The best $10 catch can on the market? Let's try it out

I just got finished installing a catch can (mostly out of boredom) on my 2009 4.6 Hyundai Genesis and I figured I would share how I did it if anyone else wanted to see.

So I've found that air-water separators for air compressors make great catch cans, and a handful of other people on the internet thing so too, mainly because they are cheap and have a fine brass filter/screen in them which is pretty good at grabbing the oil vapors out of the crankcase before entering the intake manifold. I previously had one from Lowes ($35) on my old big turbo 300zx and it worked great. This time I am trying out the separator from Harbor Freight ($10).

For anyone wanting to understand how the air-water separators work here's a good picture showing it.

This is the Separator that I'm using, they have a slightly larger one as well but I didnt have any 1/2 npt fitting so I went with the smaller of the 2.

Here's my mess of hoses and fitting while I was getting everything sorted for what I needed

There are only a couple things you have to do to make them ready to be a catch can. The biggest thing is sealing the valve at the bottom. It is usually held shut by compressed air but since it will be seeing vacuum most the time it needs to be sealed off. Unfortunately I didn't get any pictures of this part but it's pretty simple, I just sealed it up with a healthy coating of oil-friendly RTV.

The next thing is for mounting it. It does have 4 m4 (if i remember correctly) bolt holes in it for mounting a plate over the top of it but I wanted to keep a smaller bracket so I ended up drilling and tapping a hole for a m8 bolt. The big thing is to make sure to not drill into anything important on the other side and to put thread tape on the bolt to seal it up since it will be in the separator.

When mounting it just make sure you have enough room below it so that you can drop the bowl down to get it off when it's ready to be drained. I used a small piece of aluminum angle for my bracket with 2 short self tapping screws to hold it to the wheel well, nice and simple. Then it's just mount the separator and route our hoses.

I'm looking forward to see how it works and how much it will catch on my 192k mile Korean v8.

why a catch can on a modern engine?  

What testing backs up any tangible benefit...

Sorry to poop on this, but catch cans remind me of lifting "bro science"...  

Interested to see how fast it fills up. Looks a little small.

Fueled by Caffeine said:

why a catch can on a modern engine?  

 

What testing backs up any tangible benefit...

 

Sorry to poop on this, but catch cans remind me of lifting "bro science"...  

mostly because when i had the TB off to clean it the inside of the intake had a pretty solid coating of oil in it. Not that it was causing an issue but it's probably not a terrible idea keeping as much oil out of the intake as possible.

Neat!

Fueled by Caffeine said:

why a catch can on a modern engine?  

 

What testing backs up any tangible benefit...

 

Sorry to poop on this, but catch cans remind me of lifting "bro science"...  

There’s a ton of money in the catch can biz....  don’t interfere with the money choo choo train.

edizzle89 said:

Fueled by Caffeine said:

why a catch can on a modern engine?  

 

What testing backs up any tangible benefit...

 

Sorry to poop on this, but catch cans remind me of lifting "bro science"...  

mostly because when i had the TB off to clean it the inside of the intake had a pretty solid coating of oil in it. Not that it was causing an issue but it's probably not a terrible idea keeping as much oil out of the intake as possible.

That's literally the only reason I run one too.

So what is wrong with a little oil/moisture mist going in to the top end.    A little oil for top lube and "water injection" helps cool things off.

In reply to iceracer :

I don't want it going through the compressor side of the turbo in my case. 

I also own a first generation DI car with no PI or meth injection. The oil will form a sticky semisolid mass on the back of the intake valves and cause them to stick partially open.

In the case of the Vibe it also sort of solidified with some dust in the throttle body and was causing it to stick. That was causing a stall condition when I came to a stop. Granted it had 200k miles when I cleaned it.

In reply to iceracer :

That oil mist slightly reduces effective octane and can gum up the intake systems on some cars.  So there are downsides.  Realistically, even if removing the stuff doesn't actually help much, it's not going to hurt to prevent it from blowing into the intake.  

Fueled by Caffeine said:

 

Sorry to poop on this, but catch cans remind me of lifting "bro science"...  

On modern supercharged cars where the intercooler lives below the blower they keep everything so much cleaner and they tend to heat soak less. 

In reply to wearymicrobe :

Still sounds like Bro Science.. Like.. Ohh it's better for DI engines... 

In reply to Fueled by Caffeine :

I know there's an argument to be made about why the factory doesn't include them. The counter argument is: If emissions engineers are doing away with dipsticks to get a minor improvement in emissions testing, I can only imagine that they would just outright reject another 2 hoses and multiple other connections.

Does it improve performance? ¯\_(ツ)_/¯ .

Does it keep the intake tract cleaner? In my experience, it sure does.

Some BMWs actually do have a sorta-kinda catch can from the factory.  Not a typical catch can, but it's a cyclonic oil separator that the PCV vapors run through.  Unlike most cans that require maintenance to drain them (which would be a problem for a factory setup), the BMW ones just return the separated oil to the crankcase. 

In reply to edizzle89 :

We're did you buy it at??

The ND Miata comes with a catch can/separator, it's DI. 

In reply to Alfaromeoguy :

I got this one at Harbor Freight but you can pick up similar ones at lowes, Home Depot, menards, etc.

Fueled by Caffeine said:

In reply to wearymicrobe :

Still sounds like Bro Science.. Like.. Ohh it's better for DI engines... 

 

the carbon build up issue of DI is literally due to the oil vapors from the PCV system not being cleaned by the injections spraying on the back of the intake valves. So if you can prevent the oil from getting into the intake in the first place it is better. 

Regardless of DI or not less oil in the intake is always going to be better. Doesn't take a 'bro scientist' to know that.

the lack of science is startling..  Let's have some fun.

https://doyouevenboost.com/blogs/news/50063555-how-does-an-oil-catch-can-work-and-why-is-it-beneficial

Look, I took disgusting pictures of valves... Something must be done....   I can't really figure out what is wrong.. so I'll pretend I'm doing something by adding a catch can..  

https://blog.modbargains.com/turbo-car-need-oil-catch-can/

all turbocharged cars experience oil blowby when under boost.

Ohhh Really tell me more?  This guy seems smart.  Technically all engines produce some level of blowby when running.  Stupid circular argument.

https://www.lsxmag.com/tech-stories/engine/catch-can-why-direct-injection-makes-them-a-must/

Ohh.. Moroso wants to tell my why I need one of their products.. 

reminds me of the "You gotta run premix in rotary engine" argument.  There is an issue.  Person deduces symptoms...  Treats symptoms with placebo.  Placebo produces some effect.  Effect not clearly related to issue by any testing or proof...

OP is doing what's commonly known as "tinkering" Science be damned. It's fun and rewarding for some of us. :)

In reply to Fueled by Caffeine :

Your 'science' of just saying it doesn't work with no real backing is no different then my 'science' of saying it does work with no backing. So agree to disagree.

I'm just trying to share that for $10, some hose, fittings, and some clamps you can make a decent catch can if you so choose.

In reply to Fueled by Caffeine :

I think it’s worth mentioning that the placebo effect does not apply to machines. 

I'm 50/50 on catch cans, I see both sides of the argument. I have personally never run one, but this is indeed cool if it works, because brand name catch cans are stupid expensive for what they do.

People on the Elantra Sport forums, say you NEED 2 CATCH CANS one for the intake pcv, one for the diverter valve. I laugh over the latter of the 2.

But, I think this is a really cool experiment, please keep this updated!

In reply to edizzle89 :

I can understand that. 

dculberson said:

In reply to Fueled by Caffeine :

I think it’s worth mentioning that the placebo effect does not apply to machines. 

But it sure applies to owners.