Ilmor and Advanced Engine Research (AER) have registered interest with the FIA about supplying Formula One with an alternative power unit for 2017.
The sport's governing body is pushing ahead with its plans to get an independent manufacturer to produce a cheaper alternative to the current engines in order to help balance the budgets of smaller teams.
Speaking to German publication Auto Motor und Sport Ilmor design guru Mario Illien, who has been linked with Red Bull's engine plans for 2016, confirmed: "Ilmor has applied for it."
The publication also quotes Red Bull's motorsport advisor Helmut Marko, who claims Ilmor's plan to become F1's alternative engine is what stopped the team following through on its threats to quit.
"We stand behind this engine and will drive it," Marko said. "It was the condition that we have stayed in F1."
British company AER, which currently supplies a twin-turbo V6 engine to WEC teams and held the GP3 engine contract between 2012 and this season, has also formally declared its interest.
"AER are very interested in the proposal from the FIA," founder Mike Lancaster told Motorsport.com. "We're putting in a submission for it. The request seems to fit nicely with our latest V6 GDI engine. They're looking for something which produces a lot of power, and we have an engine that can do that.
"The WEC engine is the P60, the engine we're proposing is called the P66, which is a higher revving version of that. It will be ideal for the job, we believe."
Cosworth is also expected to register its interest in being F1's alternative power unit supplier. The new 650 kW units can be no bigger than 2.5 litres and will not be allowed to have KERS. The FIA is confident it can equalise the regulations to ensure both engines remained equal, but Mercedes is sceptical the FIA will be able to do this successfully.
The plans for an independent engine supplier still need to be ratified by the F1 Commission next week but the FIA may well try and force it through the World Motor Sport Council regardless of whether it gains majority support.