How Porsche turned its WEC LMP1 winner into an F1 beater

This week, Porsche managed to shatter the unofficial Formula 1 lap record around Spa-Francorchamps with an upgraded version of its 919 Hybrid

It's rare that we get to see what racing cars are capable of once their programmes come to an end, but Porsche has done something incredibly special by creating the 919 Evo tribute, a machine that totally ignores the technical regulations that held back the potential of its World Endurance Championship-winning counterpart.

The lap record it beat around the Belgian Grand Prix venue was relatively fresh too, having been recorded last year by Lewis Hamilton in his Mercedes W08 - a car that also had a serious increase in downforce thanks to the new Formula 1 regulations introduced in 2017.

Neel Jani's target time to beat was a 1m42.553s - a feat that seems even more implausible if we consider the standard car managed a 1m54.097s in WEC qualifying in 2017. But Jani smashed that time, recording a 1m41.770s that was 0.783 seconds quicker than Hamilton's pole lap and more than 12 seconds faster than the WEC pole lap.

But how did the car achieve that time?

Firstly, it's worth noting that as part of the project it was decided that the 919's powertrain would remain untouched, as the Evo continued to be powered by Porsche's turbocharged two-litre V4 engine with two energy recovery systems.

But without the limitations imposed by WEC's LMP1 regulations, the development team was free to ignore fuel flow constraints and upped the flow rate to allow the Evo's engine to deliver 720bhp in its own right (up from 500bhp) while still using regular race fuel.

As part of the efficiency matrix that shackled the 919 Hybrid on its 2017 pole lap, the driver only had 6.37 megajoules of energy at his disposal. But for this run, Porsche exploited the energy recovery system's full potential, gaining another 40hp as it utilised 8.49MJ of energy.

Combined, that meant the powertrain's output increased from an already-healthy 900bhp to 1160bhp - an astonishing achievement given it was done with the same equipment and fuel, albeit with a number of software updates.

Increasing the car's output by a third would be useless without being able to control it, so it's no surprise that under the car's frame numerous changes had to be made too. The Evo utlises a four-wheel brake-by-wire system, giving the driver more control in yaw. New front and rear suspension wishbones had to be crafted in order to endure the higher loads that the car would be put under.

The Pitch Link System used to control the car's attitude was also updated and includes an actively controlled lockout system, which was not possible under WEC regulations. All of these changes required the power steering to be adapted, too, so Jani could exploit the 919's newfound agility.

All of this would have been for nought had it not been transferrable to the tarmac, and Michelin developed new compounds to provide the necessary grip.

A motorsport engineer's biggest enemy is weight. As such, the 919 went on a serious diet, shedding all non-essential components. The Evo weighs 39kg less than its sibling, with the air conditioning, windscreen wiper, several sensors, electronic devices from race control, lights systems and the pneumatic jack system all discarded.

Aerodynamics are a huge differentiator in top level motorsport, and the Evo's aero package was a significant upgrade on its WEC version - with drag reduction systems (DRS) added to the front and rear and a totally revamped aero solution resulting in 53% more downforce and an increase in efficiency of 66%.

Of course, these gains are predominantly down to the fact that aerodynamicists threw the technical regulations in the bin, but there are also developments that didn't see the light of day because Porsche didn't compete in WEC this year that have made their way onto the car.

The front of the 919 has been totally reworked and, with the headlight assemblies considered total dead weight, designers could streamline the fenders and dramatically reduce the size of regulatory holes introduced by rulemakers to reduce the chance of takeoff when the car goes sideways (red arrows).

A major driving force in the car's drag reduction and improved downforce comes from the hydraulically-operated DRS, which changes the angle of the front splitter's trailing edge. It's a solution that's twinned with a much larger and more rearward-cited rear wing assembly, that also features DRS - improving balance, reducing drag and increasing downforce.

The floor was also reworked, optimising flow towards a revised diffuser that takes advantage of fixed-height side skirts that help to seal the edges of the floor and increase ground effect.

The slatted rear assembly in the rear wheelpods have been discarded too, as they were more about fulfilling regulatory criteria than enhancing performance. Along with this, the team tidied up the entire rear end, while the side skirt was modified further during the course of three-day test, undoubtedly as a result of needing to improve the aerodynamic behaviour of the car (red arrows).

You might argue that the Evo is a pointless exercise, but it allowed engineers that worked on the 919 for more than four years to loosen the reins and at least take a glimpse at what is possible.

That said, the Evo is still barely scratching the surface of what would be attainable, with the limitation of time, funding and resources holding back its absolute potential. Perhaps one day management will see fit to loosen the purse strings even further.

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