[GI] Ultimate catch cans

[cjthor]

For an outlet dont you just unscrew the lid and pour it out?

[Mnemonic]

yea for getting the gunk you would, but what about the good oil that is caught? how do you get that back to the engine? pull the can out and pour it back into the engine?

[tehbrookzorz]

I've actually addressed that topic in conversation with fowljesse.

His concern was the added cost and difficulty in tapping in a return line to the oil pan. It would not be terribly difficult to add the fitting or petcock to the bottom of his catch can. For those who are turbocharged, and have an oil drain line in place already, I don't foresee it being too hard to tee into the drain line.

It's interesting to muse on, anyway.

[Mnemonic]

Even with his design, I think it would be best to remove that hose, that a way its a bit more functional at keeping the air/oil separated. If you get enough oil to cover the opening of the hose with air/pressure it will just push the oil back out the hose instead of leaving it caught at the bottom of the tank.

Imagine it like this, you and your girl get a soft drink with 2 straws, she decides to be silly and instead of drinking the drink she blows into it, with the pressure coming through it would push the soda out of the other straw and into your eye. You have a similar design going on here.

[tehbrookzorz]

You're going to make me pull out all the stops here.

I had thought about the possibility of reduced flow-through as well. I'm not sure if vacuum would actually draw oil out of the tube, but a submerged inlet tube would definitely cause some form of problem. Fowljesse didn't seem too concerned because he figured at the frequency with which he checks his catch can, the oil level rarely rises enough to cause the hose to become submerged.

One could suggest to leave open a constant drain, but this would create a new vacuum path to the crankcase, rendering the pcv system less efficient.

I do not know how deep the inlet hose goes into the can in fowljesse's setup. If it is not too deep, there will be no problems so long as the end user understands he needs to empty the can as part of regular maintenance. My only further solution is to use an inlet design with pressure release holes, similar to this:



The thing I like about Fowljesse's though is that you can take it apart and clean it out, and it has a built in oil/air seperator.

Perhaps the design isn't perfected, but our talk can only stand to improve upon it.

[Mnemonic]

I agree a submerged inlet would cause a problem. I guess if you don't mind constantly checking your engine fluids a lot, or you drive enough that you change oil pretty regularly it wouldn't really matter. Though I still think a outlet for oil would be a bit nicer. I mean its not really that hard to drill and tap a oil pan, just do it the next time you change your oil


*edit but now that i think about it if you were to do a oil outlet I would probably run a secondary filter to help keep more gunk out. Hmmm Jesse you could put a filter in there then have a outlet at the bottom and outlet/inlet at the top But now that I think about this, if i were building a rat rod, i would probably do something like this, just maybe not in a japanese performance car hehehe

[cjthor]

Every time I empty the catch can on my MINI it is always dingy looking oil...mostly mixed with a bit of water vapor. I would never reuse the oil from the can..

[fowljesse]

It's true; The oil in the can is tainted. It has a mixture of unburned gas, exhaust, and water, as a combustion by-product in it. I wouldn't re-use it.
Since I'm kind of, well.. astute about checking/ changing things in my vehicles, I didn't really think about what if someone didn't change it for a long time. However, even if the oil level went above the bottom of the inlet hose, it wouldn't cause a significant amount of drag. Think of a "tobacco water pipe"... A person would draw the smoke through the water the exact same way that the catch can would draw the vapor through the oil if the the inlet was submerged. It's not ideal, but wouldn't cause problems.
I made mine serviceable, because that's what helps it be so efficient. It takes less than 5 minutes to pull the bottom part out, and dump it. Of course, you should have a sealed container to put it in that you can take to be recycled. I just assumed that someone interested in this level of filtration wouldn't mind dumping it every couple of weeks. I could make a completely sealed unit with a petcock, or a return line, but wouldn't feel good about it. The oil in it also tends to be acidic.