Racecar Engineering Le Mans 2022

A digital supplement from the publisher of

Le Mans 2022

>> Happy hour analysed >> BoP and raceability

LE MANS 24 HOURS 2022 | COMMENT

T

he 90th edition of the Le Mans 24 hours will be the final one of the ‘transitional years’, before more competition comes to the top class from Ferrari, Peugeot, Cadillac and Porsche in 2023. Toyota and Glickenhaus bring two cars each to the 2022 edition, while Alpine brings its grandfathered LMP1 that has already won a race this year, at Sebring in March. This edition is the final time that the GTE-Pro cars will be at the race, to be parked for 2023 and ready to come back as a pro-am category in 2024 with GT3 cars.

There will be much interest this year in the LMP2 and the GTE-Am classes which together make up 50 of the 62 cars that will start. The LMP2 class features a spectrum of drivers and the teams are at the highest level ever seen, utilising the latest technology to extract the most performance from their cars that have been largely fixed in specification since 2017. They have had their performance curtailed, of course, this year running with even less power, even less downforce thanks to reduced strakes in the rear diffuser and diveplanes on the nose, and the cars are even harder to drive quickly. Yet, the teams have a handle on how to get the most out of their equipment.

The issue for LMP2 is its future, and while the FIA, ACO and IMSA remain committed to the class as a customer-friendly concept, it has pushed back the introduction of new cars to 2025, and some in the paddock expect that to be pushed even further, perhaps to 2028.

There is an argument to say that this is a good idea, that the teams will be spared the need to buy new machinery at a time when the

world economy is struggling. However, there are others who need the new cars to come, such as Dallara and Ligier, which has only one car in the 27-strong LMP2 field. Their first attempt at LMP2 was not as successful as ORECA which has dominated the class in terms of numbers and results for many years. The ORECA was the base line model against which the others were balanced, but in their upgrade kit, introduced in 2018, Dallara was not able to make the corrections needed to be competitive. That’s the failure of long homologation periods.

Dallara will partner BMW and Cadillac for the LMDh programmes. Ligier has been confirmed to partner with Lamborghini. ORECA will partner with Alpine and Honda through HPD, while Multimatic will supply Porsche.

They have a business, but for LMP2 to have long-term success, they must be allowed to bring their new cars. The supply chain issues, and resultant higher costs, mean that they may well struggle to hit the price cap mandated by the governing bodies, designed to protect the teams, so there will need to be a compromise.

In GTE-Am, the teams were guaranteed the chance to race their cars for a specified period of time, and the governing bodies have remained true to their word. The variety of engine notes, looks and concepts will continue to be seen next year in the hands of the non-professional drivers. As always, Le Mans turns to its privateers in times of need.

As always, Le Mans turns to its privateers in times of need

Andrew Cotton, Editor

CONTENTS 4 NEWS BMW reveals LMDh, Ligier partners Lambo 6 TOYOTA 2022 UPGRADE Changes to last year’s dominant car due to reg changes 12 LMP2 EVOLUTION Tracing the upgrades that have led to an incredible performance increase 20 NASCAR TO LE MANS Chevrolet’s bid to bring its Gen7 racer to endurance racing 24 HAPPY HOUR Just why does dawn breed quick times?

XPB

28 RACEABILITY Scott Raymond on the focus for overall performance, not just laptime

Racecar Engineering • Le Mans 2022 3

NEWS

IN BRIEF The ACO and FIA will push for a ban on tyre warmers as early as next year in all classes of the World Endurance Championship. Michelin already runs without tyre warmers in the IMSA WeatherTech series but Goodyear, which supplies the LMP2 field in the WEC and which has been forced to bring harder compound rubber to the WEC to help to separate the LMP2 class from Hypercar, has yet to complete its evaluation tests on their rubber.

The ACO has announced that it will introduce Le Mans-specific aero kits for the GT3 cars, called GT3 Premium, when the class comes to the WEC in 2024. The move has met with resistance from manufacturers that have to design and build the bodykits, and the teams which will have to buy them but organisers say that it will increase the value of their cars.

The FIA will introduce a seventh race to the FIA World Endurance Championship in 2023. It is part of an escalation process from the six races that was enforced by Covid restrictions.

Rumoured venues include South America, or Europe if costs prove to be prohibitive.

BMW launches GTP BMW has released some of the details of its new GTP challenger, which will race in the IMSA WeatherTech Sportscar championship in the US and which many expect to eventually race in the FIA World Endurance Championship and at Le Mans. The car, named BMW M Hybrid V8, will make its debut at the Daytona 24 Hours in January, 2023, and will be run by the RLL Team that has been campaigning the GTE and GTD cars in the series.

While there was little detail of the car itself, the company did reveal that it would be powered by a four litre, V8 engine taken from the DTM programme and which was first run

4 Le Mans 2022 • Racecar Engineering

hybrid system, with motors from Bosch, gearbox from Xtrac and battery from Williams Advanced Engineering, is currently testing in Porsche’s LMDh car, and is still in its development phase. Final sign off of the system has yet to happen.

The BMW M Hybrid V8 is designed and built by Dallara, which will also provide the spine for the Cadillac LMDh which will also enter Daytona in January, but which has confirmed an FIA World Endurance Championship programme.

The differences between the two cars will be the engine, and the bodywork with styling cues taken from the production cars.

BMW released images of its LMDh car with a retrospective livery that sadly is unlikely to make it to the track

Lamborghini and Ligier seal the deal French company Ligier has confirmed that it will supply the spine for Lamborghini for the Italian company’s new LMDh venture that is due to hit the track in 2024.

Lamborghini’s confirmation that it will enter the WEC was a long time coming, and eventually came on May 17 with many anticipating at the time the partnership with Ligier.

The Lamborghini will run with a brand new engine, designed for the purpose of competition in the top class prototype, and it is expected that the engine will be evaluated to form the basis of the new Huracan road car. ‘We are extremely proud that Lamborghini has selected Ligier Automotive for its LMDh programme,’ said Jacques Nicolet, President of Ligier Automotive. ‘Proportionally we have

in 2012. Consideration was given to the M8 engine, which would have given the powerplant a relevance to production, and the smaller two litre, four-cylinder engine taken from the DTM Class 1, but the P66 engine was instead selected.

Formerly normally aspirated, the company has fitted a twin turbo to it to help to meet the power curve mandated by the regulations as part of the balance of performance.

Power is limited to 500kW, through a combination of ICE and hybrid.

The engine, with the gearbox and electric motor, has been tested on the dyno ready for on-track testing. The complete

remained in our respective fields of activity as companies on a human scale. A commitment to reaching determined objectives in record time is a priority for our entire staff.’

Giorgio Sanna, Lamborghini’s Head of Motorsport, was at Le Mans to get a feel for the event ahead of the company’s debut. ‘We are glad to announce the technical partnership with Ligier on the LMDh project,’ said the Italian. ‘As in Lamborghini Squadra Corse, we have found in Magny Cours a team of young, competent and motivated people.’

The partner team has yet to be selected to race the car, but it is likely to be the Prema team, and Iron Lynx. The car will likely later be sold to customers to offer an escalation of activities for its GT3 and Super Trofeo teams and drivers.

PROJECT GTP HYPERCAR

Cadillac joined the list of LMDh manufacturers to reveal the latest details of their prototype, which will be powered by an all-new 5.5 litre V8 engine

Scene is set for Le Mans 24h Toyota headed the times in testing for the Le Mans 24 hours, with Jose Maria Lopez setting fastest time of 3m29.896s in the number 7 car, two tenths faster than the evergreen Romain Dumas in the Glickenhaus 007 LMH. The times were down on last year’s test day, and more than two seconds slower than the race fastest lap in 2021.

The team worked through a test programme with its car, updated from last year’s GR010 with narrower front tyres, wider rears, and with modified aerodynamics compared to the 2022 car.

The minimum deployment speed of the hybrid system remains at 190km/h as part of the balance of performance system implemented by the ACO and the FIA, which is a further change compared to last year’s car as is the weight, 4kg more and power which is down 12PS. Glickenhaus runs to the

same spec as in 2021, while the Alpine has lost nearly 40bhp.

‘We got through our programme, trying a few different set ups and seeing what we can improve,’ said Toyota driver Mike Conway.

‘There have been some changes to our car since last time we drove here and the hybrid deployment speed is different as well, so it was good to get some laps in.’

Felipe Albuquerque was the fastest of the LMP2 drivers in the United Autosport ORECA with a time of 3m32.099s. There have been changes to the 2022 LMP2 cars that include a reduction in power and downforce levels for this year’s race.

Alexander Sims was the fastest GTE Pro driver in the Corvette with a 3m54.001 that is unchaged from 2021, and Mikkel Jensen was quickest in the GTE-Am category with a time of 3m54.827s in his Kessel Racing Ferrari.

Toyota headed the times at Le Mans as expected in the Le Mans test day

Glickenhaus perfected its brake by wire system in preparation for Le Mans

Acura teases LMDh design concept for 2023 Acura Motorsports released the first images of the company’s new Acura ARX-06 LMDh prototype, which will race in the IMSA WeatherTech SportsCar Championship GTP category beginning in 2023. The car, which has yet to start testing, will debut at Daytona in January 2023 with Wayne Taylor Racing and Meyer Shank Racing, although there was no news of a European programme, or an entry to Le Mans.

This was something of a surprise to the WTR team which is keen to return to Le Mans and it has not ruled out making the trip to France in 2024.

The ARX-06 nomenclature derives from Acura Racing eXperimental, generation 6. Acura Motorsports programmes have been integral to the Acura brand since its launch in 1986. It currently campaigns the ARX-05 DPi in the IMSA WeatherTech SportsCar Championship and won the team, manufacturer, and driver championships in 2019 and 2020.

It also won the Rolex 24 at Daytona in 2021 and ‘22, including a 1-2

finish at the 2022 twice-aroundthe-clock endurance classic.

Based on the ORECA LMDh chassis, the ARX-06 will feature Acura-specific bodywork, aerodynamics and internal combustion power unit.

As was the case with the DPi that has campaigned so successfully in the IMSA series, the exterior styling of the newest prototype race car was led by the Acura Design Studio in Los Angeles, California, in conjunction with Honda Performance Development, the

racing arm for Acura Motorsports and Honda Racing in North America, and chassis-supplier ORECA. ‘The process we used in creating the exterior design for the Acura ARX-06 is the same as how we create a new Acura passenger vehicle,’ said Dave Marek, Acura Executive Creative Director. ‘The same world-class stylists that lead Acura production car design created initial sketches, then pared those down to several potential designs.

Next, we created a scale model, did aero and wind tunnel model testing,

HPD and Acura have taken camouflage livery to a whole new level

and brought Honda Performance Development and our partner teams in for their feedback. The design continued to be refined throughout the testing and evaluation process until we came up with a final treatment that met our performance goals while maintaining allimportant Acura styling cues.’

Engine supplier for ARX-06, HPD, has a rich heritage of creating, manufacturing, and supporting Honda Racing and Acura Motorsports customers since 1993.

It leads all of Honda and Acura’s high-performance racing programmes in North America and specialises in the design and development of powertrain, chassis, electronics and technical and race support.

HPD delivers parts and race support to Honda and Acura amateur and professional motorsports racers and is expanding its palette of racing programmes to make Honda racing products available to all racing disciplines, from karting and Quarter Midgets to the highest levels of professional racing.

Racecar Engineering • Le Mans 2022 5

ENDURANCE | TOYOTA GR010

Evolving doors Toyota returned to the FIA WEC with an updated car, but is saving its ‘joker’ package for 2023

By By Andrew Cotton

6 Le Mans 2022 • Racecar Engineering

T

oyota may have had a dominant season in the 2021 FIA World Endurance Championship, having won every round, but that did not mean that the team could stand still for 2022. Having completed the first season of the Hypercar era against opposition from Alpine and Glickenhaus, there were a few issues with the team’s GR010 that needed to be addressed for the forthcoming campaign.

Upgrades to the aerodynamic kit were introduced over the winter in order to accommodate the rapidly changing regulations, designed to bring the cars into line through Balance of Performance.

The team introduced a new tyre size, from the same size tyres all round to a narrower front, wider rear, similar to LMDh tyre sizes, to accommodate the change in weight distribution since the car was first designed.

These tyre sizes bring the car into line with the new convergence regulations between two and four wheel drive cars for 2023 and reduced limit on hybrid deployment speeds.

As a result of this, according to Toyota, the aero package had to change in order to maintain stability at both high speed and in yaw. The team also had to work on the airflow around the front wheels, as well as modify the rear diffuser to fit the wider wheel.

Minor upgrades to the engine have also been made as the car runs on the new bio-fuel developed by TotalEnergies, though this had a smaller effect on the car, and particularly cooling, than was expected.

Significant change Since the original regulations were produced, the Sportscar world has changed significantly.

Aston Martin and McLaren both stopped their programmes to bring productionbased cars to the top Hypercar class leaving just Toyota, Peugeot and Ferrari as OEMs supporting the rule set. Since the Hypercar regulations were announced, there has been

Racecar Engineering • Le Mans 2022 7

ENDURANCE | TOYOTA GR010 a new development in that LMDh cars, based on customer chassis but with OEM engine and aero kit, will be allowed. All of this has led to some significant regulation changes, particularly for the LMH cars, and among them Toyota which was first out of the blocks and has faithfully supported the WEC through its transition years before others arrive.

For the 2022 season, the WEC once again sees Glickenhaus with a non-hybrid Prototype, and a grandfathered LMP1 car from Alpine for the second year in succession.

As a side-note, Alpine won the opening round of the series at Sebring as Toyota had further hybrid restrictions introduced as part of BoP. The reduced deployment speed is designed to bring the prototypes closer together in terms of performance, and hindered Toyota’s ability to dominate the class with its new car.

Clumsy introduction The way that the new regulations have been introduced can only be described as clumsy.

Multiple delays, changes of concept and broken promises have been highlights of this process thus far. However, Toyota was the first of the OEMs to create a Hypercar and, following all the changes to accommodate new concepts, was given dispensation to change its car for 2022 without penalty.

Under Sportscar rules, the car homologation is fixed for five years, but within that timeframe a series of ‘jokers’ can be played, where performance can be improved. Toyota successfully argued that the changes it made were not performance

enhancing, rather that they were simply adapting the GR010 to the changing rules.

Perversely, once this package had been agreed and tested in the wind tunnel, the regulations changed again and the minimum speed the car was able to deploy its hybrid system at increased significantly at Sebring as part of the BoP process.

‘BoP is the reason they keep changing,’ says the team’s Hypercar project leader, John Litjens. ‘We have three Hypercars on the grid, one is an LMP1 carryover and the difference between the other two [Toyota and Glickenhaus] is significant. Within the parameters they’ve set they try to balance it.’

The reduction in base weight changed from the original plan in 2018, from 1100kg to 1040kg, but at Sebring the car raced at 1070kg. Toyota originally took ballast out of the car at the front, and tried to take weight out of the hybrid system and engine to keep the car balanced, but that was not allowed.

With the weight distribution as it was originally, it made sense to have the same size tyres all round. But, following Toyota’s weight shifting back, and the reduced hybrid deployment capability, the regulators changed the tyre concept, too. Now, all new Hypercars introduced from 2023 onwards, notably Ferrari for next year, will have no option but to run 29 / 34 tyres. Only Peugeot, which has gone more extreme on its design according to the original regulations and cannot make the change to the narrow front, will be the outlier in the field. It can keep its tyre concept as it will debut in July.

‘Development in the Hypercar class is tightly controlled by homologation rules,’ says the team’s technical director, Pascal Vasselon. ‘Consequently, there are relatively few changes for our GR010 Hybrid in 2022.

Hypercar manufacturers can choose between 31 / 31 or 29 / 34 tyres, and this year we moved to the 29 /34 option, triggering some bodywork changes for cooling and to maintain aerodynamic performance within the homologation window.’

Obvious changes to the Toyota were to the rear wing end plates, the fin over the engine cover and strakes added on the roof.

‘We did some adaptations to the aero because you have the different size tyres, so you have different air flow,’ confirms Litjens.

‘You see the rear wing end plates, the fins over the cockpit and so on are all for stability regulations. There are two stability criteria, one is stability in yaw, and the other is takeoff speed. You have to calculate yaw, and your point of rotation, and the other is more like a land speed record car, that you go in a straight line and don’t lift off.’

Efficiency drive Toyota had originally tried to design the car without a fin on the engine cover, using only the rear wing end plates to ensure stability in yaw, but in the end decided against that for simplicity’s sake. The fin is just a more efficient device. However, with the changes to the tyres and subsequent airflow, the design team then had to increase the size of the fin. ‘The fin is now higher, the maximum

‘BoP is the reason they keep changing. We have three Hypercars on the grid, one is an LMP1 carryover, and the difference between the other two is significant’ Toyota Gazoo Racing

John Litjens, project leader for Toyota Hypercar

Obvious changes to the 2022 car are a taller fin and revised wing end plates, but ducting has changed front and rear, due to a change from 31 / 31 to 29 / 34 tyres, and strakes appeared on the roof 8 Le Mans 2022 • Racecar Engineering

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XPB Images

ENDURANCE | TOYOTA GR010

Just when the team thought it had its revised aero package sorted, the regulations changed again, this time restricting the effect of the hybrid system from track to track

that we could go because of the stability of the car,’ notes Litjens. ‘We then looked at the rear wing end plates and cockpit strakes [to further balance it].’

Airflow around the front brakes changed, and the team worked to increase cooling to them, rather than decreasing it, as might be expected with a smaller tyre. ‘In the end, we tried to keep the number of changes to the minimum, so the brake drums stayed the same. But although the tyre is narrower, and you have a different flow around it, our inlet ducts are actually bigger than they were last year,’ confirms Litjens.

‘The ducts are also bigger at the back.

The front was a surprise for some people because they thought a smaller tyre would lead to more air, but it still has to pass in the same way. And as that changed, so the temperatures changed.’

Revised aero So, with more ducting to the brakes, bigger rear wing end plates and a larger fin on the engine cover, the revised aero package was complete. Or so the team thought.

The change in deployment speed for the hybrid meant that the car did not perform well in its opening race at Sebring.

The minimum deployment speed was set at 190km/h and some within the team muttered that, with the nature of the Sebring track, it might be better to leave the system off altogether, but that was not to be.

With the speeds around the Florida track, it could still be used for fuel saving, but the 10 Le Mans 2022 • Racecar Engineering

GR010 gave up significant performance as the traction control and engine maps were all set around the hybrid system working at lower speeds. Although Toyota had tested extensively with deployment at different speeds, Sebring saw the GR010s out-paced.

Things returned to normal at Spa in May, after extensive testing, and at Le Mans Toyota will still have its advantage but it is not easy for the team.

‘Every BoP adjustment that is made we have to see how the car behaves,’ comments Litjens. ‘We have different car weights again [this year under BoP]. You have to be flexible because at a certain point you have more teams and you might have to again take the weight out. But that is the normal set-up parameters of the car. We are not starting from zero [at every track], though there is not a great deal of carry over either.

‘We did the last bits of this design in November of last year, and then we had to produce things, wind tunnel tests at Sauber again to go testing. The change to the hybrid system then came after that so, although that is more on the control side of things, it affects the set-up because you have a more two-wheel drive car than before, that’s clear.’

The team has adopted the attitude that it will just spend the time learning about the car, and hope to be able to use that learning later in the development programme, though there are already rumours of a new car coming in 2023. In order to face the Peugeot, Ferrari, Glickenhaus, and possibly the ByKolles, along with the LMDh cars.

The team has adopted the attitude that it will just spend the time learning about the car, and hope to be able to use that learning later in the development programme ‘Part of it will be corrected by the BoP, but you can see now that’s challenging. We have to do something though. We are looking to do some upgrades, but we have to see.’

Volatile environment One of the unknowns is the availability of raw materials due to the war in the Ukraine.

Long lead time parts, such as the tub, have become more difficult to source in terms of materials. ‘Every manufacturer will be struggling more in terms of supply, and for some parts the lead time has doubled,’ confirms Litjens. ‘The metallic parts for example are taking a long time. In terms of the carbon parts, there are a few specific fibres [that might be a challenge] but we didn’t struggle yet. However, driveshafts, hubs and this kind of stuff doubled in lead time and increased in cost, and we have to see how this ends up.’

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WEC | ORECA LMP2

Evo tech Racecar talks to ORECA’s former technical director, David Floury, about how the constructor became the reference car for the LMP2 class

By Andrea Quintarelli

12 Le Mans 2022 • Racecar Engineering

S

portscar racing has gone through an evolution in 2021, with the ACO and FIA introducing the Hypercar category as the top class of the World Endurance Championship. In doing so, the top-class prototypes are slower by design than the old LMP1 cars, and that in turn has shifted attention onto the raw speed and reliability of the LMP2 machines.

LMP2 was designed for privateers, yet has seen such a huge improvement in performance over the past decade, that in professional hands the cars challenged Hypercars on certain circuits. Efforts have been made to slow the cars in 2021, and more restrictions are in place for 2022.

This current generation of LMP2 cars was introduced in 2017. Four chassis manufacturers were selected by the FIA to supply the category – ORECA, Dallara, Multimatic and Ligier. These chassis then formed the basis of the DPi cars that were the top class in IMSA. Dallara became the Cadillac, Multimatic the Mazda, Ligier underpinned the Nissan and ORECA the Acura.

The base LMP2 cars were homologated for five years, and one ‘joker’ package was permitted within that time. The ORECA LMP 07 chassis was taken as the benchmark for this joker package, and the other cars were balanced against it.

To put into perspective the lap time improvement of the [ORECA] LMP07 that was introduced in 2017, the pole position time on the car’s first run at Le Mans was faster than the 2011 overall pole position time set by Audi in LMP1

Racecar Engineering • Le Mans 2022 13

WEC | ORECA LMP2

Figure 1: Le Mans pole position lap time comparison between 2011 and 2021

However, for various reasons, the LMP2 class for the 2022 FIA WEC is solely the domain of the ORECA chassis. Racecar Engineering had the opportunity to sit down with David Floury, former technical director at ORECA at the formative time of the LMP 07, and who has now moved to TMG in Cologne to continue his role as race engineer for Toyota. He was involved in the design, development and track operation of some of the most successful LMP1 and LMP2 / DPi cars of the last 15 years, including the forerunners of the 07, namely the 03 and 05 designs.

The time frame we will follow for this article is between 2011, when the ORECA 03 set pole position time at Le Mans for the first time, and 2020, before the LMH

rules were implemented, which directly led to the LMP2 cars being slowed in international and regional series. Within that time, the LMP2 cars have gone through major rule changes that have seen them develop into much faster cars.

ORECA’s cars have been the reference in the LMP2 class for many years, and so it is apt we should focus on this example.

Besides the regulation changes, there has also been incredible optimisation and development on the cars, that in every area have improved lap times. Figure 1 shows how Le Mans pole position lap time has evolved during this era.

ORECA has won all the pole positions at the French endurance classic since 2015

and even before that, the ORECA 03 had a 50 per cent strike rate, scoring pole in two of the four Le Mans it contested.

Poles apart To put into perspective the lap time improvement of the LMP07 that was introduced in 2017, the pole position time on the car’s first run at Le Mans was faster than the 2011 overall pole position time set by Audi in LMP1.

In absolute terms, comparing the LMP2 pole position time of 2011 with that of 2020 before the cars were artificially slowed to make way for Hypercar, we can see the times improved from 3m41.458s to 3m24.528s, a staggering difference of 16.9s.

Jackie Chan Racing, Nürburgring, 2017, the first season of the ORECA LMP07. Rule changes worked in favour of the car, making it much quicker at Le Mans, but ongoing development helped, too 14 Le Mans 2022 • Racecar Engineering

‘Overall, from regulation evolution, I would say the lap time gain at Le Mans is probably in the order of 6.5s’ David Floury, former technical director at ORECA Also interesting to note is that between 2017 and 2020, performance in qualifying improved by a second, despite there being no update to the car, which shows the optimisation that has gone on since the car’s introduction.

The latest LMP2 regulations state that cars cannot be modified for the whole homologation of the car, other than to balance the class, should a manufacturer fall behind in terms of performance. In this respect, as ORECA has always been the reference car (and the fastest), the constructor has not been allowed to update the car since its introduction. That has had the happy knock-on effect of teams not having to invest heavily in an upgrade package in five years.

The final point to make is that from the 2011 pole position time to 2017, when the new generation LMP2 cars were first introduced, there was a lap time improvement of 15.9s.

At that point, a major regulation change was introduced, which can be broken down into the following categories: • Engine: the class switched from a free engine formula, with motors limited by air restrictor or turbo boost limitation to around 500bhp, to a

• •

•

commonly available Gibson engine with an output of around 600bhp.

Weight: minimum weight limit was increased from 900kg to 933kg Dimensions: the maximum width reduced from 2000mm to 1900mm, while the overall length of the car went up from 4650mm to 4750mm.

Aerodynamics: detail changes such as floor leading edge and increased wing dimensions led to a performance improvement, while other changes were focussed on safety, including holes over the wheels to reduce air pressure in the wheelarches.

So, how much of ORECA cars’ lap time improvement is due to proper development work, and how much is related to the 2017 rule changes? ‘The engine power increase explains a lap time gain at Le Mans of just under 7.5s per lap,’ says Floury. ‘The increase in car weight and reduction in width led to a lap time penalty of 1.6s and 0.6s per lap respectively. The effect of increasing car length [and wheelbase] are more difficult to quantify, but this surely improved corner entry stability and driver confidence.

‘The impact of the aerodynamic regulation changes are also not easy to estimate as the rules changed over a longer time frame, and every time you work around new regulations you regain some of the induced penalty.

Overall, from regulation evolution, I would say the lap time gain at Le Mans is probably in the order of 6.5s. The rest of the performance gain came by development, in every area of the car.’

Tyre development Before 2021, the World Endurance Championship and the European Le Mans Series had Dunlop / Goodyear competing against Michelin in what were two of the few

championships in the world where a choice of tyre was allowed. The manufacturers declared their specification of tyres and their rival was able to check tyres at random throughout the year to ensure they conformed.

In 2021, though, the rules were changed to a single tyre supplier, Goodyear, and the company was charged with the task of reducing performance by the rubber alone.

‘Tyre development has enabled a big performance gain through the years,’ says Floury. ‘The competition has been quite tight between Michelin and Dunlop / Goodyear and we experienced very interesting seasons with intensive development on the tyre side.

‘The rear tyres always kept the same size, but the front diameter increased. This has not contributed directly to more grip potential, but it has enabled a higher load capacity and consistency. We have taken this into account to set different targets in terms of weight distribution and aerodynamic balance.

‘Through these years we have also learned a lot about how to optimise the tyres’ working point and this pushed us to change our cars’ architecture and evolve the weight distribution, aerodynamic balance, suspension geometry characteristics and suspension concepts.’

It is difficult to quantify quite how much tyre development could mean in terms of lap times as they have a very complex behaviour that depends heavily on ambient and track conditions, on tarmac, car set-up and design, as well as driving style.

Moreover, from year to year, tyre manufacturers may decide to focus their development effort on different areas, depending on the feedback provided by teams and racecar manufacturers.

Sometimes tyre evolution is not aimed at pure, single lap performance, but rather at improving consistency or driveability.

With no 06 designation, the constructor’s preceding car was the ORECA 05, seen here at Silverstone in 2016. Less powerful and shorter, but also lighter and wider, it was still a formidable racecar Racecar Engineering • Le Mans 2022 15

WEC | ORECA LMP2

From the start of our journey, the ORECA 03, which made its debut and set pole position at Le Mans in 2011. Developed from a Courage design, it was the last of ORECA’s open top LMP2 cars

ORECA’s first LMP2 car, the 03, had an open cockpit, in line with the standard approach used in the category at the time.

Despite being successful, ORECA had to face some significant compromises. ‘The ORECA 03 was an open car and employed a survival cell that had been designed by Courage, and which we inherited when we bought Courage Competition in 2007,’ says Floury.

It’s worth noting here the Courage monocoque was already relatively old when the ORECA 03 started racing in 2011.

‘We switched to closed cars in 2015 with the ORECA 05, and the ORECA 07 uses

the same survival cell as the ORECA 05 We designed their monocoque in house.’

Open and close Switching to a closed cockpit brought many advantages, as Floury highlights: ‘A closed car enabled multiple gains: aerodynamic efficiency, safety, stiffness and weight. The ORECA 07’s survival cell is more than 25kg lighter than the 03.’

One of the most significant advantages, at least in part linked to designing a car around a closed cockpit, was the impact on aerodynamics.

‘A closed cockpit brings a good step in terms of aerodynamic efficiency, and the new survival cell also enabled us to improve flow management under the monocoque and the internal flow. We could increase front-end aerodynamic performance quite significantly.’

Monocoque design also influences significantly suspension layouts, in particular on the front axle.

‘On the 03, we were quite limited by the survival cell,’ notes Floury. ‘Once we introduced our own monocoque, we could review some of the suspension concepts, parameters and directions.

Figure 3: Breakdown of lap time improvement between 2011 and 2020, a total delta of 16.9 seconds. The total gain due to the 2017 regulation changes was about 6.5 seconds, largely attributable to an increase in engine power and aerodynamic development of the car

16 Le Mans 2022 • Racecar Engineering

Figure 4: Comparison between ORECA 07 (top) and 05 (bottom) front end

‘There is nothing fundamentally revolutionary on the suspension side.

The regulations ban many advanced concepts, like FRICS (front-to-rear interconnection) or inerters anyway.

Suspension philosophy ‘Still, our suspensions are designed to optimise tyre performance and are well integrated in the car’s general concept and philosophy. We developed them to fit our vehicle’s aerodynamics and architecture.’

Suspension is a critical tuning parameter.

In very high downforce cars, such as a modern Le Mans Prototype. Beside playing a crucial role in ride height control (and, hence, downforce and aerodynamic balance), they also define dynamically how the tyres come into contact with the road and the way forces are exchanged, both in terms of direction and magnitude.

Quantifying their effects in terms of absolute performance is not easy because they are so closely linked to driver perception.

‘We did a lot of simulation work to refine our suspensions parameters,’ says Floury. ‘We have developed specific dampers with PKM and our philosophy has been to define a base set-up that is easy to use for teams and drivers, with specific focus on amateur ones.’

Indeed, it is important to ORECA that when an

‘With more budget, we would have elected to develop our cars in the wind tunnel in parallel to the CFD’

amateur driver is in the car, the performance remains consistent and as high as possible.

To achieve this, the car must be predictable.

‘We have a reduced number of options available as the testing time is limited during a race weekend, when you have three drivers sharing the same car. Normally, there is no time for big set-up changes,’ explains the designer. ‘So, we wanted to avoid the teams getting lost with too many set-up options.

‘Obviously, this can be felt as a limitation for some teams, but I think it fitted quite well with the philosophy of this LMP2 generation.’

Another critical parameter for every racecar is weight. This is particularly important in classes where a minimum weight for the car alone is mandated as being underweight allows teams to use ballast as a tuning element, a very powerful set-up tool.

‘We have always paid a lot of attention to weight and weight distribution,’ says Floury.

‘On the ORECA 07, we saved quite a lot of weight thanks to an extensive FEA [finite element analysis] programme. The car has to carry between 70 and 75kg of ballast to achieve the minimum homologation. This enables it to have a lower c of g, and for teams to tune the weight distribution to adapt to different tracks, tyres or conditions.

‘Our baseline weight distribution has been carefully optimised to adapt to the tyre characteristics. We approached this differently to our competitors, and we are clearly using the tyres in a completely different way.’

Aero development In a car with a high downforce and a sophisticated aerodynamics such as an LMP2, this area remains, together with the tyres, probably the strongest performance driver. This is also where ORECA’s cars seem to outpace their competition.

‘This is where we gained the most through the years,’ explains Floury. ‘The ORECA 07 [2017] has a 40 per cent higher aerodynamic efficiency than the 2011 03.

This has been achieved by both reducing drag and increasing downforce.

‘We also worked on the aero map shape and robustness of the aero concept in order to ensure a consistent performance throughout a race and a more userfriendly behaviour and handling. At Le Mans, the aerodynamic gains are worth around 7.2 seconds per lap and around 17kmh of top speed.’ And that’s on top of the 33km/h top speed difference between an ORECA 07 and 03.

Interestingly, none of the ORECA designs have undergone wind tunnel testing, all development work having been completed in CAD. ‘Since 2009, all our cars have been developed using CFD only on the aerodynamics side, employing our in-house capabilities,’ confirms Floury. ‘We worked to improve our cars’ performance, but we also considerably evolved our process and tools.

We developed our own methodology and worked extensively on the correlation with track data. With more budget, we would have elected to develop our cars in the wind tunnel in parallel to the CFD. The two are indeed very complementary. But the cost cap in place in LMP2 pushes us to be as efficient as possible, and we therefore preferred to focus our effort on CFD and expand our in-house know how.’

‘CFD, like the wind tunnel, is just a method that has his own strengths and weaknesses. Wind tunnel testing is also normally performed using a scale model and this is also an approximation. You need to know the limitations of your method and work accordingly. We have validated our CFD methods using both track and full-scale wind tunnel testing.

‘Also, the data we provide to our teams are always checked against data logged during track testing, at the end of the development phase.’

This approach has allowed the French company to take different routes, compared to their competitors, and this paid dividends.

Conceptually, the 07 is very different all other current LMP2 cars. It is the only one to use a closed front aero concept, unlike the 05.

Working points ‘All the other LMP2 are using a through flow between the splitter and the top shroud covering the upper wishbone,’ explains Floury. ‘They are following a trend that has been set in LMP1 in the last decade. But LMP2 regulations are less permissive than LMP1 ones in this area, and the working points are quite different. LMP1 rules were really pushing towards fuel efficiency. The Racecar Engineering • Le Mans 2022 17

WEC | ORECA LMP2

The Le Mans aero package is slightly more efficient than the sprint package and it reduces the drag level by around 15 per cent ICE power out of the boost was low in LMP1 and you had to do fuel lifts at the end of straights, so this was pushing towards lower drag. The 2017 LMP2 rules lead to a different sweet spot, mainly because of an increased ICE power. So, we investigated both concepts, but it appeared to us that the closed concept was better suited to the LMP2 working point.

‘Also, the aero concept on the side of the car, the way the bodywork geometry is treated around the exhaust outlet, and the rear wheelarch geometry, is really dictating the flow structure to the rear end. That has been a key feature in the development.’

LMP2 2022

I

n order to reduce the performance of the LMP2 cars for the 2021 FIA WEC season, the FIA and ACO dropped power, minimised the aero options, and prescribed less performant tyres that Goodyear had to supply. Yet LMP2 cars were considered too fast (see table below) and Hypercar teams were unhappy.

For the 2022 season, further restrictions have been introduced. These include: l For WEC and 24h of Le Mans o Further reduction of engine power by 8kW (including the effect of the 2022 fuel specification).

The power reduction will be performed with an air inlet restrictor (at full throttle) developed and managed by Gibson. o The bodywork configuration is: • Le Mans kit (as per 2021).

• Removal of front dive plane.

• Diffuser strakes shorten by 50mm, modified / produced by chassis constructor.

• Addition of 10mm Gurney on rear flap to compensate aerodynamic balance o Reduction of fuel tank volume to 65 litres (the ACO / FIA are working with constructors to find a simple, mandatory method to implement such a change). o Adaptation of driving time (if need be) to be aligned with the onboard fuel volume.

2021 race AFLT20% gaps (sec) SPA -1.2

PORT

MONZ

LM24

BAH6

BAH8

-2.9

-3.0

-0.9

-2.7 -3.9

Survival of the stiffest Floury also underlines how carrying over the previous car’s monocoque actually became an advantage: ‘FIA and ACO regulated very early on in the 2017 LMP2 project the need to use a survival cell homologated to the 2014 LMP1 regulations. We built one according to this standard already for the ORECA 05, in 2015. Although we could have improved significantly from the existing survival cell [in weight reduction, aero performance, stiffness and packaging], it would have required a lot of resources.

‘We decided that it was probably not the most efficient way to use these resources and therefore kept the existing survival cell and focussed our attention and energy on other topics, especially aerodynamics. This enabled a much more detailed work up and a lot of the performance gain produced by 07’s aerodynamics comes from the details.

Another challenge for Le Mans Prototype cars is to suit a very special and fast circuit like Le Mans, as well as the more conventional tracks where sprint races for the WEC, ELMS or IMSA championships take place.

‘The car has been developed for both HDF tracks, as well as Le Mans, even though the working points and targets are quite different. In LMP2, you could develop a specific aero package for the Le Mans race, but its price has been capped at €10,000 (approx. $11,350 / £8,350). So here as well, you must be very efficient.

‘The Le Mans aero package is slightly more efficient than the sprint package and it 18 Le Mans 2022 • Racecar Engineering

During the 2021 FIA WEC, the ACO / FIA used stratification helping factors (see table below). This meant that more performance was given to Hypercars by removing, for example, the penalty for altitude at circuits such as Spa. However, the FIA/ACO made it clear that this will not be possible from 2022 onwards as the cars already run at maximum power and at minimum weight. No more performance can be gained from changing the Hypercars which means that LMP2 has to slow.

2021 stratification help (sec) 2.9 2.2 1.1

SPA

2.0

1.8

0.8 PORT

MONZ

LM24

BAH6

BAH8

For the European Le Mans Series, in which the LMP2 cars are the top class prototypes, teams are allowed to run a standard body kit, but the power reduction, fuel tank size and driving time will all follow the regulation changes of the World Championship in order to help teams with the costs for the season.

reduces the drag level by around 15 per cent.

We run extensive simulations on all tracks to precisely define our aerodynamic targets.’

Floury is also aware that this could have been the last platform where the search for performance was only limited by cost, making it a memorable engineering experience.

‘It has been a very enjoyable project. From an engineering standpoint, it is probably also the last one for a period of time where we actually have freedom to search for performance in an open competition and try to beat our competitors on pure merit.

‘Nowadays, most motorsport categories are becoming either onemake series or managed by a Balance of Performance system. If this is beneficial for the show and enables cost saving, it does not allow us to express, nor develop, engineering skills and know how.

‘BoP is clearly not pushing you to be a better engineer, and in various categories there are successful cars that would never win on pure merit. That’s a shame, but that’s the way it is, and we have to live with it and adapt.’

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NASCAR | LE MANS GARAGE 56

GM to race 24 hours 2023 could see the return of Stock Cars to Le Mans for the first time in almost half a century

By Andrew Cotton

N

ASCAR’s Next Generation Stock Car will race at the Le Mans 24 Hours in 2023 if plans by Hendrick Motorsport, Chevrolet and Goodyear come to fruition. The go ahead to race still needs to be given by the ACO’s selection committee, but the idea is to run a Gen 7 car fitted with a hybrid system taken from the manufacturer’s LMDh platform as a Garage 56 entry.

The plan was hatched in 2020 between NASCAR president, Jim France, and ACO president, Pierre Fillon, and unveiled at Sebring. If it goes ahead, it would be the first time a Stock Car has competed in the great endurance race in nearly 50 years.

The last time was in 1976, when the Grand International category was formulated specifically for such cars, following a vision laid out by NASCAR founder, Bill France, with a view to expanding the global exposure of his top class. Two Stock Cars raced that year, a Dodge Charger owned and driven by Hershel McGriff, and a Junie Donlavey-owned Ford Torino driven by Richard Brooks and Dick Hutcherson.

‘From the early days of NASCAR, it was important to my father that we played a visible role in international motorsports, and there is no bigger stage that the 24 Hours of Le Mans,’ said Jim France, NASCAR chairman and CEO. ‘In partnering with Hendrick Motorsports, Chevrolet and Goodyear, we have the winningest test, manufacturer and tyre in NASCAR history. We look forward

20 Le Mans 2022 • Racecar Engineering

to showcasing the technology in the Next Gen car and putting forward a competitive entry in the historic race.’

Forging links Confirmation of the programme is one of a series of announcements that closely link the American IMSA series to the ACO

and FIA, following the revelation over the Sebring in March that the LMH cars will be able to race in IMSA’s series in 2023, provided they take part in a test in December.

The Garage 56 entry (so named when Le Mans accepted only 55 regular entries, plus one for innovative technologies that operates outside the normal class structure)

Getty Images

The car will need to be significantly different to the standard Cup car to get around NASCAR’s strict testing restrictions

will replace one of those entries on the grid as Le Mans only features 62 garages.

However, while the Hypercar and LMDh cars will fill a large proportion of the Prototype grid next year, there is some uncertainty as to what the GT field will look like with a transition year from GTE-Am to GT3 cars in 2024.

The NASCAR showcase model run by Hendrick Motorsport will be based on Chevrolet’s Camaro ZL1, but will have to undergo some major changes before it can be accepted to race at Le Mans.

Not only will it need to be technically modified to achieve the target lap times, it will need to be significantly different

to the standard Cup car to get around NASCAR’s strict testing restrictions.

‘We don’t want one team to have an advantage over another,’ said NASCAR’s Steve Phelps. ‘We are not interested in letting that happen.’

To start with, weight will need to be removed from the 3300lb (approx. 1500kg) Racecar Engineering • Le Mans 2022 21

NASCAR | LE MANS GARAGE 56

Expand to contract

NASCAR chairman and CEO, Jim France (left), and Rick Hendrick, owner of Hendrick Motorsports, at the announcement at Sebring

wet and intermediates that will be capable of double stinting at Le Mans to meet with the ACO’s mission to reduce the number of tyres used in a race.

Hendrick’s vice president of competition, Chad Knaus, will oversee the project, but there was no official word at the announcement on who would drive the car, other than that it would be a Cup series driver.

One possibility that has been mooted is Jimmie Johnson, who has been racing in the IMSA series in a Cadillac.

In order for a Cup driver to race, NASCAR would need to accommodate not only the Le Mans 24 Hours race week in its schedule, but also the test weekend, too.

Hybrid future?

Although there has so far been no confirmation from the team behind the programme, Fillon did reveal the car will feature a hybrid system and the engine would use TotalEnergies’ synthetic fuel, developed from the waste products of wine making.

The Gen 7 car was designed from the start to have hybrid capability, and series insiders hinted the car would likely use the hybrid and gearbox system developed for LMDh by Xtrac, Bosch and Williams Advanced Technology.

ACO

However, Rick Hendrick, owner of Hendrick Motorsports, promised it will be a ‘full bore, full blown effort,’ from the team, which may have to expand in order to make the programme happen.

‘We want to run 24 hours and post competitive times,’ said the veteran team owner. ‘With the aero, weight and bhp, we are not going there just to ride around. We will put in a big effort and finish the race…

‘Even though Garage 56 is a ‘class of one’, we are competitors and have every intention of putting a bold product on the race track for the fans at Le Mans.

‘It’s a humbling opportunity – one that will present an exciting challenge over the next 15 months – but our team is ready.’

Part of that development programme is the tyres. Goodyear, which provided the rubber for the last NASCAR entry in 1976, will have to develop all-new specifications for the event from its base in Akron, Ohio, due to the different demands Le Mans places upon the tyres. A global collaboration between the European and US bases will help formulate the constructions and compounds, based on Goodyear’s previous experience in GT racing, coupled with the latest Prototype technology.

There will be a push for NASCAR’s sole tyre supplier to develop 18in slick,

Getty Images

car in order to achieve the target lap time of 3m50s – 4m00, in line with the approx. 1300kg GT3 cars that will race at Le Mans in 2023.

The reduced weight should help the team achieve the necessary crash testing criteria, conducted by the ACO and the FIA before the car can be considered for the event.

That won’t be easy, though, as the Gen 7 NASCARs feature tube frame construction and, although Le Mans has made major changes recently in a bid to improve safety and meet FIA criteria, the Gen 7 car has been designed to accommodate the types of accidents NASCARs normally have; glancing blows on full oval tracks. And as speeds on the road courses the series run on are significantly lower than those seen at Le Mans, getting the Gen 7 car through the required crash test may take significant work.

The last time NASCARs competed at Le Mans was in 1976, in a bid to make the series more visible on the world stage 22 Le Mans 2022 • Racecar Engineering

‘We are not going there just to ride around. We will put in a big effort and finish the race...’

Rick Hendrick, owner of Hendrick Motorsports Testing the car is going to be a problem as NASCAR operates strict rules to prevent any team gaining an advantage. Consequently, the car will need to be suitably different to the standard racecar in order that the team does not have the opportunity to take learnings from the programme into the Cup series, where it is already the most successful team.

The car will likely be fitted with a new engine, developed by ECR, although Hendrick confirmed the current engine and transaxle would be capable of completing the race in current spec.

Getting the project even this far has taken significant work from all parties.

‘When the ACO receives an application for a Garage 56 programme, we begin by talking with the designers, team partners and suppliers in order to set out performance parameters such that the programme can be successful for everyone involved,’ said Fillon. ‘We will continue to work with NASCAR and all their partners as they work towards their proposed 2023 Garage 56 project.’

The Garage 56 car will likely be GM’s third class entry in 2023, as the brand’s Cadillac LMDh will race in the Hypercar class, plus there is a good chance its Corvettes will be back to contest the GTE class in Am hands for 2023 per regulation, in addition to the NASCAR project.

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ENDURANCE | PERFORMANCE ANALYSIS

Happy hour Analysing the potential gains to be had during the performance ‘sweet spot’ of the Le Mans 24-hour race

By Andrea Quintarelli

T

he 24 Hours of Le Mans is one of the most exciting and demanding races in motorsport history. It catches the attention of millions of fans around the world, and fascinates experienced professionals due to the very special challenges it poses.

From an engineering perspective, beside the complex task of building a car reliable and safe enough to be driven at the limit for 24 consecutive hours, yet still capable of competitive performance at the more conventional tracks and events that are part of endurance championships around the world, there are a number of human and physical challenges the teams working on track need to overcome.

For starters, driver crews normally include three or more drivers, with different driving styles and preferences in terms of set-up. In some classes, at least one of them is normally not a professional driver either, so the teams must find the best compromises to enable the best possible average performance across the whole race.

Then there’s the track itself, which has a layout unique in today’s motorsport scene.

The combination of a permanent circuit and open street sections include very long straights, separated by a mix of slow corners and extremely fast sections, such as Indianapolis or the Porsche Curves. At 13.6kms, the circuit is also very long, nearly

24 Le Mans 2022 • Racecar Engineering

twice the distance of Spa Francorchamps, the longest track on the Formula 1 calendar.

Top class cars operate at full throttle for more than 80 per cent of each lap, with top speeds in excess of 330km/h (205mph) and lateral acceleration peaks over 3.5g.

To complicate things further still, both track and weather conditions can change dramatically over a 24-hour period. Even in the lucky event of not having any rain during the race – an unusual situation at Le Mans – ambient conditions vary enormously between day and night, which have a significant impact on tyre, car and driver performance.

This means variables like tyre choice, driver rotation, stint length and set-up decisions can make a huge difference to how a team performs over the duration of the race. Even without considering technical troubles, a car with a slightly lower potential than another over a single lap can easily be lapped more than once at Le Mans.

Special moments During the 24 Hours of Le Mans there are many special moments, but the start and finish of the race are two inevitable highlights, while some very emotive impressions can be experienced when night falls on the Saturday evening. Similarly, at sunrise on Sunday.

These two latter moments are also particularly interesting from an engineering

perspective, because they represent the two zeniths of transition regarding track and ambient conditions. As night comes, temperature drops, visibility reduces and both drivers and engineers have to adapt their targets accordingly.

At sunrise, on the other hand, besides offering improved visibility for the drivers and wonderful picture opportunities for photographers, performance picks up again.

This is the time many call ‘happy hour’, because it is the phase of the race when the cars perform best and, coupled with less traffic on circuit due to the inevitable retirements overnight, has historically often produced the quickest lap times of the race.

Traditionally, happy hour occurs roughly between 5 and 7am on Sunday morning, with sunrise occurring around 6am at Le Mans in June. Last year, however, was an

The cooler ambient conditions lead to a higher air density that influences two crucial parameters linked to car performance

Aside from being the photographers’ favourite part of the race, the time between roughly 5am and 7am on the Sunday morning of Le Mans offers a unique and rewarding engineering experience

Porsche won in 2015, after returning to the French classic the previous year following a long absence. The winning crew, with F1 driver, Nico Hulkenberg, at the wheel, achieved its best lap early in the morning, as did the winning LMP2 car that year.

The rest of the table shows how other cars achieved their fastest laps immediately before or after sunrise and, incidentally, either won their class or finished in the first positions.

During happy hour, temperatures are still low, compared to the warmest hours of the race, which normally occur shortly after the start (usually around 3pm, local time). The cooler ambient conditions lead to a higher air density that influences two crucial parameters linked to car performance: engine power and aerodynamic forces.

Fig 1: Overview of the best laps achieved by different cars during various editions of Le Mans

Engines benefit from a higher air density because a greater amount of oxygen enters the combustion chambers for a given volume of air / fuel mixture, and this improves the combustion process.

Aerodynamic forces, on the other hand, are directly proportional to air density, meaning a change in this parameter is reflected by a change of the same magnitude in downforce and drag.

Moreover, a dry track in this phase of the race will have a high grip level because of the rubber that has been laid down during the first portion of the competition.

These factors all combine to produce substantial growth in car performance potential compared to the opening stints.

How great the improvement is depends, of course, on weather conditions and how the early stages of the race have evolved.

In this article, we will analyse how big that performance gain in happy hour could potentially be, taking into account weather information from the last three editions of the 24 Hours of Le Mans – 2018, 2019 and 2020 – and also using some lap time simulation runs.

Air conditions The first thing to consider is how much air conditions differ between a certain, reference moment during the race and the happy hour phase. For this study, the reference point we have chosen is the warmest time during the Racecar Engineering • Le Mans 2022 25

XPB

anomaly as the race was held in September due to the Covid pandemic, and the sun rose later, around 7.40am. That year, happy hour could probably be better identified as the window between 6.30 and 8.30am.

Figure 1 contains data relative to five recent editions of the 24 Hours of Le Mans, showing examples of cars achieving their best lap times during these happy hour phases.

In 2011, Audi won the race against all odds, with a single car of the three entered by the German manufacturer surviving and overcoming strong opposition from Peugeot (see the wonderful documentary, Truth in 24 II: Every Second Counts, for the full story). The winning crew achieved the best lap of the race during the happy hour, producing a faster time than in qualifying.

ENDURANCE | PERFORMANCE ANALYSIS

Fig 2: Temperature evolution during 2018, 2019 and 2020 editions of 24 Hours of Le Mans

first half of the race, which typically occurs on the Saturday afternoon. The evolution of air temperature during the three editions of the race under scrutiny are shown in Figure 2.

The red circled areas highlight the highest temperature achieved each year. In 2019 and 2020, the warmest temperature was recorded around the third hour of the race, while in 2018 it was reached at the end of the first hour. It is interesting to note here how the 2020 race was, on average, the warmest of the three, due to it being held later in the year than usual because of the pandemic.

The happy hour can therefore be identified as the time approximately between the 14th and 16th hours for editions held in June, and a bit later, between the 16th and 18th hours, in 2020.

Beside temperature, air humidity and pressure also change during the race, and these both exert an influence on engine and aerodynamic performance.

Figure 3 summarises the values that have been taken into account for this study. For the happy hour phase, an average over the two-hour window of time mentioned has been considered.

The influence temperature, humidity and pressure have on air density is relatively easy to quantify. Based on air density, a correction factor for the aerodynamic forces has then been applied, while the whole power / torque curve has been shifted by

an amount computed using SAE references for aspirated engines. This is a similar approach to that used by engineers when testing motors at the dynamometric bench, in order to normalise measured power to a standard set of ambient conditions.

For this article, the effect each year’s happy hour conditions have in terms of performance, compared to the reference baseline, were then evaluated by running lap time simulations.

The correction factors to engine power and aerodynamic forces have been applied as a relative, multiplication factor on top of the simulation tool’s built-in baseline.

The initial results obtained without any correction have been just used to get a feeling of the magnitude of performance change one could expect during happy hour, in relative terms.

The reader should keep in mind that the overall effects shown must be considered an upper limit of how much more performance a car could gain. This does not necessarily translate to a real driver being able to explore all of this potential.

In a simulation environment, the effects of complex phenomena such as tyre wear, traffic, driving approach, fuel saving measures and even the ideal operating window of a particular tyre compound choice cannot easily be reproduced. For all these reasons, it is a sensible approach to focus on the

Fig 3: Ambient condition values used for the performance study

26 Le Mans 2022 • Racecar Engineering

relative changes in performance with respect to a reference lap, because a relative delta can more easily be applied to understand what the new performance could be, following a change in boundary conditions.

Lap time simulation The vehicle model used for this study refers to a 2020-specification LMP2 car, fitted with the Le Mans body kit, which offers lower drag and downforce compared to the sprint one.

Even in this low-drag configuration, LMP2 vehicles still exhibit high levels of downforce.

In 2020, the minimum weight for these cars was 930kg, without driver and fuel, so considering a total weight of 1030kg could be a good picture of qualifying running conditions, while a 1050kg overall mass could be representative of midstint status. The car’s normally aspirated, V8 engine produces about 600bhp and the gearbox has six forward gears.

This vehicle model, configured with a reference set-up, has been run on a virtual representation of Le Mans circuit, using a lap time simulation tool the author coded.

Beside the effects of ambient conditions, a ‘rubbering in’ grip improvement over the whole circuit of two per cent has also been accounted for. Again note, this approach does not consider explicitly any thermal aspects with regards to tyre grip, and is simply based on the assumption that all track and tyre-related effects can be roughly depicted by increasing track grip with a factor equal to 1.02.

Considering the simplified approach employed for this investigation, this amount of change in track friction coefficient seems reasonable, according to a number of experienced vehicle dynamics

engineers and tyre specialists Racecar Engineering consulted about this aspect.

To summarise, the following are the changes considered to represent the happy hour phase of the race: • Engine power / torque curve.

The whole curve was scaled up employing the multiplier calculated according to methods proposed in SAE papers for aspirated engines.

• Aerodynamic downforce and drag.

The change in air density was assumed to have an effect on the whole downforce and drag aeromaps, without affecting the aerodynamic balance one.

• Track grip.

To account for the effects of track rubbering on grip, track friction coefficient has been increased by two per cent.

Fig 4: Simulation results summary table

Car settings have always been kept the same, with the aim of simulating what would happen when running the same set-up in different ambient and track conditions.

has at Le Mans. With this vehicle model, it equates to about 0.9s, or 0.45 per cent.

Taking these two reference runs as the starting point, Figure 4 shows how lap times improve with the ambient and grip changes experienced during happy hour.

It is clear that the performance improvement produced by weather-related parameters is greater, although the 2020 set of conditions produced the biggest delta, despite the race being held in September.

Also, both grip and weather-related performance deltas are greater with a higher vehicle mass. This is probably related to the car operating in grip-limited conditions for a longer time over a lap, therefore benefiting more from higher downforce and a greater track friction coefficient, while also profiting more from the increase in engine power during acceleration phases.

Simulation results The first simulation run, with the car set-up in base configuration and a ‘qualifying’ fuel load, produced a lap time of 3m23.763s.

That compares decently (with a deviation below 0.4 per cent) to the 2020 LMP2 car’s pole position lap time of 3m24.528s.

Adding 20kg of fuel and assuming this does not change the static mass distribution, led to a lap time of 3m24.678s.

These two lap times will be used as our references for the rest of this analysis.

Comparing these two runs also offers an interesting insight into the effect on performance 20kg of additional mass

This approach does not consider explicitly any thermal aspects with regards to tyre grip Also interesting to note is the effect a sole track grip correction of two per cent has, which seems to produce roughly a 0.5 per cent improvement (about one second) in lap times.

Figures 5 and 6 show a comparison between the baseline run (shown in red) with a mass of 1030kg, and the best overall run (shown in green), which considered the 2020 happy hour set of conditions and produced a lap time of 3m21.792s.

Fig 5: Logged results of baseline (red) and Run 8 (green). From the top down: speed trace, front ride height, rear ride height and compare time

Racecar Engineering • Le Mans 2022 27

ENDURANCE | PERFORMANCE ANALYSIS

Fig 6: Logged results of baseline (red) and Run 8 (green). From the top down: speed trace, overall vertical load and aerodynamic balance

28 Le Mans 2022 • Racecar Engineering

Besides this, these two sets of plots are intrinsically linked. Figure 5 highlights how front and rear ride heights are actually lower in Run 8, compared to the baseline.

The reason for this is the greater air density experienced during Run 8, where the downforce acting on the car at a certain speed also increased, increasing suspension travel and tyre deflection. This initiates a chain reaction: more downforce means lower ride heights; lower ride heights mean the car operating at a different point on the aeromap where the downforce coefficient is likely higher, leading to even higher downforce than if it were operating at the same ride heights as in the first run, but simply at higher speed.

Besides this, the aerodynamic balance also changes because the ride heights are different. This can be seen in the last trace in Figure 6. At nearly every point on track, downforce distribution between the two axles is different and, most of the time, it moves toward the front in Run 8.

Straight sections are less interesting in this respect, but a difference in balance can

The main performance gain builds up in corners, thanks to the higher downforce and track grip available, and in the first portion of each straight / full-throttle section of the track also be seen in corners, especially higher speed ones, where the downforce is higher and its effect on ride heights greater.

The key message here is that, without changing the car’s set-up, the behaviour and balance of a high-downforce LMP can alter due to the effects of a temporary change in air density and cornering speeds. In Run 8, the car has a higher performance potential and operates in a different performance window to that of the baseline run.

XPB

Again, the reader should focus on the relative improvement with respect to the baseline (about 0.97 per cent) more than on pure lap times, as these have been calculated under very ideal assumptions.

The horizontal axis represents the travelled distance, so Figure 5 shows, from the top down, the traces relative to car speed, front ride height, rear ride height and the compare time. That tells us which run is faster, and by how much, at each point of the track.

In Figure 6, starting from the top, the reader can again see car speed, but also the overall vertical load acting on the car (assuming a constant mass, that is a basic representation of overall downforce) and aerodynamic balance.

The first thing to notice is how, and where, Run 8 performance differs from the baseline. Top speed is very similar for the two runs, so the main performance gain builds up in corners, thanks to the higher downforce and track grip available, and in the first portion of each straight / full-throttle section of the track.

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BALANCE OF PERFORMANCE | A LEARNING PROCESS

Raceability Explaining the concept using first-hand experience of imbalance of performance

Jake Galstad

By Scott Raymond

GT3 racing was originally formed using the BoP process, and it has been the bain of organisers’ lives ever since

R

aceability is not a real word, but what I mean by the term is the ability of cars to race each other.

When all cars are the same, or at least within the same class, I am referring to following each other on track, and being able to set up and execute passes.

The idea is similar to when cars from different classes are on track together, although in that case passing, or being passed, are givens, so raceability in that sense refers more to the cars’ ability to deal with traffic between disparate classes.

With respect to Balance of Performance, it is one thing to balance lap time performance, but ensuring balanced cars can properly

30 Le Mans 2022 • Racecar Engineering

race against each other is a much more difficult thing to achieve correctly.

Let’s go back in time over a decade to examine a first-hand experience I had with a situation where the raceability between cars was not well balanced. Okay, I’m being kind, it was horribly imbalanced!

In 2009, I worked as a performance engineer with de Ferran Motorsports, and we ran an Acura ARX-02a LMP1 car against the likes of Audi R15 TDI and Peugeot 908 at a few races in what was then called the American Le Mans Series. The Audi and Peugeot were both diesel-powered with lots of torque and, while I believe the Acura produced more overall downforce and had excellent

mechanical grip (thanks to running wide rear tyres on the front axle), we didn’t stand a chance against the diesel engines when it came to pure straight-line acceleration.

At the 2009 Sebring 12 Hour race we qualified the Acura on pole and showed the world that, on pure pace alone, the Acura was quick over a single lap to be competitive.

In hindsight, some might argue that our pole position that day came down to the Audi and Peugeot teams not being willing to show too much performance in the lead up to that year’s 24 Hours of Le Mans. Nevertheless, I was about as excited as possible for the race, though I knew in my heart it could be a total shit show.

Scott Raymond works with the Wayne Taylor Racing Acura team in this year’s IMSA series

Multi-class racing is not limited to GTs, and adds a critical extra dynamic to a race – traffic

Racecar Engineering • Le Mans 2022 31

BALANCE OF PERFORMANCE | A LEARNING PROCESS Now, I should mention here that my wife and friends call me an eternal optimist, so it must have been pretty evident that potential problems existed if I was remotely pessimistic.

Areas of concern The layout of the Sebring circuit presented a couple of areas of concern to the team and me. The first was the very long back straight between turns 16 and 17. Any car getting a good run out of turn 16 could easily employ the draft and set up a leading car for a pass before the braking point for turn 17. Now, imagine exiting that corner with a torque-monster diesel following behind.

The other area of concern was the front straight between turn 17 and turn one. While not as long as the back straight, the exit speed of turn 17 is quite high, so a similar problem was easily imaginable. The optimistic side of me hoped we would exit turn 17 so quickly that the diesels wouldn’t be able to swallow us up in the distance before turn one. I knew we had an advantage there because that first turn is a high-speed, aerodynamically dependent corner. If we could just keep cornering faster than the diesels, maybe we stood a chance of winning the race.

At least I wasn’t alone in being concerned.

In a pre-race interview between Chris Neville of Speed TV and Scott Dixon, who had driven the car on our pole-winning lap, Neville remarked, ‘You’ve got four diesel beasts behind you, what’s the strategy when the green flag comes down?’ To which Dixon replied, ‘Gil [de Ferran] is starting the race and he’s going to have his hands full going into turn one. The diesels have a lot of torque and a lot of power down the straight, so hopefully he can keep it in front in turn one.

We’ve then just got to be aggressive and try to remain in front as long as possible.’

Simple when you put it like that.

However, at the start of the race, the no.2 Audi, driven by Allan McNish, had passed the Acura before the start / finish line…

I told myself that was okay, we’d get past the Audi in the infield with its slower corners.

Still on lap one, de Ferran beautifully defended an attempted pass by the no.7 Peugeot, driven by Pedro Lamy, into turn nine. (I forgot to mention above that there was a shorter straight section out of the infamous Sebring Hairpin that I hadn’t even considered would be a problem because of our higher cornering speeds). Speed TV announcer, Dorsey Schroeder, said the following after the attempted pass: ‘Here’s the problem with the Acura… it is making its speed in the corners, so he’s going to have to be aggressive throughout this 12-hour race. He cannot give up corner speed because he gets out-drag raced between the corners.’

No shit, Schroeder.

32 Le Mans 2022 • Racecar Engineering

‘If this was Long Beach, or the Belle Isle circuit in Detroit, we would have kicked their diesel butts’ De Ferran reached my area of highest concern on that first lap still in second position, but the Peugeot was following close behind. Sure enough, out of turn 16, on the long back straight, the no.7 Peugeot simply drove past our no.66 car before the braking zone like we were standing still. Another Speed TV announcer, Calvin Fish, noted: ‘These Acuras are going to be fighting this all day long.’ To which Schroeder retorted, ‘No question. And traffic is going to be another problem for them because if they get hindered on that corner speed… mid-corner speed is their forte… if they get slowed up mid-corner they’re going to just fall back into the hands of these more powerful diesels.’

Just as Schroeder finished that comment, out of turn 17, the no.1 Audi of Mike Rockenfeller blew by our Acura going into turn one. My concerns were proven on the very first lap, while my Sebring in 2009 was the domain of the diesels so, although Scott Raymond’s Acura was fastest over a lap in qualifying, it was no threat during the race. Traffic was not the Acura’s friend on this circuit, as Peugeot and Audi had the torque on tap to pass at will

hopeful prediction of us manhandling the diesels in the infield? Well, not quite.

Speaking of the infield, as we drove through that section on lap two, Schroeder offered up this pearl of wisdom: ‘The entire design of this new Acura was to make speed in the corners. They said, “We cannot do battle with the diesel power down the straightaways, we’ll make our speed and time in the corners,” but at a track like Sebring, with long straightaways, that’s a long road to home, is it not?’ Indeed Schroeder, indeed.

Traffic report Now, let’s remember that Schroeder had predicted traffic would be a problem for the Acura. To demonstrate just how much of a problem it would be, we need to look at what happened with the second Peugeot I have not mentioned yet. It’s not that we were faster than this car and pulling away from it like some magical petrol-powered unicorn. No, this car had started the race from pit lane behind the entire field because of a pre-race hydraulic issue, and just hadn’t caught up to us yet.

So, while we were out there fighting – and losing – to the other diesels, the no.8 Peugeot 908, driven by Franck Montagny, had been slicing its way through the GT field. With the race still less than two laps old, and under four minutes having elapsed on the clock, ‘Franck the Tank’ had passed all the GT cars. And not all on that long back

The Acura ARX-01 ran the same size tyres front and rear, had a huge development for 2009 and was quick, but didn’t have the raceability to compete for the overall wins

straight I was talking about either, he was through the entire GT field before turn 14!

What was even more telling about Montagny’s passing prowess was his lap time while he chewed his way through the GT class. Below are the lap times for the cars in question on the second lap of the race: • No.2 Audi R15 TDI (Allan McNish): 1:46.271 • No.7 Peugeot 908 (Pedro Lamy): 1:47.182 • No.1 Audi R15 TDI (Mike Rockenfeller: 1:47.453

• • •

XPB

No less than four minutes into a 12-hour race, we had been put in our place

No.66 Acura ARX-02a (Gil de Ferran): 1:50.319 No.9 Acura ARX-02a (Driver??): 1:49.521 No. 8 Peugeot 908 (Franck Montagny): 1:50.125

So, Montagny was able to carve the dieselpowered Peugeot through the traffic of the GT field with ease and go 0.194 seconds per lap faster than de Ferran, who was running in clear air because he had been passed by the Audi at the beginning of that lap.

No worries about traffic for him then!

No less than four minutes into a 12hour race, we had been put in our place.

To make matters worse, the lack of relative torque compared to the diesels caused no end of headaches when it came to passing GT cars as we navigated traffic. Where an Audi or Peugeot could motor past two GT cars with ease, we could only get past one.

Montagny’s performance on lap two was just a prelude to the passing nightmares we would experience through the race.

There is no happy ending to this story.

We didn’t beat the diesels. At no point did an Acura lead the race. In fact, both Acuras fell out of the race with mechanical failures.

But still the optimist in me said, ‘If this was Long Beach, or the Belle Isle circuit in Detroit, we would have kicked their diesel butts.’

Career philosophy Needless to say, this experience certainly left a mark. It helped cement an engineer philosophy I have employed throughout my career since, which is to play to a car’s strengths rather than compromising a set-up in an attempt to rectify an impossibly overcomeable discrepancy.

For example, later in 2009 we raced the Audis and Peugeots again at Petit Le Racecar Engineering • Le Mans 2022 33

XPB

BALANCE OF PERFORMANCE | A LEARNING PROCESS

Nürburgring 2014 was a haven of multiclass racing, with everything from GT3 cars to this BMW 235 out on track at the same time. Balancing lap times and stint times require different calculations

Mans. De Ferran wanted us to trim the car to reduce drag on the Road Atlanta circuit but, in doing so, we would have been compromising the cornering speed of the car with a reduction in downforce. The problem was there was no way we could close the gap in top speed to either diesel car. Rear wing angle changes aren’t typically worth 20km/h, so all we would have been doing was hurting our cornering speed to still be slower on the straights than our competitors.

I recall adamantly telling de Ferran that we had to ‘play to the car’s strengths’, and explaining that over a 10-hour race the car would be easier to drive. Hopefully, this would mean less chance for errors.

In racing, it is always better to be good at one thing than mediocre at everything.

The other impact this experience had on my engineering philosophy surfaced later in my career once I had gained more experience and credibility in the world of Balance of Performance. Recall that I started working on BoP in 2014 when I was technical director at IMSA. At that time, the primary goal of BoP was balancing lap times, so the idea of attempting to balance cars over a stint or improve raceability was honestly not at the forefront.

Of late though, as I contemplate changes to the BoP for the Nürburgring 24h GT3 cars, I find myself asking what I can do to improve 34 Le Mans 2022 • Racecar Engineering

the cars’ raceability? What can I do to make sure the cars are balanced over a stint?

I recall a paraphrased conversation prior to last year’s qualifying session for the Nürburgring race where a manufacturer representative said to me, ‘You are really willing to let that car do well in qualifying just to improve their performance in the race?’

‘Yes,’ I replied. ‘I want to improve the raceability of that car. I want them to have just as much chance of winning the race as you do.’

Work to be done And that is just it. As someone responsible for the Balance of Performance between cars, I am no longer satisfied by just balancing lap times. It must be better.

It must take more into account. Hence the idea of balancing raceability.

It was with those thoughts in mind that I started down the path of writing this article. I am in a unique position to be working directly with a racing series, a manufacturer and a racing team, so I get to see the consequences of good and bad BoP from all sides. With everything I have experienced first hand, I honestly do not feel like most BoP processes, even my own, adequately address the issue of raceability.

But, by the same token, I am just one person, with my own opinions on the

I am no longer satisfied by just balancing lap times. It must be better.

It must take more into account. Hence the idea of balancing raceability matter. The topic of raceability is much bigger than my own field of experience, so I felt it was important to gather input from other people within the motorsport industry to make sure my opinions did not skew the facts too much in one direction.

To obtain a broader perspective, I reached out to several people representing racing series, car manufacturers and racecar drivers. Thankfully, I received some excellent feedback from people across my desired spectrum, so what is presented here, and in the article(s) that will follow, are some quotes and discussion around the topic of raceability from the perspective of those who most certainly have the knowledge.

In this first article, we speak with a representative of a sanctioning body / racing series.

The sanctioning body perspective

O

The side effect that occurred with such an aggressive BoP target was that suddenly other aspects of races rose in importance.

As we started getting better at achieving the targeted performance deltas, the importance of pit stop refuelling times rose to the surface as a priority. Not only was it important to balance lap times, but an aspect of racing that I attribute more to execution of the race became just as important.

It is just such progress that I believe is the reason why the topic of raceability has become more important. As with any complex problem, the low-hanging fruit needs to be addressed before the more difficult items can be tackled.

Nicolas continued: ‘Actually, we not only have BoP to ensure good competition, we also have homologation, which is usually forgotten by competitors, but which is very important in the achievement of close competition.’

So, the FIA looks at making competition closer using a two-pronged attack: homologation and Balance of Performance.

Let’s briefly discuss both of those.

Homologation The homologation regulations for a vehicle category define the fundamental design characteristics for any new vehicle destined to compete in a category homologated by the FIA. Cars must be designed to comply with these requirements if the vehicle manufacturer wishes to receive approval from the FIA. For categories that employ Balance of Performance measures, such as Hypercar, GTE and GT3, the FIA has implemented the concept of performance windows.

These consist of defining acceptable windows of performance for specific vehicle parameters, including power, weight and aerodynamics. Both downforce and drag targets are imposed with respect to aerodynamics, and Aubourg feels the aerodynamic targets are of the highest importance. For the performance windows, minimum and maximum values for each parameter are prescribed, which, in turn, defines the desired performance targets for the vehicle manufacturers at design time.

Manufacturers then work with the FIA during the design process to keep themselves on track and within the desired performance windows. Once the vehicle is completed, manufacturers must bring the car to the Sauber wind tunnel for testing. The FIA uses this tunnel to ensure the vehicles fall within the performance windows defined by the homologation regulations.

Once vehicles have successfully passed the wind tunnel testing, all bodywork design is frozen and the FIA completes a 3D scan of the car to generate a reference point.

The objectives of the homologation performance windows are to ensure acceleration, top speed and speeds in high-speed corners are similar between cars in the same homologation category.

As Aubourg notes, ‘It’s a powerful tool to gather not only the lap times, but also the speed profiles.’

Balance of Performance The vehicle parameters used by the FIA in the Balance of Performance process are similar to those used by most racing series.

The FIA starts out by freezing a range of

XPB

ne of the first people I heard back from was Nicolas Aubourg, the head of performance for the Federation Internationale de L’Automobile (FIA). I have known Nico for about eight years now and have always been impressed by his knowledge and skills. I have no idea how he handles all the responsibilities he has, especially when you consider the sheer number of racing series that fall under the FIA umbrella, but somehow he does it, and does a very good job of it.

When I first approached Nico about the topic of raceability, he said, ‘Very good topic.

Raceability and BoP are discussed a lot with manufacturers. Balancing lap time is one thing, but not enough to get good BoP.’ Good. At least I am not alone in thinking about this, and it is good to hear that the manufacturers who participate at the Nürburgring are also not the only ones interested in raceability.

Speaking strictly about BoP, he followed that with, ‘Because of all the progresses achieved by all of us in the bopped championships in the past years, the level of requirement is now very high. Competitors require less and less differences between cars. 10 years ago, a BoP with a delta of 0.6 seconds / lap was acceptable. Now, a BoP with a range of 0.3 seconds / lap is the standard.’

Aubourg’s point supports my own opinion that progress with respect to BoP has been made over the years. The fact that we now target just 0.3 seconds per lap speaks volumes just by itself. I remember introducing this target of 0.3 per cent while working at IMSA. At the time, it worked out to roughly 0.3 seconds on a lap of Daytona.

Allan McNish leads into the first corner at Sebring in 2009, having used the torque of the diesel to power past pole-sitter, Gil de Ferran, on the short shute to the first corner

Racecar Engineering • Le Mans 2022 35

XPB

BALANCE OF PERFORMANCE | A LEARNING PROCESS

The Spa 24 hours is another of the classic races but, with up to 70 GT3 cars taking part in the same race, it’s a perplexing computation to get the BoP right

rear wing angles, which has the effect of fixing the maximum top speed of a car. In addition to this aerodynamic parameter, the FIA uses ballast (mass) and power to then adjust two performance parameters at the same time: lap time and PDST (power dependent sector time).

Regarding the latter performance metric, Aubourg has this to say: ‘PDST is a virtual loop timing we compute with the data logger, GPS and a specific sensor to estimate the acceleration time of each car on straights.’

The use of virtual timing loops is clever because it does not allow savvy competitors to manipulate the PDST metric when they know the physical location of a timing line.

The sensitivities of power and mass on acceleration and lap time are different, so Aubourg explains there is a unique combination of these two vehicle parameters required to achieve a target lap time and PDST.

Combining targets By addressing performance targets at design time through the homologation regulations and performance windows, and at race time through the Balance of Performance, the FIA hopes to achieve the best balance possible when the cars are on track.

In summary, the performance metrics the FIA is looking to balance include lap time, acceleration, top speed, high-speed 36 Le Mans 2022 • Racecar Engineering

cornering, low-speed cornering and braking.

Lap time is addressed with mass, power and aerodynamics both during homologation and with BoP at race time, with BoP adjustments used to fine tune lap time within the homologation performance windows.

Acceleration is also addressed at homologation, and through BoP, by setting power and mass targets with the performance windows, and then fine tuning as needed at race time. Top speed is locked in at homologation by setting a minimum drag level and maximum power level through performance windows.

High-speed cornering and braking are both addressed during homologation through aerodynamic downforce, while low-speed cornering is addressed by mass and making sure all cars use the same tyres.

‘This is the theory, and it works quite well,’ says Aubourg. I tend to agree.

Conclusion It is clear the processes surrounding BoP have evolved over time, and hopefully the experiences I had racing against the diesel cars in 2009 are now ‘a thing of the past’. Again, targeting 0.3 per cent lap time delta between cars, which is literally the blink of an eye, should say a lot about what engineers like myself are trying to do with Balance of Performance. The FIA leads the way in terms of homologating vehicles and,

By focusing on first principles that limit the lateral and longitudinal accelerations of vehicles during the design phase, [the FIA] is making the BoP process easier by focusing on first principles that limit the lateral and longitudinal accelerations of vehicles during the design phase, it is making the BoP process easier. After all, it is much easier to balance two vehicles that are already relatively close out of the box.

I still don’t know that we are doing enough. As I have said in the past, racing is an entertainment and marketing industry. I sincerely wish (with all my naïve optimism) that every single race has a ‘made-for-TV’ finish where no one can predict who is going to win a race until the chequered flag falls.

Only when finishes like that regularly happen will I feel like I am doing my job well enough.

I don’t know right this second what areas to focus on to help achieve that, but I can promise you I will keep searching for the answers until I can figure it out.

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