Using an electric deep fryer does the food need to be totally immersed?
Based on the comments, it sounds like your fryer has a fill line for just the oil, calibrated so that if you use that much oil then add a reasonably-sized turkey, you'll end up with the oil still safely below the top of the fryer. You'd never actually use 22 quarts of oil; then it'd be completely full of oil, on the verge of overflowing, with no room for food.

In that case, your chicken test doesn't really tell you very much. A turkey will fill the vessel more completely, so it may well take less oil to cover it. If you end up able to put your whole turkey in, and cover it with liquid, without getting dangerously close to the top of the pot, then you're okay. I would hope your fryer has another line closer to the top to tell you what a safe margin is there.

Do note that testing with wrapped birds also is misleading. That keeps the liquid from getting into the cavity, so it'll take less liquid to fill and cover that way.

And if the turkey is too big, then filling it to that 8 quart fill line then adding the turkey could cause it to overflow. So it really seems like you need to test with the turkey first (not wrapped!), to be sure it'll fit safely.



With all that said, supposing you do actually end up in the situation you mention in the question - not enough oil to cover the food - that's not good.

If your food is sticking out of the oil, it's not really cooking. It'll be in contact with hot air over the oil, but that's nowhere near actual hot oil.

Along with that, it'd indicate you've overfilled it, which is asking for trouble. The manual for your fryer almost certainly has some really strong warnings against that sort of thing. And even if the oil stops at the fill line, you have a huge turkey in there just waiting to shift or settle a bit, displace more oil, and push the oil above the max - it's still overfilled.

Doing something like that would make it really easy to splash hot oil out of the fryer, especially while you're putting the food in and getting that burst of boiling water and steam, which is incredibly dangerous. It's probably a fire hazard even with an electric fryer. And even without a fire, it's nothing you want splashing on you.

And in general, I'd strongly suggest you look at general safety guides before you attempt to deep fry a turkey, especially if you're not sure about part of the process.