I need a 220 volt sub panel about 80 amps.. it says for the common to be shielded like the 2 hot wires... the 6-2 is 6 gage but the ground is about a 8 gage.. is it OK to cover the 8 gage wire a few layers of tape to shield it ? Will the 8 gage be OK as a common with the 2 how wires being #6 ?
Yes I will have a separated ground going to a ground rod... thank you

Wow, wow, wow. A lot wrong here. Please do not do anything until you get this sorted out.

6/2 is not good for a sub-panel. The bare wire is a ground, not a neutral, and can never be used as a neutral.
You must used 6/3 with an insulated white neutral, and the neutral and grounds must remain on separate bars in the panel with the bond screw not installed.
The ground rod is not what gives you your equipment ground.

Also... #6 is not enough for 80A. You need #4cu wire, or 4/3nm cable.
And you still need a ground rod.

If you are setting this panel in a separate building, you will not be allowed to use type NM cable.

You will have to use a cable type that is listed for the environment that the cable will be installed in.