McLaren boss Zak Brown says the team has entered a crucial decision window with Honda, the end of which will make or break the relationship between the two partners.
In an interview with Reuters, Brown confirmed that an engine upgrade anticipated for this weekend's Canadian Grand Prix has been delayed, taking down the Woking-based outfit's hopes of a step forward in performance.
"Missing upgrades, and upgrades not delivering to the level we were told they were going to, you can only take that so long. And we're near our limit.
"I don’t want to get into what our options are. Our preference is to win the world championship with Honda. But at some point you need to make a decision as to whether that’s achievable. And we have serious concerns.
The McLaren-Honda partnership, now in its third year, has fallen dramatically short of expectations. While Brown has often insisted on McLaren's commitment to its engine partner, the American executive says the team has now entered a pivotal 90-day period in which crucial decisions will be made.
"It will all come together," said Brown.
"There's lots of things that go into the decision and we're entering that window now of 'which way do you go when you come to the fork in the road'."
The McLaren boss revealed that the outfit can afford to give up the financial package that comes with the Honda deal - estimated to be worth around $100 million including supply of free engines - as its lack of competitiveness has considerably reduced its income from other sources.
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