There’s a whole other thread dedicated to this. Here’s my recipe for 90g of carbs. Details are in the post in the SIS Beta thread.
1/2 cup maltodextrin
1/4 cup fructose
1 tab Nuun sports hydration
After having used this recipe for 18 months, I now put it in a 1 L bottle (roughly 33 oz) and use heaping measures of the maltodextrin and fructose. If I can down a bottle in an hour then I’m comfortably above 90 g/hr.