McLaren MCL39 vs Ferrari SF-25: a deep dive into floor efficiency and downforce generation. Detailed analysis of McLaren's MCL39 floor reveals why it generates superior downforce compared to Ferrari.

With Lando Norris’s crash in his Lando McLaren during the first Q3 attempt at the Jeddah circuit in Saudi Arabia, a fairly clear photo of the floor was captured. Currently, the MCL39’s platform ranks second in terms of downforce, behind Red Bull, which still has a slightly higher maximum load, although it cannot always deliver it easily.

Ferrari must learn from McLaren
In contrast, the car from Woking is easier to get into the correct operating window. This allows it to generate the right vertical load in various situations. In technical terms, this means the key component has a wider aerodynamic map—precisely the goal Ferrari is chasing in recent months: generating stable load across a wider range of ride heights.

This applies whether the car is rolling, pitching, or yawing. The design philosophy adopted by the historic British team focuses exactly on this, which is why they use a suspension system that aims for more rigidity. A significant advantage that the papaya-colored cars can exploit throughout the race weekend, showing impressive setup flexibility.

That’s why any type of layout poses no issue. Meanwhile, the Ferrari suffers significantly under these conditions. We discussed this earlier today, referring to the supposed issue of generating grip in the SF-25’s slow corners. The Italian car can do this, and quite well. Unfortunately, having to chase more compromises, the team in Jeddah had no choice but to sacrifice the only technical section in favor of the more numerous fast ones.

MCL39: how the inlets and floor edge work
Focusing specifically on McLaren’s floor structure, the green highlights mark the elements that make up the initial area. Specifically, we note the two most important appendages among the four at the mouth of the Venturi channels. These are key to generating outwash, significantly increasing downforce. Their shape is therefore crucial and subject to multiple developments throughout the year.

The floor produces the highest percentage of downforce in a ground-effect car, and its performance must be protected as much as possible. The so-called inwash effect—where dirty air flows laterally into the floor volume—must be minimized. The better this is managed, the more effective the floor becomes. On the other hand, the fences in question direct the airflow outward.

This achieves two outcomes: a forward shift in downforce generation via the so-called edge wing, which also works to divert turbulence from the front wheels. It does this by creating multiple vortices that combine into the so-called edge vortex, which seals the floor and prevents the aforementioned dirty airflow infiltration.

About halfway along the appendages, a vortex detaches, illustrated in the graphic and labeled “A”. The appendage design is intended to control its position. Since this vortex is strong and energized by others, it helps lower pressure further due to its high rotational speed.

MCL39: the efficiency of the Venturi Channels
In yellow, the graphic outlines the Venturi Channel roof, specifically designed to house large vortices with a particular structure. This is why the channel walls must be shaped to avoid disrupting their rotation, ensuring they do not “break” under certain driving conditions. Their trajectory changes over time depending on the floor’s movement.

Once again, the more stable the floor configuration, the fewer “risky variations” the airflow mass will experience along its path. Also in yellow is the distinctive keel shape, with a ‘kick’ at the leading edge. This geometry should increase local low pressure. Finally, we reach the diffuser, the most delicate part of the floor where airflow expands.

The goal is to maximize extraction volume, where every single cubic centimeter matters. Two indentations are visible in red, designed to increase this expansion. A solution already seen on the Red Bull RB20 and partially adopted by McLaren last season. In this area, we’ve diagrammed the rotation of the strong vortex that reaches the floor.