Honda tested 'Spec 3' engine with Alonso
https://www.motorsport.com/f1/news/f1-h ... ku-922148/
"With Alonso and Stoffel Vandoorne running more similar downforce levels in FP2, the main speed trap in Baku showed the new power unit at
327km/h, with Vandoorne getting just up to
312 km/h with the ‘Spec 2’ version."
...
"Despite the clear benefit the ‘Spec 3’ engine has delivered, however, Alonso will revert to the old version of the power unit from Saturday"
...
"Switching power units will also allow Honda to check on any potential reliability issues that may have come up after initial running – with the ‘Spec 3’ then expected to return at the Austrian Grand Prix."
printscreen FP2 - finish line speed km/h
Alonso
342,4 km/h
Vandoorne
319,7 km/h