The URL can't have spaces so you can't do what I was thinking you could do
Atleast not without some jiggery pokery
@kimholder You can do this: https://www.google.com/search?q=%s%20site%3Astackexchange.com
Add a new search engine= StackExchange Google, Keyword= se, URL= https://www.google.com/search?q=%s%20site%3Astackexchange.com
Then, when you type "se " into the address bar, chrome will say "Search StackExchange Google: "