The T9354 is a fully recirculating direct factory replacement for the pneumatic diaphragm type BPV (Bypass Valve) used on Ford, Volvo, Porsche, & Borg Warner Turbos – when you want the performance WITHOUT the noise!
Using GFB’s TMS technology the T9354 can help return the engine to peak boost up to 30% faster than a factory diverter valve when shifting gears
The factory BPV (bypass valve) has a couple of key shortcomings, in construction and operation.
First of all, tuned engines running high boost also produce a lot of heat in the charge air. Because the BPV is situated right on the compressor, it is subjected to the hottest part of the intake charge, and the heat from the compressor cover itself. This can cause the factory diaphragm to rupture, and if that happens and goes undetected for a while, it can cause damage to the turbo, as the ECU will try to compensate for the lost boost pressure by increasing turbo speed.
Second, the operation of the factory BPV is not aimed at throttle response. Because of the soft spring and the solenoid valve that is in-line with the vacuum hose, it can only operate in two states – fully open, or fully shut.
The factory BPV does not have the ability to open and close progressively in response to the existing boost pressure, and throttle response suffers when the valve vents more than it should in situations where you are not fully lifting the throttle. The T9354 solves these issues using proven metal and silicone construction of the valve components, meaning the DV+ will last a lifetime regardless of the harsh conditions.
As for performance, because the DV+ features a carefully selected spring rate AND spring pre-load adjustment, it can operate progressively to help sharpen throttle response. This is the basis of GFB’s TMS principle, which has been shown to reduce the time to peak boost on gearshift by 30%. This benefit is also particularly noticeable in situations where you are modulating the throttle to balance the car in a corner.