​Motorsport photoMcLaren team principal Andrea Stella has clarified the issues with Lando Norris’ current Mercedes power unit, as the reigning champion rued the lack of straightline speed in Formula 1 qualifying for the second week running.Although McLaren is known to be missing straightline speed versus its other Mercedes-powered counterparts owing to its selected gear ratios being lower, Norris had a deficit on top of that across the Baku weekend. This deficit has resurfaced, although McLaren was losing further time across qualifying when compared to the Red Bulls and Ferraris. Norris confirmed this, stating: “I’m just down on every single straight, so every time I get a good exit, I’m just slower at the end of the straight. It just hurts seeing this every single time.”Stella explained the mechanics at play with Norris’ power unit issue, but added that it was difficult to diagnose given the complexities of the current regulations and the myriad factors that could hold an effect. A deployment issue, for instance, would be easier to spot – but a mechanical issue outside of the reach of sensors would be tough to identify. The Italian believes that this is costing Norris somewhere between 0.1-0.2s seconds per lap, a not-insignificant deficit given the margins involved in qualifying for this weekend’s Bahrain GP in Malaysia.”I think more precisely we should say that the issue we see on Lando’s car is about a lack of straightline speed. So we see that in the power limited section, the car accelerates a little less and develops a little bit less top speed, all the other parameters being the same,” Stella explained.”We talk about probably between one and two kilometres per hour, they are small quantities, and they are even difficult to see. As soon as Lando, for instance, has a little bit of slipstream from a car 4 seconds ahead, now you see Lando faster than the other car. Lando Norris, McLarenLando Norris, McLaren”So, it’s a small quantities but that we see statistically and we should more precisely talk about the deficit of straightline speed, which we can quantify in a lap time loss that I would say in excess of one tenth of a second, possibly between one and two tenths of a second. “A different conversation is about why that is and while we can talk immediately about a lack of power, in reality there can be different reasons. “As you say, it’s in a way more difficult to monitor what is happening from a power unit point of view, because if it was deployment we would be able to see it, possibly has to do with some other parameters.”Stella added that those external factors could be nothing to do with the power unit at all, and was keen to avoid a situation where his comments could be construed as blame on Mercedes’ High Performance Powertrains division. The main issue seemed to be largely restricted to the latter half of the lap, where Piastri found more top speed over Norris between Turns 13 and 14, and then on the back straight towards Turn 15