exterior & aerodynamics

The Challenge Stradale builds on aerodynamic concepts employed on the 360 Modena by taking advantage of the racing suspension set-up (stiffer and lower) and adopting specific solutions that have led to a gain of 50% in vertical load compared with the 360 Modena.

The results are extremely significant: at 200 km/h the load increase is about 40 kg for a gain corresponding to the effect of a wing with 15 cm chord length and 1.8 metre span. 

Despite such a significant increase in vertical load, after all the modifications and adjustments to set-up, the car has a Cd equal to that of the 360 Modena (Cd= 0.335).

Three? Four areas feature in the  improved aerodynamics of the Challenge Stradale.

• Front section: modification of the bumper, which now extends below the air intakes to increase load at the front but without disrupting airflow towards the rear.

• Aerodynamic study of the car's underside and rear section: with the result of an increase in height at the rear and introduction of longitudinal fins to balance the load. The decision was also taken to modify the rear nolder to achieve greater efficiency by adopting a shape more appropriate to the function. 

• Drag and modification of the sills: the new shape sills streamlines the rear wheels more completely and contributes significantly to improving the car's efficiency and balance. The combined result of these changes  is that compared with the 360 Modena drag has remained unchanged, so leading to a significant increase in efficiency.

In addition to the changes  outlined so far, the focus on the Challenge Stradale's aerodynamics and styling has been enhanced by a painstaking review of all technical details of the project: 360 GT-style aerodynamic, carbon mirrors, new 19" wheels with a Challenge-type design.

weight reduction

Careful project development has led to a Challenge Stradale car weight that is fully 110 kg less than the 360 Modena, achieved by concentrating on three complementary areas : materials, construction technology and project optimisation.

The basic material used to build the Challenge Stradale is aluminium, as is  the case for the 360 Modena and Spider. Aluminium has been used for both body components and, above all, the space frame, a combination of castings, extrusions and plates. This initial approach towards drastically reducing the Challenge Stradale's weight already made it extremely competitive (compared with the 360 Modena) given that the basic material used, aluminium, has a specific weight one third of that of steel.
Starting from this base new developments were introduced specifically for the Challenge Stradale. Titanium, already used for the piston rods, was also adopted for parts of the suspension, in particular for the wheel bolts (a 50% weight reduction) and damper springs (a 27% weight reduction). 
Carbon technology, derived directly from Formula 1 and used extensively on Ferrari limited-run road cars, is  employed here for the first time on an 8-cylinder car. 
For the Challenge Stradale it has been used for both structural parts (door panels, racing seat shells, filter-box covers) and for interior and exterior trim features. 
A particularly advanced construction technology was adopted for the car's floorpan. This involves impregnating the resin with multi-axial carbon fibres in a vacuum in order to obtain the necessary rigidity, but which simultaneously leads to a 50% reduction in the weight of the floorpan itself. 

A key factor in the search for the best weight-performance ratio for the Challenge Stradale was adopting a braking system comprising carbon-ceramic (CCM) discs developed for Formula 1 combined with aluminium brake carriers as standard equipment.

In terms of weight, the reduction achieved on the Challenge Stradale as a result of CCMs is 16% compared with conventional brake discs, but given that the weight eliminated affects unsuspended masses, its contribution to the car's performance is  even more significant.

Below is an overview of the drastic weight reduction achieved for the Challenge Stradale (-110 kg), subdivided by the car's sub-assemblies:
 

	reduction	% reduction in terms of total weight
engine & gearbox	11kg	4%
unsuspended mass	5kg	3%
body	94kg	12%

Reducing a car's weight also means a reduction in its inertia. The main effect of this on the Challenge Stradale, together with the peak power increase provided by the V8 engine, is a considerable increase in performance, particularly as regards pick-up and acceleration. 

The car accelerates from 0 to 100 km/h in 4.1 seconds and covers 400 metres from a standing start in 12.1 seconds.

racing interior

Only the essential remains  is the dominant characteristic of the Challenge Stradale's interior, right from the elimination of unnecessary features like carpeting and mats, to a racing-style interpretation for every single feature.

The rev counter located right in the centre of the instruments becomes the driver's main point of reference, emphasised by the yellow graphics and red indicator that ensure optimum contrast and legibility. The entire panel is enclosed within a carbon-fibre element that also houses secondary instruments and other telltales.
The new steering wheel, with a squashed crown in the upper section fitted with a sight just like on the racing version, has F1 gear-change paddles, the right one having been lengthened to facilitate changing up when pulling out of corners.

The car is fitted with carbon fibre-structure racing seats upholstered with a high-grip textile.

Door panels are made entirely of carbon fibre, as is the central tunnel, which has been designed to house all the car's main controls - ignition button, reverse gear button, dynamic vehicle settings (race, launch control, ASR excluder) within easy reach of the driver.

The car can be fitted with either 3-point attachment or 4-point attachment racing seat belts and an aluminium roll-bar that's 40% lighter than a conventional type, developed specifically for the Challenge Stradale.

engine

The Challenge Stradale is equipped with the existing  360 Modena 90° V8 engine mounted centrally behind the cabin in a longitudinal configuration as a single block together with the gearbox and differential. Peak power output of the V8 engine has been raised to 425 bhp at 8,500 rpm to give an exceptional power rating that exceeds 118.5 bhp/litre, which makes it the most powerful normally-aspirated V8 ever built by Ferrari. The extremely high peak torque remains unchanged at 373 Nm (275 lbft) at 4,750 rpm.

On the mechanical front, couplings for rotating parts in the Challenge Stradale's V8 have been carefully selected and this has led to a significant improvement in performance.

Modifications to the engine can be grouped in the following areas:

1. Optimisation of the compression ratio by means of additional work on components involved in it (Heads, Pistons)

2. Optimisation of the engine's fluid dynamics, by means of the following modifications:

• use of an intake manifold with inserted stacks and burnished ducts, in addition to burnishing the intake ducts and head exhaust;
• optimisation of the section and head of the intake manifold coupling;
• use of a specific intake timing;
• use of a new low-load loss, airflow meter;
• new low counter-pressure exhaust silencer.

3. Optimisation of mechanical performance was achieved by means of the following interventions:

• selection of low-friction cylinder blocks;
• new positioning of valve-springs.

F1 gearbox

The entire development of the Challenge Stradale was based around the F1-type electro-hydraulic transmission that controls the clutch and gearbox by means of blades integral with the steering column - a trademark of Ferrari cars and a solution developed specifically for racing.

The increase in precision guaranteed by the new control strategy applied specifically to this car, and also by a faster processing speed, has reduced gear-change time throughout the entire range of use, with a minimum of 150 milliseconds when using the super-performance option.

The available gear-change configurations are consistent with the car's top-level sporting profile and so only include manual gear-change operated by the driver using F1-type paddles (there is no automatic gearbox option).

The reverse gear is engaged by means of a button on the central tunnel.

There are two gear-change configurations (Sport and Race): each of these configurations corresponds to an integrated car-control logic as regards damper set-up and traction control (ASR).

In “RACE” mode and with the ASR disengaged there's also a “launch control” strategy as used in Formula 1, a feature specially designed to give drivers a high-performance start in good grip conditions.

chassis & suspension

The Challenge Stradale has been derived from the 360 Modena and maintains the same basic approach and architecture. 
However significant changes have been made to the suspension system and set-up. The titanium front and rear springs are stiffer  than on the 360 Modena (around +20%), and  the rear anti-roll bar has a larger diameter. These interventions have increased resistance to roll and to dip and in general terms have made reaction to direction changes more rapid, giving the driver a more direct feel of the car. 

Damper settings have been reviewed and defined specifically for this model. The car's centre of gravity has been lowered by 15 mm.

The tyres are Pirelli P Zero Corsa type - this new Pirelli super-low profile tyre adopted specifically for the Challenge Stradale measures 225/35 at the front and 285/35 at the rear and is fitted on 19" Challenge-style wheels secured by titanium bolts. The choice of these tyres exclusively for the Challenge Stradale confirms the effectiveness of cooperation between two of motoring's historic brands, not only in the case of the Ferrari Challenge-Pirelli Trophy but also in the FIA GT Championship. A long series of tests carried out together with Pirelli has identified a tyre compound and tread design that maximises torque transfer  to the road surface and produces very high lateral acceleration (1.3 g) while maintaining superb balance between the two axles. The innovative characteristics of this tyre, which makes  its world debut at the Geneva Show together with the Challenge Stradale, means grip can be adjusted to suit the thermal conditions under which the tyre must perform.

carbon ceramic brakes

The braking system on the Challenge Stradale comprises carbon-ceramic (CCM, Carbon Composite Material) discs: the result of highly advanced studies conducted by Ferrari in conjunction with Brembo, the supplier of this system.

Dimensions of the brake discs are as follows:

front: 380 mm diameter x 34 mm thickness; and a differentiated-diameter, 6-piston calliper;
rear: 350 mm diameter x 34 mm thickness; and a differentiated-diameter, 4-piston calliper

The carbon-ceramic system installed on the Challenge Stradale, together with the aluminium brake carriers, makes for astounding performance and short braking distances. 

In terms of weight, the reduction achieved for the Challenge Stradale is 16% when compared with conventional brake discs.

Overall deceleration rates for the Challenge Stradale are 15% better than for the 360 Modena.