INSIGHT: How will Mercedes be affected by F1's new PU mode rules?

Charles Coates/Motorsport Images

INSIGHT: How will Mercedes be affected by F1's new PU mode rules?

Formula 1

INSIGHT: How will Mercedes be affected by F1's new PU mode rules?


Mercedes has explained the different power unit modes it uses in Formula 1 and how the new technical directive will impact the team at the Italian Grand Prix.

From this weekend’s race at Monza, all teams will have to run the same power unit mode from the start of qualifying until the end of the race because the area falls under parc ferme regulations. Mercedes often makes a major step forward during qualifying with its power unit modes in Q2 and Q3, with much of the focus being on how the change might impact the defending champions’ advantage at the front.

Mercedes High Performance Powertrains managing director Hywel Thomas explains how the power unit modes differ from each other, and what the team might usually change during a race weekend.

“An engine mode is a set of control parameters which control exactly how the engine and the electrical system work,” Thomas said. “We typically split the load into two: there’s the ICE (internal combustion engine) combustion parameters, and there’s the ERS electrical parameters.

“In the combustion engine we’re changing things like the amount of air that goes in, the amount of fuel that goes in, perhaps when we spark the engine to make the combustion happen, and we’re changing all those things to get different power outputs, different energy level outputs and we’re changing that through the race weekend to maximize the lap time at the right time.

“On the ERS side, the complication is you cannot deploy your MGU-K for the full lap every lap. You can’t do that without running down the battery. So we have three typical settings. One is neutral, so we deploy the same amount of energy as we recover, and that means you can run that lap after lap after lap.

“On the other hand, if you’re wishing to attack somebody, you might choose to deploy more MGU-K through more of the straights, but what that does mean is that your battery power will come down. If you’ve done that for a couple of laps, you’ll be getting to the bottom of the pack and you need to reduce even more the MGU-K from the neutral lap, and charge the battery back up. So it’s very tactical, when you use those different ERS modes, and the driver will choose those by choosing one of the different ‘Strat’ switches.”

Mercedes’ ‘Strat 2’ PU mode – aka ‘Party Mode’ – has been an effective qualifying weapon during the current engine formula. How will the game change when teams are forced to use a single mode through qualifying and the race? Sutton/Motorsport Images

The strongest Mercedes mode is known as ‘Strat Two’ and usually used in qualifying, but Thomas explains why it is not possible to use that throughout a race.

“Whenever you talk about modes, what people ask about is ‘Party Mode’ and what is ‘Party Mode’ and does it exist? For us, ‘Party Mode’ is Strat Two, and has been since the start of the hybrid era in 2014. What does Strat Two really mean? It’s really quite straightforward. It’s strategy position two on the steering wheel, and that’s where the driver goes for those really important laps in qualifying, maybe just through those two laps in Q3 when they’re trying to get pole position.

“And what does Strat Two do? Well if you go back and think about what we’ve talked about, it’s about all those control parameters and turning those up to the absolute max so that the engine is screaming, the engineers are wincing, and also the electrical energy is going from the full pack to the bottom of the pack – all of the charge we’ve got in the electrical energy all in that one lap. We’re just giving it everything we’ve got to give us the best chance of getting on pole.

“As of this weekend, there’s a new technical directive – technical directive 37 – and what that says is that you can only use a single mode from the start of qualifying to the end of the race. So we might use currently two or three modes during that time, from the highest crankshaft mode that we’ve got to a medium mode, and what we’re now saying is it has to be all the same mode. So that absolute ‘Party Mode’ will probably disappear, but maybe we’ll be able to do a little bit more during the race. Just as long as it’s the same all the way through: that’s what the TD says.”

Despite the focus on the new technical directive, Thomas says there will still be tools available to drivers to change the power unit performance during a race, but he does envisage some movement in the competitive order on both Saturday and Sunday.

“What’s the impact on us going to be? We don’t know yet,” he admits. “I imagine some power unit manufacturers might find that they are going forward relatively to the others in qualifying, but maybe it will be someone else that gains a little bit more than the others in the race. I guess we’ll find out in a couple of days at the end of the Monza weekend.

“The drivers will still be making switch changes, they’ll still be doing that in order to manage the energy in the pack in the way that we’ve described previously when they might want to attack or they might be wishing to charge the pack to allow them to attack later. So they’re still going to be doing those sorts of switch changes. What has changed slightly is that the layout of what strategies are on different switches. So there’s going to be quite a lot of work between the engineers and the drivers to make sure that they understand what those changes are to make sure that they can optimize their races.”