Catch Can BULL

Anyone out there think that the catch can systems everyone is selling is a crock?

I've talked to a couple mechanics, one who specializes in VW/Audi, and both said they are a waste of money. Dangsr thinks all are poorly designed and personally I just don't know... Everyone seems to be in love with them, but there has been nothing to show they work other than a cup of water and some gunk. Honestly, if the amount of gunk I see collected monthly out of someones can actually got stuck in the valves, then in a year your valves would be stuck shut!!!! But they obviously don't.

I'm just not sold, and think its annoying to either have your car smell like ass or have to empty out a can of water maybe every week in the winter...:iono:

Anybody with me?

Staulkor recently cleaned out his valves. They looked pretty nasty. Whether it affects performance and engine life significantly is difficult to prove either way, but the cans definitely do what they claim.

I've seen Staulkors pic along with many others... How do you know your valves wont look like that again in 30,000 miles even with the catch can? They haven't been out long enough and to my knowledge, none of the companies who make them tested them for thousands of miles to show the comparison. Otherwise, I'm sure I would have seen the pictures by now.

Well I definitely noticed a smoother build up of boost after installing a catch can, which makes sense since the blow-by is no lounger fouling up the intake air and mixing with the charge. It's also one less potential boost leak.

As for whether they actually work or not, that's kind of a silly argument. The only things that feed into the valves are the intake and the PCV system. There's no fuel hitting the valves. So the carbon build ups could only be coming from the PCV system. If you are running a VTA or slashcut, then you are completely removing the blowby and there's nothing being introduced that could cause the valves to get gunked up. A recirc catch can, depending on its design, could very well be completely useless if the oil is not given sufficient opportunity to condense before the air is reintroduced. But with the non-recirc cans, the source of the carbon build up, i.e. blowby, has been removed entirely.

Perhaps the smoother build of boost has to do with the fact that you fixed your pcv, not the can itself...

I understand the theory behind it. Why would the two mechanics I asked tell me its a waste of $? The one who specialized in vw just told me to get the PCV fix and call it a day.

What is a slashcut catch can? And out of curiosity, who's can are you running? BSH fanboi?

Catch cans on a turbo car are not bull. Any turbo car has a lot of blow by. The piston rings have gaps in them that gasses creep around with the extra pressure of a turbo and the combination of the high 10.5:1 compression you get a TON of blow by.



Not VW, but just an example of piston rings.

All that pressure has to go somewhere and it goes out your breather and is sucked into your engine and oil comes along with it. A normal car wouldn't have such an issue, but this is a direct injection car and it's turbo charged and it's high compression! No bull about it at all. If any car ever needed a catch can, it's this car.

I mean it will run just fine without it, that's how it was designed. But over a long period of time all that oil in your intake softens the rubber intake boots and they eventually tear or crack, it coats your valves, coats the tops of your pistons. It's just plain messy. When your rings really get worn down after 100,000 miles it'll just get worse. I had so much blow-by on my Subaru from worn out rings on piston #4 that the pressure pushed out of the valve cover gaskets and pushed oil onto the exhaust and caused a fire. It happens on the MKV too when the PCV gets clogged, your oil filler neck leaks. The signs of the problem are obvious. It's just less maintenance in the long run and easier to fix with a catch can.

SweetMeatMKV said:

I understand the theory behind it. Why would the two mechanics I asked tell me its a waste of $? The one who specialized in vw just told me to get the PCV fix and call it a day.

What is a slashcut catch can? And out of curiosity, who's can are you running? BSH fanboi?

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Mechanics will always tell you OEM is best. That's how a mechanic thinks and it's usually right. They don't want to go off re-designing a car and messing with custom shit. They've probably seen a lot of really bad installs or cheap catch cans.

A slashcut can is an old and effective trick. You put a slashcut pipe in the exhaust and the exhaust blowing by the tip creates suction and it sucks your crank case fumes into the tail pipe. You should know this stuff if you want to make a topic about catch cans.
Look up vacuum pumps and dyno tests of recirc catch cans. There are dyno proven HP gains.

SweetMeatMKV said:

and to my knowledge, none of the companies who make them tested them for thousands of miles to show the comparison. Otherwise, I'm sure I would have seen the pictures by now.

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I've had our very first prototype can on my car since MAY of this year before having sold more than a handful of pre-production kits, and never emptied it once for the purpose of conducting a long term test prior to full production and release.





I don't really care what any "certified" VW mechanics or any disbelievers tell you. There is no arguing the fact that without a catch can, this fluid will be entering your intake manifold causing a buildup on your intake valves, or turbo inlet allowing the fluid the collect in the intercooler piping. I don't understand how anyone can make any claims to the contrary. The immense amount of photos of fluid collected posted all over the forums should be all the evidence anyone needs.

If I'm not mistaken, the only two things that pass by your intake valves are air and the recirculated crankcase vapors. Since the 2.0 FSI is direct injection, you don't get any fuel passing by the valves. In a normal engine, the detergents in top tier gasoline help to breakdown the deposits that inevitably occur. With a direct injection engine, this doesn't happen. With the catch can, the oily vapors from the crankcase get filtered out and you get much cleaner air flowing to the intake valves. The catch can isn't going to catch all of the "gunk" but it will significantly reduce it. Hence, you will be able to go far longer before your intake valves need to be cleaned.

Just because a mechanic works on VW/Audi doesn't make him an absolute authority on the subject. I was a certified VW/Audi tech, and I can tell you there are more than a few techs who don't really know that much about cars. It really isn't that difficult to be a dealership tech.

^
I hope you poured that into an oil burner to heat your shop. See there's another advantage! With the amount of oil collected from your catch can you could probably heat your garage all winter.

Here I'm gonna let you in on a little secret. If you want the best catch can money can buy get this:


MANN&Hummel Provent 200. It's designed for big rigs and has an actual replaceable paper element inside of it, can operate in recirc or VTA, and has a nipple on the bottom to drain it. It's big and flows A LOT since it's meant for a semi truck. Seals perfect and even has a check valve. The filter in there will catch all the oil too. A lot of Subaru, TDi and Jeep guys use em because their good and cheap. They just aren't too pretty.

We're in Florida.

I know not of this season you refer to as Winter. :wink:

Use it to fry up some gators or something then hehe

Ok, thanks guys, I learned a lot. No need jump my ass though, why so serious?

And Forge... when was that emptied? may until ??? Thats a lot of gooooo.:yikes:

This is a pic I took of the hot side of the FMIC 4000+ miles after the FMIC was installed.

I posted this pic weeks ago and the car has been driven nearly every day since, and it still looks the same.

This is not a new science, just a little new to the mainstream VW tuning scene. :wink:

SweetMeatMKV said:

or have to empty out a can of water maybe every week in the winter.

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You live in AZ, you don't have as much moisture in the air as you do in places where it snows. those guys are emptying mostly water in the winter.

SweetMeatMKV said:

And Forge... when was that emptied? may until ??? Thats a lot of gooooo.:yikes:

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From early May until the day that video was uploaded Nov. 10th

It wasn't even half full.