Did you know you can tell Siri which specific search engine to use on the fly?
In Settings > Safari you can define your default search engine. If you ask Siri to search for something, it will use whatever search engine you have chosen in your Settings. If you temporarily want to switch engines, all you need to do is ask Siri to search with a specific service. You can do so simply by saying “Search Yahoo for Siri”, and it will look up “Siri” on Yahoo without changing your default search engine.
