Preheat oven to 325 °F. Grease and lightly flour a 9-inch tube pan (or two 9 x 1-1/2 inch round baking pans or a 13 x 9 x 2 inch baking pan).
Cream oil and 2 cups of the sugar until blended. Add egg yolks one at a time, beating well after each addition. Beat in hot water.
Sift dry ingredients together, beat into egg mixture. Stir in carrots, pineapple, and walnuts.
Beat egg whites until soft peaks form. Gradually add the remaining 1/2 cup sugar, beating until stiff.
Fold into batter. Pour into prepared pan. Bake 60-70 minutes (tube pan), 30-40 minutes (round pans) or 50-60 minutes (rectangular pan) or until cake tests done.
When cool, frost with Cream Cheese Frosting or brush with Butter Rum Sauce.