So Mercedes team boss Brawn told Germany's Auto Motor und Sport that the single specification will be specifically tailored to the works teams -- Mercedes (Mercedes), Red Bull (Renault) and Ferrari (Ferrari).
"We will work together as one team at Brackley and Brixworth to get the best result from the complete car," he said. "Engine and chassis."
So that will mean the customer teams will have to make the most of engines that are tailored to the rival cars of the works teams.
"We will help our customers as far as we can, in terms of information," said Brawn. "But if I'm honest, they won't have a big say.
"We have developed a solution for us, so the others will have to adapt."
2014 Mercedes customer Williams' new technical boss Pat Symonds confirmed that, "In practice, we will have to go with the Mercedes package as it is delivered".
Meanwhile, Honda on Friday released an audio clip of the sound of its turbo V6 engine, which was recently fired up for the first time.
The engine will not be raced until 2015, when the works collaboration with McLaren begins.
The clip can be heard at http://www.youtube.com/watch?v=431h20gvm3M
"It is exciting to hear the cry of our newborn formula one engine for the first time," said Honda's European president Manabu Nishimae.