Thank you!!!
Yeah, that's the plan. It's not designed to run on the high frequency duty cycle the DME outputs, but hardparker tested it out in this thread, and it seemed to work:
Conventional pressure operated wastegates on the N55
f30.bimmerpost.com
He used a 7.01024.02.0 valve which I was planning on buying. But I see the turbo came with a 7.01024.00 valve. I've been searching, and it seems these may actually be the same valve.
I plan on testing functionality of this valve on the higher duty cycle first though. So I bought this fully adjustable duty cycle generator. I'll connect the valve to an air compressor and measure the pressure output vs. duty cycle at the higher frequency with this generator. Then I'll know for sure if it will be sufficient. I'm guessing it may not be linear at the higher frequency, but it will certainly be interesting to compare it's performance at 32Hz vs. 200 or 250 (don't remember off the top of my head if it's 200 or 250).
So, I finally got around to testing this boost solenoid at a higher duty cycle frequency.
But first, I tried a baseline test at the 32Hz duty cycle frequency (what the valve was designed for). With about 23 psi supply pressure, It worked as expected. From 100% to 81% WGDC, the wastegate was fully closed with no boost pressure hitting the wastegate. Reducing from 81% WGDC gradually sent more pressure to the wastegate. By 30% WGDC, pressure in the wastegate had reached about 14psi, at which point the gate started to open (it had a 14psi spring, so it was nice to see the results align
). Continuing to reduce WGDC gradually opened the gate further until at 13% WGDC the gate was fully open, with full boost pressure (about 23psi) holding open the gate. This would allow for a good range of wastegate positions, and varying boost force on the gate by varying duty cycle.
Testing at high frequency:
At duty cycle frequencies above around 100Hz, the valve fell on its face. It essentially turned into an on/off switch. There was no gradual transition or pressure control to the wastegate, beyond all or nothing. At high duty cycles, the gate was closed, with no pressure sent to the gate. As duty cycle decreased, pressure sent to the gate was relatively unchanged, until some point, the valve transitioned and sent all pressure to the gate, and it would fully open. And then increasing WGDC back up, there was a lot of hysteresis, as you needed a higher WGDC% to get the gate to transition back to closed than was needed for it to open.
So. I'm not liking how this valve performs under the high duty cycle frequency range our DME runs in. I'll be sourcing some different valves to test to see if I can find one that seems to work better at the 250Hz range.
Attached are some pics of the setup, and some videos of testing at 32Hz and 200Hz.
Testing at 32 Hz:
Testing at 200 Hz:
. (Spacer part of harness circled in blue) Got some vacation time in late January, hope to make some more progress then
This will allow external wastegate control by the DME with no external boost controllers required!!
