As many have said, longer hours do not necessarily translate into less bugs, more features or a better product in a reduced period of time. Changing processes if they are broken and motivating employees to work more effectively are going to be better bets in the long run (and probably even in the short term). Brute-forcing software development is not sustainable.
On the subject of motivation, you can point your boss to a couple Dan Pink videos:
http://www.youtube.com/watch?v=u6XAPnuFjJc (short version)
http://www.ted.com/talks/dan_pink_on_motivation.html (long version)
I am not sure what "space" you are developing in or what processes you use in your software development, but it may be worth considering Agile processes if you are not currently using them. They are not panacea, but if implemented properly they can bring some gains in efficiency and the effectiveness of the programmers you have now at the hours they are working.