Does the Fire8 have a specific video out port? If not, a simple USB > HDMI adapter might not do anything except empty your wallet. Check your documentation or forums for your specific model and look for "Video Mirroring" or "External Video".
You may find you need something with what amounts to an external video card.
The thing is, video out is not as simple as just plugging in a cable. The Fire8 has to specifically have provision for it or it won't work. So if it's not in the documentation and the Fire8 forums don't know of a third party solution, you will be out of luck.
Were it me I would be looking at solutions over WiFi with something like a ROKU streaming stick or a Google Chromecast. That IS a pure data transfer, not requiring specific video provisions. See if that will work for you.
'57 FL Straight 50 wt
'90 Miata 1.8L w/Rotrex Supercharger [Mobil1 0W-40]
'96 Ram 1500 [3.7L Mobil1 0W-20 / 1L 15W-50]
'01 PT Cruiser [Mobil1 0W-40]