Preheat oven to 325 ℉. Grease and flour a 10-inch tube pan.
In a large bowl, whisk together the flour, sugar, baking powder, and salt.
In a medium bowl, whisk together the oil, egg yolks, water, orange rind, and vanilla.
Add the wet ingredients to the dry ingredients and mix until just combined. Do not overmix.
In a clean bowl, beat the egg whites until stiff peaks form. Gently fold the egg whites into the batter.
Pour the batter into the prepared pan and bake for 1 hour and 10 minutes, or until a toothpick inserted into the center comes out clean.
Let cool completely in the pan before frosting. Good frosted with a butter cream frosting with 1 tsp orange rind (lemon) or an orange (lemon) glaze or icing.