In a mixing bowl, mix sugar, vegetable oil, and eggs. In another bowl, sift together flour, baking soda, salt, and cinnamon. Fold dry ingredients into wet mixture and blend well. Fold in carrots and chopped nuts until well blended. Distribute batter evenly into 3 (9-inch) oiled cake pans. Place in preheated oven and bake for 25-35 minutes. Cool layers in pans, for approximately 1 hour before removing. To remove layers from baking pan, turn upside down, tap edge of pan on a hard surface.