F1 engine supplier Renault is now devoting 70 percent of its efforts into the sport's new 6-cylinder turbo formula for 2014.
This year's championship and the next are the last in which the cars will be powered by the current generation of normally-aspirated V8s.
"We are now working 70 percent on the new engine," Red Bull supplier Renault Sport F1's Jean-Francois Caubet told Germany's Auto Bild.
"Next year it will be 100 percent," he added.
Renault also supplies the Lotus, Williams and Caterham teams.
The report said Renault's estimated cost of development for the 1.6 litre V6 is EUR 50 million.
A significant part of that is KERS.
"That (KERS) is an integral part of the new engine," Caubet explained. "In 2014 we will supply Red Bull not only with the engine, but the complete powertrain."