Romain Grosjean has paid tribute to the efforts of the Haas mechanics after the power units in both cars were replaced on Friday at the Belgian Grand Prix.
Grosjean was on his second installation lap in FP1 when he complained of "no power", leading to elements of his PU being changed, including the engine.
A different issue accounted for team-mate Kevin Magnussen after one install lap, leading to his PU requiring a new engine, MGU-H and traction control.
Magnussen made it out in FP2 with 32 minutes remaining, followed by Grosjean a few minutes later, with both drivers eventually completing 12 laps apiece.
“It was a tough day for everyone, especially the mechanics," said Grosjean.
"Going out in the morning and having to change straight away the engine wasn’t ideal, especially on both cars at Spa which is a track where you want to get some good knowledge, but then we managed to get out in the afternoon.
“The boys did a mega job and the car didn’t feel too bad. Obviously yes, we are not top of the sheets but that is understandable after doing one timed lap on a one-lap tyre.
“Being two-tenths [of a second] away from [Sebastian] Vettel [who was only 17th quickest] having done only one lap is not bad.”
The Ferrari-powered cars struggled for pace across the two sessions, with Alfa Romeo leading the way in 13th and 14th, whilst factory Ferrari drivers Charles Leclerc and Sebastian Vettel limped to 15th and 17th.
Grosjean admitted: “I think here we are going to pay the price in a straight line and I believe it will be a fight between 15th and 20th. I don’t really see much more but I hope I’m wrong.”
Magnussen described the day as being "not ideal" but was happy with the feel of the VF-20 when he did eventually take to the track.
The Dane said: "[It was] Not too bad. It’s just you get one lap on the C4s [soft compound] so that’s your first lap but it will come. We will see where we are tomorrow. We’ll get on top of the pace.
“You can’t just go into the first lap and be right on the pace so there’s a lot of lap time missing from us just getting up to pace. So we’ll see.”
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