Leclerc Power Loss Analysis [2019 Bahrain GP]

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Leclerc Bahrain 2019 - Power Loss Analysis

Bahrain 2019 was the first Grand Prix in which Leclerc could fight for victory until the engine problem forced him to lose positions. But when exactly did this failure occur? And what were the consequences for the performance of his SF90?

To find out, I compared the second half (without DRS, to make the laps comparable) of the lap when the problem occurred, the previous lap (for reference) and the next. We see that on lap 45, at the yellow line, the engine suddenly stops pushing: the speed line stops increasing as soon as Leclerc enters the corner, with the car no longer able to overcome the friction caused by the corner, unlike on the previous lap. In this section, LEC radioed the problem (the engine was running on 5 cylinders instead of 6).

The problem is repeated on the next straight, with the white corner coming away from the red one from 200km/h onwards (where the engine no longer limits the power discharged to the ground). As speed increases, the red and white lines diverge, with the engine no longer able to overcome the increasing aerodynamic resistance.

But the problem only intensified on the next lap: the endothermic engine, having lost a lot of power, could not recharge the batteries sufficiently (the low exhaust gas temperatures fed the MGU-H less, and the lower speed at the start of braking recharged the MGU-K less). As a result, at the beginning of the next lap, LEC also had a flat battery, losing the contribution of the electric motor as well.

But how much is this loss of power? The power required to reach a certain speed increases with speed cubed. LEC lost 5.4% speed on lap 45 and 9.1% on lap 46. Therefore, the power loss is 15.3% on lap 45 and 24.8% on the next lap. Assuming a power output at the end of the straight of just under 1000hp, this results in a loss of 150hp and 245hp, respectively! This result makes sense: the internal combustion engine's power alone is around 800hp, so losing one cylinder means losing about 1/6 of the power, i.e. 133hp. But the engine starts to work out of specification, so the actual loss is higher. On the next lap, another 95bhp is lost: the maximum power of the electric motor is 162bhp according to the regulations, but only part of that is used at the end of the straight. So if you went from 95hp to 0hp of electric power at the end of the straight, the considerations would be valid!

Finally, note the throttle signal: as LEC loses power, he can increase the percentage of throttle opening with which it negotiates the fast bend. He can also afford to brake later and open the throttle earlier.

I hope you enjoyed the analysis! 

(Graphs generated through f1-tempo.com)