Chrome has built-in support for multiple search engines (many sites take the liberty of doing this automatically). You can customize the keyword that triggers each one.
For example, if you want to search HN you could add:
URL: https://hn.algolia.com/?query=%s
Keyword: hn
Then you simply type "hn" in the omnibox, hit space, and enter your search term.
https://support.google.com/chrome/answer/95426
