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Understanding the MK7 PCV function, retrofitting the MK8 PCV, and why catch cans are bullshit(IMO)

summerflame

New member
Location
malaysia
Car(s)
Golf 6 GTI
Nice job man finding this out, altough I'm not on MK7, but I do have a MK6, which goes slight positive crankcase pressure when it's starting to boost until idk what rpm, don't have a logger, just have a analog sensor. I initially thought it's just me having too much blowby, but looks like that's not the issue. I have the APR 2867 kit TIP installed, which could be the cause.
Tiguan's hose is so damn expensive, compared to MK8's one.
So I'm now trying to make a venturi tube myself, and 3d printed it, let's see if this works or not.
Btw, if anyone could send me dimensions of the MK8 PCV hose venturi, maybe I can make an adapter to make it works. But you sure need to find someone to print that out for you.
 

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nomunic

Drag Racing Champion
Location
East Coast
Car(s)
MK7
Anyone tried putting a barb on the stock charge pipe, maybe jb weld or something?
 

nomunic

Drag Racing Champion
Location
East Coast
Car(s)
MK7
I was wondering if there was a bulkhead fitting that could be used.
If someone has an oe charge pipe I could figure it out lol
 

summerflame

New member
Location
malaysia
Car(s)
Golf 6 GTI
Hmm so the one I posted earlier broke at the thin part when I tried to install, then I suddenly changed my mind and make another one to adapt at the rear pcv hose going to TIP instead of the one going to manifold, it idles fine, but when going into boost the pressure is slightly higher than it originally was.
I did try to blow air with mouth into the boost port (lower) and it indeeds sucks air at the left inlet, I guess it has not enough suction effect to pull out the blowby?
Now I have two options:
1. Getting the MK8 hose to adapt instead, but our MK8 locally only have ea888 gen 3, dealer and parts supplier here doesn't have the venturi hose.
2. Getting the exhaust venturi catch can kit. This option sounds more promising for me, since it sucks out the blowbys which is non combustible air away from the intake tract, so not displacing the combustible air inside it, which means more power and also reducing chance from engine leaks causing lean condition. I already ordered one, almost here, guess I'll be testing out that first.

Btw @DerHase , do you know if the mk8 pcv also have one way going into the head and the another one into the TIP? Or just one path to the TIP?
 

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JTM88

Autocross Champion
Location
Broken Arrow, OK
Car(s)
2016 GTI
I; 'm wondering if there is enough room in the silicone coupling between the charge pipe and turbo to put the barb fitting in.
 

summerflame

New member
Location
malaysia
Car(s)
Golf 6 GTI
I; 'm wondering if there is enough room in the silicone coupling between the charge pipe and turbo to put the barb fitting in.
If you want a boost source a better way is to get an adapter that goes between the manifold and map sensor, but I suggest not to get the aluminium one. I heard people having issue with the heat transfer to the sensor, not really sure since I dont have one.
Or drill a hole in your silicone hose, get a barb with external thread, a nut and 2 bigger washers sandwiching the silicone hose, plus jb weld and I guess it should be fine.
 

DerHase

Autocross Champion
Location
Hampton Roads, VA
Car(s)
2019 GTI Rabbit
Hmm so the one I posted earlier broke at the thin part when I tried to install, then I suddenly changed my mind and make another one to adapt at the rear pcv hose going to TIP instead of the one going to manifold, it idles fine, but when going into boost the pressure is slightly higher than it originally was.
I did try to blow air with mouth into the boost port (lower) and it indeeds sucks air at the left inlet, I guess it has not enough suction effect to pull out the blowby?
Now I have two options:
1. Getting the MK8 hose to adapt instead, but our MK8 locally only have ea888 gen 3, dealer and parts supplier here doesn't have the venturi hose.
2. Getting the exhaust venturi catch can kit. This option sounds more promising for me, since it sucks out the blowbys which is non combustible air away from the intake tract, so not displacing the combustible air inside it, which means more power and also reducing chance from engine leaks causing lean condition. I already ordered one, almost here, guess I'll be testing out that first.

Btw @DerHase , do you know if the mk8 pcv also have one way going into the head and the another one into the TIP? Or just one path to the TIP?

There's no one way valve in the hose. There are check valves within the PCV for the cyl head to ensure boost doesn't enter the PCV valve at all. Look at the diagrams again and it'll be more clear.

On a side note why does this thread always blow up right before I'm headed to the track for a weekend? :ROFLMAO:

I've got the BMS catch can inline w/ the MK8 full retrofit so will be interesting to see how much/how quickly it fills up on track.
 

summerflame

New member
Location
malaysia
Car(s)
Golf 6 GTI
There's no one way valve in the hose. There are check valves within the PCV for the cyl head to ensure boost doesn't enter the PCV valve at all. Look at the diagrams again and it'll be more clear.

On a side note why does this thread always blow up right before I'm headed to the track for a weekend? :ROFLMAO:

I've got the BMS catch can inline w/ the MK8 full retrofit so will be interesting to see how much/how quickly it fills up on track.
Sorry I mean one path to the cylinder head, and another path to the TIP, not one way valve. So it indeed has two path, then I'll should retain the front PCV hose.
Will you be interested to testing out the exhaust venturi method? Based on guessing it should have good response wether it's part throttle, just getting back on throttle or don't have enough boost. I only have a simple vacuum sensor and not much knowledge about calibrating it etc, it's quite cheap you can get lots of results just by typing "exhaust venturi catch can" in google.
 

tigeo

Autocross Champion
MK8 full retrofit @ VIR this past weekend with @DerHase. Zero smoke. Zero oil consumption.
 

MonkeyMD

Autocross Champion
MK8 full retrofit @ VIR this past weekend with @DerHase. Zero smoke. Zero oil consumption.
Which pcv were you running before and what issues were you having?
 

tigeo

Autocross Champion
Which pcv were you running before and what issues were you having?
Originally the AP (?)/OE on the 1.8 Golfs, had smoke after getting a bit faster in a few spots at VIR and adding 200 tires. Replaced with BL, no issues on that one but did the MK8 to be part of the popular kids group.
 
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