GFB SV52 Blow-Off Valve with Aluminum Weld-on End

BOV capable of handling over 20 bar!

Specifically developed open blow-off valve for vehicles with over 500 HP for motorsports

With a height of only 86 mm (including the weld adapter), the SV52 is 10 mm shorter than the smallest competitor product available on the market and yet offers even more flow!

The SV52 includes two springs PLUS a spring pre-load adjustment system, allowing it to be fine-tuned for optimal throttle response and shift recovery. Unlike with competitors, there’s no need to purchase extra spring packs for different boost pressures.

Note: This valve only works on engines with a manifold vacuum of 5-22 inHg (17-74.5 kPa, 2.5-11 psi vacuum).

Features:
The body of the SV52 is CNC-machined from a single block of aluminum, ensuring strength without unnecessary extra mass. The anodized piston bore creates an extremely hard and low-friction surface where the one-piece 52.5 mm aluminum piston slides, ensuring durability over countless cycles. It uses GFB’s unique Viton O-ring seal design, with one seal at the piston’s front end to block incoming boost pressure and another seated in a groove on the piston to engage the specially shaped cylinder wall with varying compression levels, ensuring optimal sealing when the valve is closed and minimal friction during opening and closing movements.

Why does GFB use a piston rather than the usual diaphragm design?
Strength and reliability are the primary reasons, as a diaphragm cannot achieve these in a highly stressed BOV environment. Diaphragms are useful (we use them in our wastegates) because they offer low friction and good sealing capabilities. However, a rolling diaphragm is designed to receive net pressure on one side, essentially inflating it against the chamber walls, as is done in a lock system.
A BOV, however, is exposed to frequent pressure reversals — every time the accelerator is engaged and released. For a diaphragm, this means it repeatedly collapses under boost and inflates under vacuum, which eventually leads to diaphragm failure. A piston, on the other hand, is immune to this issue and continues to function under extreme pressure, temperature, and cycle conditions.

The unique mounting method of the SV52 is one way we managed to save unnecessary bulk: By eliminating V-band mounting, the piston and its venting ports can sit much lower, reducing the overall height to a level competitors cannot match.