Ferrari has revealed an “Evo” version of its track-only FXX-K, which will be available both as an extremely limited-run model and as an upgrade package for the existing XX cars.
As was the case with the Evo versions of the FXX and the 599 XX, the FXX-K Evo is not homologated for road use and will not be used in competition except as part of Ferrari’s XX Programme, which in the 2018/2019 season will span nine track outings between the start of March and the end of October.
When developing the new hardcore variant, the designers at Ferrari Style Centre say they worked on a broad range of different aspects, starting with reducing the car’s overall weight. By increasing the number of carbon-fibre components, they claim to have succeeded in producing a lighter car than the previous FXX-K despite introducing new elements such as the fixed rear wing as part of an evolved aero package.
The product of over a year of CFD simulations and wind tunnel testing, the Evo’s aerodynamics are claimed to deliver downforce figures very close to those of the cars competing in the GT3 and GTE championships, all to the advantage of lateral acceleration in cornering.
Compared to the previous version, for example, the Evo’s downforce coefficient has been improved by 23%, which is the equivalent of a 75% increase on the LaFerrari road car from which it is derived. Downforce of 640 kg is generated at 124 mph, and exceeds 830 kg at the car’s red-line speed.
The Evo’s downforce level is boosted by a twin-profile fixed wing on the tail. This new addition was developed to work in synergy with the active rear spoiler. In fact, the pressure fields developed by the two downforce-generating systems are claimed to support and amplify each other. To guarantee both improved downforce and drag results, the mobile spoiler’s control logics and range of movement were also reviewed and reprogrammed.
The twin-profile rear wing is supported by two side fins as well as by a central fin. The latter plays a dual role: firstly it acts as a vertical fin, boosting stability at low yaw angles, and secondly, it supports the action of the three delta (triangular) vortex generators.
The vortex generators, on the one hand, clean the flow field striking the wing of the effects of the wake of the hot air flow from the radiators which vents onto the bonnet. On the other, they create a downwash component in the flow which boosts the twin-profile’s downforce capacity. The result is a 10% increase in the downforce developed by the rear system.
The design of the rear bumpers was also modified in the light of the new flow structures. The by-pass vent from the rear wheel arch has been enlarged, hollowing out the volume behind the wheels to ensure the wake from the wheels is efficiently channelled. The result is that the flow to the rear diffuser is protected and losses are reduced so that downforce has been boosted by 5%.
Ferrari designers say the increase in rear downforce subsequently demanded an in-depth review of the shape of both the front bumpers and underbody to guarantee a balanced development of the downforce.
The geometry of the sides of the front bumper was therefore altered by hollowing out the surfaces beneath the headlights. This made space for a couple of flicks divided by a vertical turning vane and an additional intake ahead of the front wheels. This system alone delivers 10% of the increase in downforce gained on the FXX-K. It also makes good use of know-how acquired in the GT racing programmes in which rules introduced in 2016 permitted extensive study of the interaction between horizontal (flicks) and vertical (dive plane) flow management systems, optimising their efficiency.
Ground effect was also boosted by the introduction of vortex generators on the undertray. This capitalised on the accelerations created by the rear system and the front underbody, generating 30% of the extra downforce the car delivers compared to the FXX-K.
The Evo’s boosted performance also demanded new front brake air intakes which, although no wider to avoid increasing drag, are more efficient owing to a complete redesign of the intake itself.
Furthermore, the suspension was specifically calibrated to adapt it to the car’s new aerodynamic efficiency figures.
On the inside, a racing-inspired cabin gets a F1-derived steering wheel design complete with integrated gear-shifting paddles, while the rear video camera screen to the right of the driver has been replaced with a larger 6.5″ version that displays data from a new telemetry system with clearer, more direct performance parameter and car status readouts.