Ross Brawn has admitted Formula 1 could delay the introduction of a new engine formula for 2021.
The 2021 engine rule change has been long touted, although most of the existing manufacturers are opposed to big tweaks including the scrapping of the MGU-H.
Recently, Mercedes' Toto Wolff said he thinks the rules should not change dramatically if a new engine supplier like Porsche does not commit to entering the sport in 2021.
Liberty Media's F1 sporting boss Brawn now says: "We want to devise new technical rules for the engines, with which we can arouse the interest of new manufacturers and at the same time keep the existing manufacturers on board.
"That's why I think we should think about the timing," he added. "I'm not sure if 2021 is the right date or whether we should wait until we can be sure that extensive adjustments will also bring fresh blood into the sport."
Brawn said there are rule tweaks that can be made instead, like engine development limits during the season.
"With the engine, we have to decide whether we want revolution or evolution for the time being," he declared.
