How to use more than 80 characters in page layout section Name in sales force
I can see a few options to this, as per our discussion in the comments. Given your goal to add a description aspect to your section.
NOTE: That neither of these options, will sadly appear in Edit mode.
Finally, though not directly related to your question, but in relation to make the native UI more descriptive, don't forget you can also provide field level descriptions, which surface as little yellow popups when the user hovers over the question mark icon.
Another option is similar to the Formula Field option provided by Andrew, but you can have it displayed in Edit mode. It's not going to lengthen the section name, but means you can have a description or blurb to help describe the section.
Instead of using a Formula Field with some message text, you create a standard Text Area field and add your message as the Default Value. Make the field read-only for the profiles that will create these records.
This will result in the field displaying on the page in both Edit and View mode, which can be really handy.