Adrian Newey fears that a move to abandon Formula 1's engine token system could make grand prix racing less competitive.
F1's manufacturers have agreed to lift restrictions on engine development for 2017, after feeling that the limits on what car makers could do was not allowing the field to close up.
But rather than it being good for competition, Red Bull technical chief Newey fears that the gaps between pace-setter Mercedes and the others could actually increase.
He is especially worried that his team's partner Renault which may not be able to match the spending power of its German rival.
"If you look back on the original technical working group meetings and minutes from 2012-13, the agreement at that point was that the engines would be frozen but teams that were behind would still be allowed to keep developing," Newey told Reuters.
"That's not happened.
"So it becomes a spending frenzy...the numbers being spent by the big manufacturers are eye-watering and so I think potentially for companies such as Renault who aren't prepared to spend that sort of money it means actually the gaps get bigger not smaller."
As well as his worry that big-spending manufacturers will pull clear, he thinks there is a flaw in the rules that allows the works teams to maintain any advantage they want over customer outfits.
"It's very curious to me that we have this set of regulations where the manufacturer has to supply the same hardware to other teams but it's no under no obligation to supply the same software and therefore the same performance," said Newey.
"Nobody is complaining about this because the customer teams can't complain because their contract doesn't allow them to."
Newey thinks that F1 has got it wrong in allowing the engines to be so critical to performance, because of the difficulties there is in understanding where a car maker has an advantage.
"You can't photograph an engine, not the internals anyway. So if you have an advantage, you can lock it in for some time," he said.
"That happened with Ferrari last season where some Mercedes engineers left and joined Ferrari and were able through their knowledge to bring a very considerable jump in the performance of the Ferrari engine," Newey said.
And after Mercedes admitted last week that there was no stopping the improvements it is making to its engine, Newey agrees.
"These engines are still relatively infant technology," he explained. "We have already seen the steps that can be made. There's no reason to suspect they've [Mercedes] suddenly reached a plateau."