Air Oil Separator Vs. Catch Can Part 3 - So what is Blow By? The Analysis is in!

[@elcapitan83]

Brilliant! You employ a logical, technical approach, supported by data, and analysis. I wish all performance and tuning channels would follow your example. 👍🏻👍🏻

[@FlatironsTuning]

Thanks Scott! Thanks for watching, and it is good to hear that you appreciate the direction that we are going with the channel.

[@BAMEFR]

Love your videos! Truth is I've been meaning to call and tell you how helpful you've been. Within the last few days I've binged on your content. Take a search and nothing comes close to how informative this channel is. I'm purchasing a bugeye wagon mid December with over 300k on it. Any mods I do will be purchased from flatironstuning. I'll be calling soon! Some reasons why I like the vids are the thought out explanations, one take recordings, actual tested theory and physical descriptions. Please make more reviews on parts or an in depth video about coilovers. Maybe reliability mods, brake pads, suspension tuning, DIYs/installs and gauges.

[@FlatironsTuning]

Thanks for watching Bamefr, and thanks for your feedback. That is exactly the goal that we are shooting for with our videos, and it is great to hear that you are getting so much out of them. Many suspension videos are in the works, so stay tuned!

[@WifeBTR123]

Over 300k. Very niiiice. Keep the community updated. Nasioc.com if you don't know about it.

[@charliedee9276]

Excellent video, subscribed. A while back, the early 90's, I worked at a shop that specialized in Buick Grand Nationals and catch cans were mostly fabricated then. We would always mount them close to a heat source (turbine housing or exhaust piping) to do exactly what you explained about wanting to burn off the fuel and water. We would run into the same problem of the can filling too fast with a good portion of what was in the can to be fuel and water vs actual oil. Modified fire extinguishers were a favorite to use, they were plentiful and always had a good mounting bracket.

[@FlatironsTuning]

Thanks for that input Charlie, and thanks for watching!

[@SC-ec9fx]

Excellent info and series! You helped me decide NOT to install any form of basic catch can on my 2.0 turbo street driver. Even the heated separator sounds iffy and over complicated. Thank you!!

[@FlatironsTuning]

Thanks for watching and glad that you found this helpful. Stay Tuned!

[@oliverscorsim]

This is great love your process. I wanted to share a tip I drag race so it's a bit different but we run big ring gaps and vertical gas ports. On my drag bike you can put your hand on the vent and feel rediculous blowby from idle to 20% throttle. As soon as it gets over 5psi of boost it stops almost completely. On the Dyno we got it over 35psi and it never got worse with the vertical gas ports. Standard we had less blowby on idle and it got worse as boost came in to the point that at 20psi I was having a hard time making the hose stay on the vent without a clamp. I do see my rings wearing a bit faster than normal. Used to get about 150hrs from a set now I get 60hr at best but it's well worth it. Same piston too just took a jet drill to it and made x size hole evenly around wanna say I did 8.

[@FlatironsTuning]

Thanks for the comment, and that is really interesting. It seems like blowby gets worse on Subaru's the more boost you run, so very similar to your initial problem. Definitely something to keep in mind as we research and try different things. Thanks for watching and Stay Tuned!

[@oliverscorsim]

@@FlatironsTuning appreciate it

[@2018wrxaddict]

Is there a video 4? Did you discover what happens to the oil in the pan?

[@FlatironsTuning]

Thanks for your question. I'm not sure what you mean by the oil in the pan. If you can give me a little more detail on the question, I'll do my best to answer. Thanks for watching and Stay Tuned!

[@alexudolkin2146]

Do you recommend using a stainless steel wool pad in the catch can to capture more oil out of the intake air?

[@FlatironsTuning]

Thanks for your question. It does seem to help. You just have to make sure that you are using a large enough fiber that it won't come apart. Thanks for watching and Stay Tuned!

[@MrBillDaBear]

On my Cobb AP, I rarely see coolant temps go above 212 Fahrenheit on normal or spirited driving, so wouldn't the water not evaporate well enough? Would using an AOS just add water to the oil? Boiling point of fuel is around 180 F so fuel into the oil shouldn't be an issue EDIT: I realized the PCV/catch can/AOS system is primarily driven by vacuum to suck out all the crankcase blow-by. The boiling point of fuel and water should certainly be lower than 212 F while those fluids are under vacuum. The question still remains however, how good is an AOS at evaporating water and fuel from blow-by oil...

[@FlatironsTuning]

That is a great question Bill. There are a couple of things going on related to your question. The first is that if the can/AOS is cooler than where the crank-case gas is coming from, this will encourage liquids to condense out. If you are running a catch can, this is fine, as in a lot of ways that is the goal. But when you are running an AOS that is also returning the captured liquids to the oil pan, you really don't want to dilute your oil with fuel or water. The idea behind keeping the AOS at engine temperature is that it will keep the fuel and water in their vapor state, and let them exit the tank either to the inlet or to atmosphere depending on set-up. We have actually not been running the coolant lines to our race car's AOS for a bit, and we were concerned that in doing so, the fuel and water content would go up. In that case though it turned out that the oil itself was hot enough to keep the fuel and water in their gaseous state, and there was no issue with diluting the oil. But that is a race car, and it is always running pretty hot. So there is also a big part of the necessity of the coolant going to the tank that comes down to what is done with the car. Ultimately, you just need to start by getting a good baseline of what is happening in your tank, and decide if you need to make any changes. I hope that helps and thanks for watching!

[@K03sport]

So, who makes the better AOS? I bought a Radium BMC brace because it is also the mounting location for their AOS kit. Are you going to to run 1 or 2 AOSs?

[@FlatironsTuning]

Thanks for your question. This is a tough one. We have had good luck with the Radium, IAG, and Killer-B AOS kits. It largely depends on how much oil you see going through your PCV system. And in some cases, a dual catch-can can be more ideal if you aren't seeing much oil going through your PCV as well. We are going to be taking a look at this here soon, so Stay Tuned!

[@bishoujokai]

Thanks for the tip! I drive a Mitsubishi evolution 6 (bone stock with just a pod filter) and I am on the fence as to what catch can or air-oil separator to get. Seeing that my engine is stock, I think I'll go for the simple catch can like the cusco/greddy ones so I can see if its filled up.

[@FlatironsTuning]

Thanks Andrei and thanks for watching!

[@Silent_Keith]

Glad you guys posted up on the AOS/catch can and it being a good modification to the car. Although as I have said in a previous video, my car is basically a stock S202 with a cat back exhaust, better pads and tires used for track days and future hill climb events. I sway on whether to update the parts that Subaru already put into place as they have never really given me any ill effects. Keep up the great work and information.

[@FlatironsTuning]

Thanks Keith!

[@mattmahoney9369]

I have an S202 Drivetrain (matching trains, axle, and diff) in my 06 Wagon. I love the feel of that transmission. All Mechanical, All Day.

[@Smokkedandslammed]

Super informative, thanks for the video. Can you guys do a video on vent to atmosphere vs returning it back into the intake tract? I'm going single turbo on my 335xi and venting my occ to atmosphere, theres no way to route it back into the loop cause the air filter is put straight on the turbo lol Since there is no more "dirty air" going back into the intake tract, I won't have any carbon build up on my intake valves. I'll never have to walnut blast again! Woo!

[@FlatironsTuning]

Thanks for watching, and thanks for your question! We actually have a 335I that we are going to be working on here shortly :-). The simple answer is that if your are going to vent to atmosphere, you have to make sure that you completely separated your PCV system from the intake because you don't want to pull in unmetered air. And usually doing so will require a tune because you are no longer pulling in spent exhaust gas that no longer has any usable O2. On the directed injected engines, keeping that oil vapor out of the inlet track is very important because it can lead to a lot of deposits as you say. We have a catch can in line for the 335, so stay tuned. Hopefully that will be one of our winter projects :-)

[@kricker4245]

this has brought a lot of perspective to my car. I run Skyline Low Compression, High boost and My catch can just fills up like crazy on full boost on the track and i just get kicked off. Im stumped, help me please man.

[@FlatironsTuning]

Thanks for your question. Go through this video that we put together talking about what you can learn by monitoring crankcase pressure: kzbin.info/www/bejne/fnLZqZ2Jmbamjqs That would be the piece of information that you want to start looking at as it may well point you to the cause of your problem. At this stage in the game, it could be a lot of things. Once you have a sense of what is going on in your crankcase, if you still need help, let us know and we'll see what we can do! Thanks for watching and Stay Tuned!

[@titorojas333]

So any updates on the research for the oil separator? I have a 2005 WRX STI fully stock with 108k and It is my daily drive. I’m starting to see that yellow butter looking stuff. I know is blow by..... I’m here like an ape scratching my head.... I heard from the Subaru community that I should buy an oil catch can but after seeing your videos it makes very anxious as I waiting to hear the results from the oil separator research maybe that’s something I will be needing soon! Tito

[@FlatironsTuning]

Thanks for your question Tito. We have been working on a few different projects, but this is certainly one of them :-) I am close to being done with the next video and it should be out this week, or early next week. As I say in the videos, the biggest thing to look at is how much oil you are going through. If you are having to add more oil between changes than would fit in your desired catch-can, something like an AOS with a return would be a good idea. I'd say start there, and stay tuned. More information is on its way :-) Thanks for watching!

[@paulmarsdensr1095]

A great explanation of what happens in this system. I have a base model 2020 STI with 24K miles. when should I put an AOS on my car? or do I even need to. This STI is my daily driver frome Oceanside CA and I drive to lakeforest, Irvine California everyday. 50 miles each way. I had a Base model 2017 WRX and I took it to 101K. I love this community and our cars. I plan on keeping my 2020 STI forever. A great video brother. Stay safe.

[@FlatironsTuning]

Thanks for the question. It really all comes down to how much oil, if any, you are seeing move through your PCV system. The first indicator of that is how much oil you have to add between changes. If you don't need to add any oil, then you are not moving any through the PCV system most likely. So the need for a catch can or AOS is minimal. Just keep an eye on your oil consumption and that will tell you when you need to do something. Thanks for watching and Stay Tuned!

[@paulmarsdensr1095]

@@FlatironsTuning Thank you for that Response brother. Subies forever.

[@OlegBak]

Thanks for video! I like your channel as it gave me an answers to some issues with my PCV system (it was absolutely dry during normal spirited driving and it has some oil after track days - modified EJ25 engine, no AOS, no catch can, Redline 5w50). Will you consider heated AOS? Do you plan to collect oil from heated AOS and to make UOA? P.S. Water could be collected with "bypass oil filter system" with Cellulose Filter Media (like Frantzfilters), I placed my install pictures on BITOG in " Engine Oil Bypass Filters" section (thread is named "Frantz Bypass Oil filter pictures: Subaru Forester". At the moment I have Synthetic Filter Media for break-in period, but plan to change to Cellulose Filter Media due to daily shot trips and wet climate). Manufacturer claims, that it will filter particles up to 2 microns and remove up to 6 ounces (177 milliliters) of water from the oil and I don't see the reason why it shouldn't.

[@FlatironsTuning]

Thanks for watching Oleg. Yes, we are going to be putting on an AOS here shortly, and we'll go through that install. Our plan is to run the car in various different conditions, and then check the oil and see what we find. Stay tuned!

[@paladain55]

A+ You're the first one to at least comment on the makeup of the oil coming out and the amount of oil it is catching. A lot of us drive shitboxes and need to keep the oil in the pan and can't really just throw it all out as with a catch can. Some oil is better than less oil.

[@FlatironsTuning]

Thanks for watching, and glad that the video was helpful. Stay Tuned!

[@ilikedonut343]

Awesome videos Frontline! Couple more months until I buy your 'build your own' hybrid rotating setup from you guys!

[@FlatironsTuning]

Thanks for watching Marco. Appreciate your support!

[@LIFEISAHUSTLE1]

What is your take on an air oil separator that screws into the oil fill tube? Based on these results you got would you consider using something like that or would you run into the oil,water, fuel mixing issues? In theory.

[@FlatironsTuning]

Thanks for your question. I'd definitely recommend taking a look at what we found when we started to look at crankcase pressure. Here is a link to that video: kzbin.info/www/bejne/fnLZqZ2Jmbamjqs

[@LIFEISAHUSTLE1]

@@FlatironsTuning thanks. Watched the vid after I asked my question. Very interesting findings. Great info.

[@gearhead4005]

I put my catch can on my Hemi for performance enhancement only. I get so much Blow by on that thing it has to be ruining my air/fuel ratio and octane level. I did feel a difference.

[@patricksalfer1294]

I have a 2021 outback xt Onix what's do you recommend as far as oil in intake, car is stock, Cobb hasn't made a map yet still waiting on that...

[@whitelion4072]

im lost, so you run coolant through to keep it hot? that doesnt seem akin to physics and thermo dynamics. thats the only thing im not understanding, if you could please explain it to me further that would be outstanding.

[@FlatironsTuning]

Thanks for the question. The reason that keeping the can at coolant temperature is significant is in order to allow the fuel and water that are trapped in addition to the oil to evaporate and leave the oil before it returns to the pan. If the liquid is allowed to cool, then the fuel and water that is captured would get returned to the pan in addition to the oil, and over time, that could significantly increase the percentage of those fluids in your oil. Hope that helps, and thanks for watching!

[@whitelion4072]

oh okay so adding the coolant helps keep the can "hot" with respect to the liquid rather than the air? thats interesting. thank you!

[@davepedro1544]

I’m assuming they use water coolant after it’s heated by the motor, so that it passes through the separator heats the condensed water and fuel -they pass through to the cylinders and are burned off, while the coolant then cycles through to the radiator, and the a/o separator is left with heavy particles and contaminants.. would be my guess.

[@FlatironsTuning]

That is correct. The AOS taps into the cooling system, and uses engine coolant to increase its temperature.

[@cruzinUSA_]

Extremely helpful video thank you!

[@FlatironsTuning]

Thanks Benjamin!

[@p9917j]

Very interesting series and thanks for taking the time to make/upload this. I'm coming from Audi S3 and additionally wondering about having a closed system without a crank case diaphragm in the stock pcv to regulate the pressure... Could blow seal's elsewhere causing bigger issues than it solves, along with very rough idle. An inherent issue across manufacturers I'm sure regardless of how they tackle it.

[@FlatironsTuning]

Thanks for the question Paul. You definitely don't want to seal up the PCV. That would cause some really nasty problems pretty quickly. The need for some form of crank-case ventilation comes from the fact that your rings will never seal 100%. This means that some part of the combustion gasses will get into your crank-case (can be tested with a "leak down" test), and this causes positive pressure. You need to give that pressure a way to escape, and that is where the PCV system comes in. Beyond that, the crank-case will actually go through a few different conditions as you drive, and one of the main reasons that there is a PCV valve incorporated is because you need to the PCV system to act differently when the intake manifold is in vacuum compared to when it is under positive pressure. This is something that we are exploring, and we may dive into it in detail later. For now, if you haven't all ready, I'd recommend looking at the video that we have done about the Atmospheric vs. Recirculated AOS. It starts to go down that road a bit. Here is that link: kzbin.info/www/bejne/bJOzmKaipbydl80 Thanks for watching, and please feel free to reach out to us if you have any more questions!

[@doubletee4391]

This was incredibly helpful, thank you so much for those results

[@FlatironsTuning]

Thanks Dagan, and thanks for watching!

[@louisroutier]

Absolutely amazing content guys! I was wondering very quickly, I have a lightly modified ´13 WRX, I check my oil regularly, it always hovers around full. I don’t track my car and only have a few spirited moments every now and then when the twisty roads clear of traffic, should I get a AOS?? Or should I spend money on a mod that would make a bigger difference?? Please keep producing this amazing content!!! There’s no other channel on KZbin that is this informative for Subaru’s!!

[@FlatironsTuning]

Thanks Louis! If you aren't losing much if any oil, and you aren't tracking your car, then I'd say that the need for any modification of the PCV system is minimal. If you decide to start making more power, or you do notice that you are using more oil, or if you start to see more signs of oil in your intercooler, etc., then that would be the time to reconsider. Thanks for watching!

[@ChiSpire]

hello Flatirons, my 2016 STI (26,000 miles) is stock except for CAT back exhaust and I just got back a very good engine report from Blackstone Labs. Also I haven't noticed any oil loss, so I'm sure you would probably say AOS is not needed. However if I was to go stage 1 (Cobb SF intake and accessport ots map tune) in your opinion would you recommend getting AOS? thanks

[@FlatironsTuning]

Thanks for your question. My recommendation would be to put on the intake, and just monitor your oil usage for about 1/2 to a full oil change interval. Most likely you won't see any change, but keep an eye just to be sure.

[@ChiSpire]

Gotcha, so monitoring oil will be key. I was also leaning in the direction of not getting AOS, especially after reading that an AOS can potentially void warranty. Thanks for all your help. I love the channel, keep up the greate work :)

[@thepseudomasterchef7238]

Looking for some help...i have a 2018 wrx and have an IAG comp AOS...Today i noticed some foamy oil residue on my driveway coming from the vent to atmosphere hose...Is this normal? I thought only vapors would come out

[@FlatironsTuning]

Thanks for your question. I would not say that would be normal under most circumstances. The best place to start would be to go back and check the routing of all of your hoses, and double or triple check that everything is connected correctly. Is the car modified? If so, ho far have you gone? Bigger turbo, etc.? And what kind of use does the car see? Is it a track car or a daily driver, etc.? Lastly, were you seeing oil consumption before you installed the AOS? With some more information, we'll do our best to help out!

[@dmkazich]

Did you get a tune for your comp series? Need one if you’re running one

[@tospace2006]

Which AOS did you guys choose?

[@FlatironsTuning]

Thanks for your question Brian. We haven't installed one yet, but as soon as we do, we'll post up the results.

[@4RT0119]

Oil dilution is normal?

[@FlatironsTuning]

Thanks for your question. To an extent, yes. To a certain extent, this is what the PCV system is designed to handle. Hope that helps, and Stay Tuned!

[@danpollard4210]

Why not seperate the highest volatiles off the blow-by gasses, oil and water,burning them in the combustion chambers,and capturing the harmful components in your catch-can? Which would, or might require a catalytic component and precise temperature control of heat to your catch-can .three percent fuel in the blow- by is a significant waste,and a bit dangerous, wouldn't you agree?Thank You! Your work is appreciated and very good, sir.

[@armindogomes47]

Blow by is the reason direct injection motors get sludged up. Catch can almost stops this Normal injection cars dont get build up due to the injectors keeping the valves clean..... I run catch cans on my VR6 V2, 1.8t 20v, and BMW x5 335i xdrive N55

[@TR-sg9jc]

Almost. I have a very modified bolt on challenger. I believe the edelbrock intake manifold and massive 90mm throttle body is the cause because if I goose it then turn my car right off I'll have a smokey next startup. I assume the vacuum has increased drastically from those intake mods and has more pull, pulling everything (gases and oil vapor) through the catch can. It's only happened 3 times but I need to look at a air/oil separator.

[@anonjohnnyG]

Absolutely Phenomenal

[@highrzr]

You're going to need a bigger can. Bottom line is it keeps the crap from going back into you engine! Moisture is normal as its part of what the PCV system is supposed to help evacuate. My car even has a heated PCV valve to help deal with the moisture.

[@moeshouse575]

all acid in the crank case are water base.

[@dresnick12]

The purpose of PCV systems is to prevent air pollution (by not venting crankcase gases to the atmosphere). There is no use for them in racing!!!!

[@Portmore78]

He mentioned that in video #1, but since ventilation into the atmosphere is probably illegal the PCV systems were made.

[@jimschwarz3901]

Just eliminate your pcv system altogether, if you run big boost and are constantly hitting big revs. It restricts the amount of blowby that you can evacuate - You'll know to do this after you blow out oil seals!

[@Saintbricks]

Please keep making Videos

[@FlatironsTuning]

Thanks Isaiah! Stay tuned, more are on the way!

[@paul1der]

put a mann provent 200 on my sprinter after using other junk catch cans. provent is scientifically designed and works best.

[@epiksol_]

Do yourself a favor and watch this @ x1.25 playback speed.

[@brussell639]

It's mixed with fuel.

[@FlatironsTuning]

Yep, fuel vapor and water vapor. Thanks for watching and Stay Tuned!

[@brussell639]

@@FlatironsTuning I had the same thoughts of re-routing it back to the oil pan. I'm so glad I didn't. Several years ago I accidentally filled my freshly rebuilt transmission with a couple of gallons of water. Someone had repurposed some empty jugs of transmission fluid and had sat them down by my transmission fluid. I didn't notice until I was checking the level and the dipstick came out bright pink. Took me forever to get that flushed out.