Cooking experts: What are the cooking times for various weights of turkeys with the dressing in it?

Question

I cook my fully thawed turkeys with dressing in it at 450 °F sealed in aluminum foil. I throw away the timer and I don't open it at all until it's done. I'm trying to develop a simple chart with a sliding scale so can take the turkey weight and cross reference it with the cooking time when I bake it. I usually bake a 20 pounder for 3 1/2 hours and it comes out perfect. I did a 17 pounder once at about 3:06 and it came out perfect. However when I did a 24 pounder at 4 hours (my straight line estimate) that wasn't enough. So maybe a curve would be better than a straight line. However I really don't know. If you have worked out perfect cooking times for various weights of turkey with dressing in it I'd like your input. It doesn't bother me what temperature you do yours (350 °F or whatever) as long as you have worked out the perfect time for cooking all your various turkey weights while cooking in a similar manner to the way I do. It would give me useful information that I could work with.

Answer 1

You will dind all the information you need here:
http://hgic.clemson.edu/factsheets/HGIC3560.htm

Answer 2

According to Wegmans.com:

Start the bird at 450 degrees for 15 minutes, then lower the temperature to 350 and continue to roast for about 15 min/lb until turkey internal temp is 165 degrees.

Stuffed turkeys: Increase cook time by 15-20 min; stuffing must reach 165 degrees too.

Answer 3

Ignoring the fact that you shouldn't be cooking stuffed birds for a moment; the best solution is to get a dual probe digital thermometer. One probe measures the oven temperature and the other meaures the food temperature. The thermometer magnetically sticks to the outside of the oven and they come in two basic types wires and wireless.
Get a piece of graph paper and start plotting time temp points.
The goal is 165 degrees measured at the deepest part of the stuffing.