I've successfully deep fried a turkey for the past 6 Thanksgivings without burning down my house or requiring skin grafts from the burn unit of the local hospital.
Most of the information available says the maximum turkey size that can be successfully deep fried is 12-14 lbs. Any bigger and you'll run into problems like incomplete submersion, and undercooked areas of the thickest parts like the breasts and thighs.
The key to doing it safely:
- use an electric fryer. I use a round Charmglow 28 Qt fryer model 380-894. Cajun Injector is similar in design, while Butterball by Masterbuilt is a rectangular unit. An electric flyer eliminates any open flames that can set spilling oil on fire. It includes a sturdy fry basket for lowering and raising the turkey out of the oil and it clips to the side of the fryer to allow draining without having to hold it over the boiling hot oil.
- put the fryer on a sturdy table. I use a heavy duty 6' folding resin table, which gives me room for platters and tools.
- use the shortest heavy duty extension cord that will reach the nearest outlet.
- do not exceed the max fill line on your fryer.
- ensure the turkey is thoroughly defrosted, and dried with paper towels before putting it into the fry basket.
- use thick silicone oven mitts to slowly lower the fry basket into the oil.
- keep away flammables, children, pets, and anyone under the influence (F.U.I. or F.W.I. may not be a crime but it has severe consequences)
- keep a fire extinguisher (rated for grease fires) handy just in case
To answer the OP's question, the timing suggested in my fryer's manual has produced good consistent results for me: 3 minutes per pound + 5 minutes at 400F.
I generally fry a 13lb bird so that's (3x13) + 5 = 44 minutes. That's right, less than an hour for a thoroughly cooked, juicy and delicious turkey! I can fry two 13 lb turkeys in less time than roasting one 26 lb bird! It cooks so quickly that we often fry appetizers before the turkey like wings or tots or fries.
- I've found 13 lbs to be the largest size I can completely submerse in this fryer. Larger birds tend to stick out about a half inch or more, leaving a pale oval on the breast.
- make a turkey lifter out of kitchen twine and use that to put the bird into the fry basket. It makes it easy to take the hot bird out of the fry basket and onto a platter for resting away from the fryer.
- a lot of steam condenses on the glass lid, which easily exceeds the shallow metal lip around its edge and drips back into the oil, causing a firestorm of bubbling. So every few minutes, I'll carefully take the lid off as level as possible and then pour out the condensed water into a pail.
- I let it rest for about an hour before carving.
- one of the caveats of using an electric fryer vs a propane one is that it takes longer for the oil to heat up- as much as 55 minutes if the ambient temperature is unusually cold. To shorten this time, a few days before I fry, I store the oil indoors near a heat vent so that it'll be starting off at indoor temps rather than late November outdoor temps.
- peanut oil is quite expensive so I mix it with canola or vegetable oil. I get some of that peanut oil flavor at less expense.
- I brine the turkey for 24 hours in an apple cider brine recipe from GeniusKitchen.com