MK5 Catch Can Questions/Design

Hey everyone,

so we recently picked up a 2008 mk5 GTi for Time Attack build to Race alongside our Focus ST225.

Knowing very little on these engines, we beginning with replacing all the bits and what not. and one of the bits to replace seems to be the PCV, Now we would like to just delete it and go for a catch can as the car is going to spend a fair bit of its life on the track but will be driven to the track as both it and the ST are entered into Street Class.

My question for guys in the know, and please correct me at any point if I'm wrong. With the EA113 engine it has a breather out the back into the induction Pipe, and the PCV out the front (Ignoring the Crack case breather, We replacing that pipe with a Steel braided AN one)

Now some of the PCV delete kits just remove the front breather and let the engine all go out the exhaust breather. others keep it but add a catch can in the original place of the PCV.

I would like to know, If I put on a plate in the front with only a single outlet and run a tube from there AND from the rear exit to a Catch can with a breather on it, would this create any issues? essentially removing any breathers from the Intake manifold & turbo intake and isolating them on their own.

something like whats Attached (Please excuse the awful Paint lines, just seeing if its possible)

Looking forward to the responses

If you are going to use a VTA catch-can(CC)...you are only going to have one hose coming from the blue x-circle to the VTA CC as the red circle is just the valve cover pass through for recycling. The rear tube, @ the blue circle is deleted and you would plug off the valve cover and also the turbo inlet with one of these; https://www.uspmotorsports.com/Inte...RzXxZqrAcw46BFtX1worMi2COnNeOLC8aAldTEALw_wcB

You can see a VTA CC here, but you can see they didn't eliminate the rear tube and so crankcase breathing can avoid the VTA CC altogether; http://i30.tinypic.com/hrxwcp.jpg Now, the recycle passage should be sealed off at the PCV-to CC plate...but then the valve cover must remain sealed inside to keep the passage closed.

If you leave the rear breather tube, the VTA CC is useless...as crank vacuum and pressure can be done through the rear tube rather than through the VTA CC. The only reason to have a rear tube is for a recycling system such as the oem PCV or a recycling CC.

Catch cans are a scam that don't really work. They just provide a sample of your crankcase vapors and VTA will just dirty your engine bay.

If you don't want to use a stock evacuation the best solution is to run a vent hose underneath the car. I did this and the biggest consequence is you will probably need to change your oil more often since fewer volatiles (gasoline) are being removed.

ROH ECHT said:

If you are going to use a VTA catch-can(CC)...you are only going to have one hose coming from the blue x-circle to the VTA CC as the red circle is just the valve cover pass through for recycling. The rear tube, @ the blue circle is deleted and you would plug off the valve cover and also the turbo inlet with one of these; https://www.uspmotorsports.com/Inte...RzXxZqrAcw46BFtX1worMi2COnNeOLC8aAldTEALw_wcB

You can see a VTA CC here, but you can see they didn't eliminate the rear tube and so crankcase breathing can avoid the VTA CC altogether; http://i30.tinypic.com/hrxwcp.jpg Now, the recycle passage should be sealed off at the PCV-to CC plate...but then the valve cover must remain sealed inside to keep the passage closed.

If you leave the rear breather tube, the VTA CC is useless...as crank vacuum and pressure can be done through the rear tube rather than through the VTA CC. The only reason to have a rear tube is for a recycling system such as the oem PCV or a recycling CC.

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Thanks man,

We are building all the parts our self including the catch cans.

So if I understand what your saying we can just block off the Rear pipe with a Catch can on the Front? that would be a lot cleaner and then just go with the tradition plates with 3 outlets that I see for sale, or even having that one singular pipe would prob be the cleanest solution. Why is it that some kits run a return via the front?

Does the catch can need to have a air filter on it or can it be a sealed one?

Thanks again

Explain why you want something that doesn't work that well and mostly catches water vapor, vs a solution that totally removes any ingestion of crankcase vapors.

If you want the good solution, block off the port in the back and the one on the turbo, as well as the port on the intake and run a dump hose from the UFO deal to underneath the car. Simple, and it will expel all the shit out of the car instead of catching a sample while running business as usual. I ran this setup for 20K miles. A VTA catch can does mostly the same thing but fouls up your engine bay. Bad idea.

flat tire said:

Explain why you want something that doesn't work that well and mostly catches water vapor, vs a solution that totally removes any ingestion of crankcase vapors.

If you want the good solution, block off the port in the back and the one on the turbo, as well as the port on the intake and run a dump hose from the UFO deal to underneath the car. Simple, and it will expel all the shit out of the car instead of catching a sample while running business as usual. I ran this setup for 20K miles. A VTA catch can does mostly the same thing but fouls up your engine bay. Bad idea.

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You seemed to missed the part about the car competing in Time Attack, so No running a pipe underneath the car and dumping it onto the track or worst case onto the underside of the car is not an option, great way to ether get black flagged or start a fire.

I've been competing in motor sport for around 8 years now, and Have seen the difference Catch cans make on the track, YES on a road car, even a "Fast" road car they are not needed as most OEM systems will easily suffice, but those fail, and a failure on the track at the temps and heavy use could lead to a much bigger bill. Hence a simple catch can system that can be emptied between races is the perfect solution.

Not_Sean said:

You seemed to missed the part about the car competing in Time Attack, so No running a pipe underneath the car and dumping it onto the track or worst case onto the underside of the car is not an option, great way to ether get black flagged or start a fire.

I've been competing in motor sport for around 8 years now, and Have seen the difference Catch cans make on the track, YES on a road car, even a "Fast" road car they are not needed as most OEM systems will easily suffice, but those fail, and a failure on the track at the temps and heavy use could lead to a much bigger bill. Hence a simple catch can system that can be emptied between races is the perfect solution.

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You can put a collection / vent can underneath the car, and regardless it will not start a fire. This is a better solution than recycling your vapors into the intake or dumping them under the hood (how on earth are you ok with that but worried disposal under the car could pose a fire risk? lol). Basically, dump and catch under the car is the same as installing a VTA can but with better placement and no vapor return.

The problem with stock PCV is check valves not holding up under modified boost. People think catch cans fix this but it's actually the removal of the weak valve assembly in front of the head that fixes the problem. You may have been doing motorsport for 8 years but you're asking extremely basic questions that make it clear you shouldn't be relying on your own judgement. The fsi PCV system is very simple, and documented to death on these forums and in VW's mechanic education pdfs, all easily accessible on google. If you'd been wrenching for 8 years you probably wouldn't even need those.

Not_Sean said:

Thanks man,

We are building all the parts our self including the catch cans.

So if I understand what your saying we can just block off the Rear pipe with a Catch can on the Front? that would be a lot cleaner and then just go with the tradition plates with 3 outlets that I see for sale, or even having that one singular pipe would prob be the cleanest solution. Why is it that some kits run a return via the front? If you find a CC plate with just two ports...the one to the right connects to the oil filter housing and the other to your VTA CC. If you get one with three ports; the two already mentioned remain as described, but the third to the left is for recycling CC and sends vapors back through the valve cover and into the turbo inlet. Since you would not be recycling...you'd plug that third port at the far left.

Does the catch can need to have a air filter on it or can it be a sealed one? NO!...If you did that, you'd likely blow seals very quickly because there would be no way to equalize crankcase pressure with atmospheric pressure. Been that way since the dawn of, engine, time. The Filter is the vent to atmosphere...other wise you would need to recycle vapor & pressure to the open to atmosphere turbo inlet.
Thanks again

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Flat Tire's suggestion is to eliminate the VTA CC which is valid in that "why have a VTA CC that you'll need to empty often, when you could just run a downward hose underneath and never worry about it" as long as you add a simple catch-all can at the end of the hose for track purposes. You could add a screen of sorts to the end of that hose to keep small critters from climbing aboard and plugging said hose and remove the catch-all when/if not on the track. Just use something for a screen that will not clog itself over time or give it a regular inspection yourself. It would be set-up the same except that you would run the hose that would go to an unnecessary VTA CC downward and underneath the car...typically near the center.

But yes, it is simple...and your choice.

flat tire said:

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ROH ECHT said:

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So flat tire, do owe you an apology, pulled the system apart the other day and got a much better understanding of how it all works.

So what I'm looking at doing now, So get the blanking plate for the front PCV, the one that's only got the outlet for the Crankcase.

And on the back, put a blanking plate on the rear breather turbo side and from the hose out the back, replace that with a better line and just run that to a small K&N Oil breather. and mount that somewhere.

see what you mean now that a catch can is pointless in that part of the system.

Most I could see is one in between the head and the front crankcase breather pipe but don't think that'll chuck up enough oil through the line for it to be an issue.

So while I was away fetching a new car, the GTi owner decided to go ahead with a CC Setup, He based it off the APR one.

he says he's got some smoke coming from to Quote "From the outlet to the turbo oil line I blanked off" Now from what He's described it looks like he's done What I've got in the CC Setup attachments.

I Got a pic of his engine (Attached with the long name)

The issue he's having is that the is a mist smoke coming out of the Back breather as well as the engine is making a louder than normal ticking from the Tappets.

Any ideas??