Maranello, 29 June 2023 – Based on the SF90 Stradale, the new special limited
series SF90 XX Stradale was unveiled today alongside its SF90 XX Spider
counterpart. To be built in just 799 and 599 examples respectively, these new
V8-powered PHEVs represent the latest and most extreme example of a concept of
special versions, which pushes the performance of Ferrari’s road-going models
to new levels.
The concept has been honed over the
past 20 years or so, with many of these models quickly becoming considered
benchmarks in the Prancing Horse’s line up, such as the 488 Pista and 812
Competizione. Over the same two decades, Ferrari has also developed the XX
Programme to offer a select group of expert client drivers extreme cars that
are not homologated for the road, but that can be driven at the very limit on
the track. All of the models produced by the programme have proved a huge
success, with the most recent addition being the FXX-K EVO.
Drawing on its experience in both of
these spheres, Ferrari decided to create a road-legal car which embodies the
maximum expression of the two programmes’ engineering concepts. The SF90 XX
Stradale is based on the supercar in the range, the SF90 Stradale, and raises
its already impressively exhilarating track and on-the-limit driving experience
to new heights. Performance is boosted thanks to its impressive 1,030 cv (30
more than the SF90 Stradale), specific software logics and the use of radical
new aerodynamics solutions, including a fixed rear spoiler – the first to
appear on a road-going Ferrari since the days of the F50 – which delivers an
unparalleled 530 kg of downforce at 250 km/h.
The same concept provided the
inspiration for the SF90 XX Spider, which combines the ultimate on-track
adrenaline rush with the heady pleasure of en plein air driving,
where the iconic sound of the Ferrari V8 gives such a vital contribution. The
SF90 XX Spider benefits from the same sophisticated aero solutions as the SF90
XX Stradale, as well as specifically developed cockpit air flows that guarantee
superb occupant comfort with the top down. It is equipped with Ferrari’s
acclaimed Retractable Hard Top (RHT), which comprises aluminium panels and not
only deploys and retracts in a mere 14 seconds, but can also be activated at
speeds of up to 45 km/h.
POWERTRAIN
The SF90 XX Stradale has also inherited
the signature PHEV layout found in the SF90 Stradale and SF90 Spider, in which
the V8 internal combustion engine is integrated with three electric motors, two
independent on the front axle, and one located between the engine and gearbox
at the rear. This configuration allows the car to unleash a maximum of 1030 cv (+30
cv more than the SF90 Stradale), setting a whole new performance benchmark.
INTERNAL
COMBUSTION ENGINE
Thanks to its 797 cv, the
mid-rear-mounted V8 turbo raises the performance limit bar still further for
this particular architecture. The SF90 Stradale’s power unit was used as the
starting point for the F154FB engine which powers the SF90 XX Stradale, and is
now significantly more extreme. Efficiency was increased by polishing the inlet
and exhaust ducts and the compression ratio was increased with the adoption of
new pistons and specific machining of the combustion chamber. The removal of
the secondary air system also slashed 3.5 kg off the engine’s weight compared
to the previous application.
ENGINE SOUND
The SF90 XX Stradale’s soundtrack was
redesigned to become the ultimate encapsulation of the car’s racing soul. To
produce an even fuller, richer sound and celebrate the harmonics right across
the V8’s rev range, the hot tube system was optimised. This transmits the
combustion pulsations into the cabin, highlighting the higher frequencies to
reveal the ultimate evolution of the Ferrari V8.
The use of innovative materials
improved the acoustic clarity of the system: the result is a wonderfully rich
explosion of iconic Ferrari V8 sound. The tube from the intake plenum has been
redesigned and repositioned closer to the cabin’s bulkhead so that occupants
are treated to even edgier, more raucous harmonics as the engine takes in
greater quantities of air to deliver the desired torque. The resonator is now
nearer the engine to create a richer harmony and increase intensity.
Work carried out on both branches of
the hot tube system has produced a clear improvement in sound quality, which is
at its finest at mid revs. However, as the car edges nearer to the limiter, the
point at which the car unleashes the pinnacle of its power and might, the
modifications ensure both quality and intensity continue to increase smoothly
and progressively.
ELECTRIC MOTORS
Like the SF90 Stradale, the SF90 XX
Stradale has three electric motors, one located between the ICE and the gearbox
and two on the front axle. In this instance, they deliver a maximum of 233 cv
or 171 kW, thanks to the patented extra boost vehicle dynamics logic, an absolute
first on a Prancing Horse road car. The SF90 XX Stradale’s high performance
lithium-ion battery powers the three motors, guaranteeing a 25km range in
full-electric mode. When the ICE is off, the front motors give the car a
maximum speed of 135 km/h.
The control logic optimally manages the
power flows focussing on either efficiency or performance as required. The
driver can use the eManettino selector on the steering wheel to choose from
four different power management modes. In eDrive mode, the internal combustion
engine is turned off and traction is entrusted entirely to the front axle; in
Hybrid mode, it favours battery energy depletion and manages transitions
autonomously, maximising the full-electric range; in Performance mode, the
internal combustion engine is kept running as the priority is on maintaining
consistent performance, rather than on achieving the peak power; and in
Qualifying, the system unleashes its maximum power output, thanks to a control
logic that prioritises performance, using the brand-new extra boost function.
GEARBOX
The SF90 XX Stradale and the SF90 XX
Spider retain the 8-speed dual-clutch gearbox that made its first appearance in
the Ferrari range on the SF90 Stradale. However, the gear-shift logic has
changed significantly: the car uses the patented logic introduced on the
Ferrari Daytona SP3 to reach more engaging dynamic acceleration profiles.
Furthermore, the new logic improves the gear-shift sound by introducing an
exhaust note similar to the overrun on lift-off noise typical of
high-performance driving at medium/high revs.
To that end, the Ferrari engineers
developed a specific engine calibration that works in synergy with the gearbox
control logic: the SF90 Stradale’s actuation sequence was redesigned and the
combustion chamber pressure cycle was optimised to maximise the intensity of
the gear-shift sound, at exactly the point of lift-off to allow the gearbox to
engage.
AERODYNAMICS
The SF90 XX Stradale delivers the most
efficient aerodynamic performance of any road-going car in Ferrari’s history,
making it comparable only to that of the LaFerrari supercar. It delivers double
the maximum downforce of the SF90 Stradale, improving grip and yielding a
palpably faster lap time at Fiorano. The product of Maranello’s inestimable
racing experience, this result was reached by redesigning the cooling flow
management for the thermal and electric components as well the engine
compartment to cope with the higher maximum power available.
From an aerodynamics perspective, the
signature element is most definitely the rear fixed wing which was developed
from experience with the XX Programme cars. This is an element with enormous
aero potential that proved a natural fit for this particular application,
thanks to close collaboration with the Ferrari Styling Centre. Its shape was
dictated by the need to efficiently hone the way in which the pressure field
created by the wing interacts with the complex pressure and backpressure
systems that develop around the shut-off Gurney.
The latter, which was also redesigned,
efficiently manages the downforce/drag trade-off and has two configurations: LD
(Low Drag) in which the mobile element is raised and is faired in with the
fixed section, minimising drag to enhance longitudinal performance, while in HD
(High Downforce), the mobile element is lowered, closing the blown area,
thereby allowing the air to hit the fixed area. This generates an overpressure
area which, aside from generating rear downforce, also deflects the incoming
flow vertically to help deliver the absolute maximum rear downforce possible:
315 kg at 250 km/h.
The ICE benefits from improved cooling
thanks to the fact that the front radiators for the high temperature cooling
circuit are more efficient. The new layout of the underbody was also optimised
to guarantee improved extraction of the air coming off the radiators ahead of
the front wheels. The side louvres on the lower part of the front bumper,
already seen on the SF90 Stradale, were also redesigned and are now larger to
reduce backpressure.
The simultaneous increase in power and
downforce posed a new challenge which Ferrari’s engineers tackled by reversing
the layout of the medium temperature radiator, tasked with cooling the
electrical components, increasing its efficiency and also enclosing a part of
the car’s underbody, thereby increasing the effective surfaces that would help
generate front downforce. It should come as no surprise that this very clearly
race-derived architecture is shared by the brand-new 296 GT3.
The different inclination of the front
radiator improved the aerodynamic coefficients, simultaneously channelling hot
air flows through and over the front bonnet. These flows are controlled and
channelled over the car by two S-Ducts located one on either side of the vents in
the centre of the bonnet.
At the rear of the car, a scoop in
front of the entry to the intercooler air intake cleans and slows the expansion
of the flow arriving at the radiators. When the car is moving, cool air is
drawn into the engine compartment through three apertures: the first located
above the intercooler intake on the side and the second crossways on the engine
cover, while the third is a pair of ducts located to the sides of the struts of
the fixed spoiler.
The car also has a specific front splitter,
which is larger than the SF90 Stradale’s, and is the result of meticulous work
in the wind tunnel. It generates a highly energised tube of air flow under the
car and this is then exploited by the redesigned underbody. A larger, wider
front diffuser contributes to the increase in downforce of over 45 kg at 250
km/h, by working in synergy with vortex generators that themselves have been
redesigned. The downforce generated by the underbody is stabilised and
multiplied by specifically shaped bodywork surfaces.
As already mentioned, the two S-Ducts
alone help increase front downforce by 20% compared to the SF90 Stradale. The
introduction of the louvres on the front wheelarch was fundamental to this,
however, as they allow dynamic extraction from the front wheel housing, thus
giving the car an overall front downforce figure of 325 kg at top speed.
The increase in drag was managed by
working on the forms with the greatest potential impact on the body’s Cd: two
different blown ducts have been incorporated into the front bumper to reduce
overpressure and increase the permeability of the bodywork. The first, located
at front radiator height, creates a small bubble that shields and fairs in the
front wheel in more efficiently. The second channels the energised air directly
onto the front bonnet, thereby encouraging the air to flow over it and the
flanks, and keeping the flow tube entering the radiators at the sides clean.
The evacuation of the rear part of the
wheel housing has a beneficial effect on both downforce generation and drag,
and the surfaces created allow the correct management of the air flow exiting
the wheel.
The rear diffuser was further developed
to guarantee it makes a pivotal contribution by generating highly efficient
downforce, thanks to carefully designing the trailing edge around the expansion
volume, which helps keep the car’s wake compact.
VEHICLE DYNAMICS
The focus with the SF90 XX Stradale’s
development was to produce the most high-performance Ferrari road car ever that
also delivered maximum fun behind the wheel, whilst fully retaining all of the
functionalities of the SF90 Stradale’s hybrid powertrain. Usability of
performance was especially important, particularly in terms of the electric
mode’s ability to deliver surprisingly high performance driving both in
typically urban settings and in out-of-town trips – in fact, the top speed in
eDrive mode is 135 km/h.
The transition from electric mode to
hybrid mode is extremely smooth thanks to the seamless coordination between the
electric front axle, the 8-speed DCT gearbox, the rear-mounted electric motor
and the V8 engine. This in turn guarantees progressive, continuous acceleration
and makes all the powertrain’s power available as rapidly as possible.
The Torque Vectoring and Energy
Recovery under braking and lift-off functions are available in all
configurations, and the Ferrari Dynamic Enhancer (2.0) makes its debut. It is
also active in all dynamic Manettino positions and all grip conditions. The
various systems are all managed by the electronic Side Slip Control (eSSC) 1.0.
Another major new addition is the ABS
EVO controller, which debuted on the 296 GTB. Thanks to its integration with
the 6W-CDS sensor it improves both performance and repeatability in high
performance braking in dry conditions. It functions in high grip situations and
in the Manettino positions from Race upwards using the data from the 6W-CDS
sensor to obtain a precise estimation of the car’s speed. This makes it
possible to determine the target slip of all four wheels and consequently
optimise brake distribution.
Consequently, the longitudinal force of
the four tyres can be better exploited both in braking in a straight line and
under braking during turn-in, where the rear axle has to deliver a natural
trade-off between longitudinal braking performance and lateral stability. The
system maximises the repeatability of the braking manoeuvre to a target value,
reducing losses due to the tolerances of the components or the natural
variability of test conditions. The controller thus allows the SF90 XX Stradale
to brake later and in a more repeatable manner, thus enhancing its handling on
the track.
The 6W-CDS sensor delivers much more
data than the previous iteration: in particular, its ability to measure both
the acceleration and the speed of rotation on three axes (X, Y, Z) enables the
other vehicle dynamic controls to more accurately read the car’s dynamic
behaviour, thus optimising their intervention with much greater precision.
In addition to this, also debuting on
SF90 XX Stradale is the extra boost control logic which guarantees additional
power in short bursts. The job of this software, which is only active in the
Qualifying mode of the eManettino, is to produce an extra boost of power at the
critical moment when the car is exiting a bend, something which alone improves
lap time by 0.25s at Fiorano. The logic controls the power delivery, managing
peak performance with battery charge, also monitoring the status of the
components with the aim of optimising electric power delivery.
The availability of the extra boost is
indicated by a graph on the right-hand side of the dash display, and shows the
remaining number of bursts left (maximum 30). The control logic guarantees this
feature is fully useable for at least one or more laps of the track depending
on the latter’s individual characteristics. This is thanks to the fact that the
areas of the track where activating the power surplus is most useful are
pinpointed heuristically, attempting to exclude areas where using it would not
reduce the lap time.
The car has a set-up with elastic
characteristics and kinematic angles designed solely to optimise its behaviour
on the limit. There is a 9% improvement in lateral performance (Ay max)
compared to the SF90 Stradale in high speed handling conditions, mostly as a
result of downforce. Furthermore, the roll rate was reduced by 10% thereby
guaranteeing better body control.
Because the new car delivers
significantly more downforce than the SF90 Stradale and consequently more rapid
deceleration, the SF90 XX Stradale’s braking system was also upgraded. While it
retains the Aero callipers at the front, the front discs have been completely
redesigned to improve cooling, there are now bigger 390mm-diameter rear discs
and the brake pads are a new design that maximise the contact surface to
improve the coefficient of friction.
STYLING
EXTERIOR
The SF90 XX Stradale is the most
extreme version of the SF90 Stradale; its design criteria are thus those of a
track car, calibrated to ensure it can be homologated for road use. That said,
the SF90 XX Stradale is not just a special version: it is the first XX model to
go through the factory gates, transferring the very pinnacle of Prancing Horse
track technology, aerodynamic efficiency and power, to the road.
Designed by the Ferrari Styling Centre
headed by Flavio Manzoni, the SF90 XX Stradale incorporates the engineering principles
that underpinned the SF90 Stradale and pushes them to new extremes. Thanks to
the close synergic relationship between the Styling Centre and the Technical
Department, significant modifications were carried out, predominantly with the
aim of increasing the downforce of the original car.
In terms of its concept, this is to all
intents and purposes an XX car. Its characteristics, the fruit of a more
incisive, radical design language, are even more extreme still. The SF90 XX
Stradale’s styling cues are designed to highlight its thoroughbred performance
characteristics whilst still retaining the pure lines and forms of its
predecessor. Hence the decision not to hide air intakes and vents, a
fundamental part of racing cars’ stylistic language. A technical solution that
also becomes a signature element: the three louvres on the SF90 XX Stradale’s
front wing and on the rear one are an example of this. As was the case with the
F12tdf, these are typical cues from Ferrari’s styling language.
There is no doubt that one of the most
distinctive characteristics of the SF90 XX Stradale’s design is its rear wing.
The tail volume, which has been specifically redesigned with aero in mind, is
now sleeker, giving it the long tail silhouette typical of racing cars. The air
intakes for the intercoolers are now larger too, channelling the air towards
the radiators more efficiently.
The arrow-shape front wing concept has
been retained on the SF90 XX Stradale. The headlights, which now have an even
lower upper profile, are now integrated into this area by two external vertical
wing profiles. This creates what we might call a more geometric language that
reflects the spirit of this new car. New and distinctive elements of the front
section are the two imposing lower wings that dominate the air intakes, which
look as if they are floating, making the SF90 XX Stradale itself seem broader
and more glued to the asphalt than any other.
The rear of the car is characterised by
the trimaran design of the tail. Compared to the SF90 Stradale, the SF90 XX
Stradale features more imposing rear vents behind the wheels. The trimaran
section also incorporates two central exhausts. Design-wise, the aim here was
to visually underscore the impressive width of the rear of the car and this was
achieved by drawing on a layering concept.
One of the layers is the fixed rear
wing, a solution not seen on a street legal Ferrari since the 1995 F50. The
second is the body-coloured profile that wraps around a light-bar, an element
that is a complete departure from the twin-taillight concept of the SF90
Stradale. The third layer, already seen on the SF90, is the blown spoiler
combined with an active aero concept known as a shut-off Gurney.
Carbon-fibre elements stand out from
bodywork colour elements all over the car, but most especially in its lower
section, to underscore the car’s technical aspects. Other connotative elements
are the air vents in the shape of rounded-off quadrangles on both the front
bonnet and rear engine lid, which effectively become a part of the car’s
livery. They are designed as touches of colour that coordinate with the end
plates on the carbon-fibre rear wing, for instance. The car also sports
specific star-burst wheel rims with prominent aerodynamic profiles.
INTERIOR
The guiding principle of the SF90 XX
Stradale’s interior design was highlighting the cockpit’s racing vocation
through solutions that would provide significant weight-savings. The main areas
involved were the door panels, tunnel and mats, which are now simpler in terms
of their shape and the mainly technical fabrics used, while carbon-fibre was
used for functional areas. The upper part of the dashboard is trimmed in
Alcantara®, while the lower part is trimmed in technical fabric. Both are
inspired by the racing world.
The door panels emphasise the theme
seen aboard the SF90 Stradale: the concave sections that converge on the
dashboard are highlighted by the colour contrast. The three louvres in the
middle zone, on the other hand are a nod to the air vents on the wheel arch, creating
an overall dynamic, sculptural effect. The three apertures, which reference the
exterior language, also seamlessly integrate technical and control functions,
in a completely new stylistic interpretation.
The pared-back central tunnel not only
looks, but is exceptionally light. It is dominated by the gear shift gate which
is located now centrally and more forward on the tunnel compared to the SF90
Stradale. The window lifters and the key compartment are on a secondary level.
The styling theme is characterised by volumes that create a sophisticated
combination of functional voids and structural solids, lending the tunnel a
sporty yet sophisticated appeal while still highlighting its functionality.
A specific racing seat with a visible
carbon-fibre tubular structure and cushion supports was designed for the car to
enhance sporty driving pleasure without compromising on comfort. The backrest
rake mechanism has been integrated into the seat using elastic trim materials
which hide the separation between the backrest and seat squab. This means that
the structure looks seamless at all times – just like a single-piece seat while
also allowing the backrest to be adjusted. Together with the carbon-fibre
structure, this feature saved 1.3 kg in weight compared to the SF90 Stradale’s
single-piece seat.
SF90 XX Spider
The SF90 XX Spider allowed the Ferrari
Styling Centre to use the modifications made to the rear of the car to create
an instantly recognisable architecture in which the flying buttress, a
much-loved part of Ferrari tradition, seamlessly melds with the arrow theme of
the front. The resulting visual effect extends the body forwards and lending it
a completely different connotation to the SF90 XX Stradale.
The car’s centre of gravity thus
appears to be lower too, particularly from the side. This is not just because
of the roof, which has a wraparound windscreen that seamlessly melds with the
side windows, but also because the flying buttresses are lower than on the SF90
XX Stradale. Although the roll-bars protrude from the rest of the bodywork when
the roof is lowered, the fact that they are carbon-fibre means they don’t sully
the broad, squat look created by the flying buttresses. This in turn enhances
the visual lowering of the car’s volume.
When the roof is up, the roll-bars seamlessly connect to and become one with the roof structure. Like the roll-bars, the top is carbon-fibre and thanks to the renowned Ferrari Retractable Hard Top (RHT) mechanism, can be opened while the car is moving in a mere 14 seconds at a speed of up to 45 km/h, allowing occupants to enjoy the car to the utmost in all kinds of weather.