GFB DV+ T9388 Diverter Valve for Mercedes applications

• The T9388 is the latest addition to the DV+ range of diverter valves from GFB (Go Fast Bits). It is designed as a complete drop-in replacement for the OEM diverter valve in late-model Mercedes vehicles.

  Unlike the earlier generation diverter valves manufactured by Pierburg, the newer AMG-branded OEM valves cannot be disassembled and incorporated into a DV+. Therefore, GFB developed the T9388 with a low-profile integrated solenoid as a complete replacement for both the AMG and Pierburg diverter valves, enabling a hassle-free installation with no clearance issues.

  Like all valves in the DV+ range, the new T9388 delivers the following benefits over the OEM diverter valve:

  • Improved boost holding
  • Sharper throttle response
  • Faster boost recovery after a gearshift or brief throttle lift
  • Unrivalled longevity, backed by our Lifetime Warranty

  Improved Boost Holding

  Since electronic OEM diverter valves first appeared in the mid-2000s, there have been many revisions over the years in an attempt to address reliability issues. Whilst the latest generation of OEM diverter valves has become more reliable, there is always a performance trade-off due to their operational method and plastic construction.

  When GFB engineers performed boost leak testing on the OEM diverter valve in a C63S, they found the leak was significantly larger than in earlier generations.

  This excessive leaking is due to the emerging trend of manufacturers mounting diverter valves remotely on plastic intercooler tanks rather than directly on the turbocharger. A plastic valve mechanism closing onto a plastic seat resulted in the largest OEM diverter valve leak we’ve seen yet at 28L/min at 1 Bar of boost.

  Even with the Viton face seal (featured on all DV+ pistons), the plastic OEM seat face was found to be so uneven that it was impossible to achieve a reliable seal. The T9388 successfully addresses this issue by incorporating an integral piston seat machined into its body. This design ensures a proper seal, even on uneven plastic OEM seats.

  Sharper throttle response, faster boost recovery after brief throttle lift

  Factory electronic diverter valves are binary in operation - they’re either open or shut. Your throttle, however, isn’t. When you make small throttle adjustments, the binary operation of the factory diverter results in abrupt changes in power delivery, which is the very definition of poor throttle response.

  The DV+ patented “pilot actuation” system allows the piston to open and close progressively, thereby smoothing the power delivery during throttle modulation, and ultimately improving throttle response.

  Unrivalled longevity, backed by our Lifetime Warranty

  The combination of precision manufacturing, attention to detail, and robust materials mean the DV+ will last a lifetime. So does the warranty!

TÜV / ABE available upon request

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Products come with a warranty, detailed in a certificate included in the box.

To make a valid claim, you must prove the damage was not caused by you and that the warranty certificate is valid.

Full terms are on the “Terms & Conditions” page — the link is at the bottom of the page.