Lotus technical director Nick Chester says the FIA's latest push for a budget engine could open "quite a can of worms".

After Ferrari vetoed the FIA's proposed engine cost cap, the sport's governing body adopted Bernie Ecclestone's push for the introduction of a €6-7 million budget engine as an alternative for smaller teams. The proposed engines are likely to be larger capacity, twin-turbo V6s with a basic energy recovery system (ERS).

The FIA is confident it could suitably balance the performance of both engines to make the cheaper option a logical solution, but Chester is not convinced this would be an easy task.

"It's quite a can of worms," Chester said. "A two-tier championship would be very difficult to operate. There would be so many different challenges for equalisation and this would be exceedingly difficult with engines of different characteristics."

Lotus is in ongoing talks with Renault about a takeover for 2016, and this week revealed it has a contingency plan involving Mercedes engines if the current negotiations are unsuccessful. However Chester says the lack of development on the team's E23 chassis this year has given it time to push ahead on next year's design.

"We're well progressed through the design process and most of the layout has been done. We've learnt a lot over the past two seasons and all this knowledge is being put into next year's car. There hasn't been the greatest amount of development through the year on the E23 Hybrid, so we've been able to dedicate quite a bit of additional manpower to our 2016 challenger. Manufacture of some of the parts is already underway and we're looking at a lot of the final detailing."