McLaren racing director Eric Boullier says the pressure on engine supplier Honda is huge this year following a series of failures during pre-season testing.
The team completed limited mileage in the opening week of testing due to two major problems and was forced to make another engine change on the first day of this week's second and final test. The MCL32's fastest lap during testing is over 2.5s off the pace, and with just three days left of testing Boullier was no longer sugar-coating the situation.
Asked how big the pressure was on Honda to improve, Boullier said: "Maximum. But obviously we are in Formula One, we are racing and we have to perform, so the pressure is obviously huge. We put the maximum pressure on all of our relationships with Honda and it's the same from them. We can't put a foot wrong, we need to be able to deliver the best car as well, so this is both sides."
Boullier said the inability to run the car at its maximum potential has had several knock-on impacts on performance.
"It does affect your development understanding," he said. "If you are not running fast enough, you don't put the right energy in the tyres, you don't put the right energy in the brakes or car and your ride height targets are different. So there are a lot of consequences to running 15 or 18 km/h slower in a straight line.
"But still, we can make most of the data just by running the car and obviously that is what we want to see. This is to make sure we get correlation with the simulation back in Woking, to know it's good, because that allows us to keep the same process and the same way to design and develop the car and make predictions for the future.
"But it would be easier, yes, if we had the same speed as the others because then you would have a better understanding of some different factors."
Asked about rumours Mclaren and Honda could split as a result of its third consecutive year with troubles in testing, Boullier dismissed the suggestion.
"No. We have a contract in place and actually normally it's seven years in every marriage or relationship, not three! No, we don't even think about it. There is a solid contract between us, a long-term contract and obviously we want to build on it even if it's not the ideal times yet."
Honda is planning to bring a new specification engine to the car ahead of the season-opening Australian Grand Prix. Honda would not confirm how many power units it has used so far in testing, apart from saying it was less than six.