Mods please move to appropriate section.

Whilst home on Spring Break, I figured I would dive into something I've been wanting to do for a while now; and that is making (or modifying) a catch can. Bought one off of eBay for $17, $8 worth of high-temp RTV, and $1 worth of Stainless Steel scrubbers and you too can have yourself a functional Catch Can.

(Only really made this because I was bored and I know my PCV valve allows a bunch of oily air into the plenum. Mainly the former though)

Please take note of the bold explanations above each picture.


Showing how the can came out of the box.


Drilled out one of the nipples (left) to accept the copper tube


Inserting said tube into nipple.


Drilled holes in the tube (I cleaned the holes up later)


Making template for the baffle to separate the halves.


Showing how the baffle splits the can into 2 separate halves.


View from the nipples, showing the separation.


Cut 2 semi-circles out of aluminum for later use.


Showing fitment of the semi-circle.


Baffle now cut out of aluminum.


Wrapping one of the stainless scrubbers around the copper tube. I secured this with aluminum wire.


Drilled holes in both of the semi-circles.


Attached one of the semi-cirlces to the baffle.


Inserted baffle into can and sealed the sides.


Showing my crappy sealant job. The copper tube goes on this side.


Inserted the other scrubber on top of the semi-circle.


Pressed the other semi-circle down on top of the scrubber. The scrubber is now 'sandwiched' between the two semi-circles.


Showing placement of the lid with the tube attached.


Sealing the lid on. Note the glob of RTV on the underside of the lid to ensure the baffle seals off the 2 halves.


Secured the lid down, showing the baffling.



Note that the copper tube (right nipple) is the 'dirty' side, the side that connects to the PCV on the valve cover. The left nipple is the clean side, the side that connects to the plenum. The dirty air from the valve cover runs down through the copper tube and the oily particulates condensate on the stainless scrubber. That air then travel up the other side (the whole point of the baffle) and through the other scrubber, that is sandwiched between the 2 semi-circles, before traveling out of the left nipple and into the plenum. I'm relying on the scrubbers to give the oil, and whatever else is saturating the air from the valve cover, something to condensate onto and then fall to the bottom of the can.

I also removed the clear tube that sticks off of the side of the can and just ran 2 (way too long) bolts in the holes.

May have been a waste of time, but I'm happy with how it turned out and I feel that it will be pretty effective in keeping oil out of the plenum. Let me know what you guys think.

 

Long time no see. Thanks for the share.

 

The only problem I see is the bottom "reservoir" is fairly small and it won't take much oil for it to physically separate the two halves so air no longer flows freely.

If you drain it frequently that won't be an issue but I know mine is a pita to drain (mishimoto baffled) and I FILL that thing in 3k miles.

 

Good point, I didn't think of that. The can should be able to hold ~250mL of oil before it 'clogs'. Really wish I had thought of this and I could've drilled holes in the 'sandwiched' section that are much higher up. I used to have the cheapo air compressor filter on as a cheap alternative, and it collected a small amount of oil (roughly a tablespoon after 500 miles). I'm curious as to how much this one will catch. I'll update this thread after 1000 miles to compare.

 

UPDATE. Actually installed the can. Took a bit longer than expected and I had to remove the headlight, but it fits perfectly and I'm super happy with the mounting location.


Simple bracket I made that utilizes the holes where the longer bolts were.


Showing where the can will be mounted. 1 bolt holds the coolant res tank in and it slid up and out of the way.


Some shielding to keep the can from rubbing on the power steering line.


The bolt passes through a square hole which is already in the upper core support. This picture is from where the headlight should be. Once the light is in, this area is very tight which keeps the bolt in place, making removal of the can for draining much easier.


Coolant res back in place. You can see the nut that is attached to the bolt in the previous picture.


Tucked away nicely under the res.


What it looks like from the outside.



I had originally planned on mounting it between the power steering reservoir and the hood latch sensor, with can down on its back (where the nipples were facing straight up), but I didn't like how it looked. I ended up mounting it below the coolant res for a much sleeker look IMO. I plan on swapping out the crappy looking clear lines for actual rubber tubing, but the clear is all I had at the parents house. The clear tubing will help me see if the can is actually working in the meantime though. As previously mentioned, I will update this thread after 500 or 1000 miles with the amount of oil the can has caught.

 

Watch the clear lines for possible collapsing, happened to my NRG can back in the day. I eventually went with braided aluminum tubes for a cleaner look and better strength.

Oh and you need some hood struts like yesterday lol.

 

Since the lines are so relaxed with the can being under the coolant res, I don't think they will kink but I will definitely keep an eye out for it. The clear lines were only meant to be temporary anyways as they'll probably discolor and be an eye sore. And speaking of the struts, I just installed some the other day on my bosses car. I'll probably pick up a set sometime soon.

 

Blue Dream is talking about engine vacuum sucking the hose collapsed, I used fuel injection hose (high pressure stuff not regular fuel supply hose) and haven't had any issues.

 

Ahh gotcha. Like I said though, only temporary. Tubing is crazy stiff though.

 

As long as it stays stiff when it's sucking hot crankcase air then it should be fine. You'll know the first time it's hot outside if it works or not

 

Little update to make the can easier for draining. The nut and bolt method that held the can to the rad support was a little dinky and non-intuitive. I replaced the bolt with a carriage bolt, remember that the hole on the rad support is a square, and the square part on the carriage bolt fit perfectly into the hole. I also replaced the nut with a wing nut, so all I need to remove the can and drain it is the 10mm that holds the coolant res in place and a 16mm to remove the drain bolt (or just the pliers I have in my glovebox). If need be I can post pictures of it, but it SHOULD be self-explanatory.

 

Interesting work and I am sure it works but why? To me the entire point of putting in a catch can is to eliminate a source of oil going into the air intake and air plenum. A vented can to me is a better (and easier) move to me that is going to yield better results.

 

Not sure venting would yield better results. I read somewhere, either on here or 350z forum, but our cars don't really like the PCV to be vented (I'll see if I can find the thread). Now whether or not that is true, I can't tell you, but I do know that I personally wouldn't vent for 2 reasons.

1) It's technically metered air, aka air that has been accounted for from passing by the MAF. Venting this could cause undesirable effects.

2) The air from the valve cover is oily, therefore the filter you're going to use as the breather is going to get oily, and therefore will make that area of your engine bay dirty and oil saturated.

The can is just a very large filter, to put it simply. It cleans the air that leaves the valve cover and allows the clean air to enter the plenum. The unmolested PCV allows oil to accumulate in the plenum, and obviously your engine shouldn't be running/burning this oil.

Call me crazy, or tell me it's a placebo, but I swear my car is more responsive on partial throttle (think 5-10% throttle). Beforehand my car would bog taking off from lights and plume smoke out the exhaust, both of those have since been eliminated. I also like to heel-toe going up to a corner and/or pulling up to a light. The amount of smoke that is leaving the exhaust in this scenario has also been eliminated. That oil has to have gone somewhere, and I'm willing to be that it's in the can. I would rather have it in a sealed container then floating around in my engine bay, but maybe that's just me.

In my short test run of the can, to McDonalds and back, there was already 2 small drops of oil that exited the can when the plug was removed. Also I noticed that after the first startup, there was a considerable amount of oil already in the inlet tube. Wish I had taken a picture, but sadly I didn't. This can was mainly made because I like to make things, and it gave me some piece of mind by keeping oil out of intake. It just so happened to fix my "clouding" from downshifts and accelerations. I will still have to put oil into the engine before it's time for an actual oil change, but at least I know now that not as much oil is being burned.

EDIT : Also, I seem to have picked up some MPG's. I have tracked my mileage via the Nav unit in my car on my way from Statesville to Charlotte multiple times and I usually get 25.5-26 mpg. On my most recent trip I got 28 even, and I did a solid 4th gear pull getting onto 485 so I definitely wasn't driving like grandma. I feel that this large of an increase is outside of margin of error. Maybe it was just a fluke, thought it was a nice addition though.

 

Across 3k miles I catch about 1 cup (full measuring cup) which is a pretty substantial amount. Obviously it's not going to catch ALL that atomized oil but that's 1 less cup of oil that got ingested. Vented works but I don't like it for exactly the reason you mentioned, it's messy under the hood no matter how good that breather is, you're going to get oil mist on stuff which will collect dirt.

 

1) It's technically metered air, aka air that has been accounted for from passing by the MAF. Venting this could cause undesirable effects.

So, essentially causing a possible lean condition at best. Actually I don't buy it but you might be right. I will be finding out.

2) The air from the valve cover is oily, therefore the filter you're going to use as the breather is going to get oily, and therefore will make that area of your engine bay dirty and oil saturated.

Yes there will be some oil residue around the vent filter - oh well the engine gets dust, dirt and whatever else on it every time I drive it. That's why from time to time I shoot it with some spray cleaner and hose it off. I'm good on this subject.

From both valve covers to a vented catch can is where this residual oil is going on mine. No PCV in the deal and all of the "oil entrances" to the intake plenum will be sealed off. I just haven't decided if the cover plate over the oil galley is going to be retained or not.

I can actually believe your fuel mileage increase although that is a hefty one. If you think about it, you are no longer contaminating the fuel/air mix with an oil byproduct. Combustion is going to be better, more even and output better power therefore you do not need quite as much throttle to maintain a certain RPM or MPH.