What happens when you add more letters — and a lot more imagination on the part of the contestants — to “American Idol”? You get “American Inventor.”

The ABC reality contest, set to air in March, is the brainchild of “AI” producers and its prince of darkness, Simon Cowell (who will not appear on the show).

The unusual premise: To find America’s best new invention, as voted by the public. The prize: A cool $1 million and the chance to have the product mass-produced.

It remains to be seen whether the show can produce the inventor equivalent of a Kelly Clarkson or Carrie Underwood, just two of the sensations launched by “American Idol.”

Auditions for “American Inventor” began last week in Los Angeles, where producers were “overwhelmed” by the turnout at the Renaissance Hollywood Hotel. Some 400 would be Thomas Edisons showed up with prototypes, sketches, even just ideas.

Executive producer Liz Bronstein, who says she didn’t expect that kind of crowd for a show that hasn’t been on the air, had to make instant changes in the audition process.

“Initially,” she says, “the producers were all going to be in one room to see the inventors, but we got such a big crowd that the four producers had to split up into four separate rooms.”

Even so, the one-day audition quickly turned into two.

“What blew my mind,” says Bronstein, “was the high quality of the inventions. People have spent so much of their own money and care so deeply about these things. We’ve already seen a couple of products where we all went, ‘Wow, holy cow!’”

While she won’t get specific, Bronstein says there were a number of baby products, safety products, clothing and novelties. As for the inventors, there was a surprisingly even split between male and female. The youngest was nine, the oldest, 67. Each got two minutes to make their pitch.

Check out the Web site, Americaninventor.TV, for more information.