This is a Chevrolet v8 engine meant for decoration. It's dimensions are roughly 100x100x70mm except for two 2mb models, which are slightly bigger to fit 2cm (OD) bearing.

If you have any doubts as to what file to download, I recommend downloading the "engine block with crank shaft area" or the "engine bigger" (this one prints in one piece) since the other ones can cause errors in some slicers. In this file, to fit the parts, there are rectangular marks that show where to put each piece inside the engine block in case you want to glue them together.