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Catch cans

20K views 55 replies 20 participants last post by  Hemissary 
#1 · (Edited)
I dont have one so I'm supposed too be sucking gobs of to into my engine. However, I fill with 7qts but whenever I check the dipstick on oil-hanging day, the level is maybe two hairs down from the max level. These things are frauds.

I conclude the only engines on which catch cans catch cans catch oil are beat and near death.
 
#3 ·
I conclude the only engines on which catch cans catch cans catch oil are beat and near death.
Your conclusion is not only wrong but an ignorant statement as well. I will almost fill my catch can between oil changes and my engine is far from death.
 
#5 · (Edited)
As accurate as your observations are about the actual losses / dipstick level, it'll still make some folks butt hurt :^)

 
#9 ·
I have one and it works as it should. [emoji849]Does everyone need one, no.... in warm weather I can go months and not have to drain it(oil). With cold weather (40 deg down) I will have to drain it once a week, not from oil but mostly water. That's driving about 250 miles weekly. It's not worth having one in my case. And if I take the 4 ozs the can holds and divide the by the 250 miles worth of engine rotations... I have no clue what that would be but that 4 oz would make no difference to my engine.

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#27 ·
I have one and it works as it should. [emoji849]Does everyone need one, no.... in warm weather I can go months and not have to drain it(oil). With cold weather (40 deg down) I will have to drain it once a week, not from oil but mostly water. That's driving about 250 miles weekly. It's not worth having one in my case. And if I take the 4 ozs the can holds and divide the by the 250 miles worth of engine rotations... I have no clue what that would be but that 4 oz would make no difference to my engine. Sent from my iPhone using Scat Pack Forums
I believe the condensation would freeze in the winter. Would internal ice completely block the airflow through the catch can?
 
#11 ·
In my Hellcat I emptied a nearly full Billet Technology catch can just before getting an oil change.
 
#15 ·
What else is Santa gonna do when it hot out...
 
#18 ·
Visual evidence that catch cans are simply not doing anywhere near as much as people really wish to believe...
 
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#20 · (Edited)
Visual evidence of my catch can doing exactly what I bought it to do.
I agree catch cans are successful at collecting a portion(!) of aerated oil / water that resides in the crankcase.

If you were to take your intake manifold off your car and saw the same oil residue as seen in punisher69's pics, that is present all the way to the intake valve, would you consider that an issue?

 
#23 · (Edited)
Here's mine after 38k , with the cheapest(used) catch can I could find for engine bling , because I'm well aware they are not needed on our engine. Direct port , sure , forced induction, sure. NA Hemi , no sir. But I got it for 60$ and it looks good. I don't think the intake or the heads would look any different had I not had a can.

Here's the heads :


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#24 ·
IMO, catch cans do help, probably more in the winter months, especially in damp/wet weather areas. Here's mine off both my early Hemi's....05 LX (83K), and 06 Hemi Jeep with with just over 100K on it. I pulled them all to install new seats, port/polish and mill .030 in. off to increase the compression about a half point. The LX has run synthetic oil (Mobil One) since about 5K and had a catch can since about 10K. The Jeep most likely ran dino. oil without a catch can for the first 49K. After that it had nothing but Mobil One synthetic and a catch can. The crap in the intake ports of the Jeep heads was sticky....like crude oil. Notice the LX heads are almost totally clean and free of any crap.

Gas Composite material Automotive exterior Bumper Auto part
Automotive tire Circuit component Font Audio equipment Engineering
 
#28 ·
I have never seen it frozen.. I could only guess the oil vapor may lower the freeze point. I have the inlet side pitched down towards the can, so that any vapor that could condense would still flow to the can. Outlet is pitched up .... I would like to think the engine bay temp would keep the line from freezing, long enough that the hoses have time to clear mostly any vapor/con.
I will definitely check the can early morning before startup this winter.


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#29 ·
My experience with them on these motors seems to indicate that the "caught" oil is proportional to the amount of horsewhipping you do to your motor.

I put a half inch of oil in my 5.7 Charger can, from one day at Laguna Seca (that was five track sessions of 45 minutes each).

Barely put anything in it while driving sanely - this all in Calif. If you drive it like you stole it 100% of the time, might be worth it.
 
#31 ·
The condensation present within the engine crankcase at start-up is never present at shut-down...let's see if anyone can figure out why.
 
#32 ·
Elementary thermodynamics and phases of water
 
#33 · (Edited)
The sequence of events is what I was eluding to:
- Start car on a sub-zero morning
- As engine heats up, condensate returns to a gaseous form and is carried along with some aerated oil / blow-by, past the PCV valve on its way to the combustion process
- A portion(!) is captured by a relatively cold catch can, returns to water form (because the tubing / container is cold). If someone elects to look in a catch can at this point, without(!) the understanding of what is happening...they sh!t their pants and point to how "important" a catch can is (FYI - it ain't)
- As engine / crankcase contents / catch can continue to warm up, within short order 100% of any condensate or water evaporates and enters the combustion process including any H2O in the catch can
- When vehicle is shut down and allowed to cool back to ambient, more condensate than people realize (a good analogy is all the water that exists the cold exhaust system) - once again re-develops on all inside surfaces including(!) the transmission / differential / fuel tank. This happens every single day - winter or summer

The water / condensate is harmless...difficult to believe for those who don't know better. Engine oil detergents and additives are designed to address internal components, hence why(!) it is important to change the oil - even if the vehicle has been parked for months and is subject to ambient weather / temperature deltas (detergents / additives wear out - even when not driven hence why Owner's Manuals xxxxx mileage or six months - whichever comes first).

Once again...when the touchie-feelie innuendo associated with catch cans is exposed for what it is, there isn't much validity / viability left (FA; slightly different story - especially when the engine has not been designed for higher than expected cylinder pressures)...

Edit: where the above sequence can go awry is when the driving distance does not allow the engine components to reach temperatures that force evaporation.

p.s. anyone who insists on starting up a car that has been parked for the winter - are doing everything a disservice (including the battery) - another example of a touchie-feelie exercise that is hurting significantly more than helping anything under the hood - whatsoever.

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#35 ·
The emotionally-driven marketing / peddling that lies - and those who elect to pile on from an emotional POV - are also the problem...
 
#36 · (Edited)
I’m not sure what those pictures prove on such low mileage cars. The test is after 100,000 miles. If it made a difference after 30,000 miles then they would put them on from the factory. After warranty if it loses some power they don’t care.
I built mine out of a mason jar and a couple plastic nipples. It collects a bit of nastiness and I’m glad I have it. I don’t want that stuff caking in the back of the valves.


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#38 ·
I'm not sure what those pictures prove on such low mileage cars. The test is after 100,000 miles. If it made a difference after 30,000 miles then they would put them on from the factory. After warranty if it loses some power they don't care.
I built mine out of a mason jar and a couple plastic nipples. It collects a bit of nastiness and I'm glad I have it. I don't want that stuff caking in the back of the valves.

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<laughing> installing a catch can will not reduce build-up. The amount of aerated crankcase contents still being ingested will deposit whatever it decides to deposit. You can keep dreaming it does though :^D

Regrettably catch cans have no real way of stopping "backflow" from catch can to intake.
When you are NA and running down the road....the manifold intake pressure is negative and that actually is negative on the line from the catch can also, so some vapors are stlll getting "sucked" into the intake as they enter the catch can, before they condense.
The negative pressure in the intake runner is not low enough to suck the liquid from the catch can, but vapor yes.
Exactly :^)
 
#37 · (Edited)
Regrettably catch cans have no real way of stopping "backflow" from catch can to intake.
When you are NA and running down the road....the manifold intake pressure is negative and that actually is negative on the line from the catch can also, so some vapors are stlll getting "sucked" into the intake as they enter the catch can, before they condense.
The negative pressure in the intake runner is not low enough to suck the liquid from the catch can, but vapor yes.
 
#39 ·
However, I would much rather catch what oil I can in the catch can, than burn it through the chamber....
 
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