jqavins wrote:... Which is whyspeising wrote:they also say "Never attempt to microwave a turkey that is larger than twelve to fourteen pounds or that is too large for your microwave," both of which would probably be violated by a 24lb monster.
In a conventional oven, the heat flowing into a stuffed turkey all enters at the surface and reaches the middle by conduction. In a microwave oven, the heat is generated inside the food, but only a short way inside, since the microwaves are absorbed by the food before penetrating very far. For relatively thin things like TV dinners, the penetration is deep enough to go through for all intents and purposes. But for a large bulky item like a turkey, heat has to reach the middle by conduction just like in a conventional oven. So the first calculation, scaling time by weight alone, is bogus.
The second one is closer; if a(n assumed reliable) source says 9-10 minutes per pound at half power then I can buy that up to a point. The time includes the time required for heat to be conducted all the way through, so halving the time by doubling the power is still wrong; you'd overcook the outside before that time is up. And if the weight is really large, it's plausible that you'd have the same problem even at half power. (Which is the same reason that a really big bird in a regular oven is usually done at a low temperature.)
So, if some other (assumed reliable) source says don't go over 12lb, I'd believe it. Maybe you could do it by reducing the power still further, but then it would take so long to cook that you might as well use the conventional oven. Which is as it should be when the time requirement is mainly driven by the thermal conduction rate.
You can trust that this is absolutely authoritative, because I'm some guy on the internet.
Back in the '60s we got an early "Electronic Oven" made by GE--although they would never admit to it, but we had the monster in our kitchen as proof--with a full size oven with both conventional and microwave elements--it cut the cooking time for turkeys, even big ones, down by about 1/3--and they were consequently always moist.