Awesome GTI tuning this week!
Go Faster Bits DV+ T9351 turbo bypass valve for TFSI engines review
I've just fitted a GFB DV+ T9351 turbo bypass valve to my Audi A4 B7 2.0 TFSI Quattro, and I'm so impressed with it I thought I would write a product review and installation guide for ASN.
This is what it looks like -
So what is it, how does it work, how do you fit one, what are the benefits and how much does it cost? Go Faster Bits have written a good description of their product as follows, copied from their website -
- Retains the factory solenoid coil for seamless integration
- Replaces plastic valve parts with metal for reliability and strength on chipped engines
- Direct-fit replacement with GFB’s TMS benefits
- Exclusive “pilot-actuated” valve mechanism for rapid response at high boost
GFB expands the DV+ range with a direct-fit solution for the weak factory diverter valve used on many European vehicles. The solenoid coil itself from the factory-fitted valve is great (the ECU opens it faster than any pneumatic valve so why replace it?), but the weak point however is the valve mechanism itself. So GFB’s DV+ solves this problem by replacing just the valve parts with an anodised billet aluminium housing fitted with a brass piston machined to exacting tolerances. The end result is sharper throttle response, lightning-fast valve actuation, and it will hold as much boost as you can throw at it.
Other manufacturers’ products involve replacing the entire system with a traditional pneumatic valve, requiring long vacuum hose runs, additional parts for tapping into the intake manifold vacuum, plus either a different solenoid valve to actuate the pneumatic valve or a ballast resistor to plug into the OE wiring loom. All these additional items result in a product that is slower, less responsive, more expensive and takes much longer to install.
GFB’s DV+ solution on the other hand is more responsive, less expensive, easier to install, and doesn’t cause compressor surge/turbo flutter. Oh, and it doesn’t require different springs or frequent re-builds.
The DV+ story: Better performance - more reliable
Many late-model European cars use ECU controlled solenoid-type diverter valves. This is a good concept because the valve can react very quickly and it only opens when it needs to. However, there are some problems with these valves. There are typically two types of solenoid-actuated diverter valves found standard on VAG and European cars, both of which have their shortcomings.
Additionally, in both cases, the solenoid on the OE diverter is directly connected to the valve mechanism, which is not ideal because neither it nor the return spring are strong enough to open and close the valve reliably at high boost. With problems like this, you can see why other aftermarket manufacturers assume the best solution is to replace the factory diverter entirely. Unfortunately though, whilst their replacement kits might be stronger than the factory diverter, their slower response speed and lower flow do not justify the extra cost and complexity - more of a compromise than a solution. GFB has taken a different approach to deliver a complete solution that solves existing problems and improves performance, without compromise or a hefty price tag. The DV+ addresses the factory valve problems with a very simple and elegant solution. Keeping the factory solenoid retains all the benefits of the stock system, and replacing the valve parts with indestructable metal components ensures strength and reliability no matter how much boost you run. That's not all. Rather than using the solenoid to directly actuate the valve, we’ve introduced a unique “pilot-actuation” system. This means the solenoid controls the air pressure that is used to open and close the piston, so it doesn't matter how much boost you push through it, the DV+ will open and close reliably without ever exceeding the solenoid’s capability. This feature also improves on the factory system by opening the valve progressively in response to boost pressure, so it only opens as much as required to get the job done (the factory valve simply opens and shuts, it cannot partially open if boost pressure is low), resulting in better throttle response.
Common OE Problem #1
The diaphragm types are commonly known to rupture, especially when boost and temperature are increased as a result of chip tuning.
Common OE Problem #2
The plastic piston-type leaks far more than most people realise (by design, not from wear), and doesn’t always close after a high-boost gear shift.
So that's what GFB say, how do you fit it? Firstly, remove your turbo bypass valve. It's best to start with an Audi 06H145710D 'rev D' valve, as this is the best, revised design -
Then dismantle it -
The new valve kit contents -
A comparison of the old and new valve components -
Oil the first piston -
Fit the first piston with the replacement and stronger spring -
Fit the alloy housing on top, lining up the dimple to the hole in between -
So it looks like this -
Then oil the second brass piston, fit the spring and fit to housing -
Notice the design of the brass piston end seal with the hole plus the bypass air holes in the housing -
Longer bolts are included in the kit to allow for the thicker housing. Once the valve is built, install on car. Mine is an A4, so K03 turbo mounted valve -
So how does the car drive? Does it work? Was it worth the money (£97.80 delivered) and effort to fit? In a word, YES!
It's brilliant, the car feels much more responsive both on & off the throttle, you can feel the boost being kept (rather than fully lost) between gear changes. The turbo must be stalling less as the boost appears to hold better changing gear. As a bonus it sounds nice too, not as loud as a Forge FMFSITVR valve, but obviously louder than OEM anyway! I highly recommend this kit, it's great.
I just want to point out I don't represent GFB, their importers, their retailers (I bought from AMD Essex) or have any affiliation with GFB the Company in any way. I'm just a regular Audi enthusiast who is impressed with this product.
This is a link to the AMD Essex website I bought it off -
GFB GFB DV+ for late model VAG 2.0T for Audi A4 B7 2.0 FSI quattro
Last edited by Big Al; 27th October 2013 at 05:55.
Audi A4 B7 2004 red 2.0 TFSI Quattro Sport saloon, Servotronic steering, MFSW, CDIS, DRL with Coming Home, auto dual xenon lights/wipers/mirrors, split folding rear seats, 3rd headrest, centre armrest, Isofix mounts, RS4 rear ARB, pedals & carbon dash trims; Audi TTS 9Jx18alloys (2 sets), Yokohama AD08 summer, Conti TS830P winter 245/40/18 tyres, TPI 15/20 spacers/lockers, Pipercross filter, GFB DV+ turbo valve, NGK BKR7EIX plugs, Osram Silverstar Xenarc D1S bulbs. Build thread