How to find one or two good recent PhD theses (that are internationally recognized as best) in your chosen area I am finding it difficult to select a topic for my masters thesis (my advisor is unwilling to offer suggestions on the matter). I intend to do thesis in the field of internal combustion engines. To get some good ideas about finding a good topic I want to study some recent PhD theses in internal combustion engines but I don't know where to find them. Also I would like to know about modern research trends in that field.
In general, doctoral theses do not receive much recognition outside of a university, let alone on an international scale. The reason for this is that nowadays the thesis is nowhere near as widely circulated as the papers that can be extracted from the thesis. 

Moreover, if you want to find out about good thesis topics, look up what's going on in the scientific literature of the area you're interested in—in this case, internal combustion engines. Find the most highly-respected journals, and see if they've published recent review articles in different areas related to your topic. That might give you a sense of where recent work has been, and provide you with a good body of reading material to work from.