Cosworth, the only engine provider to run a restricted V10 engine as well as a V8 engine this season, believes the current V10/V8 equivalency formula are fair and likely to remain in place.
Following the regulation changes for 2006, all teams but Toro Rosso have elected to run a 2.4-litre V8 engine. The Red Bull-owned team, formerly Minardi, will run with a restricted V10 Cosworth.
However, there are growing concerns among the teams running V8 engines that the restrictions placed on the V10 - including an air restrictor and RPM limit - are not enough to make the V10 on par or weaker than the V8.
The FIA said it would monitor the situation and could change the equivalency formula in a day's notice, if it proved insufficient.
But Cosworth CEO Tim Routsis believes the current formula is accurate and suggested the only measure is between a Cosworth V8 and a Cosworth V10 - and not between a Cosworth V10 and another maker's V8.
"The equivalency rule causes a lot of fluttering in the F1 pitlane, there is no doubt about that," he said at Williams's launch yesterday. "Essentially, it is there for the next two years - if Toro Rosso want to take up the option.
"We were asked by the FIA to propose some equivalency rules, and obviously the data we had was the comparison between our own V8 and our own V10, and we put forward a set of suggestions regarding what we thought would be a laptime equivalency taken across the season.
"Equivalency is a difficult thing to define, and we have tried to take it on laptimes across the season. You cannot just pick power, there are too many differences between the engines - weight, torque, fuel consumption.
"So quite a lot of work was put in to try and come up with that equivalency, and we still see no reason to change the numbers that are being put forward.
"I know a lot of other people are looking at how their V10 would perform against those parameters and measured up against what their V8 could do, and that has caused some teeth sucking. But I don't see anybody else running a V10 at the moment, so I think it will be a moot point."
Routsis, whose company provides V8 engines to Williams along with V10 engines to Toro Rosso, added: "The conversations we've had with the FIA are very straight forward.
"We have made it very clear that taking all the factors as being equal, a car with our V8 should finish ahead of a car with our restricted V10. Where that will put everyone else in the pecking order, is outside the conversation we had.
"And what would the FIA do if we ended up with a situation of Williams 1-2 and Toro Rosso 3-4? I'm not suggesting this will happen, but that is the logical end of this argument, because you could say it is equivalent to the V8, and it wasn't better than the V8.
"It will be interesting to see how it pans out, but my expectation is that the rules will stay pretty much as they are at the moment in terms of where the equivalency figures are."
Asked if Cosworth would be able to adjust their V10 engines overnight if the FIA demands it, Routsis said: "Yes, we have to."
And he rejected suggestions that Toro Rosso could have elected to upgrade their V10 engine supply to a V8.
"The contracts were already in place with Minardi, and when Red Bull bought the team they inherited the contract," he explained. "So there was never any discussion about moving it across to a V8."