Converting a recipe from 6qt Instant Pot to 8qt I have an 8qt Instant Pot. Most of the recipes online are for 6qt Instant Pots. I find that since my 8qt takes a lot longer to come to pressure (about 18 minutes, depending on the amount of liquid inside the pot) than the 6qt ones do, my food often ends up getting overcooked if I follow the instructions exactly.

Is this normal? How should I convert recipes from 6qt to 8qt?
The answer is you may have to experiment.  

I believe the problem lies in the fact that more water takes longer to reach temperature, given the same burner arrangement.  This means whatever you have inside the pot is exposed to the lower grade heat for a longer period and by the time you reach full pressure, the food may already be over cooked.  I have not tried this myself but consider using preheated water at the beginning in order to shorten the overall cook time.