Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 12x18 inch pan. Sift together the flour, baking powder, baking soda, salt and cinnamon. Set aside.
In a large bowl combine sugar and oil. Blend in vanilla and pumpkin, then beat in eggs one at a time. Gradually beat in flour mixture. Stir in nuts. Spread batter into prepared 12x18 inch pan.
Bake in the preheated oven for 30 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow to cool.
