Mario Illien has played down suggestions that Ilmor might be set to re-enter Formula 1 in 2021.
Liberty Media hopes that by simplifying the engine rules, independent players like Ilmor and Cosworth will consider launching projects.
However, Ilmor co-founder and chief Illien says that is unlikely.
"In principle it is the right direction - the technology must become simpler and cheaper," he told Auto Motor und Sport of the 2021 plan.
"But for a private manufacturer, we cannot do it without outside help.
"I could not develop a business model like we have in Indycar, because I would have probably only one or two customers. And if one does not pay the bill, I'm dead.
"Without a sponsor behind me I could not build this engine for Formula 1."
This year's championship concludes this weekend with the Abu Dhabi Grand Prix.