DV mod I have not seen on a 4.0T before (GFB DV+)

[gk1]

Special thanks to member "15 Phantom S6" for mentioning this product as I had not heard of it prior.

The GFB (Go Fast Bits) DV+ has been around for quite a while and is popular on the VW Golf scene. The basics are that it replaces the guts of your stock solenoid powered DV with a machined adapter plate, pilot actuator, brass piston with silicone gasket and a couple springs. If you want more detail on how exactly it works head over to their website https://gfb.com.au/products/blow-off...alves/dv-plus/ they offer excellent explanations and videos. (P.S. they also have excellent support.) (BTW I have no affiliation with GFB.)

I have never seen anyone attempt to install them on a 4.0T before...

...and for good reason.

There is literally no room to install the adapter as it extends the length of the DV by 11mm. Which on the drivers side pushes it all the way into the engine cover standoff and a piece of valve cover casting that is in the way. There is no way to rotate the valve either as the electrical connector will only fit in the one spot and you'd have to extend the wires in any other position anyway.
Regardless, based on Phantom's experiences and literally dozens of other positive reviews I decide to move forward and grind out a spot for them to fit.

Here is before grinding. (The end of the stock setup has the OE valve sitting about 3mm from that casting part of the valve cover.)


Here is after grinding.


I took off more than was necessary to allow a little breathing room, plus I am not that adept at grinding of this nature and was only using a dremel tool. So please excuse the messy look. Anyway I managed to make enough room for it to fit. The passenger's side is further away from a similar spot and required less grinding.

On too the impressions...
My uncalibrated butt dyno and the lap timer boost gauge makes me think there is a difference. It does seem like it holds boost better to redline now. In particular in 3rd gear it just seems like it keeps pulling right to redline where before it felt like it ran out of breathe earlier. It actually surprised me a little because it was pulling like a freight train and seemed like it wasn't going to shift at first but it did...right at redline and full boost on the bar.
I did not notice any downsides. No extra unusual noises (the coming off part throttle low speed release is still audible like with stock valves and RS7 airbox), no fluttering or other weird noises at all. Driving normal it feels as normal as you'd expect.
I'd like to give it some more seat time and maybe get it over to the strip to see what difference it makes there, but overall it seems like it does as advertised.

Is it for everyone...probably not...there is quite a bit of grinding involved. It also doesn't magically create more boost than you had before. I feel it does holds available boost better (as intended). I'd be curious how it is on Stage 3 cars since holding boost better would seem paramount at their increased boost levels. It is quite pricey, but less than some full vacuum operated ones and (grinding aside) less complicated to install.
As always let me know if you have any questions and I'll do my best to answer them.

Passenger's side after grinding


Driver's side reassembled


Passenger's side reassembled


Overall reassembled.

[cdoug3]

Thank you for sharing this! I have been investigating the same mod and planned to grind the valve cover as well. I have this slated for next weekend and will report back on improvements with the stage 3.

[gk1]

Thank you for sharing this! I have been investigating the same mod and planned to grind the valve cover as well. I have this slated for next weekend and will report back on improvements with the stage 3.

Cool.
FWIW I had to grind a little more on the engine cover post/mount point. The end of the solenoid and the electrical connector were barely touching it, but I did not want any contact so i shaved down a little bit more.

[DoItAllGarage]

I installed this GFB on my B8 2.0 TFSI a few months ago. Don't know why it didn't cross my mind about installing it on my S7. This is awesome!

[viceroy1976]

While I would love to install a GFB DV into my S6, I'd rather not have to grind away at parts of the engine to make it fit.
Sadly I'll be giving this mod a miss unless GFB or someone else comes up with a part that actually fits correctly.

[gk1]

While I would love to install a GFB DV into my S6, I'd rather not have to grind away at parts of the engine to make it fit.
Sadly I'll be giving this mod a miss unless GFB or someone else comes up with a part that actually fits correctly.

Yep, understood. I thought the same at first too. However, it is just extra casting of the valve covers. Even as much as is taken away from the plastic cover mount area it is still very solid. Maybe the pictures make it look more severe.
I thought about it for a while and it would be a miracle if anyone comes up with a way to make something like this fit without grinding. GFB even makes the T9359 that makes the solenoid perpendicular to the piston, but I don't know if that would even fit without grinding, plus then you have to contend with maybe extending the wiring and cutting the plastic engine cover to make room. It is just too tight in that spot. Grinding was the best option for now. Also the DV+ has been around at least 5 years and this iteration of the 4.0T for 7-8 years. So holding out hope that someone will eventually make something to fit correctly one day is unfortunately a longshot as is the likelihood of it being worthwhile for someone to make it since the 2.0T market is significantly larger and it certainly didn't seem like anyone was beating down GFB's door to get something specific to the 4.0T.
Cheers.

[V10Jon]

Do you see value in the GFB units compared to a whole new diverter valve like what Forge makes?

[kaploww]

I’m struggling to see how an, electronically actuated solenoid, piston diverter valve would cause a boost leak.

The solenoid is either open or shut. There is no spring to leak against.

[gk1]

Do you see value in the GFB units compared to a whole new diverter valve like what Forge makes?

I never tried there's, so I can't say anything about performance. Those are all-vacuum operated and require more installation albeit no griding...with vacuum hoses, cutting into the vacuum system and wiring.

[gk1]

I’m struggling to see how an, electronically actuated solenoid, piston diverter valve would cause a boost leak.

The solenoid is either open or shut. There is no spring to leak against.

I was thinking the same until I took the stock one apart. There is a very lightweight spring. All the parts other than the armature are plastic. The seal on the piston is plastic on plastic to the housing it sits in. There are numerous holes in the piston which then rely on the small rubber ring on the back side and the plastic body to form the valve chamber and hold the boost and the valve shut.. The stock internals came apart as I removed them from the car. Again they are not fitted together with any seal or anything it is just a tight plastic/plastic fit.

The solenoid is either energized or not. Energized to open and vent or not-energized to hold boost. Basically it does not energize to shut, or another way...the solenoid does not electronically force the valve shut. It relies solely on the spring and the valve chamber filling quickly enough to hold it shut. Which is why I think GFB felt it was good to retain the electronic solenoid for its speed to energize and allow boost to be released when the ECU demands it. I feel they have just sped up the rate at which it closes and its ability to seal tighter and enhanced the valve chamber behind the piston to fill quickly and hold more than stock boost compared to the OE valve.. Remember the original diagram style solenoid valves had a rubber/silicon seal so audi must have felt it was better too at one point if it weren't for the leaky tear-prone rubber diaphragm.

This is not to say the OE D valve is bad, it is better than having to deal with a broken rubber diaphragm on an older valve. I guess I am just saying it is a compromise and may not be the best solution for a modified motor.

[kaploww]

It is held shut by the solenoid.

When it vents, it shuts off the power.

Air pressure is released from the intake tract, and then the spring moves it back to the closed position where it is held shut again by the solenoid.

[gk1]

It is held shut by the solenoid.

When it vents, it shuts off the power.

Air pressure is released from the intake tract, and then the spring moves it back to the closed position where it is held shut again by the solenoid.

That is not my understanding from both GFB's information and this video where you can see he powers the valve and it pulls open and he shuts off power to the valve and it closes.
http://stratifiedauto.com/wordpress/...Action.mp4?_=1

[kaploww]

EDIT:

I’ve been thinking about this further.

The guy has the polarity backwards on the DV.

There is no way the DV would be able to hold even 2psi if it wasn’t held shut by the solenoid.

It slides in and out with light pressure from your finger.

[gk1]

EDIT:

I’ve been thinking about this further.

The guy has the polarity backwards on the DV.

There is no way the DV would be able to hold even 2psi if it wasn’t held shut by the solenoid.

It slides in and out with light pressure from your finger.

OK.
It is held shut by boost pressure just like the GFB. Air enters those holes in the center and fills the larger chamber behind the blue seal forcing it closed. Which is why if the red rubber diaphragm ripped you had a problem (boost leak). If it didn't work that way then why not just use a flat spring loaded metal disc covered in rubber and with the solenoid closing the disc whenever it wanted there would be no ripped diaphragm boost leak issues. From my understanding if it did work the way you described a solenoid of that size is not strong enough to hold by itself against boost pressure, it needs the mechanical action/pressure differential. And as you can see it would be quite slow to close.
Also the way you are describing things then the GFB DV would not work at all. The solenoid only opens the pilot hole in the center of the aluminum adapter plate when it needs to release boost pressure allowing the piston to open. The pilot valve cannot push through the solid aluminum plate and shut the piston itself. It shuts with boost pressure and opens with the solenoid action.

Also the wiring diagram and measurement shows the ground wire to be on the flat side of the solenoid so lets give him the benefit of the doubt that he used standard black wire to connect to the negative of his power supply.

[cdoug3]

I got the DV+ installed last night. The grinding wasn't all that bad. Tight spaces so a careful approach is required.

My initial impression is my boost profile is similar with the DV+ versus stock type D. This assessment is based on the P3 boost readings. I have been tracking down the cause of a P0299 code with my stage 3 and have damn near replaced all boost control related parts (n75, vacuum lines, wastegate actuators, dv)

I spike at 21.4 but the boost settles around 19 generally. I hoped the diverter valve was leaking but no such luck.

I'll report back as I do some more testing and logging.

[cdoug3]

UPDATE:

I pressure tested the intake system after the turbos and found the GFB valves leaked. I tested the factory valves and they leaked worse. I tested at pressures ranging from 5psi to 25psi.

I installed a slightly longer spring in the GFB valve and had zero leakage. I triggered the solenoids to test their operation and the valve still opened.

There is definitely a difference in boost response after installing the longer spring in the GFB valves!

[gk1]

UPDATE:

I pressure tested the intake system after the turbos and found the GFB valves leaked. I tested the factory valves and they leaked worse. I tested at pressures ranging from 5psi to 25psi.

I installed a slightly longer spring in the GFB valve and had zero leakage. I triggered the solenoids to test their operation and the valve still opened.

There is definitely a difference in boost response after installing the longer spring in the GFB valves!

Good to know. Thanks for testing. Where did you source the slightly longer spring?
From my understanding the valve should hold pressure even if there is no spring...
It might be good to send feedback to GFB.

[cdoug3]

Good to know. Thanks for testing. Where did you source the slightly longer spring?
From my understanding the valve should hold pressure even if there is no spring...
It might be good to send feedback to GFB.

Good call. I will send them feedback, I was extremely surprised with the leakage. In fact, If uninstalled the DV adapter and blew in the TB end, it leaked. Regarding the spring, I pulled one from our inventory... Our company develops new products and has a plethora of knick-knacks for prototyping. I will get you the spring specs.

[scott99c2]

I guess I don't understand why you did this vs. install the Forge DV's. Was it cost? Do they not fit? Am I missing something? (yes, I'm dumb, make me smart )

[gk1]

I guess I don't understand why you did this vs. install the Forge DV's. Was it cost? Do they not fit? Am I missing something? (yes, I'm dumb, make me smart )

For me...I didn't necessarily want the Forge. Not a cost issue.
Also the Forge is a vacuum operated system. I didn't want to go that route.
Sometimes I like to try different things...i.e H&R sway bars when everyone else goes another route.
Also wanted to see if I could decrease some of the air rush noise but I see now that is solely a function of RS7 intake/airbox.
Next up is creative stock heat exchanger cooling...that one may be a long ways off though.

[N041136]

May I ask what's the Part Number for this product? Thank you !

[N041136]

Are they T9351? If it is possible to fit a T9359 for s6 application?


C7.5 S6 APR STG2 ECU+TCU, Eventuri Intake, AMS Cooler, Akrapovic Exhaust, Catless DP, BBS FI-R, Ceramic Brake

[gk1]

Are they T9351? If it is possible to fit a T9359 for s6 application?


C7.5 S6 APR STG2 ECU+TCU, Eventuri Intake, AMS Cooler, Akrapovic Exhaust, Catless DP, BBS FI-R, Ceramic Brake

The T9351 is what I used.
Neither actually fits the S6 without modifications.
The T9359 was suggested as a possibility by GFB but if it fits in the space without grinding...(maybe not) then the solenoid would be vertical and the plastic engine cover would have to be modified as well as the wiring to the solenoid extended as they have no extra length in them.

[N041136]

The T9351 is what I used.
Neither actually fits the S6 without modifications.
The T9359 was suggested as a possibility by GFB but if it fits in the space without grinding...(maybe not) then the solenoid would be vertical and the plastic engine cover would have to be modified as well as the wiring to the solenoid extended as they have no extra length in them.

Thank you very much for your reply!


My car is a stg3 audi s6, may I ask if the performance for T9351 and T9359 are the same? (same internal but the 59 is just vertical?)

If so, I will try T9351, i guess T9359 creates more troubles.

[gk1]

Thank you very much for your reply!


My car is a stg3 audi s6, may I ask if the performance for T9351 and T9359 are the same? (same internal but the 59 is just vertical?)

If so, I will try T9351, i guess T9359 creates more troubles.

IDK. Might want to reach out to GFB to be sure if it is just a different mount solution....it does appear that way.

[ericw.]

I was curious about this after learning last month that the 4.0T diverter valve is the same part number from the B7 A4 2.0t. There should be a few options for aftermarket DV on this car considering how long that part has been in production.

[MolonLabe300]

I was curious about this after learning last month that the 4.0T diverter valve is the same part number from the B7 A4 2.0t. There should be a few options for aftermarket DV on this car considering how long that part has been in production.

With that said I wonder if these would fit.

https://www.ecstuning.com/b-turbosma...0223-1263~tsm/

[ericw.]

With that said I wonder if these would fit.

https://www.ecstuning.com/b-turbosma...0223-1263~tsm/

I'm not totally sure but it looks like the dimensions might not require any grinding on the block to fit. Could be perfect. Are you going to give them a try?

Sent from my SM-G950U using Tapatalk

[MolonLabe300]

Im going to boresscope and compression test this weekend, if my blown turbos havent killed my block, then I probably will try those out, they have a recirculate and a BOV option.

[ericw.]

Im going to boresscope and compression test this weekend, if my blown turbos havent killed my block, then I probably will try those out, they have a recirculate and a BOV option.

Nice, if you confirm fitment I might even make the swap for a recirc configuration. I was meaning to ask you how the diagnostics were going. Hoping for some good news soon.

[kaploww]

May want to be cautious with the BOV option vs the Recirc.

If you go with the BOV keep in mind the driver side valve is connected to the PCV system via the intake tract.

Over time it could vent oil vapor into the engine bay, and you could end up with a mess on your hands.

It wouldn’t be a lot, but it will be there for sure with the way the intake tract is designed.

On the bright side if there is a large build up quickly, it could be the canary in the cave that your oil separator is on it’s way out.

[MolonLabe300]

I'd probably be go with the recirculate option. But that's really good information. Thanks

May want to be cautious with the BOV option vs the Recirc.

If you go with the BOV keep in mind the driver side valve is connected to the PCV system via the intake tract.

Over time it could vent oil vapor into the engine bay, and you could end up with a mess on your hands.

It wouldn’t be a lot, but it will be there for sure with the way the intake tract is designed.

On the bright side if there is a large build up quickly, it could be the canary in the cave that your oil separator is on it’s way out.

Sent from my Pixel 2 XL using Audizine mobile app

[jazzyjay18]

Are there any updates

[ZTM pearl]

While I would love to install a GFB DV into my S6, I'd rather not have to grind away at parts of the engine to make it fit.
Sadly I'll be giving this mod a miss unless GFB or someone else comes up with a part that actually fits correctly.

I've got the GFB DVs on my S7. Only one side needed grinding, and it was only a small amount. It sounds way worse than it looks. It has no structural significance. If you don't tell anyone, no-one will know. It's like when your dog poops in the park, and nobody saw, it didn't really happen. Hope that helps.

[jazzyjay18]

I've got the GFB DVs on my S7. Only one side needed grinding, and it was only a small amount. It sounds way worse than it looks. It has no structural significance. If you don't tell anyone, no-one will know. It's like when your dog poops in the park, and nobody saw, it didn't really happen. Hope that helps.

Did you log before and after doing this mod? trying to see it boost faster or maintains boost longer