Pat Goss on GDI / low tension p. rings / catch can

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I surely would not recommend catch cans. I have one on my airplane and it dumps the crankcase ventilation overboard. When it's cold, it drips out milky death. They are known to freeze over too since there is moisture in the oil. If you live in colder climates I believe this will become an issue.
 
Originally Posted By: A_Harman
I think there has to be a way to pull the blowby gases through the system, such as an electric AIR pump. I worry about losing the "Positive" aspect of PCV.


Lose the bottle and run the tube to your exhaust. Keep the fresh air inlet from after the air filter to the valve cover.
Done
smile.gif
 
Originally Posted By: Olas
Originally Posted By: A_Harman
I think there has to be a way to pull the blowby gases through the system, such as an electric AIR pump. I worry about losing the "Positive" aspect of PCV.


Lose the bottle and run the tube to your exhaust. Keep the fresh air inlet from after the air filter to the valve cover.
Done
smile.gif



Yes, I've thought of that. If I put the feed into the exhaust far downstream of the O2 sensors, maybe it won't affect the readings.
 
Originally Posted By: A_Harman
Originally Posted By: Joe90_guy
A catch-pot, just like a complex PCV oil separator, will not prevent oil recirulation/burning problems unless some effort is made to cool (or alternatively compress) the volatalised oil out of the vapour phase and into the liquid phase where it can be mechanically separated. Rather than having a catch-pot, you want a 'condensation pot' where the condensate (mainly oil) can be returned to the sump.

It strikes me that these things would function far more effectively if they were designed by chemical engineers rather than mechanical engineers. Oil refiners do this kind of thing all the time but on a far larger scale...


I've been thinking that the catch cans should be stuffed full of stainless steel wool, or some kind of non-corrosive mesh that would catch the pulverized oil, consolidate the drops and let it drain to the bottom of the can. Don't know how to take care of the water vapor that comes in the crankcase gases along with the oil mist. Having the water mixed with the oil would make it a definite no-no to drain the catch can into the sump. Maybe heat the catch can to boil off the water?

I have modified the PCV system on my high-miles Camaro. I was having a lot of trouble with detonation occurring on hard acceleration after long periods of idle or low-power operation. I theorized that the foul air tube running to the intake manifold was carrying oil, and causing the detonation, so I disconnected it and capped the fitting on the manifold. I ran the hose into a catch bottle, and it solved the detonation problem. On the first track day that I did with this setup, I checked the level in the bottle, and found 4-6 ounces of oil in it after every session.

I was satisfied that I was keeping this much oil from going through the combustion chambers, eliminating the possibility of detonation. During subsequent track days, the amount of oil being carried into the catch bottle got less and less to the point that it was only catching the "dirty-whipped cream" water-oil emulsion. The engine runs noticeably better now, probably freeing up stuck rings.

A problem that I found running the PCV into the catch bottle was that over 2-3 months of street driving (low-rpm, low-power, day after day in the winter) was that it would fill up with the dirty whipped cream, and start belching that stuff out into the engine compartment. I think there has to be a way to pull the blowby gases through the system, such as an electric AIR pump. I worry about losing the "Positive" aspect of PCV.



I'm going say something silly to make a serious point.

Let's say you're running your engine on the ultimate non-volatile oil, combustion is perfect (so no unburnt fuel) and separation of blow-by gas and engine oil is perfect. The blow-by gases leaving the engine now only contain nitrogen and oxygen (from the intake air) and carbon dioxide and water as the only products of combustion. The gas is hot; say 100C. Now let's say you want to remove the water from the blow-by. It's the least volatile component so you know it should be removable. You run this through a catch pot containing wire wool. Does it remove the water? No, not a drop. Why? It's because water, at 100C, is fully in the vapour phase and mechanical traps don't function on pure gases.

However if you cool the blow-by to say 10C, you go below the gas dewpoint and minute droplets of water appear in the blow-by. Repeat the exercise and this time you remove most (but importantly not all) of the water by putting it through the wire wool catch-pot.

When most folks think of oil in blow-by, they tend to 'see' that smelly smoke which does indeed contain some entrained oil droplets (which is why you can see the smoke in the first place). However what they fail to imagine is that part of the oil that is invisible because it exists as a pure gas. Normally this shouldn't happen but if for whatever reason, you have fuel dilution, this will happen. Just as with the 'perfect' example above, mechanical separation devices (eg wire wool) won't work if the oil exists as a gas but will work if you cool the blow-by and condense out the oil.

If it helps any, I think this is the essential point that Audi's engineers failed to comprehend on their 2.0L TFSI engine and why catch-pots didn't fix their problems.
 
Originally Posted By: Joe90_guy
Originally Posted By: A_Harman
Originally Posted By: Joe90_guy
A catch-pot, just like a complex PCV oil separator, will not prevent oil recirulation/burning problems unless some effort is made to cool (or alternatively compress) the volatalised oil out of the vapour phase and into the liquid phase where it can be mechanically separated. Rather than having a catch-pot, you want a 'condensation pot' where the condensate (mainly oil) can be returned to the sump.

It strikes me that these things would function far more effectively if they were designed by chemical engineers rather than mechanical engineers. Oil refiners do this kind of thing all the time but on a far larger scale...


I've been thinking that the catch cans should be stuffed full of stainless steel wool, or some kind of non-corrosive mesh that would catch the pulverized oil, consolidate the drops and let it drain to the bottom of the can. Don't know how to take care of the water vapor that comes in the crankcase gases along with the oil mist. Having the water mixed with the oil would make it a definite no-no to drain the catch can into the sump. Maybe heat the catch can to boil off the water?

I have modified the PCV system on my high-miles Camaro. I was having a lot of trouble with detonation occurring on hard acceleration after long periods of idle or low-power operation. I theorized that the foul air tube running to the intake manifold was carrying oil, and causing the detonation, so I disconnected it and capped the fitting on the manifold. I ran the hose into a catch bottle, and it solved the detonation problem. On the first track day that I did with this setup, I checked the level in the bottle, and found 4-6 ounces of oil in it after every session.

I was satisfied that I was keeping this much oil from going through the combustion chambers, eliminating the possibility of detonation. During subsequent track days, the amount of oil being carried into the catch bottle got less and less to the point that it was only catching the "dirty-whipped cream" water-oil emulsion. The engine runs noticeably better now, probably freeing up stuck rings.

A problem that I found running the PCV into the catch bottle was that over 2-3 months of street driving (low-rpm, low-power, day after day in the winter) was that it would fill up with the dirty whipped cream, and start belching that stuff out into the engine compartment. I think there has to be a way to pull the blowby gases through the system, such as an electric AIR pump. I worry about losing the "Positive" aspect of PCV.



I'm going say something silly to make a serious point.

Let's say you're running your engine on the ultimate non-volatile oil, combustion is perfect (so no unburnt fuel) and separation of blow-by gas and engine oil is perfect. The blow-by gases leaving the engine now only contain nitrogen and oxygen (from the intake air) and carbon dioxide and water as the only products of combustion. The gas is hot; say 100C. Now let's say you want to remove the water from the blow-by. It's the least volatile component so you know it should be removable. You run this through a catch pot containing wire wool. Does it remove the water? No, not a drop. Why? It's because water, at 100C, is fully in the vapour phase and mechanical traps don't function on pure gases.

However if you cool the blow-by to say 10C, you go below the gas dewpoint and minute droplets of water appear in the blow-by. Repeat the exercise and this time you remove most (but importantly not all) of the water by putting it through the wire wool catch-pot.

When most folks think of oil in blow-by, they tend to 'see' that smelly smoke which does indeed contain some entrained oil droplets (which is why you can see the smoke in the first place). However what they fail to imagine is that part of the oil that is invisible because it exists as a pure gas. Normally this shouldn't happen but if for whatever reason, you have fuel dilution, this will happen. Just as with the 'perfect' example above, mechanical separation devices (eg wire wool) won't work if the oil exists as a gas but will work if you cool the blow-by and condense out the oil.

If it helps any, I think this is the essential point that Audi's engineers failed to comprehend on their 2.0L TFSI engine and why catch-pots didn't fix their problems.



So, in essence, what you're saying is the wire wool would maybe catch the oil droplets, and let the water vapor pass through? That would at least be some form of separation between the oil and the water. Of course, everything depends on the temperature of the blowby gases coming through the hose. Your number of 100C is just a guess. And if the catch can is in the engine compartment separated from the engine, the blowby gases would be considerably cooler than when they came into the crankcase.

Cooling the crankcase vapors would require another circuit on the air conditioning system, which would add cost, and would increase parasitic power loss from running the AC to get air/oil separation. But it may be worthwhile to keep from getting oil into the combustion chambers of downsized boosted DI gasoline engines. OEM's are running in fear of Stochastic PreIgnition, and lube oil in the charge is one of the main culprits.
 
I think this is much about nothing.

I researched this, caught the direct injection scare , but then I learned more about my "at risk" engine.

Within my direct injected, turbocharged engine, is a blow by pathway in the engine block,check valves to prevent vapors and condensation from going where you wouldn't want the and map controlled intake ports among other things. Also high mileage records and anectdotes are coming in with low levels of deposits.

Manufacturers in most cases have addressed the issue. I think a catch can would be a bad idea unless I remapped and upped my boost. Which I have no use for.
 
I think it's one thing to consider if you have evidence of oil in the intake...

I see he mounted it up front so it's near cooling system temps. I'd be more inclined to mount it in front of the radiator support so it was even cooler (ambient outside air temp)
smile.gif


You don't need to use Moroso, but they do make nice stuff. I'm sure their kit comes with nice brackets and is pretty easy to install
smile.gif
 
A Harman,
I've got a little experience in trying to catch the droplet phase stuff...have a look at the top of the turbine house here
http://www.spec-net.com.au/press/0509/cly_200509.htm

and see the four streaks across the roof, they are residue of the oil mist that comes out of the turbine main oil tank...bane of every turbine engineer's existance, as you can see the oil mist from the car park, and it leaves mess everywhere.

OEM came with a wire packed separator, which did a poorly decent job, big advantage being low restriction, but the couple of micron particles still whip through.

Using "coalescing filters" in their place grabbed all of the particles, but rapidly produce a high DP, requiring the filter to be paritally bypassed...didn't seem to matter how much filter surface area we provided, they'd blind (doing their job), and have to be in bypass.

My view for collection the droplet phase is that you need an impingement surface where the gasses are forced to violently change direction, and oil has a chance to impact and form a film...after that, steel wool, made up of layers with baffle plates to change direction a few times and extend the tortuous path.

The vapor phase ?

Go with Joe90_guy.

Here's a Honda paper on some of their systems.

https://www.hondarandd.jp/point.php?sid=41&pid=1027&did=1027&lang=en
 
Originally Posted By: Shannow
A Harman,
I've got a little experience in trying to catch the droplet phase stuff...have a look at the top of the turbine house here
http://www.spec-net.com.au/press/0509/cly_200509.htm

and see the four streaks across the roof, they are residue of the oil mist that comes out of the turbine main oil tank...bane of every turbine engineer's existance, as you can see the oil mist from the car park, and it leaves mess everywhere.

OEM came with a wire packed separator, which did a poorly decent job, big advantage being low restriction, but the couple of micron particles still whip through.

Using "coalescing filters" in their place grabbed all of the particles, but rapidly produce a high DP, requiring the filter to be paritally bypassed...didn't seem to matter how much filter surface area we provided, they'd blind (doing their job), and have to be in bypass.

My view for collection the droplet phase is that you need an impingement surface where the gasses are forced to violently change direction, and oil has a chance to impact and form a film...after that, steel wool, made up of layers with baffle plates to change direction a few times and extend the tortuous path.

The vapor phase ?

Go with Joe90_guy.

Here's a Honda paper on some of their systems.

https://www.hondarandd.jp/point.php?sid=41&pid=1027&did=1027&lang=en


I did a similar thing with a very worked Ford Cleveland.
I was running the PCV against the recommendations of all and sundry. The hot trend is to run a catch can.
I was getting very high oil consumption when the engine was opened up(high RPM's with large throttle openings).
The oil was literally pooling in the bottom of the inlet and being mixed with the intake charge below the Carb.
The runners and backs of the intake valves were quite wet-damp with oil.

Drawing on my Marine Engineering background with water vapour separating screens of incoming air to the engines(Salt water mist is a quick death to highly developed Marine Diesel engines).
The screens use a series of rapid change of direction and small scoops to separate the water mist from the incoming air and drain it overboard.

I modified the area around the PCV pick up inside the Rocker cover complete with an integrated dripper at the bottom of the baffling to allow the condensed oil to run down and away from the opening, then fall back into the flowing oil gathered in low parts the inside of the rocker cover.
The intention was to attempt to imitate the action of the screening on the boats.

The system worked very, very well, and reduced the oil consumption to about half but couldn't really bring it down to an acceptable level.

Coming back to the title and subject matter of the thread.
At the end of the day, it was revealed the engine builder had spec'd and ordered the wrong ring diameter by mistake because they failed to take into consideration the actual bore diameter of this particular engine.
The result was ring tension on the very bottom side of acceptable even though the intension was for low tension rings.

The final remedy was to do a rebuild with much better consideration to the final ring tension by altering the ring pack slightly.
Oil consumption issues were completely cured at that point with no catch can.
 
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Originally Posted By: A_Harman
Originally Posted By: Joe90_guy
Originally Posted By: A_Harman
Originally Posted By: Joe90_guy
A catch-pot, just like a complex PCV oil separator, will not prevent oil recirulation/burning problems unless some effort is made to cool (or alternatively compress) the volatalised oil out of the vapour phase and into the liquid phase where it can be mechanically separated. Rather than having a catch-pot, you want a 'condensation pot' where the condensate (mainly oil) can be returned to the sump.

It strikes me that these things would function far more effectively if they were designed by chemical engineers rather than mechanical engineers. Oil refiners do this kind of thing all the time but on a far larger scale...


I've been thinking that the catch cans should be stuffed full of stainless steel wool, or some kind of non-corrosive mesh that would catch the pulverized oil, consolidate the drops and let it drain to the bottom of the can. Don't know how to take care of the water vapor that comes in the crankcase gases along with the oil mist. Having the water mixed with the oil would make it a definite no-no to drain the catch can into the sump. Maybe heat the catch can to boil off the water?

I have modified the PCV system on my high-miles Camaro. I was having a lot of trouble with detonation occurring on hard acceleration after long periods of idle or low-power operation. I theorized that the foul air tube running to the intake manifold was carrying oil, and causing the detonation, so I disconnected it and capped the fitting on the manifold. I ran the hose into a catch bottle, and it solved the detonation problem. On the first track day that I did with this setup, I checked the level in the bottle, and found 4-6 ounces of oil in it after every session.

I was satisfied that I was keeping this much oil from going through the combustion chambers, eliminating the possibility of detonation. During subsequent track days, the amount of oil being carried into the catch bottle got less and less to the point that it was only catching the "dirty-whipped cream" water-oil emulsion. The engine runs noticeably better now, probably freeing up stuck rings.

A problem that I found running the PCV into the catch bottle was that over 2-3 months of street driving (low-rpm, low-power, day after day in the winter) was that it would fill up with the dirty whipped cream, and start belching that stuff out into the engine compartment. I think there has to be a way to pull the blowby gases through the system, such as an electric AIR pump. I worry about losing the "Positive" aspect of PCV.



I'm going say something silly to make a serious point.

Let's say you're running your engine on the ultimate non-volatile oil, combustion is perfect (so no unburnt fuel) and separation of blow-by gas and engine oil is perfect. The blow-by gases leaving the engine now only contain nitrogen and oxygen (from the intake air) and carbon dioxide and water as the only products of combustion. The gas is hot; say 100C. Now let's say you want to remove the water from the blow-by. It's the least volatile component so you know it should be removable. You run this through a catch pot containing wire wool. Does it remove the water? No, not a drop. Why? It's because water, at 100C, is fully in the vapour phase and mechanical traps don't function on pure gases.

However if you cool the blow-by to say 10C, you go below the gas dewpoint and minute droplets of water appear in the blow-by. Repeat the exercise and this time you remove most (but importantly not all) of the water by putting it through the wire wool catch-pot.

When most folks think of oil in blow-by, they tend to 'see' that smelly smoke which does indeed contain some entrained oil droplets (which is why you can see the smoke in the first place). However what they fail to imagine is that part of the oil that is invisible because it exists as a pure gas. Normally this shouldn't happen but if for whatever reason, you have fuel dilution, this will happen. Just as with the 'perfect' example above, mechanical separation devices (eg wire wool) won't work if the oil exists as a gas but will work if you cool the blow-by and condense out the oil.

If it helps any, I think this is the essential point that Audi's engineers failed to comprehend on their 2.0L TFSI engine and why catch-pots didn't fix their problems.



So, in essence, what you're saying is the wire wool would maybe catch the oil droplets, and let the water vapor pass through? That would at least be some form of separation between the oil and the water. Of course, everything depends on the temperature of the blowby gases coming through the hose. Your number of 100C is just a guess. And if the catch can is in the engine compartment separated from the engine, the blowby gases would be considerably cooler than when they came into the crankcase.

Cooling the crankcase vapors would require another circuit on the air conditioning system, which would add cost, and would increase parasitic power loss from running the AC to get air/oil separation. But it may be worthwhile to keep from getting oil into the combustion chambers of downsized boosted DI gasoline engines. OEM's are running in fear of Stochastic PreIgnition, and lube oil in the charge is one of the main culprits.



In answer to you questions...

Because of the way the gas laws work, it's almost impossible to get fuel, water and oil to separate cleanly. At a given temperature, every component will exert it's own vapour pressure and each component will exert that vapour pressure in proportion to it's molar percentage in the blow-by gas (sorry, that's the easy version! Reality is far more complex). Ideally, you would condense and reflux the blow-by until you could separate pure liquid oil (and return it to the sump) and allow gaseous water, evaporated fuel and combustion gas through the PCV and into the intake system. This would be far too complex to engineer so the most you can hope for is single separation stage.

As regards blow-by cooling, I'm no automotive engineer but I would have thought something simple could be done to cool the blow-by without absorbing too much mechanical energy.

The first thing I'd look at is partially replacing the rubber hoses currently used. If your objective is to keep the blow-by hot, then rubber is a brilliant insulator. A metal hose, preferably with metal cooling fins on the outside and hedgehog like metal 'spikes' on the inside might effect a degree of cooling. Also I'd look hard at where the blow-by was drawn from the engine; preferably you want it close to the fan (especially if the hosing contained my metal, ribbed, hedgehog thingy!) to get it in the cold air flow.

Once you've got the blow-by cool then any simple form of oil droplet removal (wire wool, baffles, cyclone) will work.

Interestingly I wouldn't worry about returning some water and fuel to the sump. The way the gas laws work, you'll just set up a new vapour-liquid equilibrium position which will push more water and fuel (but not oil) through to the intake system.
 
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Originally Posted By: A_Harman

I ran the hose into a catch bottle, and it solved the detonation problem. On the first track day that I did with this setup, I checked the level in the bottle, and found 4-6 ounces of oil in it after every session.

…... During subsequent track days, the amount of oil being carried into the catch bottle got less and less to the point that it was only catching the "dirty-whipped cream" water-oil emulsion. The engine runs noticeably better now, probably freeing up stuck rings.


And from here
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/2780756

Originally Posted By: pitzel
The key with a direct injection engine is to not change the oil any more frequently than the owners manual or oil life monitor demands (some people think they're 'helping' their engine by changing oil more frequently than spec -- this is wrong, especially for a DI engine!). And pay particular attention to the oil actually used. DIY or physically observing the mechanic/technican pouring sealed bottles of the properly spec'ed oil is best, if you can. Don't just blindly assume the dealer or the quickie lube will use the appropriate, specified lubricant, rather than low-bidder bulk 5W-30 dino that might not meet the latest specs on volatility.

Most of the trouble reported with DI engines and oil, particularly the notorious intake contaminant occlusion issues, has been related to either the use of improper lubricants (either out of ignorance, or out of profit seeking motives by less-than-reputable maintainers). Or the overly frequent changing of oil by good meaning people stuck on maintenance practices more typically recommended 30+ years ago. Old habits die hard, but with DI and the lack of fuel vapour diluting the recirculated crankcase fumes, intake contamination is exacerbated by those extra oil changes.


Originally Posted By: pitzel

The premise is that the intake occlusion/contamination issues are mostly caused by recirculated volatilized products of motor oil depositing on intake components as they mix with fresh intake air and are drawn into the cylinders as part of the intake air charge.

Motor oil volatility is at its peak when the oil is brand new. And declines over time as the oil is in service and is subject to repeated distillation inside the engine under the vacuum imposed on the crankcase by the PCV system.

So to fix the problem, simply minimize the volatility of the oil. By both selecting the least volatile oil as possible. And using that oil in its least volatile condition -- when its been in-service for a while, minimizing the exposure to 'brand-new' oil which is susceptible to higher distillation loss.

In Europe, and even in the manufacturers' labs in the USA, the problems could not be replicated, as manufacturer-recommended maintenance practices were adhered to in the test environment (over-maintenance isn't generally a usual test case!) and the actual European end-user environment. A few years back, I personally did a meta-analysis, on BiTOG, of a lengthy car-proprietary non-BiTOG forum thread where people were complaining of issues -- there was a very strong correlation between improper maintenance practice (too frequent oil changes) and intake contamination.

Also, manufacturers have tightened the volatility spec severely over the past few years in response to the DI intake contamination troubles. Ostensibly because controlling volatility is a significant component to the overall 'solution' to this problem.

Some people have had decent luck with "catch cans" and other inserts to the PCV/breather system. If there's no adverse affect on instrumentation or the normal characteristics, this can be a valid solution albeit requiring additional maintenance. However, it really doesn't address the root cause of too much, and too poor of quality motor oil causing the problem in the first place.


I think Pitzel may have a point. You want a high quality synthetic oil with low Noack, as thick as you can get it for your temperature environment to reduce the light volatiles, then don't change it too frequently as all you are doing is replacing the light fraction in your sump.
 
Originally Posted By: FastLane
I surely would not recommend catch cans. I have one on my airplane and it dumps the crankcase ventilation overboard. When it's cold, it drips out milky death. They are known to freeze over too since there is moisture in the oil. If you live in colder climates I believe this will become an issue.

Yes, the law of unintended consequences, of course. In an airplane, yes, I could see there being issues. In my G37, if I were to use a catch can, it spends the bulk of its life in a heated garage, and the engine and underhood temperatures get very hot very quickly, so it wouldn't be a concern. But, what about something that sits outside all the time in Saskatchewan or Manitoba and only does short trips?
 
Originally Posted By: SR5
....I think Pitzel may have a point. You want a high quality synthetic oil with low Noack, as thick as you can get it for your temperature environment to reduce the light volatiles, then don't change it too frequently as all you are doing is replacing the light fraction in your sump....

I had not read Pitzel's thoughts before but the '"don't change it (oil) too often" and the reasoning makes sense to me.

As for using the thickest oil for ambient temps environment, that one can be a little tricky while under vehicle warranty with only one specific oil spec recommendation.

It could make the Hyundai/Kia recommendation of changing the oil every six months no matter how low the miles to keep warranty, suspect imo.

Thanks for posting Pitzel's quotes.
 
Originally Posted By: user52165
"With what? The VW/Audi cars with the GDI and carbon buildup issues report no real change with or without a can."


As I said - the Hyundai/Kia owners.................. I did not mention VW/Audi.


So what do the cans help the Hyundai/Kia owners with? IIRC their engines don't carbon up like VW/Audi. They do have LSPI issues but I don't think a can helps with that.
 
Originally Posted By: Joe90_guy



In answer to you questions...

Because of the way the gas laws work, it's almost impossible to get fuel, water and oil to separate cleanly. At a given temperature, every component will exert it's own vapour pressure and each component will exert that vapour pressure in proportion to it's molar percentage in the blow-by gas (sorry, that's the easy version! Reality is far more complex). Ideally, you would condense and reflux the blow-by until you could separate pure liquid oil (and return it to the sump) and allow gaseous water, evaporated fuel and combustion gas through the PCV and into the intake system. This would be far too complex to engineer so the most you can hope for is single separation stage.

As regards blow-by cooling, I'm no automotive engineer but I would have thought something simple could be done to cool the blow-by without absorbing too much mechanical energy.

The first thing I'd look at is partially replacing the rubber hoses currently used. If your objective is to keep the blow-by hot, then rubber is a brilliant insulator. A metal hose, preferably with metal cooling fins on the outside and hedgehog like metal 'spikes' on the inside might effect a degree of cooling. Also I'd look hard at where the blow-by was drawn from the engine; preferably you want it close to the fan (especially if the hosing contained my metal, ribbed, hedgehog thingy!) to get it in the cold air flow.

Once you've got the blow-by cool then any simple form of oil droplet removal (wire wool, baffles, cyclone) will work.

Interestingly I wouldn't worry about returning some water and fuel to the sump. The way the gas laws work, you'll just set up a new vapour-liquid equilibrium position which will push more water and fuel (but not oil) through to the intake system.


you could reroute the pcv hose so it follows the ac return line if you want to cool it.

But the OEM are actually adding heaters to the pcv hoses to prev
 
Originally Posted By: Quattro Pete
That goes against everything I've read on this subject. Most say that driving hard actually helps burn off the deposits.


The harder the engine is run, the higher the amount of oil that's going to be sucked into the intake (crankcase pressure will be higher, and more oil will be volatilized due to higher temps and turned into mist via mechanical forces in the crankcase). I've also read about the "Italian tune-up", but I'm not sure I buy that because of what I just mentioned, above.

Originally Posted By: Joe90_guy
A catch-pot, just like a complex PCV oil separator, will not prevent oil recirulation/burning problems unless some effort is made to cool (or alternatively compress) the volatalised oil out of the vapour phase and into the liquid phase where it can be mechanically separated. Rather than having a catch-pot, you want a 'condensation pot' where the condensate (mainly oil) can be returned to the sump.

It strikes me that these things would function far more effectively if they were designed by chemical engineers rather than mechanical engineers. Oil refiners do this kind of thing all the time but on a far larger scale...


The catch cans are still going to be cooler than the environment that the mist/vapor came from (the crankcase). So you're still going to get condensation of oil in the cans, though surely not as much as you would if the cans were actually cooled. Also there will be mechanical separation via the fine brass screens in the filters:

yMdcxlk.jpg


I just bought a 2016 WRX (GDI, turbo) last month. I went ahead and installed a Mishimoto dual catch can system in hopes of reducing intake tract deposits, as well as improving intercooler function and eliminating low-speed pre-ignition (LSPI). In any case, the catch cans can't hurt anything and will almost certainly help.

I'll also be using PPPP 10W-30 (one of the lowest-volatility oils available anywhere, at 4.7% NOACK) when it's time to drain the factory fill.
 
Originally Posted By: Shannow



The vapor phase ?

Go with Joe90_guy.



Why all the concern about water vapour? Water is good.

Nobody ever suffered detonation or dirty valve backs because of water vapour, nor liquid water neither.

Oil vapour'd be OK too (apart from maybe a bit of detonation risk) if you could keep it in the vapour phase, but I suppose that's difficult to achieve.

Keeping it hot or getting it cold both seem to be valid blowby management regimes. I'd guess the problem area is in between.
 
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Originally Posted By: itguy08
I lost respect for Pat with this article. Catch cans do nothing for the deposits. Ask the VW/Audi guys.


+1 I never liked him. He looks like he spends more time at Mcdonalds than under the hood now a days.
 
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