Liteon, DVD-R, 8x media - That does not sound a happy combination!
Actually, SOME media, eg. Ritek G05, is classified as either 4x or 8x - the Liteon might have this one in its media code table, and burn at 4x.
Unknown media, might be burned at 2x or very badly at 4x.
If you already have the media, read the id code using
http://dvd.identifier.cdfreaks.com
There may also be some firmware hacks that can be applied, and there is a new tool which automates part of what was once an entirely manual process.