In a mixing bowl, combine sugar, flour, cocoa, salt and baking powder. Combine oil, eggs,water, corn syrup and vanilla; add to dry ingredients. Fold in nuts if desired. Spread in a greased 13-in.x 9-in.x 2-in. baking pan. Bake at 350 degrees F for 30 minutes or until a toothpick inserted near the center comes out clean.