GMS - Oil catch can system
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A bit more about OCC in 4C.
By placing a breather filter (small filters you usually see on some car builds), is not the best idea as you turn closed crankcase venting system into open. 4C would need to have 1x breather filter on the vacuum side (left outlet of the red circle) and 1x breather filter on the boost side (right outlet of the red circle).
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By having a breather filter on the left outlet of the red circle, you would change the closed PCV system into open PCV system, allowing the positive pressure in the crankcase to vent into atmosphere, dispersing oily mist in to the engine bay, but at this point you've already lost a vacuum in the PCV system which is not good. Also, under light load and cruising (vacuum) the fresh air will be sucked through the left green circle, adding unmetered (MAF doesn't know this air is coming in to the engine) which is not good, so you would need to blank this port. The same goes for having a breather filter on the right outlet of the red circle, except it is working under high load (boost) situations while the PCV NRV (non return valve) closes. With this setup you are allowing the positive crankcase pressure to be vented into the atmosphere, but you are loosing both vacuums and unless blanking the green circled ports, also providing unmetered air to the engine, messing the AFR ratio. Not good.
Keeping the 4C stock PCV system as it is, works good enough to let the car pass emission standards, requires no special maintenance, but on a long run, the amount of blowby we have, especially tuned engines, will mess your engine internals. The oil sludge and carbon build up will occur and DFI (direct fuel injection) engines are notorious for it. When it does happen, you can remove the intake manifold and take it for a cleaning. Usually, walnut blasting does the job, but it is not the easiest job and as you don't want any of the blasting particles to get in to your engine valving. Not exactly a DIY unless you are skilled mechanic. Also get ready to get charged quite a few hours of labor and if someone says it can be done in an hour or so, I'd stay away from it. Even though you cleaned your valving and intake, there will still be oil in intake piping (intercooler, throttle body, etc.) and sooner or later you will need to do this again. You cured the symptoms but not the source of the issue.
By installing closed system OCC you keep the much needed vacuum in the crankcase and prevent the oil entering the intake tract. The only reason manufacturers don't use such systems is added cost, emission regulations and fact that people want to turn the key and drive, no one wants to bother with the amount of oil in the OCC.
By placing a breather filter (small filters you usually see on some car builds), is not the best idea as you turn closed crankcase venting system into open. 4C would need to have 1x breather filter on the vacuum side (left outlet of the red circle) and 1x breather filter on the boost side (right outlet of the red circle).
By having a breather filter on the left outlet of the red circle, you would change the closed PCV system into open PCV system, allowing the positive pressure in the crankcase to vent into atmosphere, dispersing oily mist in to the engine bay, but at this point you've already lost a vacuum in the PCV system which is not good. Also, under light load and cruising (vacuum) the fresh air will be sucked through the left green circle, adding unmetered (MAF doesn't know this air is coming in to the engine) which is not good, so you would need to blank this port. The same goes for having a breather filter on the right outlet of the red circle, except it is working under high load (boost) situations while the PCV NRV (non return valve) closes. With this setup you are allowing the positive crankcase pressure to be vented into the atmosphere, but you are loosing both vacuums and unless blanking the green circled ports, also providing unmetered air to the engine, messing the AFR ratio. Not good.
Keeping the 4C stock PCV system as it is, works good enough to let the car pass emission standards, requires no special maintenance, but on a long run, the amount of blowby we have, especially tuned engines, will mess your engine internals. The oil sludge and carbon build up will occur and DFI (direct fuel injection) engines are notorious for it. When it does happen, you can remove the intake manifold and take it for a cleaning. Usually, walnut blasting does the job, but it is not the easiest job and as you don't want any of the blasting particles to get in to your engine valving. Not exactly a DIY unless you are skilled mechanic. Also get ready to get charged quite a few hours of labor and if someone says it can be done in an hour or so, I'd stay away from it. Even though you cleaned your valving and intake, there will still be oil in intake piping (intercooler, throttle body, etc.) and sooner or later you will need to do this again. You cured the symptoms but not the source of the issue.
By installing closed system OCC you keep the much needed vacuum in the crankcase and prevent the oil entering the intake tract. The only reason manufacturers don't use such systems is added cost, emission regulations and fact that people want to turn the key and drive, no one wants to bother with the amount of oil in the OCC.
@GMS thanks for the explanations. I'm just trying to gather knowledge based on my observations & knowledge.
The quality of this OCC is superb as well. No complaints on the manufacturing and GMS is great to work with and quick to respond!
Again, my concern is sludge is going to build up in the lines and not make it to the catch cans. Sure the vapors and small droplets will make it, but my concern is that oil is going to get trapped in those lines and that isn't good oil, because its going to collect a lot of the vapor looking to go past it. That's why OCCs are mounted below the PCV so that these oils have somewhere to drain to. Its the same volume of oil going through the PCV weather its mounted higher or lower. I wouldn't want it to flow back into the crankcase.
I'm concerned that the cans aren't catching anything but the vapor. I hope I'm wrong. Would like to see an example over x miles driven, but time will tell.
Here are some pics of my install!
The quality of this OCC is superb as well. No complaints on the manufacturing and GMS is great to work with and quick to respond!
Again, my concern is sludge is going to build up in the lines and not make it to the catch cans. Sure the vapors and small droplets will make it, but my concern is that oil is going to get trapped in those lines and that isn't good oil, because its going to collect a lot of the vapor looking to go past it. That's why OCCs are mounted below the PCV so that these oils have somewhere to drain to. Its the same volume of oil going through the PCV weather its mounted higher or lower. I wouldn't want it to flow back into the crankcase.
I'm concerned that the cans aren't catching anything but the vapor. I hope I'm wrong. Would like to see an example over x miles driven, but time will tell.
Here are some pics of my install!
Attachments
Oil doesn't "flow" per se through the PCV. Its all blow by. Oil Catch can or not the volume of oil that makes it into the PCV is the same regardless of where the can is mounted (high / low). However, misty oil will make it through and you want the cans to collect this oil and vapor. The oil catch can is mounted higher than the PCV and thus the oils that get trapped in the lines will not make it to the cans, the vapor willl. At least not all of the oil and will either get trapped in the lines or back into the crankcase. However, this is now contaminated oil and you don't want it in the crankcase, but rather the catch can. This is obviously my speculation as the system hasn't been tested (I assume).
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Perhaps there is a bit of confusion between OCC (oil catch can) and oil separator. They are basically the same, but the OCC keeps the oil in and oil separator drains back to the engine.
With OCC in 4C, we want to further separate oil and air, as PCV is doing it's job partially. If the vapors get to the OCC that's good and if some of the oil gets back to crankcase nothing is wrong with that either. The main purpose of OCC is that non of the oil gets back to the intake, which it does without OCC. None of the stock cars use OCC due to regulations, but they do use oil separators and in some cases they drain back to the oil pan.
It could be that some oil will condense and remain in the oil lines and eventually could build a sludge, but not really a concern.
I would also like to say that emptying an OCC is not a weekly job, unless you are a heavy tracker, monthly if you are daily driver but in most cases yearly job, so don't expect to go for a drive an have OCC 1/2 full.
With OCC in 4C, we want to further separate oil and air, as PCV is doing it's job partially. If the vapors get to the OCC that's good and if some of the oil gets back to crankcase nothing is wrong with that either. The main purpose of OCC is that non of the oil gets back to the intake, which it does without OCC. None of the stock cars use OCC due to regulations, but they do use oil separators and in some cases they drain back to the oil pan.
It could be that some oil will condense and remain in the oil lines and eventually could build a sludge, but not really a concern.
I would also like to say that emptying an OCC is not a weekly job, unless you are a heavy tracker, monthly if you are daily driver but in most cases yearly job, so don't expect to go for a drive an have OCC 1/2 full.
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Hi Rudi @GMS,
Just a thought I had this weekend: I have a lightweight battery from Enrico waiting to install. Would make a new base plate to fix it, but this could also leave room for other stuff to be placed on it, e.g. the fuse box which now is placed next to it. Or........ an OCC!! 🤩. Don’t know how it would work on a spider, but I think it would be placed high enough.
Just a thought I had this weekend: I have a lightweight battery from Enrico waiting to install. Would make a new base plate to fix it, but this could also leave room for other stuff to be placed on it, e.g. the fuse box which now is placed next to it. Or........ an OCC!! 🤩. Don’t know how it would work on a spider, but I think it would be placed high enough.
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After less than 50km on dyno. About 1 teaspoon of oil and water mix in each OCC tank. In my case, right OCC had more content than left. Right was heavily oiled with some water in it and right was lightly oiled with mostly water from condense. Better here than in combustion chamber. Or intake, or IC, or turbo, or valvetrain, or all around the engine bay.
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Mine are bone dry as well, driven about 600 km
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Should be something there after 600km champ.
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@Safire Good find regarding the weight reduction. I must also admit that your engine bay looks very clean, not greasy. Mine was pretty greasy from the oily vapors escaping through the intake manifold. Cars frequently tracked or driven hard for sustained periods of time when the engine oil is very hot will get lots of oil passing through the oil separator which will be unable to 100% separate oil and air and therefor we need OCC to keep the oil out of intake system.
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Your OCC findings seem pretty reasonable. As mentioned before, left OCC is responsible for oil filtering under light load conditions and right OCC, under boost conditions. 5 hours of drive in your case, is mostly light load situation and even if you go in to a boost situation you're not there for long, so dry right OCC is acceptable while left liek you mentiond should have a bit something in it. In my case above, about 50km of dyno running, was pretty much boost condition all the time. So in my case, left OCC had mostly condensed water with some light oil in it and the right OCC caught quite some oil with minor signs of water in it, considering quite short period time of running. But of course 50 km of boost situation is not something you will achieve with a sporty street driving in a few hour drive, so once again it is expected for street driven cars to fill left OCC sooner. On other hand, driving on a race track, if you do about 40 laps and lap is about 5km long, that's 200km in total and if we assume you are on full throttle for more than 50% of a time (accelerating) as the other 50% is light load situation (braking, coasting), than the right OCC will fill up significantly faster than the left.
@Alipapa 600km without any signs of oil or at least water in the left OCC seems unreasonable. All connected right? Any pics of connected piping?
Your OCC findings seem pretty reasonable. As mentioned before, left OCC is responsible for oil filtering under light load conditions and right OCC, under boost conditions. 5 hours of drive in your case, is mostly light load situation and even if you go in to a boost situation you're not there for long, so dry right OCC is acceptable while left liek you mentiond should have a bit something in it. In my case above, about 50km of dyno running, was pretty much boost condition all the time. So in my case, left OCC had mostly condensed water with some light oil in it and the right OCC caught quite some oil with minor signs of water in it, considering quite short period time of running. But of course 50 km of boost situation is not something you will achieve with a sporty street driving in a few hour drive, so once again it is expected for street driven cars to fill left OCC sooner. On other hand, driving on a race track, if you do about 40 laps and lap is about 5km long, that's 200km in total and if we assume you are on full throttle for more than 50% of a time (accelerating) as the other 50% is light load situation (braking, coasting), than the right OCC will fill up significantly faster than the left.
@Alipapa 600km without any signs of oil or at least water in the left OCC seems unreasonable. All connected right? Any pics of connected piping?
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I did notice it looked like Rudi had removed his as well. I don't think I can fit the engine cover back on without modification but I take it off when I go to the track so I don't care if I can't use it anymore.
Thanks, I will take these brackets off next time I work on the car.
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@Alipapa
Like a proverb says. If there is no oil on the floor under Alfa Romeo, then there is no oil in the engine either.
Joke aside... Left side OCC looks connected correctly and right side OCC looks connected correctly as well (OCC out is probably connected to preturbo pipe - check the picture below). The only reasonable explanation for system not being operative is squished hose either by engine cover, sharp bend or over tightened zip tie. Or the other way around, the connections not being tight enough and causing vacuum leak preventing the OCC system to work. First, please check any potentially tight spots preventing flow and then check the connections for possible vacuum leak.
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Like a proverb says. If there is no oil on the floor under Alfa Romeo, then there is no oil in the engine either.
Joke aside... Left side OCC looks connected correctly and right side OCC looks connected correctly as well (OCC out is probably connected to preturbo pipe - check the picture below). The only reasonable explanation for system not being operative is squished hose either by engine cover, sharp bend or over tightened zip tie. Or the other way around, the connections not being tight enough and causing vacuum leak preventing the OCC system to work. First, please check any potentially tight spots preventing flow and then check the connections for possible vacuum leak.
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I installed mine last weekend and just had a chance to get the car out for a decent run (1hr). Oil has not hit the can but I was able to find a significant amount of oil up inside the interior walls and on the filter element so the system is definitely working. I assume once those areas hit saturation point it will start dripping down and filling the can. Makes total sense with a brand new setup and filter. Happy so far!
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Okay... As promised... I know many of you in the northern hemisphere have locked your cars away for the winter, but that just means it is TRACK time for us Houstonians. I didn't get my full weekend of tracking because of an issue, but I did get 2 mild sessions, and 3 hard sessions in. (~25 minute sessions). The oil catch can system worked very VERY well.
Right Can (High Boost)
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Left Can (Sedate Driving)
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Both cans worked very well, and did their job. As normal with OCC, the fluid is a mix of oil and water condensate. There was probably 25 - 40 ml in the right can and 50 - 75ml in the left.
I know that @GMS asked about the screen or porous media, I say keep the filter we have. No need to swap, as it appears to be doing its job well.
So bottom line for fellow owners, JUST BUY IT! It works well, well designed, and can be easily accessed when the engine is very hot from a track session without worrying about spilling the oil and causing a fire.
Right Can (High Boost)
Left Can (Sedate Driving)
Both cans worked very well, and did their job. As normal with OCC, the fluid is a mix of oil and water condensate. There was probably 25 - 40 ml in the right can and 50 - 75ml in the left.
I know that @GMS asked about the screen or porous media, I say keep the filter we have. No need to swap, as it appears to be doing its job well.
So bottom line for fellow owners, JUST BUY IT! It works well, well designed, and can be easily accessed when the engine is very hot from a track session without worrying about spilling the oil and causing a fire.
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