After 1984 companies like Renault, Honda, BMW, TAG-Porsche, and Ferrari were able to develop their engines to receive much higher turbo boost than the Hart 415T.
A partir de 1984 empresas como Renault, Honda, BMW, TAG - Porsche e Ferrari foron capaces de desenvolver os seus motores cun rendemento moito máis alto que o turbo 415T de Hart.