For cake: Preheat oven to 325°F. Lightly butter 13x9x2-inch baking pan. Line bottom with waxed paper; butter paper. Using electric mixer, beat oil and both sugars in large bowl until well blended. Add eggs 1 at a time, beating well after each addition. Beat in orange juice and peel. Sift flour, baking soda, baking powder, cinnamon, ginger, nutmeg and salt into large bowl; add to sugar mixture and beat to blend. Stir in carrots and raisins.
Pour batter into prepared pan. Bake until tester inserted into center of cake comes out clean, about 55 minutes. Transfer pan to rack. Cool cake 15 minutes. Turn cake out onto rack. Remove waxed paper and cool. (Can be prepared 1 day ahead. Wrap tightly in plastic and store at room temperature.)
For Frosting: Using electric mixer, beat cream cheese and butter in large bowl until light. Beat in orange juice and 2 teaspoons orange peel. Add sugar; beat until smooth. Refrigerate until thick enough to spread, about 30 minutes.
Using serrated knife, cut cake horizontally into 2 equal layers. Place 1 cake layer on platter. Spread with 1 1/2 cups frosting. Top with remaining cake layer. Using icing spatula, spread remaining frosting in thick decorative swirls over top and side of cake. (Carrot cake can be prepared 2 days ahead. Cover with cake dome and refrigerate.) Serve cake cold or at room temperature.