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Is this an okay catch can?

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1Gina2G

10+ Year Contributor
810
2
May 6, 2011
Beaufort, South_Carolina
Hey everyone, getting close to finishing my rebuild, and was wondering through the parts I had and I remembered this catchcan that came with my car from the previous owner (new, unopend box) and was wondering if it was okay or even worth it to use this kind? I think it's a universal catchcan, since there's no brand name or markings anywhere on the can.

Is there a way to tell if a catchcan's any good or not? Are ebay catcans (like this possibly) any good at all? What are good brands for catchcans?

Does it matter which kind of catcan hooks up on either side of the PCV system? Like one specifically for the intake manifold to the valvcover, and one specifically between the intake pipe and the valve cover?

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Our cars don't come factory with venting the PCV gases and breather all in one can. It may vent them out under extreme pressure, but i have the impression that you need a vaccum source to suck the PC gasses out of the can.

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Like that other guy said, replace the filter with a hose to a vacuum source.
 
^ That is by far the best way to run a catch can. You CAN run it vented, but it's not as effective. The setup posted above is the best because it creates a vacuum and draws out the pressure, as per a stock setup.
 
still slightly confused after reading the PCV thread, so the cathcans with the filter on top like mine, are vented catchcans, which are not ideal? what makes them not ideal?

confused on the above setup too, never saw a catchcan with 2 ins and outs
 
The breather is more for race setup's. For a daily driver, you want a setup where the vapors are pulled out at idle and cruise. The above setup is the best because it's ideal, 2 in's and 2 out's. Under all conditions there is a vacuum in which draws out the vapors.
 
still slightly confused after reading the PCV thread, so the cathcans with the filter on top like mine, are vented catchcans, which are not ideal? what makes them not ideal?

confused on the above setup too, never saw a catchcan with 2 ins and outs

The reason that it is not ideal is because - like your BOV not being recirculated, you are losing registered air compounded on top of having no vacuum to help pull the pressure out of the valve cover. Think about how your stock setup is routed. It runs from the valve cover port to your intake snorkel. Why? Because it's being recycled back into the system for use as well as having a driving factor motivating it to move (vacuum).

^ +1 mine only has 2 outlets on it one for the vc and one for the PCV valve. so i should run 1 hose to vc, 1 hose to PCV, remove filter and run a hose from intake pipe to can?

There is no such thing as a "Best" Catch can. The cans use gravity vs weight to function. As the air comes in from the valve cover, the heavier liquids, fumes and such will drop to the bottom of the can while the air cycles back through the vacuum. So in this case, if you are blowing oil from the valve on your valve cover, once it reaches the can it will fall to the bottom of the can while the vacuum is only able to pick up the air in the can. In a very vague explanation.

So yes - remove the filter and add a vacuum source in it's place. This will actually be ideal as it is at the very top of the can. You don't want anything that fills the can to reach the vacuum and be sucked into it. So the higher the source the longer you can go before you risk sucking up unwanted materials.

I had to get a cathcan once, after I got into a fight and thumbody knocked my teeth out.

ROFL - Did you acquire it before or after the fight in order for it to function properly?
 
The reason that it is not ideal is because - like your BOV not being recirculated, you are losing registered air ...

Blow-by now counts as metered air?

I had the RRE, two-tube, no-vac, filter-top catch-can for years and it did its job fine. Optimal? Maybe not. Losing me metered air? Bah.

It's a trade-off and you have to choose (if you don't do one of those exhaust venturi set-ups): have a vac line and risk sucking a little oil back in or have no vac and not clear as much blow-by.
 
Blow-by now counts as metered air?

I had the RRE, two-tube, no-vac, filter-top catch-can for years and it did its job fine. Optimal? Maybe not. Losing me metered air? Bah.

It's a trade-off and you have to choose (if you don't do one of those exhaust venturi set-ups): have a vac line and risk sucking a little oil back in or have no vac and not clear as much blow-by.

In the sense of blowby I would say yes. I mean, sure it's debatable, but it is air which has been metered, not used, and would otherwise be returned to the intake system via the stock setup. Allowing that to escape by converting the system to not recycle it could cause a calculated loss. Agreeable I hope.

That's my stand on it anyhow. I know there are various conversations about it - being short winded to whatever degree.
 
ok i got it. if im goin to run the can without a vaccum and just keep the filter is there possiblity of damaging the engine? i just rebuilt and am trying to get everything in order so i have no issues with the new engine.
 
ok i got it. if im goin to run the can without a vaccum and just keep the filter is there possiblity of damaging the engine? i just rebuilt and am trying to get everything in order so i have no issues with the new engine.

No no. You won't see any catastrophic engine damage. I ran my 2.3 build with a vented Catch Can for a few months until I got my hands on an intake filter adapter with sealable ports. That way I could run a vacuum line right at the filter - before the MAF, and left the filter on the Catch can. Doing this - any air I drew in from the filter on the catch can was filtered and metered. :)
 
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Am I the only one that thinks the brake fluid cap looks out of place, as in, the only things that haven't been replaced? ROFL
 
That way I could run a vacuum line right at the filter - before the MAF, and left the filter on the Catch can. Doing this - any air I drew in from the filter on the catch can was filtered and metered. :)

Are you kidding? Your vacuum source for your catch-can was before your MAF? I don't care if you had a filter on it. I would never do that. Not even if I owned stock in CRC (i.e., the makers of MAF-sensor cleaner.)

(But at least I can stop wondering how unburnt metered air gets to your catch-can. I no longer care.)
 
Are you kidding? Your vacuum source for your catch-can was before your MAF? I don't care if you had a filter on it. I would never do that. Not even if I owned stock in CRC (i.e., the makers of MAF-sensor cleaner.)

(But at least I can stop wondering how unburnt metered air gets to your catch-can. I no longer care.)

No, absolutely not kidding. Never had a touch of issue with it either for the length of time that I had it. Then again - I didn't really suffer from blow-by issues. I suppose it's one of those preference things, right?

I don't assume I understand your angle here - seeing as how metered air, which gets around the pistons/piston rings (blow-by) which fills and is evacuated from the crank case via the PCV system back into the intake system to be reused, would still be considered metered air in the system. Why... would that NOT end up in route with a properly installed Catch Can?
 
Long story short.

DD = vacuum line as in the diagram i posted.

Indy 500 = What you got right now.

It's really up to you. Either way there will be no harm no fowl.
 
I don't assume I understand your angle here - seeing as how metered air, which gets around the pistons/piston rings (blow-by) which fills and is evacuated from the crank case via the PCV system back into the intake system to be reused, would still be considered metered air in the system. Why... would that NOT end up in route with a properly installed Catch Can?

Much more of blow-by is used air than unused. Your crazy system feeds used air - read: carbon dioxide (and other crap) - directly into the intake and MAF where it will not only be useless for burning more fuel, it will "count" as unused air and make you run rich (as well as gum up your MAF).

To be blunt, if you actual had such a system and it worked, that's impressive. Odds are, if this worked for you, you really had no blow-by at all and the whole thing was moot.
 
Much more of blow-by is used air than unused. Your crazy system feeds used air - read: carbon dioxide (and other crap) - directly into the intake and MAF where it will not only be useless for burning more fuel, it will "count" as unused air and make you run rich (as well as gum up your MAF).

To be blunt, if you actual had such a system and it worked, that's impressive. Odds are, if this worked for you, you really had no blow-by at all and the whole thing was moot.

Hm, well, don't know what the hell I was thinking. I mean, I only drove the hell out of the car for over a year like this with absolutely no issues. Ironically I also never got a drop out of the catch can. Guess that was a damn solid engine. Regardless of being moot or not, measures are taken to ensure that if there was an issue then it can be addressed accordingly. I also love seeing shiny things in my engine bay when I pop the hood at the local Fast and Furious meets.

The entire thing about it being "used" air and being measured as "unused" air also has some inconsistencies. We can review the way the stock system works and say this ; If my method would Richen the AFRs, then shouldn't the stock system Lean out the AFRs as used air is being routed back into the system that the MAF doesn't know is there because it assumes that it was used?

I'd rather run rich than lean any day. And I'm not trying to argue with you by any means - I'm doing what I can to understand how the system wouldn't account for this being metered air that you'd be otherwise losing if vented? If engines are big air pumps, aren't leaks outside of the simple "In" and "Outs" considered unintended losses?
 
Keiya -

The OE set-up has the vac tube after the MAF. Nothing getting sucked into the engine is metered and that's exactly the way it should be because there's little to no oxygen in what's being sucked into the engine via this tube. Thus, it has little to no effect at all on rich vs lean. If anything, given that the oil vapor in the blow-by is combustable, it makes you a tad rich, not lean. And, as you know, rich is always good in the eyes of a Mitsu engineer.

And I'm not trying to argue with you by any means

No problem. But it's funny how often people who are clearly arguing with me say that....

- Jt
 
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