In a large bowl, combine the flour, sugar, baking powder and salt. In another bowl, whisk the egg yolks, pineapple juice, oil and vanilla; add to dry ingredients. Beat until well blended. In another bowl, beat egg whites and cream of tartar until stiff peaks form; fold into batter.
Spoon into an ungreased 10-in. tube pan. Bake at 325° for 50-55 minutes or until top springs back when lightly touched. Immediately invert cake onto a wire rack; cool completely. Remove cake to a serving platter.
In a large bowl, cream the butter, confectioners' sugar and vanilla. Stir in pineapple. Frost cake. Store in the refrigerator. Yield: 12-16 servings.