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    Thread: Diverter valve vs. blow off valves

    1. 08-26-2019 03:45 PM #1
      Hey guys so last year I installed the upgraded piston DV from ECS . Few months back I also purchased from ECS the Atmospheric Diverter Valve Spacer. I just installed it however I feel like now boost comes on later on the RPMs . Before it was at 2800rpm, now it's after 3k.
      Do you loose power for running atmosphere valve? Since the air is not going back in motor but released out? Can anyone confirm this? Also how can I test boost leak or boost drop using VAG com or other methods? I do not have boost gauge. I do have OBD Bluetooth scanner which reads most parameters but I don't think it's accurate.

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    3. Member
      Join Date
      Dec 7th, 2014
      2007 Black B6 ___________ Passat, 2.0T ___________ 2004 Grey Silverado ___________ 1500, 4.8L Z71
      08-27-2019 09:09 PM #2
      Do not run a blow off valve or spacer. They do nothing except make noise. They act much slower than electronic diverter valves and the ECU expects an electronic diverter valve for calculations it makes. The stock rev D diverter valve can hold the boost of a stage 1-2 tune and even sometimes stage 3 just fine. If for some reason you want to "upgrade" anyway, replace it with a GFB to retain ECU control over the valve but to be stronger than stock. The reason you want to maintain the ECU electronic pulse-width modulation control over a DV unit (stock or GFB only) is because when the throttle valve closes and the motor is in overrun (translation: when you let off the throttle at WOT/high revs) back pressure develops in the turbo housing which reduces speed of the turbine and increases turbo lag for when you get back on the throttle. To combat this, the DV is opened by an electrical actuator which allows the air to blow back to the intake side to the turbine and maintain turbine speed. Then when the throttle valve reopens (when you hit the go pedal) the DV closes. These behaviors COMPLETELY rely on the pulse-width modulation (PMW) electrical signal from the ECU to operate correctly and that ONLY happens with the stock DV or the GFB DV+… so moral of the story is when you get a BOV or an analogue DV that doesn’t retain the connection to the ECU, you are robbing yourself of that design and performance/turbo spool advantage with the regular DV or GFB.

      Since I brought up the GFB DV+, here's what you need to know about it because, as good as the product and company are, GFB DV+ does get talked up a bit more than it technically deserves (if performance gains are the measuring stick)...

      Keep in mind, this is coming from an owner of the GFB DV+ on both a K03 and now on a GTX2867R setup, and also a big fan of the company. I've had several talks with Brett from GFB (the engineer behind it) and he's an awesome and knowledge dude, very kind with his time. He let me pick his brain a lot. He's also very honest and that's why the literature you get with the GFB itself will attest to exactly what I'm about to say...

      The GFB makes negligible performance improvement IF you already had a totally properly functioning (fully sealing) Rev D DV. The folks who get the GFB and say it made them faster or whatever are either suffering from placebo effect or they had a Rev D DV that was leaking an itty bit (neither of which is uncommon). The only technical performance advantage to the GFB is that the progressive nature of the piston opening/closing as compared to the stock DV's binary (full open or full closed) nature, allows the GFB to keep sliiiightly more boost between shifts so when you're back on the throttle you get to full spool ever so slightly faster. On a K03 that spools almost immediately anyway this matters very little as it might shave off a 1/10th of a second of spool time maybe. I track my car so I'm attentive to these things and I didn't notice a thing. I didn't even notice a difference before and after when I put it on my GTX2867R which obviously spools slower; but there were a couple other changes I made around that time too so it wasn't a perfect before/after test to be fair.

      Bottom line. The GFB is a great product, it's well designed, it's clever, and it is made by a cool company. But the reason to buy is not for performance gains, it is because it is durable and you will not have to replace the DV ever again, even if you upgrade to a turbo that will make much more boost.

      On the subject of data-logging for hints at boost loss... yes, if you data-log for actual boost, specified boost, and wastegate control duty cycle (N75 duty cycle), along with engine speed (RPM) and accelerator pedal position as reference points to cross-analyze with the boost data, a trained eye knows how to spot the signs of a boost leak (or other cause of boost issues, e.g. wastegate opening prematurely). If you are interested in doing such logs there are some methodologies to doing them properly that you should be aware of (data logging random driving isn't gonna help)... if you want me to explain I can. Let me know.
      400BHP / 380CTQ - 2007 B6 Passat 2.0T FSI - Weekend Track Car & Part-time Commuter

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