TBX has a full list of type-certificated engines for general aviation aircraft and business jets. In the event you are creating an aircraft profile for an experimental aircraft, you most likely will need to add an experimental engine to your aircraft profile.
To add an experimental engine, click the purple + button in the engine tab.
Type "exp" in the Model field and then click the Search button
Check next to "Experimental" in the Search Results box and then click + Add Selected Engine
The Engine will appear in the Engines for this Aircraft Profile box.
In order to change the Manufacturer and Model name of the engine, click the pencil icon next to the engine.
Enter the Manufacturer name and Model name into the appropriate fields. Scroll down and click Save Changes.
Click "Back to Aircraft Profile" to return to your Aircraft Profile.