Dont know if this is what you are after, but it does change the behavior of the Search noticeably.

type in searchBar "about:config"
Accept warning
Search "browser.urlbar.suggest.searches" and change it to false (Do this Only if you want to disable suggesions)
Search "keyword.enabled" and change it to false
Search "browser.fixup.alternate.enabled" and change it to false
Source: https://support.mozilla.org/en-US/questions/1284577