The Spaniard was happy with his qualifying lap in Montreal, saying it equated to pole when the Honda power deficit was factored in.
Amid rumours Honda is 90-100 horse power down, Alonso told Auto Motor und Sport: "I don't want to say numbers because I cannot prove them.
"But if you look at the time we lose on the straights, we would be very competitive."
The German report said McLaren has calculated with GPS that it is losing 1.3 seconds around Montreal due to Honda.
"With a top engine, we could have done Bottas' time," an unnamed team member said. "Only Vettel and Hamilton would have been out of reach."
"It's wrong to talk about a delay," boss Yusuke Hasegawa said. "We would have liked to have it in Canada, and now we hope to have it in Baku, but I cannot promise."
Some suspect McLaren has already decided to dump Honda, but boss Eric Boullier said: "We have a long term contract with Honda and are connected on many levels.
"I hope there is still a McLaren-Honda next year, as we want to believe in this project. But at the moment our patience is put to the test."
Indeed, there are now clear signs of strain even in the personal relationships. McLaren executive Zak Brown said this week Honda is "lost".
"It was an unfortunate word," said Hasegawa, according to Spain's AS newspaper.
And Brown replied: "I do not think I said unfair or unfortunate things, and I get along well with Hasegawa-san.
"We value all our options, and the whole situation is very complex with sporting but also commercial aspects, so it is not something simple.
"But we will have an engine in the car next year," Brown said.
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