Place 2 cups of sugar, the vegetable oil, eggs orange juice and vanilla in a large bowl. Beat the ingredients together until well blended.Place the flour, baking soda and salt in a medium size bowl, whisk the ingredients together to combine them. Gradually add the dry ingredients to the batter with an electric mixer just until the ingredients are combined. Stir in the apple pieces.Spread half the batter into a greased 13x9 inch baking pan. Combine the cinnamon and the remaining sugar together in a small bowl, sprinkle the cinnamon/sugar mixture over the batter. Carefully spread the remaining batter over the top.Place the cake in a preheated 350 degree oven for 40 - 50 minutes or until a toothpick inserted in the center comes out clean. Remove the pan from the oven to a wire rack to cool. Garnish cake slices with whipped cream if desired.