80megs needs to be done via the command line. I have three sites that have over 100meg databases and I wouldn't even think about putting them through phpmyadmin. Would take a lot longer to do anyway that way since it also have to go through PHP as well now. On the command line, they get inputted within a few seconds.
mysql - u username -p databasename < filename.sql
where:
username is the name of the MySQL user
databasename is the name of the database that you are importing into
filename.sql is the name of the backup database file.
If you really feel the need to change this setting though, try changing the upload_max_filesize setting within your php.ini file. I believe you need to restart Apache once you make these changes. I'd also change the max_execution_time as well since it's going to take longer than 30 seconds for your file to be processed.
Hope this helps,
-drmike