Preheat your oven to 350°F (175°C) and prepare an ungreased 10-inch tube or chiffon cake pan.

Whisk together the dry ingredients: 1 ¾ cups of all-purpose flour, 2 teaspoons of baking powder, and ½ teaspoon of salt in a large bowl.

In a separate bowl, beat 6 egg yolks with 1 cup of granulated sugar until pale and creamy. Add in ⅓ cup of vegetable oil, ⅔ cup of water, and 2 teaspoons of vanilla extract gradually.

Gently mix the dry ingredients into the wet mixture until just combined.

In a clean bowl, beat 6 egg whites with ½ teaspoon of cream of tartar until stiff peaks form, about 4-5 minutes.

Fold the whipped egg whites into the batter carefully to maintain aeration.

Gently fold in 1 ½ cups of blueberries, ensuring they are evenly distributed.

Pour the batter into the ungreased pan and bake for about 40 minutes, or until a toothpick comes out clean.

Invert the pan to cool upside down for about an hour before serving.