Combine first 4 ingredients; mix well.
Combine eggs, 1 1/2 cups sugar, and oil; beat until smooth. Add flour mixture; beat until blended. Pour batter in a greased and floured 13- x 9- x 2- inch baking pan.
Combine 3 cups peaches and remaining sugar. Arrange peaches on top of batter; sprinkle pecans over top. Bake at 350° for 1 hour and 15 minutes or until cake tests done. Cool 10 minutes. Cut into 3-inch squares. Serve with ice cream and additional peach slices.