What application/utility exactly is reporting that the Raw files from a Canon 40D are 8-bit? The Raw .CR2 files are a proprietary format (that cannot be read directly by a computer) and must be converted to a universal standard image file format to acquire access to the content.

If you use the Canon software to make this conversion, the software provides the opportunity to save the full bit-depth of the capture in a standard 16-bit TIFF if you choose that option as your output.

As an option some non-destructive applications like Adobe LightRoom and Apple Aperture have the facility to access Raw files directly and without making any change to the integrity of the a .CR2 file, and with the capability of exporting a standard format file in either 8-bit or 16-bit.

Your computer operating system only supports 8 or 16 bit file format standards so it if the files are stored in your computer and you use the computer's utilities to query the file information/properties, the operating will only report what it recognizes and supports - and operating systems do not support a 14-bit file depth, and probably assume because it is non-standard it is 8-bit.