Catch Can question
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Le Mans Master
Joined: Aug 2000
Posts: 6,273
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From: Austin TX
Catch Can question
I installed the Elite Engineering catch can on my 99 about 6 weeks ago and checked it for quantity collected over the weekend.
Not too much in the can -not surprising since I rarely wind above 5,000 RPM.
But the surprising thing was that the viscosity of the oil that was caught was considerably higher than the Mobil 1 10W30 in the crankcase - I'd guess that the viscosity of the oil in the catch can was 50 or 60.
Any ideas as to why that would be?
Not too much in the can -not surprising since I rarely wind above 5,000 RPM.
But the surprising thing was that the viscosity of the oil that was caught was considerably higher than the Mobil 1 10W30 in the crankcase - I'd guess that the viscosity of the oil in the catch can was 50 or 60.
Any ideas as to why that would be?
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I have an EE catch can on mine and the oil that is deposited in the can appears to be the same viscosity as that in the crankcase. Don't know why it would change.
Race Director
Joined: Dec 2000
Posts: 19,304
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From: San Diego CA
2 reasons:
1. If you mount your can in a high temp area, especially if the can is connected to the engine with a metallic mounting bracket, any moisture in the blowby gasses will stay in "suspension" and get pulled into your intake.
2. Small oil droplets of <5-10 microns are swimming their way around the steel wool fibers, leaving the larger droplets behind.
Rule of thumb: If you want your catch can to "catch" more oil and water, keep it in a cool area.
1. If you mount your can in a high temp area, especially if the can is connected to the engine with a metallic mounting bracket, any moisture in the blowby gasses will stay in "suspension" and get pulled into your intake.
2. Small oil droplets of <5-10 microns are swimming their way around the steel wool fibers, leaving the larger droplets behind.
Rule of thumb: If you want your catch can to "catch" more oil and water, keep it in a cool area.
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
2 reasons:
1. If you mount your can in a high temp area, especially if the can is connected to the engine with a metallic mounting bracket, any moisture in the blowby gasses will stay in "suspension" and get pulled into your intake.
2. Small oil droplets of <5-10 microns are swimming their way around the steel wool fibers, leaving the larger droplets behind.
Rule of thumb: If you want your catch can to "catch" more oil and water, keep it in a cool area.
1. If you mount your can in a high temp area, especially if the can is connected to the engine with a metallic mounting bracket, any moisture in the blowby gasses will stay in "suspension" and get pulled into your intake.
2. Small oil droplets of <5-10 microns are swimming their way around the steel wool fibers, leaving the larger droplets behind.
Rule of thumb: If you want your catch can to "catch" more oil and water, keep it in a cool area.
Race Director
Joined: Dec 2000
Posts: 19,304
Likes: 85
From: San Diego CA
Here's just one article entitled: "What is the impact of ambient temperature?" (on filter efficiency) by Atlas Copco
To aggravate this situation, synthetic oil is more slippery than conventional oil, making it even more difficult to trap at higher temps. Keep in mind that blowby gas temps can climb well past 150F. Of course, the statements made by the folks at Atlas Copco refer to oil generated by a typical oiled compressor but our engines are really not much different from said oiled piston compressor and catch can filter media is trying to do the same thing that compressed air filters are doing, but under different pressure conditions. However, whether airborn oil is pulled or pushed doesn't change the fact that hot oil is harder to filter than cooler oil.
Zorlac, longer hoses will create a very slight vacuum pressure change, but not enough to worry about. You can always run 1/2" inside diameter hose if you'd like.
One aspect of influencing efficiency and purity of air systems is temperature. When using oil-injected compressors with oil-removal filters, oil carryover through filter media increases exponentially according to the temperature at the filtration interface.
Filter performance is often specified at 20 degess C (68F). If the ambient temperature in the compressor room increases to 30C (86F), the compressor outlet temperature could be 40C (104F) with oil carryover 20 times the specified value. Temperatures also cause an increase in the vapor content of the air, which can carry through to the end product.
Filter performance is often specified at 20 degess C (68F). If the ambient temperature in the compressor room increases to 30C (86F), the compressor outlet temperature could be 40C (104F) with oil carryover 20 times the specified value. Temperatures also cause an increase in the vapor content of the air, which can carry through to the end product.
Zorlac, longer hoses will create a very slight vacuum pressure change, but not enough to worry about. You can always run 1/2" inside diameter hose if you'd like.
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
Here's just one article entitled: "What is the impact of ambient temperature?" (on filter efficiency) by Atlas Copco
To aggravate this situation, synthetic oil is more slippery than conventional oil, making it even more difficult to trap at higher temps. Keep in mind that blowby gas temps can climb well past 150F. Of course, the statements made by the folks at Atlas Copco refer to oil generated by a typical oiled compressor but our engines are really not much different from said oiled piston compressor and catch can filter media is trying to do the same thing that compressed air filters are doing, but under different pressure conditions. However, whether airborn oil is pulled or pushed doesn't change the fact that hot oil is harder to filter than cooler oil.
Zorlac, longer hoses will create a very slight vacuum pressure change, but not enough to worry about. You can always run 1/2" inside diameter hose if you'd like.
To aggravate this situation, synthetic oil is more slippery than conventional oil, making it even more difficult to trap at higher temps. Keep in mind that blowby gas temps can climb well past 150F. Of course, the statements made by the folks at Atlas Copco refer to oil generated by a typical oiled compressor but our engines are really not much different from said oiled piston compressor and catch can filter media is trying to do the same thing that compressed air filters are doing, but under different pressure conditions. However, whether airborn oil is pulled or pushed doesn't change the fact that hot oil is harder to filter than cooler oil.
Zorlac, longer hoses will create a very slight vacuum pressure change, but not enough to worry about. You can always run 1/2" inside diameter hose if you'd like.
I understand from your post why hot synthetic oil may be difficult to catch but I'm not understanding how that affects the viscosity of the oil that is caught.
W
Race Director
Joined: Dec 2000
Posts: 19,304
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From: San Diego CA
W,
Blowby gasses are commonly made up of 60% water. When you catch that water, the oil appears to be thinner. In your case, you are catching only the largest (and heaviest) oil droplets, leaving the smaller (lighter stuff) to head over to your intake. (at least that's my theory.)
Dave
Blowby gasses are commonly made up of 60% water. When you catch that water, the oil appears to be thinner. In your case, you are catching only the largest (and heaviest) oil droplets, leaving the smaller (lighter stuff) to head over to your intake. (at least that's my theory.)
Dave
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Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
W,
Blowby gasses are commonly made up of 60% water. When you catch that water, the oil appears to be thinner. In your case, you are catching only the largest (and heaviest) oil droplets, leaving the smaller (lighter stuff) to head over to your intake. (at least that's my theory.)
Dave
Blowby gasses are commonly made up of 60% water. When you catch that water, the oil appears to be thinner. In your case, you are catching only the largest (and heaviest) oil droplets, leaving the smaller (lighter stuff) to head over to your intake. (at least that's my theory.)
Dave
Race Director
Joined: Dec 2000
Posts: 19,304
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From: San Diego CA
Oil "fog" always contains a mixture of small and large droplets. This is true no matter what type of oil we're talking about. Typical wire mesh pads need to be large enough in diameter so that they don't corrode away to nothing over time, yet the larger the wire diameter, the easier it is for small droplets to get past that wire.
