MK8 PCV Retrofit UPDATES (Pt 10): User Feedback + more PCV Tech Talk

[@Some1ElsePlz]

I'm dealing with blue smoke and oil ingestion in my mk7R and I'm planning on doing the basic retrofit in a week or two.

[@JeffJonesMk7]

Interesting… would do good with some flow bench Data. You’re missing the bigger picture.

[@datadrivenmqb]

Would be neat info for sure to know how much vacuum is drawn on the TIP PCV connection through different TIP/intake combos.

[@JordieG8]

Subaru owners are worse at modding everything. lol I don’t have my miles on my Mk8 Basic retrofit yet on my 18 S3, but I’ll report more after I do. I do plan on doing the venturi, I just want to find a boost source that doesn’t require me drilling anything.

[@datadrivenmqb]

@@JordieG8best bet is the 034 TMD in my opinion. If your turbo can't (like the Vortex XL I believe), then tapping the charge pipe is the only other realistic option. Or the turbo but 😬 The Venturi source has to be between turbo outlet and throttle body. Good luck!

[@JordieG8]

@@datadrivenmqb yeah, I forgot to mention I’m running a GT2260S. It’s going to have to be the charge pipe. I’ll just have to find a way to do it so it’s secure and leak free. Plastic!

[@2001pulsar]

Might try this on my MK7R with e85, with a catch can between the PCV and TIP to reduce oil dilution issues. I have Racing line inlet and BMS TIP.

[@datadrivenmqb]

Catch cans won't help with that at all. They really need to go between the blue path in the cyl head and the PCV, which is a bit of a problem. This is covered in the original video here: kzbin.info/www/bejne/oIrHd2CphLGYaassi=pLn0XrgYoI3ktRQl Personally I think the only reasons that catch cans catch any watery stuff is because they are cold metal and when the engine is first started, any moisture in the air ingested instantly condenses. This is why they don't fill up near as quickly when it's hot outside. The MK8 valve does much better without a catch can because the can on the TIP side delays the vacuum being able to be replenished on WOT. If a catch can is "needed" (it is not), then I think fitting the Venturi would minimize the bad effects of the catch can's added volume, since it'll not allow vacuum to drop on transient throttle changes.

[@2001pulsar]

@@datadrivenmqb thanks for the feedback. I'll do it anyway, to reduce oil going n the TIP and pooling in the intercooler.

[@datadrivenmqb]

@@2001pulsar I ingested 1.5qts of oil in an hour at VIR with the BK valve. Intercooler pipes were bone dry. Oil being ingested is not through the TIP aside from the tiny bit of oil mist that might accumulate there.

[@2001pulsar]

@@datadrivenmqb my TIP, charge pipes and IC are getting quite oily, it's high boost blow by at 3.1 bar. I don't have clouds of smoke like some. Almost 100% street driven.

[@datadrivenmqb]

@@2001pulsar got it, good luck 👍

[@karstgeo7290]

The factory TIP narrows from the intake hose diameter to the turbo inlet housing. I believe that will increase velocity past the TIP hose and produce more vacuum vs. an aftermarket TIP that has a more constant diameter...I really wonder if the TIP is part of this and the reason for the OE design.

[@mjspeedzone5532]

Looking for information. Have a MK7 R.. installed a pcv valve cts catch can. Rough idle on cold starts but fine once warm. Other ppl had issues. The kit came with a venturi valve type thing but no instructions online. Not part of the original instructions nor in any pictures. I feel like it is a after part they threw in now. I never put it on the pcv valve inlet pressure line.. but im going to put it on this week and see if it makes a difference. Maybe because of issues its a walk around fix they now include? No info online.. hopefully your vid can give me some more insite into crank case pressure.

[@datadrivenmqb]

I responded to your other comment with info that hopefully helps. Also check out the APR PCV plate video as it'll be most directly applicable to how your CTS plate operates. kzbin.info/www/bejne/l5amgqh4eaqIe9U

[@tomsen77]

in my opinion the main problem seems to be the oneway valve in the yellow path. If there is not enough pressure difference between the PCV oil return side and the crankcase (oil pan) the valve may not open and the yellow path could get flooded because it cant freely drain back to the oil pan.

[@datadrivenmqb]

So I did originally think this, but people even with iAbed pans (which do away with the OEM baffle entirely) still have oil ingestion. Here's a more recent video where I looked more into my diaphragm theory (and why TIPs have a huge effect on the system overall): kzbin.info/www/bejne/hpvGoZ-XlMSln7ssi=E7QAq5zCEu1syEY1

[@molsen1029]

Your digging into this is revealing a lot of really interesting questions. Thanks for the dig.

[@diydrivenGA]

As a 2017 gti owner I wonder if the popular move of going BL instead of AH can be detrimental to the engine.

[@datadrivenmqb]

Yeah the AH valve definitely has me scratching my head since it would make it harder for crankcase pressure to vent. I want to find an AP valve and see if that one way valve is still present on it as well.

[@diydrivenGA]

@@datadrivenmqb also I was really surprised that the small triangle opening in the BL is a small port similar to the AH's big honking one but moved to a different spot.

[@diydrivenGA]

@@datadrivenmqb are you saying the AH would have a harder time venting crankcase pressure or the BL

[@datadrivenmqb]

@@diydrivenGA Correct - it seems the blowby path would be nearly useless in the AH valve due to the direction of the one-way valve just inside the PCV. It pulls vacuum on the cam cradle primarily so isn't using the red path hardly at all. AH pulls on the cam cover, BL pulls on the red path in the diagram. To be clear they are both evacuating the crankcase, but airflow throughout is very different. Not sure if you missed the part, but the BL small port doesn't go anywhere at all. It seems to just be leftover from manufacturing.

[@NinjarA7]

Seems like my 2020 MK7 GTI has a failed pcv valve at 30k miles, it has constant positive vacuum on oil cap during idle as well as multiple misfires in all cylinders in idle. It has downpipe, exhaust, stock turbo, D088 ic, CTS turbo inlet pipe, hpa hpfp running e85 with Sneeky tune. In your opinion would the MK8 pcv system last longer and be better in the long run from either the factory pcv valve or oil catch can.

[@NinjarA7]

Also forgot to say a CTS air intake

[@NinjarA7]

Also this is my daily driver, I do not track it. And I do sprited driving ever so often.

[@datadrivenmqb]

It would probably be fine with a MK8 valve, but I wouldn’t bother unless you’re willing to try the “full” retrofit. Otherwise another BK valve (which I believe should be stock for you, you’ll need to verify) should be just fine. If it’s not an overly strong vacuum at idle, it’s probably fine though. There should be some light vacuum at idle with stock valves.

[@NinjarA7]

@@datadrivenmqb I mean yeah it is a Bk, just don’t want to replace it after 30k miles every time if there is a better alternative for a little more money. Also I like upgrading stuff in my car lol. If I can upgrade to a better setup for $200 extra I want to do it. Looks like you did a good bit of research and testing on it. So yes I will be doing the full retrofit to get it done right. As once we start modding these beasts we gotta figure out better ways for the pieces to work well together after modding it. Thanks again for your feedback and all your research!

[@datadrivenmqb]

@@NinjarA7 sounds good! I do think getting an OEM-ish setup to work right is the better option for 95% of people. Especially those that don't see road course track time. I'll be posting more info as I do more testing... but I did confirm tonight that aftermarket TIP and intakes considerably drop vacuum a significant amount. If you HAPPEN to encounter any issues, I'd consider swapping those back to stock if so. I'm not sure how much of the problem is the TIP, and how much was the intake, but that will hopefully get figured out a bit more as I find a few other locals to help get some data.