Mutt, you should read a little more about engine performances. ISA reference temperature is 15º celsius measured at Alicante (a city in Spain at sea level, crossed by the Greenwich meridian) in a special day of the year.
Alicante, Spain
Latitude: 38°16' 55" N
Longitude: 0°33' 29" W
Elevation: 142
Hmmm, before lecturing an aircraft performance specialist about engines, perhaps ppppilot might perfer to get the facts straight....