When I upload a  whole bunch of files in a document library in SP2013, the Pdf's are not showing up in the search results. The word documents do though.

Have not installed Ifilter, am I correct that this is included in SP2013?

Hello Robert,

Default crawled file name extensions and parsed file types in SharePoint Server 2013

http://technet.microsoft.com/en-us/library/jj219530.aspx

PDF is also a default crawled file name extensions

Further a known issue is reported and is discussed below

http://social.technet.microsoft.com/Forums/sharepoint/en-US/f75f1795-01b8-4ec9-8a72-9fbbdb26a23a/indexing-pdf-files-in-sharepoint

Regards,

Shiva Prasad B C
Cheers!!! Happy Troubleshooting!!!