The Acer is fairly typical of a lower cost DLP projectors when it comes to brightness. Its measured lumens are likely in the middle of the range of 1080p the more affordable DLP projectors - 2D ones that start around $800 with basic features, and 2D / 3D projectors like the Acer H9500, the Epson, Optoma, etc. For example, it's not as bright as the Epson in either "best" or "brightest" 2D modes, it's about the same brightness as the Optoma HD33 in "best", but is a good deal brighter in "brightest" mode. Its single mode in 3D seems to fall in between its "best" and "brightest", but closer to "best" - probably the equivalent of around 1200 lumens, before, all the losses incurred in the process for 3D and the glasses.
3D brightness is discussed in more depth, a bit further down
Those numbers are all "right out of the box", without any adjustments, to settings like contrast, which can affect overall brightness.