In a mixing bowl, sift together the sugar, cake flour, baking powder and salt until fine
In a separate mixing bowl whisk together the egg yolks, water, vegetable oil and vanilla.
Combine the egg yolk mixture with the dry ingredients
In the bowl of a stand mixer or large mixing bowl with an electric mixer, beat the egg whites until fluffy. Add in the cream of tartar. Continue whisking the egg whites on medium speed until stiff peaks form.
Fold the egg whites into the cake batter one half at a time until combined
Pour the cake batter into an ungreased tube pan. Drop on the counter a few times to make sure the batter is even.
Bake for 50-60 minutes, until the cake is golden brown and springs back when touched.
Remove the cake from the oven and turn upside down to cool for 2-3 hours
Run a knife or offset spatula around the outside of the pan and around the center to release from the pan. Turn out onto a plate or serving platter. Run a knife along the bottom to release the bottom.