I learned how to speed read in school; I took a class. As one of the exercises, the teacher would flash a word on a screen very fast, and the only way you could assimilate the word was to remember it as a sort of picture. It was far faster than you could ever actually read something, and you definitely did not say the words in your head. From that we moved on to two words at a time, then five, and so on. It actually does work and I can still do it, but it's mentally exhausting. I use it a lot at work, where I have technical things to read, but not for pleasure reading, because it pretty much takes the pleasure out of it.
I suppose you could use this technique to read something like "War and Peace", but I don't believe that it would be very enjoyable. It sounds as though you read quite fast as it is, and maybe it's best to stay with that. If you're determined to learn this it's not hard to find a class, and you can pick it up fairly quickly; it's a technique like any other, not much different from typing when all's said and done (and about as exciting, in my opinion).