According to Official Guinness Records,
The largest Frito pie weighed 601.01 kg (1,325 lb), and was assembled by Frito-Lay (USA) at the State Fair of Texas in Dallas, Texas, USA, on 1 October 2012. The Fritos Chili Pie was assembled in a U shaped chafing dish measuring 133 sq ft. It included 635 bags of Fritos corn chips, 660 cans of Hormel Chili without Beans and 580 bags of shredded cheddar cheese, which produced 5,000 individual servings.
For a complete list of 2012 records, please visit 2012 Guinness Records in United States.