I've been tinkering around with different piston hybrid designs, and this just came to me. I'm not sure what you could call a valve like this, but it's based on Tech's QDV, but "piloted" mechanically by a pop-off valve. I hope my diagram is fairly clear, and as this is clearly still theory, I have red arrows pointing to the two areas that would need to seal, maybe with female o-rings? Will this work? And assuming it would, what could one call it?
EDIT: Picture sequence explains the valve function in more detail, hope it now makes better sense. Thinking maybe an internal check valve in the main piston will solve the problem of pressure behind the valve slowing opening.
EDIT: All problems with the valve seem to be fixed... now I'm seeing this as a viable build with some very custom parts.
