In a large mixing bowl, combine flour, sugar, baking powder, and salt. Make a well in the center and add egg yolks, oil, water, and vanilla extract. Beat until smooth.
In another bowl, beat egg whites and cream of tartar until stiff peaks form.
Gently fold the egg whites into the batter until just blended. Pour the batter into an ungreased 10-inch tube pan.
Bake for 60 minutes or until a toothpick inserted into the center comes out clean. Invert the pan immediately and let it cool completely before removing the cake from the pan.
Notes:
Make sure to invert the pan immediately after baking to prevent the cake from collapsing.