Porsche delighted the world of motorsport with a special edition of the 919 Hybrid which doesn’t obey the technical regulations of the WEC series and created a monster that was faster than fastest Formula 1 car at Spa Francorchamps in 2017 F1 qualifying – MAXF1.net reveals key modifications that made 919 Hybrid about 12 seconds faster at Spa Francorchamps.
Neel Jani was the driver who set a record time of 1:41,770 at Spa, which is 0.783 seconds faster than the Hamilton record pole position from 2017, but Porsche LMP1 boss Andreas Seidl said that all six 2017 LMP1 drivers contributed to the project. Porsche wanted to show 919 Hybrid’s abilities with eased restrictions that came from the WEC regulations.
‘Regular’ Porsche 919 Hybrid from 2017, which in its last season won the driver’s and constructor’s championship and the prestigious 24h Le Mans race is already a very fast and impressive race car.
It has a hybrid drive consisting of a 2.0-litre V4 direct injection engine and a turbocharger which delivers about 500 bhp that is sent on the rear wheels and an ERS system with about 400 bhp which transfers power to the front wheels.
That means even regular Porsche 919 Hybrid has a four-wheel drive with a total power of over 900 bhp, but Porsche has gone a lot further for their special ‘Evo’ edition.
Like in Formula 1, the WEC series has a limited fuel flow, so Porsche had plenty of space to extract extra power from its 2.0-litre V4 turbo engine.
Instead of the regular 500 bhp, Porsche has been able to extract about 720 bhp, which is more than 200 bhp without having to additional weight on their car.
Porsche’s energy recovery system saves electric energy into liquid-cooled lithium-ion batteries which powet the electric motor that then transfers power to the front wheels.
Energy is regenerated in two ways, using the heat from the front brakes (about 60%) and using the exhaust gas energy (about 40%).
The system has a standard power of about 400 bhp, but for 919 Hybrid Evo Porsche has managed to pull out another 10% of power, so the total power of ERS system is over 440 bhp.
Due to the specific purpose of this car, Porsche had the opportunity to save the weight despite making their car much faster in the proccess.
Porsche engineers lowered the total weight of the car by 39 kg, which they achieved by combining a number of minor actions such as moving wipers, lights, climate, unnecessary race control electronics and pneumatic jack.
Thus the total weight of the Porsche 919 Hybrid Evo is only 849 kg.
Active Torque Vectoring
Porsche has incorporated the technology they already use on their road cars, but which is not allowed in the WEC series. This is an active torque control that sends torque to a particular wheel.
The system works in conjunction with the differential and brakes the rear inner wheel at the corner entry to reduce the understeer and sends more torque to the outer rear wheel (which has more weight on it) for better corner exit.
And while the ‘ordinary’ Porsche Torque Vectoring System (for manual gearboxes) relies on mechanical differential control, the active system is equipped with electronic control that allows a fully variable torque distribution during driving.
Along with more power from the engine, aerodynamics is definitely the largest area that allowed Porsche to achieve a new record at Spa Francorchamps. Power without control means nothing, so Porsche, unfazed by the WEC rules, has managed to increase downforce by as much as 53% while additional drag with almost 1200 bhp and dual DRS system did not bother them too much.
Porsche used the absence of headlights and cascades that stood in front of them for a new, more aerodynamic shape of the front wheel covers (orange, see the comparison of the side silhouette on the bottom pictures), and in front of them there is only one horizontal blade (turquoise).
There is no need for multiple cascades, as the new, larger front diffuser generates enough downforce, as well as the entire floor that now has side skirts (pink) that are banned in most racing series.
By using these skirts it is possible to create much more so called ground effect in which the entire floor and body are used as a major aerodynamic element that in the interaction with the ground creates a huge downforce. Side skirts isolate underbody airflow from external turbulence (which all F1 teams are trying to do with a series of aerodynamic elements that create vortices and send them along the edge of the floor) and dramatically increase downforce.
The problem with the ground effect and the skirts is that the downforce is greatly increased when the skirts are close to the ground, but a lot of downforce is lost when that is not the case, causing drivers to suddenly lose grip and control over the car. That was the reason why ground effect and skirts were banned since 1983.
Porsche has also significantly increased the rear wing (yellow) dimensions, which is now higher, with a particularly high flap element being flattened when DRS is activated to reduce air resistance, but also changed position of the rear wing to move the center of pressure to the rear.
At the bottom you can see how the rear wing (red marked edge) is moved at least 40 cm behind compared to the regular 919 Hybrid. The new floor, side skirts and bigger front and rear diffusers have completely changed the downforce levels and Porsche altered the aerodynamic pressure by moving the rear wing rearwards.
In the lower picture you can see how high the rear wing is and how high the angle of attack is. You can also see how close skirts are to the ground (pink), even in this slow corner.
In the picture below, there is also a regular Porsche 919 Hybrid that has no side skirts and has a much lower rear wing that creates much less downforce and drag.
Rear view of the modified Porsche 919 Hybrid Evo (pictured below) also reveals a large diffuser (green) that has its own side skirts (pink) made from firm, but flexible material for greater performance and aerodynamic efficiency.
Isolating the diffuser airflow from external turbulence, especially those from the rotating rear wheels, is one of the most important tasks in Formula 1, but side skirts cannot be used since 1983, either around the floor or around the diffuser. Also, the rear wheels cannot be covered from the inside (which teams would have done immediately to reduce the negative effect of rotating wheels on the diffuser).
Also, the broken white line inside the diffuser highlights a large slope under which the diffuser is aggressively expanding towards the rear.
Interestingly, the bottom illustration shows that the Porsche 919 Hybrid Evo goes through famous Eau Rouge with open DRS, suggesting it has so much downforce that it does not need the maximum amount to pass the Eau Rouge on full throttle.
For more than 15 years, Eau Rouge is easily flat out in dry conditions for F1 car. Last time F1 cars couldn’t easily do Eau Rouge with full throttle was in 2002.