MK7 PCV Tech Talk and MK8 Retrofit Info
What if the best PCV solution comes from VW?
I was hoping to assess the cooling system my last time at VIR, as I had just gotten done with installing the Racelouvers hood vent.
But my PCV system decided it had other plans.
Earlier this year I added Powerflex offset LCA bushings (in addition to my 034 top mounts). More grip was great, but ever since then I started having problems with the PCV system and got a small puff of smoke on track at least once back in May:
There was no excessive KR (never more than 3.0 deg on any single cyl over the entire weekend), and I it didn’t look like I was trying to kill mosquitos, so didn’t really think much of it.
In June I had a little over 10 deg of KR in a few instances at an autocross as seen above. Peak values seen is the lower left corner in the [brackets].
I should have started working on a solution at that point. I guess life was busy and I wasn’t experiencing any other issues so it was out of sight, out of mind right? This was a perfect example of having all the data, but not actually using it - which bit me in the ass.
So I got my hood vent installed and was ready to test it at VIR (or so I thought) and signed up for a Track Night in America event in July.
I went through all 3 afternoon sessions in the 90F heat with constant timing pull due to KR. Up to 18 deg in all 4 cylinders. A friend behind me reported some smoke exiting T9 and through South Bend as well.
Notice the min recorded values in the lower left corner, and you can visibly see the frequency of KR occuring in the bottom graph.
Further analysis found that it seemed to heavily correlate with hard RH turns primarily:
Histogram showing KR vs lateral and longitudal G-forces, filtered for wide open throttle only.
So this finally led me to look a lot further into the PCV system on these cars. It is a relatively complicated subject to understand so put together the video at the top of this page to explain HOW the system works, and why I believe the MK8 PCV valve is worth retrofitting to the MK7, along with all the info on part numbers etc as well.
Retrofit Info/Results:
If you watched the full video, you know that I’ve been running the MK8 PCV for a little while now. It was tested at an autocross already with zero knock issues under braking + RH turns (where it did have problems when logging approximate 10 deg of KR previously).
Track testing of this initial configuration will be done later this month at Fastivus 2023 at Summit Point on the Shenandoah Circuit.
Parts Needed:
06K-103-210-D PCV Valve Hose (1) - Approx $125 USD
06Q-103-495-B Engine Crankcase Vent Valve (1) - Approx $60 USD
06M-906-094 Bung/sealing cap (1) - Approx $3 USD
3/8in vacuum cap (1) - Can be found at any local auto parts store or purchased online in a small assortment pack, such as this one: Amazon Link
Further Development and Future Plans:
I also did some initial follow-up testing based on the parting thoughts in the above video regarding a “full” retrofit of the MK8 valve, including making use of the Tiguan venturi:
On-car testing with the venturi being utilized will be done once the 034 turbo muffler delete shows up - currently on backorder per New German Performance and 034. To date (9/5/23), there have been zero problems with the MK8 valve on my GTI with the upper hose capped as explained in the videos, with one successful autocross event already done (which is covered in the first video) with no knock problems.
After a bit more time of on-car and on-track testing is done, I’ll move forward with writing a formal “How To” guide with regards to retrofitting this PCV as long as it doesn’t prove to show any ill effects. It is still very much in the testing phase currently, but for <$200 this is looking like a great option.
Follow-Up articles here:
Track Testing Results of MK8 PCV
MK8 Venturi Retrofit Testing and Results
MK8 PCV Results from others, and more questions to drive further testing
