Simplify the following text for a Grade 7 native English-speaking person.
Original: The APT-P is the most powerful domestic train to have operated in Britain , the eight traction motors fitted to the two central Motor Cars giving a total output of 8,000 hp . This enabled the train to set the UK rail speed record of 162.2 mph in December 1979 , a record that stood for 23 years .
Simplified: The APT-P is the most powerful domestic train to have operated in Britain , the eight traction motors fitted to the two central Motor Cars giving a total output of 8000 h. This enabled the train to set the UK rail speed record of 162.2 m in December 1979 , a record that stood for 23 years .