that fails to get the car running properly again, I'd say getting a professional set of eyes on the car would be the next step. Thanks for watching, and good luck with your car!
I just thought of something else. If you filled up your catch can, it is entirely possible that your crank-case was not able to breathe properly, and therefor your crank-case pressure could have spiked when the can filled. It is a worst case, but it is possible that pressure got high enough to cause some of your seals to fail, or possibly to pop off or loosen a hose that is associated with the PCV system. If that created a vacuum leak either from a compromised hose or oil seal, that could be what is causing your car to pull timing like that. If you see any signs of oil leaks, etc. I'd recommend smoke testing the car to see if you find anything hidden that you might have missed. Hope that helps!
@@FlatironsTuning I was thinking the heavy oil contamination in the cylinders might have been reducing the octane level of my fuel which could be a possibility but after looking deeper I was able to find a separated PCV hose. Thanks for all of your input!
Start by paying attention to your oil consumption. If you are not using much (or any) oil, then you most likely don't need an AOS. We did a separate video about catch cans on DIT cars, so I would recommend taking a look at that as well: ruclips.net/video/WmU_9PFo0RY/видео.html Hope that helps, and Stay Tuned!
@@FlatironsTuning I think I hardly use any oil, but with AOS i don't have to drain it like a catch can. Would AOS hurt my car since I don't use a lot of oil? I just don't want to check my catch can every so often
Very interested in what the results come back on what's in the blow by. I've seen lots of discussion on that it's just water vapor that makes it look gunky like that
Sorry to hear that Richard. With the IAG AOS installed, it should be very difficult for oil to continue to get into the engine. My best recommendation would be to first, double check the plumbing of the IAG AOS. Then clean everything up, and look for where the oil may be getting into the engine. It might be a good idea to get a second set of eyes on your setup as well because they may see something that you don't. Good luck with your troubleshooting!
FlatironsTuning thanks for the feedback! i checked it today, replaced my oem tmic hoses with a silicone hose and found out there is an oil build up by the pcv valve assembly that connects to the 3/4" drain hose. is this normal? Btw, no film of oil to the throttle body assembly and intercooler which is a good sign.
Well, very broadly speaking, an oil buildup on the PCV valve wouldn't be entirely out of the ordinary. But if you moved it over to the AOS, it should be up top, and pulling from the "separated" air, so it should be very hard for oil to get up to the PCV valve with the AOS installed. And from the valve, it should be connected to the intake manifold, not the drain. If you need further help, I'd recommend either sending us an e-mail, maybe with some pictures of what you are seeing, or reach out to IAG directly with the same. I hope that helps!
FlatironsTuning sorry it's not PCV Valve😅 the oil build up is by the center breather crank case. Sorry about the confusion, i will send a picture when i have time. Thank you
Thanks for the comment. Venting to atmosphere can certainly help, but it needs to be done properly. Plumbing is still important when going VTA though. Thanks for watching and Stay Tuned!
So far I have watched both of these videos. What I would find interesting is a compression check on this older subie. Ring sealing on one or more cylinders would add considerably to the oil blowby. Off course this would become more aggravated on the race track with sustained higher turbo ie; cylinder pressures. The brown/tan goo in the bottle, that you intended to send for analysis, is likely oil/water slush. This is often seen with head gasket failures but can also be a problem with frequent short trips in some cooler climates as crankcase condensation builds up and does not get a chance to cool off. If that tan goo became evident only after track day, you likely have a failing head gasket.
Thanks for the question Barry, and thanks for watching. There are more videos to the discovery, and at a start, I'd say to take a look at those. The engine in the car is not original, and actually only has approximately 6,000 miles on it. No signs of head gasket issues, and no overheating on the new engine. We actually did send the oil out for analysis, and that is the next video I believe. As to the cause and amount of oil, that is something that we have been exploring, and changes have been made. The short answer is that I think that a large reason for the amount of oil collected is down to the plumbing of the catch can in this instance, and removing it, and now having put on an AOS has corrected the issue, at least so far, but we haven't gone back to the track yet. At some point, a compression test may be in order, but we haven't done that as of yet, and again, it seems like our result here was due to something else. Thanks again for watching, and stay tuned!
FlatironsTuning lol... just realize it's ur channel name... but still.. not the best translation. it means more like flat iron (a flat piece of iron) adjustment.
Thanks for your question Amir. What you are describing if what is called an Air Oil Separator, at least in the Subaru world. That is what we are exploring in this series, and as you go through the videos more, you will see how we came to the point of installing an AOS. Thanks for watching!
NO .. you don't want the blow-by crap (water n sludge) going back into your oil pan! Stock, that crap gets sucked into your motor to get "re-burnt", causing build up on your intake valves and throttle body. Hense, a good drainable catch can that vents back into the intake is the best. "Vent to air" in testing has been problematic in some cars as they need the vacume to help scavange the blow by. In the old days the crank pressure vented to air in most big diesels till the EPA stopped that. Pre PCV vent to air was the norm. Next a PCV with a hose to before the air filter.. etc. .. It's evolved. Blow by crap is hazmat n should be disposed of accordingly. Drain the can often till you know how long it takes to fill 1/2 way. Then drain accordingly. Usually 3k or oil change is fine. Size of the can matters naturally.
Thanks for the comment, and I understand where you are coming from. The degree that you would need to put in a catch-can, etc. to the PCV system depends on a lot of factors, but as you turn up the power, especially on a forced induction engine, the need becomes greater. There is just a point where you do have to put something in to catch all of the oil that starts to go through the intake. And on Direct Injection cars, this can be more important. Thanks for watching!
Agreed. The tube that puts the oil in the bottom of the can that they added in video is ridiculous. Why would that tube need to be added to get the oil to the bottom. If you are concerned about gaseous oil being sucked straight through, you would need a baffle plate. In essence what that tube does is create a siphon as soon as enough oil fills the can to cover the end. The small holes to vent are limited in velocity because they are too small and do nothing to prevent the tube from filling up. Once the tube is full of oil, the oil is sucked out of the crankcase instead of blown out.
Unfortunately many aftermarket companies push this across the Subaru community and forums to sell their nuclear powered AOS to anyone who will buy it🤷♂️ you just have to start the wave 🌊 I’m fine with a $30 eBay catch can and like you said if you’re pushing that kind of crankcase pressure something is wrong.. or about to go wrong
Watch this video for a second time and still am learning Thank you guys!
I know video is a few months old.... but, if this is a dedicated track car, venting to atmosphere may be your answer. Your engine bay will be coated with oil despite the filter. If this is a street car, a catch can is your answer. A larger catch can is what you're going to need based on your consumption. It is normal to use that amount of oil on the track. You may want a heavier weight oil for the use on track and changing it when going back to the street.
Also, you're seeing water mixed with your oil, the catch can is doing its job. As the oil heats up it is boiling off moisture and going to the can and back to water. At the same time oil mist is carried out of the crank case(with other vapors) to the can which mixes with the water.
BTW, nice job detailing your experience on and off track.
Thanks for watching!
What if you remove the check valve in the pcv and let draw constantly because correct me if I’m wrong the pcv only pretty much vents on WOT.
Nibiru3064 remove the PCV check and on boost you will pressure the Crank case / sump and blow all the engine seals, and that’s if the motor don’t pop first.
Excellent video peace ✌️ and much respect to you 👍 JASON
Thanks very much. Stay Tuned!
Jesus how can I not subscribe? These videos are amazing.
Thanks for that, and thanks for watching Jachin!
Interesting about how the PCV works for a WRX to a dual can setup for a 2.5 STi Motor . You may be able to use two cans on a WRX by splicing the PCV connection hose from the tree to the manifold and placing the can between the tree and valve. PCV valve to can / to tree then take the crankcase hose from the turbo inlet and unhook the tree to turbo inlet and tee it with the crankcase hose that runs off the intercooler into a can . Then the can to the turbo inlet for fresh air back into the turbo. Just don’t forget to plug the hole left in the turbo inlet from the tree. Let me know if that sounds correct.
The tube that puts the oil in the bottom of the can that they added in video is ridiculous. Why would that tube need to be added to get the oil to the bottom? Does gravity fail to apply inside the catch can? If you are concerned about gaseous oil being sucked straight through, you would need a baffle plate.
So you had a good idea to put steel wool in but the tube is moronic.
In essence what that tube does is create a siphon as soon as enough oil fills the can to cover the end. The small holes to vent are limited in velocity because they are too small and do nothing to prevent the tube from filling up. Once the tube is full of oil, the oil is sucked out of the crankcase instead of blown out and every turn that puts oil in the valve cover is now being sucked out.
Did any CFD get done to prove the vent holes in that tube would actually prevent the scenario I just described? What about a fluid dynamic free body diagram?
How long were you on the track? 10 - 15 minutes? That means you would be burning oil at a rate of 2 quarts/hr. You'd be empty in 2 hours. If that were the normal mode of operation, without a catch can, there would be so much particulate and hydrocarbon exhaust that the car would never pass emissions even at a spirited non-track type pace. Common sense guys. Turbo cars run 8, 12, 24 hour races. They aren't all dry sump so how are they keeping oil in their engines? Easy, they aren't siphoning it out with some idiotically modified catch can. Surely, this can't be the basis of your logic.
Thanks for your question. The purpose of this catch can was to simply see how much blow-by was moving out of the PCV. The initial assumption was that the basic catch can which had no filter media at all would not capture much of what oil vapor might make its way through the PCV. Since the overall goal was to see how much fluid was moving through the PCV, I decided to put in the steel wool, and the tube to force the vapor to the bottom of the can.
As you say, this is not ideal for sure (though there are some commercially available cans that use something similar), and that is what came out when on the track. But before that, there was basically no oil collected in the can through hundreds of street miles. There is another issue with this catch can which is the plumbing to and from the can. That is at least as problematic, if not worse than the baffling going on in the catch can itself.
In short, now knowing what we know, this demonstrates a worst practice for a catch can design, and also a worst case for plumbing a catch can.
If you watch any of the other videos, we have learned more from installing an AOS, and I am working on a video to go into detail about all that we learned from the mistakes that were made in this process.
Thanks for watching, and Stay Tuned for all the details!
How do you prevent build up of sludge in an Air Oil separator return line? You are in Colorado and it would help others here.
Id love a video tour on your Bugeye and its current setup and plans.
Thanks for the comment! Changes have been happening, and more are on the way.
But. The plan is to pick back up on all of the details on that build.
Hopefully in the next couple of weeks.
Stay Tuned!
I'm wondering what I can do to eliminate oil and other contaminants from going into my intake and building upon the back of my intake valves and turbo blades and I'm sure cylinder portion heads rings and I'm sure the exhaust side as well. Oil separator or catch can. What one would work better in my DGI engine? DGI is a problem for carbon build-up and performance.on a DGI engine.
Thanks for your question. If you aren't using much oil, then definitely start with a catch can. Once you have that in place, see what results you get and go from there.
Thanks for watching and Stay Tuned!
always AOS for turbo cars. If you boost a ton you will constantly fill the can and will be too much hassle to maintain. Also if you run E85 some AOS are designed to evaporate the moisture off the oil due to E85 water content.
Doesnt matter if you're running e85 or pump gas theres still water in gas, I run a catch can vented to atmosphere on e85 never had a problem and never will. The heat that the motor generate is enough to evaporate the water from your oil, a AOS is a catch can with a coolant hose. if you haven't checked the lines running to your AOS in a while I bet that coolant line has a a minor leak or will be leaking in the near future.
love learning, and watching from these videos. Some of the best of the Net
Thanks for watching and Stay Tuned!
I recently let my catch can overflow not due to laziness but due to the musturding of the water and oil combination in the catch can. I was emptying my catch can on a very regular basis but didn't realise that every time I emptied it, it was leaving behind a thick substance in the can that I couldn't see in the can that was taking up valuable space. I was simply pouring out the liquid and reinstalling the can. Anyway, it overfilled recently and I also got a ton of smoke suddenly from the tailpipe. Now my car is backing off timing by 9.5 degrees under boost. I've cleaned the intercooler, turbo, intake and throttle body and next is to replace the plugs because they have to be shot! My question to you is, what else do I need to do to get everything back to normal and safe to run? Any help would be appreciated.
Very sorry to hear that. You have definitely cleaned all of the main things I would think of. The only other thing I would check would be your O2 sensor. If there is any oily residue on it, it could be that it got some of the contamination as well??
Beyond that, it could be that the ECU just needs a little bit of time to calibrate?
If all that fails to get the car running properly again, I'd say getting a professional set of eyes on the car would be the next step.
Thanks for watching, and good luck with your car!
I just thought of something else. If you filled up your catch can, it is entirely possible that your crank-case was not able to breathe properly, and therefor your crank-case pressure could have spiked when the can filled. It is a worst case, but it is possible that pressure got high enough to cause some of your seals to fail, or possibly to pop off or loosen a hose that is associated with the PCV system.
If that created a vacuum leak either from a compromised hose or oil seal, that could be what is causing your car to pull timing like that.
If you see any signs of oil leaks, etc. I'd recommend smoke testing the car to see if you find anything hidden that you might have missed.
Hope that helps!
@@FlatironsTuning I was thinking the heavy oil contamination in the cylinders might have been reducing the octane level of my fuel which could be a possibility but after looking deeper I was able to find a separated PCV hose. Thanks for all of your input!
I have a 2017 honda civic ext 1.5 turbo. Should I get air oil separator for my daily driving? It's a GDI as well
Start by paying attention to your oil consumption. If you are not using much (or any) oil, then you most likely don't need an AOS.
We did a separate video about catch cans on DIT cars, so I would recommend taking a look at that as well:
ruclips.net/video/WmU_9PFo0RY/видео.html
Hope that helps, and Stay Tuned!
@@FlatironsTuning I think I hardly use any oil, but with AOS i don't have to drain it like a catch can. Would AOS hurt my car since I don't use a lot of oil? I just don't want to check my catch can every so often
Great video
Would you do one on fuel stumble / the EJ fuel system?
Hello Phillip. Thanks for the question! We'll add it to the list!
Okay...with all this being said....should I install an oil catch can on my high performance vehicle...yes/no...😐?
Thanks for your question. If you are moving more oil through your PCV system than you would like to, then yes :-)
Hope that helps, and Stay Tuned!
Very interested in what the results come back on what's in the blow by. I've seen lots of discussion on that it's just water vapor that makes it look gunky like that
I have a IAG AOS street series installed but i'm still losing oil? daily driven stock 2016 sti
Sorry to hear that Richard. With the IAG AOS installed, it should be very difficult for oil to continue to get into the engine. My best recommendation would be to first, double check the plumbing of the IAG AOS. Then clean everything up, and look for where the oil may be getting into the engine.
It might be a good idea to get a second set of eyes on your setup as well because they may see something that you don't.
Good luck with your troubleshooting!
FlatironsTuning thanks for the feedback! i checked it today, replaced my oem tmic hoses with a silicone hose and found out there is an oil build up by the pcv valve assembly that connects to the 3/4" drain hose. is this normal? Btw, no film of oil to the throttle body assembly and intercooler which is a good sign.
Well, very broadly speaking, an oil buildup on the PCV valve wouldn't be entirely out of the ordinary. But if you moved it over to the AOS, it should be up top, and pulling from the "separated" air, so it should be very hard for oil to get up to the PCV valve with the AOS installed. And from the valve, it should be connected to the intake manifold, not the drain.
If you need further help, I'd recommend either sending us an e-mail, maybe with some pictures of what you are seeing, or reach out to IAG directly with the same.
I hope that helps!
FlatironsTuning sorry it's not PCV Valve😅 the oil build up is by the center breather crank case. Sorry about the confusion, i will send a picture when i have time. Thank you
the problem is you vented back into the manifold instead of to atmosphere
Thanks for the comment. Venting to atmosphere can certainly help, but it needs to be done properly. Plumbing is still important when going VTA though.
Thanks for watching and Stay Tuned!
Rather have it and not need it than need it and not have it imo. I know ancient video lol
No worries at all. Thanks for the comment!
Thanks for watching and Stay Tuned!
So far I have watched both of these videos. What I would find interesting is a compression check on this older subie. Ring sealing on one or more cylinders would add considerably to the oil blowby. Off course this would become more aggravated on the race track with sustained higher turbo ie; cylinder pressures. The brown/tan goo in the bottle, that you intended to send for analysis, is likely oil/water slush. This is often seen with head gasket failures but can also be a problem with frequent short trips in some cooler climates as crankcase condensation builds up and does not get a chance to cool off. If that tan goo became evident only after track day, you likely have a failing head gasket.
Thanks for the question Barry, and thanks for watching. There are more videos to the discovery, and at a start, I'd say to take a look at those.
The engine in the car is not original, and actually only has approximately 6,000 miles on it. No signs of head gasket issues, and no overheating on the new engine.
We actually did send the oil out for analysis, and that is the next video I believe.
As to the cause and amount of oil, that is something that we have been exploring, and changes have been made.
The short answer is that I think that a large reason for the amount of oil collected is down to the plumbing of the catch can in this instance, and removing it, and now having put on an AOS has corrected the issue, at least so far, but we haven't gone back to the track yet.
At some point, a compression test may be in order, but we haven't done that as of yet, and again, it seems like our result here was due to something else.
Thanks again for watching, and stay tuned!
Agreed. Rings, head gasket, lots of boost, something is off. 14 lb peak boost, in a tight q50, will not fill a catch can in 2000 miles or more.
what are you trying to say on the fender sticker .. it makes no sense.
Flat metal make better ie. Flatirons Tuning :-)
FlatironsTuning lol... just realize it's ur channel name... but still.. not the best translation. it means more like flat iron (a flat piece of iron) adjustment.
Prince changed his name to a symbol.
@@FlatironsTuning Not to sound harsh...but it is pretty ordinary translation...
Generic design catch can doing nothing great... What u really need is the catch can that allow return flow into the oil pan
Thanks for your question Amir. What you are describing if what is called an Air Oil Separator, at least in the Subaru world. That is what we are exploring in this series, and as you go through the videos more, you will see how we came to the point of installing an AOS.
Thanks for watching!
NO .. you don't want the blow-by crap (water n sludge) going back into your oil pan!
Stock, that crap gets sucked into your motor to get "re-burnt", causing build up on your intake valves and throttle body. Hense, a good drainable catch can that vents back into the intake is the best. "Vent to air" in testing has been problematic in some cars as they need the vacume to help scavange the blow by.
In the old days the crank pressure vented to air in most big diesels till the EPA stopped that. Pre PCV vent to air was the norm. Next a PCV with a hose to before the air filter.. etc. .. It's evolved.
Blow by crap is hazmat n should be disposed of accordingly.
Drain the can often till you know how long it takes to fill 1/2 way. Then drain accordingly. Usually 3k or oil change is fine. Size of the can matters naturally.
hell yeah recirculate all that water back into the oil pan hahahahaha
I think these things are a hoax. If your engine is barfing stuff into the pcv system there is something wrong with your engine or the way it's setup.
Thanks for the comment, and I understand where you are coming from. The degree that you would need to put in a catch-can, etc. to the PCV system depends on a lot of factors, but as you turn up the power, especially on a forced induction engine, the need becomes greater. There is just a point where you do have to put something in to catch all of the oil that starts to go through the intake. And on Direct Injection cars, this can be more important.
Thanks for watching!
High compression NA and force induction engines have lots of pressure in the cylinders. The piston rings don’t catch it all.
Agreed. The tube that puts the oil in the bottom of the can that they added in video is ridiculous. Why would that tube need to be added to get the oil to the bottom. If you are concerned about gaseous oil being sucked straight through, you would need a baffle plate.
In essence what that tube does is create a siphon as soon as enough oil fills the can to cover the end. The small holes to vent are limited in velocity because they are too small and do nothing to prevent the tube from filling up. Once the tube is full of oil, the oil is sucked out of the crankcase instead of blown out.
Unfortunately many aftermarket companies push this across the Subaru community and forums to sell their nuclear powered AOS to anyone who will buy it🤷♂️ you just have to start the wave 🌊
I’m fine with a $30 eBay catch can and like you said if you’re pushing that kind of crankcase pressure something is wrong.. or about to go wrong