Simplify the following text for a Grade 6 native English-speaking person.
Original: It was the advent of turbocharged engines in Formula One which sounded the death knell for the venerable DFV , and in 1986 Cosworth returned to the lower formulae preparing the DFV for the newly-created Formula 3000 , with the installation of a compulsory 9,000 rpm rev limiter , which scaled power back from 500 to 420 b ; the DFV remained in this class until 1992 .
Simplified: They modified the DFV for the newly-created Formula 3000 . The DFV remained in F3000 until 1992 .