Both George Russell and Lewis Hamilton found their power units running too hot, and from early in the Bahrain race they were told to adjust engines modes and their driving in an attempt to keep temperatures under control. They eventually finished in fifth and seventh positions.
Mercedes customer Williams suffered similar issues, but McLaren and Aston Martin had no problems.
Teams adjust their cooling capacity on the basis of expected race day ambient temperatures, and Allison admits that Mercedes is still trying to understand what went wrong in Bahrain.
“That was actually the biggest unanswered mystery from the weekend,” he said. “We were substantially hotter in the race than we expected to be.
“It's always something of a gamble choosing your cooling level for a given race weekend, because you're having to take a bet on free practice running what the weather is going to be like on a Sunday.
“Normally you're also making a few corrections for different power levels and other things that can vary between the race and when you're doing your practices.
“This particular weekend was one of the weekends where we had to make the fewest guesses possible, since we'd already run this cooling level loads of times in winter testing, and we'd already run these power levels in winter testing as well as free practice.”
Source: Autosport