Charles Leclerc, Ferrari, Sochi Autodrom, 2020

How Mercedes’ missing engine feature left Hamilton at a disadvantage for the race

2020 Russian Grand Prix

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Mercedes have the best power unit in Formula 1 today. They had the best power unit when the V6 hybrid era began. And they did for most of the years in between as well.

But there is one respect in which their engine is not quite a match for their rivals’. It rarely has a bearing on the competition, but it did in qualifying for the Russian Grand Prix today. And it could have crucial implications for tomorrow’s race.

Lewis Hamilton found himself on the back foot in Q2 when his first lap time was deleted because he ran wide at turn 18. This was a costly setback, as he had to come into the pits before making another attempt at reaching Q3. “We couldn’t do another lap because we didn’t have the fuel,” explained team principal Toto Wolff.

Hamilton returned to the track to make his second attempt with another set of medium compound tyres fitted. Drivers who reach Q3 must start the race on the tyres they use in Q2, and Hamilton wanted to qualify on medium compound instead of the soft, which would degrade quickly at the start.

However his second Q2 run was scuppered when Sebastian Vettel crashed at turn four. Hamilton was in the penultimate corner of his lap when the session was red-flagged.

An error on his first Q2 lap put Hamilton on the back foot
The clock froze with two minutes and 15 seconds remaining. As a lap of Sochi takes just over a minute and a half, this left sufficient time for some drivers to complete out-laps and begin timed laps once the session was restarted. However it was doubtful all 14 remaining cars could do so in the narrow window available.

In order to maximise their chances of setting a time, drivers needed to be the first in line at the pit lane exit. But with many drivers hoping to do the same, that would mean waiting for a long time with the engine running, which creates a risk of overheating.

For teams with Renault, Honda or Ferrari power units, this isn’t a problem. They can pull up, stop their engines and restart them when needed using the electrical power from the MGU-K – as Charles Leclerc did when his car stopped during the Spanish Grand Prix.

The Mercedes power unit, however, doesn’t have this capability. “We couldn’t really send him out early because you need to switch off the car and then restart it on the MGU-K, which is something we can’t do,” Wolff confirmed.

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Had Mercedes been able to send Hamilton out early and have him lead the cars out of the pits, they would have known he could drive a hard enough out-lap to bring the medium tyres up to the required temperature. But because they knew he’d be stuck at the back of the queue with a compromised out-lap, they had to put him on the soft tyres, which would warm up more quickly.

The only Mercedes engine in the queue overheated
Many of the non-Mercedes runners headed for the pit exit long before they knew when the session would restart. Alexander Albon led the queue, followed by Max Verstappen, Pierre Gasly, Daniil Kvyat, Leclerc and Lando Norris.

The only Mercedes-powered driver in the queue initially was Lance Stroll, who like Hamilton was in the ‘drop zone’. However his car had to be pushed away before the session restarted. “We had an overheating issue with the engine,” he admitted afterwards.

Mercedes knew they couldn’t take that risk with Hamilton, and sent him out shortly before the session restarted, on a set of softs.

“We felt that if he was at the back of the train and could not do the the out-lap that he would need to do, we could be caught out because the medium is simply not there yet,” Wolff confirmed. “That’s why we put him on the soft.”

Verstappen and Valtteri Bottas, Hamilton’s closed rivals on the grid, will both start on the medium tyres. “[This] is clearly compromising him for the strategy tomorrow,” Wolff admitted, “but it was the necessary safeguard today to be sure that he would make it into Q3.”

On most days Mercedes’ rivals would no doubt happily trade their MGU-K restart capability for a little more power or efficiency. But on this occasion, this difference between the power units proved significant. It remains to be seen whether it has left Hamilton at a disadvantage which will compromise his race.

Quotes: Dieter Rencken

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Author information

Dieter Rencken
Dieter Rencken has held full FIA Formula 1 media accreditation since 2000, during which period he has reported from over 300 grands prix, plus...
Keith Collantine
Lifelong motor sport fan Keith set up RaceFans in 2005 - when it was originally called F1 Fanatic. Having previously worked as a motoring...

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24 comments on “How Mercedes’ missing engine feature left Hamilton at a disadvantage for the race”

  1. Interesting, I’d assumed the restart capability was a mandatory requirement as it was touted so much when the power units were introduced.

  2. I learnt something today, thanks for the info

  3. Thanks, that clears up a lot of idle speculation (in my own head) about why Mercedes put Lewis on soft tyres. Maybe fuel for another 2 laps in Q2 would be worth them considering when they have such a pace advantage at a track where it’s easy to have a lap scrubbed.

    1. That and indeed why the team didn’t do the obvious and send Hamilton out ahead of the queue @david-br good bits of info!

  4. Thank you very much for this article!

  5. Interesting that the Mercedes is now the only engine that cannot restart by using the MGU-K. I guess by now we’ll take anything that might mean Hamilton will have a bit of a fight on his hands to win the race by a mile.

  6. So, a chink in Mercedes’ armour!

    Unfortunately for their rivals, not the most exploitable weakness…

  7. I did wonder if that was the reason

  8. I don’t think it will have any bearing on HAM. He starts on softs, RB’s are not the best starters out there.. I guess it will be Merc 1, 2 after the first corner. HAM will keep the tires alive long enough to find a gap to pit into. BOT will inherit the lead for a while but when he pits it will be HAM in front again… to the finish.
    VER will get swallowed by fast starting soft runners and will be too busy securing 3rd to trouble BOT.
    Boring after race press conference, blah blah how do you feel equaling the record blah blah

    I hope my crystal ball is off though

    1. I think it’ll be a completely different race. The slipstream will be massive tomorrow so I expect Bottas to lead Verstappen on lap 1 with Hamilton dropping to p4. I expect he’ll catch back up to 3rd and possibly 2nd before the stop but that’ll hurt him too much to consider the win. Think a podium is the best he can do but it’ll be interesting to see how the race unfolds with different strategies at play.

      1. Meh.. I’d say HAM will be fine. Last year VET started 3rd and could go through to 1st but they where on the same tire. This time HAM has the better starting tire and I believe in the end the Q2 red flag will prove to be a blessing in disguise. BOT will have the better side of the track, but the lesser starting tire. VER will be on the dirty side of the track so he’ll be the one dropping to p4

        No, I’m not putting money on it ;-)

        1. I agree, however similar to you, I’m not putting money on it 😊

    2. baasbas Race strategy will be a bit interesting though. If Bottas leads Hamilton in the first stint, then Hamilton is presumably going to be the first who needs to pit due to his soft tyres. But this would give him the undercut advantage and likely track position over Bottas – which goes against Mercedes’ usual race philosophy. But pitting Bottas before Hamilton might compromise his race later on.

      If Hamilton leads in the first stint, he will no doubt retain his lead over Bottas in the second. Bottas can go long and try to come back later with fresher tyres. Depends how many laps the softs hold on for compared to the mediums. It will probably need to be quite significant to give Bottas any chance, but I’m still hopefully for something a bit interesting. This is all without accounting for Verstappen or others ofc, who could interfere in strategy even if they’re unlikely to beat the Mercs by the end.

  9. Does anyone know what the technical reason is that they can’t restart? The have a battery, a motor, the MGU-K that can turn the crank and they have spark plugs. Is it something to do with heating the engine?

    1. They lost the keys over the winter.

  10. So Hamilton’s own mistake and Q2 tyre gimmick were were the smaller factors compared to this engine feature?
    What koolaid is the writing on?

    1. The article doesn’t say this, it’s about how the Mercedes engine lacks a feature their rivals have which compromised Hamilton’s final Q2 run. Did you even read it?

  11. We couldn’t really send him out early because you need to switch off the car and then restart it on the MGU-K, which is something we can’t do

    I’m a bit mystified by this statement. The part that isn’t a mystery is none of the cars would actually restart using the MGU-K (not unless they were being towed), they’d restart the engine using the battery charged by the MGU-K.
    My guess as to why the Mercedes power unit can’t be restarted by the MGU-K battery is the Mercedes engine has such high compression it needs more power than the hybrid system motor normally can produce to start it. For example, to start the engine in the garage they might apply a much higher than the normal MGU-K battery voltage to the hybrid motor, it starts the engine, then they remove that higher voltage. So in that scenario because the car had left the garage the only voltage available to the hybrid motor is what’s at the terminals of the MGU-K battery.

    1. They do start it with the MGU-K, not just its battery. A formula 1 car doesn’t have a starter motor – the mechanic sticks a portable motor with a long shaft through a hole at the back to start them normally. However, since the MGU-K is an electric motor (MGU means motor-generator unit) and is coupled to the crankshaft, they can use it to start the engine, by turning it over. The mystery is why Mercedes can’t do that.

    2. The MGU-K permitted output is 160hp so it is more than capable to start the engine.

  12. Didn’t FIA discuss to change the rules that all F1 cars should now be capable of starting on their own with the assistance if their MGU-K (I remember they said safety was a concern)? I thought that was implemented.

    1. I wondered about that too. Looking in the current Technical Regulations, Rule 5.20 states, “A supplementary device temporarily connected to the car may be used to start the engine in
      the team’s designated garage area, in the pit lane and on the grid.” That says to me a car doesn’t have to be able to be started alone when away from the garage.

  13. This is news. Wonder how long Stroll was on idle before overheating. Can grid formation time effect Mercedes?

  14. Weren’t Mercedes at the front of the pit lane queues in the wet Styria qualifying? Or did they not need to restart their engines then?

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