GFB T9351 User Manual

GFB DV+

Installation Instructions

Part #T9351

The DV+ difference

Whilst the DV+ might look pretty basic, there is a very significant difference in the way it operates compared to
the factory diverter valves, and other aftermarket products on the market.

The factory diverter valves use the solenoid to directly actuate the valve. The problem with this method is the
actuating forces are very weak – the return spring is weak, and the solenoid coil is weak when the valve is fully
closed because of the long 5mm stroke (magnetic force diminishes significantly as distance increases). So
increasing the spring pre-load of the factory valve doesn’t help, since the solenoid coil will have trouble opening
the valve.

The GFB DV+ uses the factory solenoid coil, but its role is to control the pressure signal used to actually open and

close the piston, which is known as “pilot actuation”. This means the forces that the solenoid coil needs to

actuate are much lower, and its operation is therefore reliable at much higher pressure. The solenoid operates a
plunger than controls pressure to the back of the piston. When the solenoid is off, there is equal pressure on both
sides of the piston, but importantly, the area the pressure acts on is about 25% LARGER on the back of the piston
than the front. So there is 25% more force holding the piston shut than there is pushing it open. The bottom line
is, it doesn’t matter how much boost you run, the DV+ will never crack open.

When the solenoid activates, the pressure on the back of the piston is relieved, and it can then open. The benefits
of this system are reliable valve actuation at high boost, no leakage, and being all metal parts, no failures due to
increased temperature.

Because the DV+ has a higher closing force than opening force, it doesn’t actually NEED a return spring behind the
piston to work – it will open and shut, and hold boost, just as reliably with or without the spring.

However, using the spring means that unlike the factory diverter, the GFB DV+ will open in response to both
boost pressure AND the ECU signal operating the solenoid. That is, if the solenoid is triggered but there is no
boost, it won’t open. If the solenoid is triggered and there is boost, the valve will open only as long as there is
boost pressure pushing it open. It will close itself as boost pressure in the intercooler drops, even if the ECU is
telling it to open. This operation method results in less turbo lag, because the valve is not opened unnecessarily.

This is the basis behind GFB’s TMS principle,

which is this; turbo lag is minimised when
the valve only vents just enough air to
prevent compressor surge – the graph
opposite illustrates the reduction in lag. To
read more about the TMS principle, visit our
website: www.gfb.com.au