Here are a few more photos to give you guys a chance to visualize how everything works.
Here's a side photo with the VANOS unit on so you can see how the helical gear works. The gear slides toward the cam carrier as the solenoid opens and allows high pressure oil into the VANOS unit and advances cam timing.
As you can see the other side of the cylinder is also covered by the VANOS unit, even though that side has no VANOS.
As you can see there's plenty of room to fit a double VANOS unit, and the Double Vanos M52 still uses the same cylinder head casting so it would make sense that with the cam carrier, camshafts and bearing caps from an M52Tu, you could mount double VANOS if you so chose. The only advantage would be infinite variability and improved gas mileage, but it would be more difficult to find aggressive enough camshafts to make a significant advantage in terms of horsepower. It's certainly true that I'm better off with S50 camshafts than with M52Tu camshafts and there's scarcely any gain in terms of fuel economy. It's likely that with forced induction and intelligent tuning, one could make a significant gain in boost response and ultimately make a gain in power as well.
