What makes a Small block a Small block and a Big Block a big block?

[PKRWUD]

Nitrous is a different animal, it doesn't increase displacement. Nitrous oxide is simply a method of adding oxygen to the mixture in a controlled manner. The burnrate of the oxygen is controlled, whereas any other method of adding oxygen is uncontrollable, and would literally explode the engine. In the "old days", people who couldn't get nitrous would install a water injection system. That was another method of increasing the oxygen content in the mixture, but it was also very dangerous because water won't compress, and if too much was injected, the engine would hydro-lock.

Take care,
-Chris