Canadian GP: Gasly to start on back row with new Honda F1 engine

The Frenchman suffered an issue with his new-specification engine in FP3, and with limited time to analyse it the team went back to the older spec he used in the first six races for qualifying.

Gasly qualified 16th, four places behind team-mate Brendon Hartley, and after work overnight in Canada and back at Honda's headquarters in Japan it was decided that it would be safe to run the new spec in the race.

A complete fresh power unit has now been fitted and the change of the internal combustion engine, which is Gasly's fourth V6 of the year, means he drops 10 places.

He has also taken a fourth turbocharger and MGU-H and third MGU-K.

That should mean he starts in last place, but as Romain Grosjean did not set a time Gasly is expected to line up 19th.

Given that he was only starting 16th, and that Red Bull's home race in Austria is coming up soon, the team felt it better to take a hit here.

"We changed the engine after FP3 because Honda recognised on the data that maybe there could be something not working in the direction they expected," team boss Franz Tost told Autosport.

"Then because of the short time to analyse it, it was safer to go back to the old spec. And then after analysing all the data with Sakura yesterday in the evening we decided to fit a new power unit.

"Also because Pierre suffered in qualifying because of the time he lost going to the weigh bridge, and we don't want to have a penalty in France or Austria.

"We decided to take it here, and then hopefully it works."

The change also means that Red Bull now has a better chance of getting the data it needs on the new Honda spec to make an engine-supply decision for 2019.

Had only Hartley started the race with the latest engine there was a risk that an early retirement for the Kiwi would leave RBR with limited information.

Tost said that was not a consideration when the decision was made but admitted that "of course, this is a valid point".

He said there were no plans to make other changes to the car that might trigger a pitlane start.

Grosjean, who suffered an engine problem at the start of qualifying and did not set a time, will revert to his first engine of the season for the race.