A vented can smells awful and coats the whole enginr bay in an oil mist.

A recirculated can doesn't...but its not very effective unless its a very nice can...and even then, if it ever fills up and sloshes, that milkshake will get sucked into whatever vacuum source you have on it.

You're also exposing your oil to moisture and contaminants. Open up a catch can that has even like...2 day oil in it and take a peek at it.

What are the up-sides to a catch can? Is the better question.

The car didn't come with a catch can. Virtually no port fuel injected car comes with a catch can from the factory.

It only makes sense to use one to solve a problem for a very specific situation. And even then, it would be better to find another solution and avoid it.

 

My super cheapo recirculated catch can on my AP1 worked fine. I spent about $50 on the whole setup, including lines and clamps. But it is only a bandaid like mentioned above and should only be needed on the track. My catch can was a small one that I found and made my own bracket for to hang it behind the shock tower. On track I was filling it enough in 2 sessions to dump it, otherwise halfway through third session it would get too full. I purchases an AP2 V1 valve cover from Charlie M that he had already powder coated and added his modified baffle to for someone and that person then decided to kswap. I stuck the Acura PCV in it and now, after 3 sessions on track I just get a very small amount of oil in the can.

But if I were just street driving it I would never even bother. I never even used one all the years that I was only autocrossing the s2k. I would every now and then run a course at Lincoln that I would have some smoke on due to the oil slosh but it was when I first started going to the track that the issue got larger.

And yeah, not fan of vented cans myself.

With the recirculated can you do want to empty it often and the cooler the weather the more often as it is a source for more condensation to collect. Outside of the condensation though you are not putting anything back into the motor that would not go in from the stock PCV system. And that stuff gets burned in combustion (The whole purpose of the PCV vs the old car method of just venting to atmosphere). As mentioned, my recirculated can would get emptied during a track event and after it. I dont drive it much on the street these days but I would empty it regularly there too. So for a street driven car it just creates more stuff to stay on top of for no real benefit.

If you drive on the street a lot and run into the smoke screen issue on track (And do not want to do the baffle mod to fix it properly), you could just run the regular line from the PCV to the intake on the street and hook up the can for track driving too. Annoying but only takes minutes.

 

Clean the pcv valve with brake cleaner. That will help if it's clogged

 

Also, if you ever forget to empty can and don't drive for a few weeks, or worse, all winter season, you'll find a horrifying amount of rust on cams and entire valvetrain area.

 

Since we've descended into catch cans...

I have likely the most cunning set of catch cans on the planet in order to catch and store all the oil my over the hill, high amount of blowby engine barfed out.

While also keeping it stank free and using coolant warmth to keep the moisture in check.

This is (2) 15-20 min sessions worth of oil catch.

 

Now you've all got me curious. What is the legitimate use case of a catch can? It's just to prevent oil directly going from the PCV into the intake manifold, right? But even if that happens... outside of a flash of white smoke, what's the downside? I don't think the oil in the catch can goes back into the engine anyways, so the oil consumption isn't alleviated.

Also, is that why my car only burns oil on the canyons?!

 

You are correct that catch cans do not alleviate consumption. They just change where the oil goes. In normal day to day driving without a catch can it just gets burned through combustion via the PCV system. With the advent of emissions rules the old days of just venting to atmosphere went away and thus, it gets routed back to the intake. And it causes zero issues, does not rob you of any measurable amount of power, etc.

Now, using the car off normal use, like on a track is another story sometimes. The AP1 is a lot worse about it due to the baffle design. The sloshing and high G cornering causes a lot higher amount of oil to go through the PCV as normal, so you make a hard right hander, go WOT down the straight and then crop dust the entire straight. This can get you black flagged and can cause you to panic if you do not know what is going on. So on track, the catch can prevents that part. Baffle mod solves most all of it.

Or like B Serious showed above, if your track car just has excessive blowby this can also create more than the normal amount of vapor going through the PCV

I honestly have never driven mine hard enough on the street to create this issue. I would argue even canyon carvers do not really need to worry about a catch can. Worst case you see some smoke now and then but not going to be massive and not going to cause issues. But, I tend to do my super hard driving on track, not on the street. I will do some spirited driving on the street, but nothing like the 85-90 mph hard right hand corners at limit of grip type thing it sees on track, when this issue really pops up.

AP2's have a better baffle and PCV layout, but they too will experience this on track, just not quite as bad as the AP1