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

[PerceivedShift]

What adds to my scenario is that I see a lot of highway miles, but I also push the car hard when I can.

The fact you see a lot of highway miles is a reason NOT to buy any plate from APR, Racing Line...etc. Honestly, the full MK8 PCV retrofit is looking like what 99.99% of MK7 and MK7.5 owners need. Don't buy into marketing hype of the aftermarket PCV systems. The MK8 PCV has done fine well beyond Stage 2 setups.

 

[avenali312]

What’s a lot harder to capture is the fact that the BMS TIP is putting 0.20psi on the crankcase for about 10 seconds every time you’re taking off from a stop.

Sounds like a solid reason to swap back to the factory TIP for the time being.

This is my plan for the time being.

I've had a lot of signs of the crankcase being over pressurized (gaskets and seals weeping and a recent N80/PCV failure). Based on @DerHase findings here, I'm removing my MST inlet kit (TIP and hose) this week, having the engine looked over at the end of the month, and will clean up and signs of oil anywhere to see if things go back to normal-ish (the seals are already compromised, but it's not bad enough to incur that labor charge for now).

 

[avenali312]

Also got a $40 knock off TIP that looks like an APR reject. To be tested with at least the MK7 BL valve and MK8 unmodded valve to see if one is "better" than the other. I doubt there will be any loggable differences but who knows?

Any interest in testing the MST inlet kit? I can ship you the TIP and hose once I get it removed as long as I get it back in one piece so I can eventually sell it haha.

 

[Torrid]

Bottom line if you’re not tracking the car at all then any kind of plate is a dumb solution as you’ll then be putting (light) pressure on the crankcase at all times you’re out of boost. There are multiple people running the MK8 basic retrofit pushing 450-550whp with no problems on the street. I suspect they’ll need the Venturi for track use though like @yakev724 .

I beat the shit out of my car on track for 20 min at a time and have had zero issues in basic or full retrofit configuration (with stock TIP). If you’re not seeing 260F+ oil temps you’re not really stressing the car that much (and assuming you’re not testing the strength of the stock bottom end parts - not really stressing in the same way).

There’s really nothing else to it. There are countless people who have issues with any of the plate systems. Knowing what I know now, it’s likely correlated to the TIP they’re running not being a good match for whatever other clusterfuck of a setup they have. The TIP vacuum testing will possibly be even more relevant for people with plates because there is no regulator to dial down the vacuum.

What’s a lot harder to capture is the fact that the BMS TIP is putting 0.20psi on the crankcase for about 10 seconds every time you’re taking off from a stop. Any plate system will be worse because at least the OEM PCV gets to start out at -0.8 to -0.9psi. Plates will all be positive at idle with no volume of vacuum storage to help.

If/when it’s released, I’d only really consider the Radium plate. They actually do real R&D, not just copy the looks of TCR stuff and sublet to the lowest bidder on AliExpress.

(This isn’t meant to be taken personally- but it’s frustrating knowing that some degree-less idiot former mechanic has done more R&D for the PCV system on this platform than any of the aftermarket parts companies. The PCV thing is just part of it. Don’t get me started on oil coolers, bump-steer, or CSF radiators

Like really - HOW does any aftermarket company not see the hump inside the OEM TIP and not think “Gee, maybe that’s there for a reason?”)


/rant

I think that’s a big issue with these products being offered. They claim to fix an issue, but detrimental to primarily street driven vehicles. I was surprised how many street cars I was able to find videos of people installing these products.

I’m still waiting for my car out of the shop so instead of playing with my car in down time, I’m reading crap and watching videos for things I shouldn’t have been considering in the first place as my initial read was due to oil seepage around the fill cap which was fixed with a new oil cap anyway.

 

[Nineeightyone]

Actually, @DerHase would you have any interest in testing other TIPs?

 

[StockblockGLI]

Hmmm…So basically what you are saying is that there is going to be an influx of aftermarket TIPs for sale soon ?

 

[Nineeightyone]

Hmmm…So basically what you are saying is that there is going to be an influx of aftermarket TIPs for sale soon ?

I feel like it's gonna be a similar situation to the diverter valve spacer. A mod people buy early on, and then a fair number of them bail on. Mine was free ages ago (likely for the same reason), but I'm still running it for funsies.

 

[mrmatto]

Hmmm…So basically what you are saying is that there is going to be an influx of aftermarket TIPs for sale soon ?

I don't see any reason for that. Unless you're smoking, it's a non-issue. And if you are, it's possibly fixed with the mk8 full retrofit.

 

[avenali312]

I don't see any reason for that. Unless you're smoking, it's a non-issue. And if you are, it's possibly fixed with the mk8 full retrofit.

I'll disagree and say that, at least for the time being, the direction this is going is showing that my non-smoking, non-tracked car is seeing some negative results from positive crankcase pressure. Obviously making some huge assumptions, but it does align with my recent issues.

P.s. MST Inlet Kit for sale soon!

 

[mrmatto]

I'll disagree and say that, at least for the time being, the direction this is going is showing that my non-smoking, non-tracked car is seeing some negative results from positive crankcase pressure. Obviously making some huge assumptions, but it does align with my recent issues.

P.s. MST Inlet Kit for sale soon!

I do think that's a big assumption. It's a very, very slight positive pressure and for a brief period of time. I don't know that data exists to show it's actually a problem. But ultimately I doubt it's possible to test that and you have to do what's most comfortable to you. And since you're having issues, it's probably smart to start eliminating variables.

 

[avenali312]

I do think that's a big assumption. It's a very, very slight positive pressure and for a brief period of time.

Yeah, but over the course of many years in stop-and-go Atlanta traffic, I feel like it could add up.

I don't know that data exists to show it's actually a problem.

Probably not haha.

And since you're having issues, it's probably smart to start eliminating variables.

Yeah, this is kind of where I'm at now.

 

[PerceivedShift]

Hmmm…So basically what you are saying is that there is going to be an influx of aftermarket TIPs for sale soon ?

So long as you run the full MK8 retrofit, you are fine running an aftermarket TIP.

 

[mrmatto]

That's my understanding as well. Of course, proof will be in the pudding, so to speak... once people get these setups on the track/course.

 

[tigeo]

One thing - plenty of folks without smoking using both an aftermarket TIP and a MK7 BL PCV (me!). Derhase feels that if that is the case, the MK8 basic setup will also be problem free. I did just order a 034 TMD and the fittings needed to go ahead and add the venturi to my MK8 b/c of peer pressure/bullying/wanting to belong.

 

[DerHase]

Any interest in testing the MST inlet kit? I can ship you the TIP and hose once I get it removed as long as I get it back in one piece so I can eventually sell it haha.

+

Actually, @DerHase would you have any interest in testing other TIPs?

Somewhat, but I've honestly got a lot of other stuff going on and would prefer to move on from the PCV stuff. I have an IS38 going on in the next month or two so that's going to re-set establishing baselines for everything as well. (Will make for good comparisons, and see what else may be needed with more turbo)

Testing this kind of stuff is the PERFECT case for a flow bench... and I've been talking with Jeff at www.mygolfmk7.com since he can control the variables a lot more for stuff like this. I'll actually be sending my non-OE TIPs to him to test and and baseline against other stuff.

I'll also add again that you can do your own testing if you fit the MK8 PCV and have a GTI (or something with SAI). Adding the PCV sensor and wire harness is not hard. Data logging the SAI voltage can be easily put through a formula in MegaLogViewer or even Excel to produce a pressure vs RPM data log like I've been doing.

I don't see any reason for that. Unless you're smoking, it's a non-issue. And if you are, it's possibly fixed with the mk8 full retrofit.

100% this. Logic dictates that any kind of pressure on the crankcase is bad, and less frequency of introducing pressure is move in the right direction.

I do think that's a big assumption. It's a very, very slight positive pressure and for a brief period of time. I don't know that data exists to show it's actually a problem. But ultimately I doubt it's possible to test that and you have to do what's most comfortable to you. And since you're having issues, it's probably smart to start eliminating variables.

Whether problems actually show up will vary car to car. Crankcase seals can take very light pressure for short amounts of time. They're not meant to so it's best to be avoided. Some cars are just sealed better than others.

Yeah, but over the course of many years in stop-and-go Atlanta traffic, I feel like it could add up.

Probably not haha.

Yeah, this is kind of where I'm at now.

If stuff is already leaking, I don't expect problems to get any better.

So long as you run the full MK8 retrofit, you are fine running an aftermarket TIP.

This is what my testing seems to indicate. Funny enough, the higher flowing/worse for stock PCV system TIP is the best of the bunch as far as stabilizing the crankcase pressures goes.

That's my understanding as well. Of course, proof will be in the pudding, so to speak... once people get these setups on the track/course.

I'll be tracking it this weekend, if not with your BMS TIP, then with my $25 Ebay TIP which is hopefully here in time (so I can do a few pulls and baseline it against the others first.

I have a buddy driving the car for a few sessions who agreed to help with testing, so the plan is to have him do a few laps in full retrofit form, come in, I'll switch it to basic retrofit and then send him back out and see if it smokes or registers a ton of knock.

One thing - plenty of folks without smoking using both an aftermarket TIP and a MK7 BL PCV (me!). Derhase feels that if that is the case, the MK8 basic setup will also be problem free. I did just order a 034 TMD and the fittings needed to go ahead and add the venturi to my MK8 b/c of peer pressure/bullying/wanting to belong.

This.

The MK7 BL vs MK8 basic retrofit seem to be basically a lateral move. There may be some weird edge case where one works but the other doesn't, but we haven't really found it yet with real effort back to back testing. People like @MonkeyMD changing his oil pan at the same time, and @mrmatto putting the BMS TIP on at the same time potentially skewing the results when swapping from one to the other