I fry my turkeys at 350 for 3.5 min per pound. So that's 56 minutes for a 16 lb bird.
One trick I use is to let the oil heat up to 375 before you put the turkey in, because a cool bird will drop the temperature quick! If the oil doesn't stay hot, it can seep into the bird, and it will be oily and the skin won't be crispy.
Also, while I'm on the subject, a couple of words about safety.
ALWAYS set up outside, away from flammable things (like your house). Have a fire extinguisher handy. A water hose is NOT a fire extinguisher, and will make an oil fire worse.
DO NOT use too much oil! You want to put the turkey in the pot and fill it up with water until it covers the bird. Then take the turkey out, and mark the water level. Dump the water out, and fill the pot up with oil to your mark. That way, the oil doesn't spill over when you put the turkey in.
ALWAYS dry the turkey before you put it in the hot oil. You've heard oil and water don't mix? Well, water and hot oil REALLY don't mix. Any water on the bird will boil instantly, and you'll have oil spitting at you.
DO NOT let the oil temperature get too hot. The reason peanut oil is preferred is it has a high smoke point, but it will burn if it gets too hot. Keep it below 375, max. This means constantly checking the temperature, and controlling the gas valve, which brings me to...
DO NOT leave the fryer unattended. You'll need to be keeping an eye on the oil temperature, and you don't want kids or pets to be poking around your setup.
And finally, BE CAREFUL. Frying a turkey is a delicious way to enjoy Thanksgiving or Christmas dinner, or really any dinner, but it can be dangerous. Having to share your turkey with your local firefighters or EMTs will ruin the experience.
Successfully frying turkeys since Thanksgiving 1995.
Don't ask about Thanksgiving 1994. :-)