Formula 1's Managing Director of Motorsport, Ross Brawn has made it clear the current engines cannot go unchanged in 2021 after three of the four engine suppliers voiced opposition to the proposals unveiled several weeks ago.

Mercedes and Renault aired concerns over the financial impact the development of two engines during the next three years while Ferrari went further criticising the wider vision of F1 owners Liberty Media and threatened to quit if the bosses at Maranello didn't agree with the direction.

Brawn, however, is standing firm insisting the flaws of today's V6 turbo-hybrid are having a too bigger impact on the racing and the attractiveness to other manufacturers who would consider entering.

“The current engine is an incredible piece of engineering but it’s not a great racing engine,” the former Mercedes boss said to BBC Sport.

“It is very expensive, it doesn’t make any noise, it has componentry that in order to control the number of uses is creating grid penalties that make a farce of F1, there are big differentials of performance between the competitors and we are never going to get anyone else to come in and make engines.”

The changes put forward have received support from Red Bull boss Christian Horner, a long-time critic of the current engine, and potential suppliers such as Cosworth, Ilmor and Aston Martin have also voiced positive responses.

Horner would go on claiming the negative reaction from manufacturers was not significant as other motives were at play and also given they were involved in the talks which have taken place throughout 2017.

Brawn too was surprised but admitted perhaps their unhappiness as to how the proposals were put forward.

“Reflecting on it, maybe we could have presented it differently,” he claimed. “But I didn’t anticipate the response to be as strong as it was.

“We’ve had another meeting since then and I’ve made that comment. If that is the thing people are most upset about, then I apologise, but let’s not lose sight of what we are trying to do.

“If they were uncomfortable with the way it was presented, it wasn’t intended that way.”

The F1 veteran added room for negotiation does remain with a final agreement due next year but was adamant suggestions would have to be in the interest of the sport.

“If a manufacturer can demonstrate that there is a better way of doing it than what has been proposed – i.e. it is cheaper, it is more appealing to the fans, it is something that a new supplier could engage with; any of those factors – then why not?" he said.

“We are not wedded to specific solutions. We think with the expertise that we’ve got and the work we’ve done, these are the solutions that can work. If somebody suggests another solution that they think will achieve the same objective, we are not going to say no.”

Brawn also directly addressed the comments by his former team Ferrari, pointing to what he thinks is an acceptable grievance the Italian team and others can have.

“I recognise it is important to keep the identity of a Ferrari or a Mercedes engine. They need to be able to say: ‘That is our engine," he said.

“I don’t think we have crossed that boundary but now the proposal is on the table we need to meet with these people and understand what it is they are comfortable with and what they are not.

“All the manufacturers like a large chunk of the proposal; it is just not the same chunk.”