Forge DV Testing
This was a semi scientific test.
I blew into the inlet pipe and drew vacuum.
Below are example to show that idle vacuum is around 19-20
In the pictures below
The first figure is the vacuum at which the valve opened and I
was able to force air trough the valve,
i.e. with effort and a hissing noise.
The second figure is the point at which the valve appears to be fully open and I could blow through it without effort.
I tested a number of valves plus the Forge Optimus with different springs.
AMD VIPER & FORGE 007P
It opened at 4.5 and was full opened very quickly at 5.5 In Hg.
I found that the FORGE DV007P operates at an identical level to the AmD Viper and recommend either valve.
(I didn't get a chance to get a picture of the DV007P)
The DV006 needed slightly higher than the Viper but is still a good valve and opens within 1 inHg so is fast reacting.
This valve was tested in it lowest setting as it is an adjustable valve.
It is Forges answer to adjustability in a diaphragm valve.
The Forge Optimus with a Yellow spring didn't open until 22.5 inHg
The Green Spring brought it a little lower and closer to oem specs.
The Japanese Valve Spring, Forges weakest brought it to an OEM Valve specification level.
As the opening vacuums were so much higher than the piston valves I tried a DV006 spring in the valve which suprisingly was higher than the levels in the DV006.
OEM Plastic DV 710N version
This opened at around 5.5 inhg but takes a good 4.5 inHg to be fully open.
I tried the Blue spring in the Optimus and I could not get it to open with my
Also interesting how the DV006 spring doesn't behave the same when put in the Optimus Diaphragm Valve.
My conclusion at this point is this....
A. I believe that the Jap spring is still too hard, its now beginning to open at the same level as a DV006 but still takes 4 InHg to be fully open.
B. Even with a lighter spring, the diaphragm valve needs to fully open and close
in less than 1 InHg to be fast. Due to the longer opening cycle the closed
throttle body is still under pressure for longer and this pressure is noticeable
on gear change by the revs blipping up before the begin to fall.
I expect the Earlier/longer closing cycle is better but the turbo has already suffered during the opening cycle and has to recover any speed losses during that process
C. With the Jap Spring in the optimus, the DV Chatter is at least gone with this spring rate, this shows that the other springs were all too hard in my opinion.
D. For an adjustable, pre-loadable valve you need to aim for 1.0 InHg opening to 2.0 InHg fully open, then the pre-load adjuster will give the user flexibility to increase the tension to shift the open point....In theory.
I haven't checked the Optimus range of adjustment but in theory if its as wide as 20 InHg then the spring rate should start at 0.3 InHg on this valve as there is plenty to cover any requirement.
I still have concerns over these 2 issues
1. The spring rate, although it is better with a lighter spring.
2. Even with a lighter spring, the range from opening to fully open is much bigger with the diaphragm.
If for example we were ONLY looking at fully open levels, the Metal DV's are still much much better at the moment In my opinion.
Go for an AMD VIPER or FORGE 007P with the weakest spring.