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ACO releases document explaining Equivalence of Technology

30 May 2018

With the Le Mans 24 Hours Test Day fast approaching, ACO Technical Delegate Thierry Bouvet explains what’s what when it comes to Equivalence of Technology (EoT). The rule is the result of many discussions between the ACO, the FIA, and LMP1 chassis and engine constructors.

Can you explain the difference between Balance of Performance (BoP) and EoT? 

Balance of Performance applies to the LMGTE class and is intended to encourage parity between sports cars with different technical features (front vs rear engine, for example). To ensure competition is as fair as possible, race organisers seek convergence in terms of aerodynamics first and then consider weight, output and fuel tank capacity.

EoT has been introduced now that hybrid and non-hybrid cars are in direct competition in LMP1, to ensure a level playing field in the top class. Toyota being the only manufacturer entering a hybrid car (classed as LMP1-H) for the 2018-19 FIA World Endurance Championship Super Season, the factory’s competitors are private teams using non-hybrid technology (LMP1-NH). EoT is designed to ensure that the new contenders can compete with the Toyota TS050 Hybrid fielded by the manufacturer since 2016.

What principles are EoT based on?

We devised an EoT in 2014, with the FIA, to create parity between petrol and diesel cars. The adjustments were based on fuel allocation (flow rate and allowance per lap), which influences performance and range. A flow metre and sensors are vital in measuring this.

Today, given that the regulations are different for hybrid (LMP1-H) and non-hybrid (LMP1-NH) cars – particularly concerning aerodynamics and weight – and that there are even differences according to engine types in the non-hybrid entries, we have again opted for an EoT.

How did you go about it?

Last winter, we set up a working group of members of the FIA, the ACO and LMP1 engine and chassis constructors to define the outline. We had all the data on the Toyota TS050 Hybrid prototype. The non-hybrids were at the production stage, so the constructors supplied simulations, which obviously meant that changes to the EoT could not be ruled out. Everyone was aware of that.

The WEC Prologue and the first round at Spa provided precious feedback. Bearing in mind that the non-hybrids are still in the development phase and therefore have plenty of potential for improvement, we have already made some alterations. Our role is to ensure fair competition. The allowances for non-hybrids are intended to make up for a handicap compared to a hybrid car, not to give them an unfair advantage. It’s a balancing act, but there are means. In the same way, hybrid technology must remain relevant. At Le Mans, a hybrid does a lap more per stint than a non-hybrid.

With the Test Day only days away, EoT is still under debate. The balance between the naturally-aspirated and turbo engines has been criticised, for example.

When we examined the situation in 2017, we decided not to differentiate between the two because there are many parameters to consider beyond output. Turbo engines have heavier components and need a cold air intake system, and fuel consumption can differ too. All of that affects the car’s performance (weight distribution, drag, etc.). Once we had analysed the data we obtained at the Prologue and Spa, we drew our conclusions and made the relevant adjustments to EoT for Le Mans.

At Spa, the Toyota was faster than the LMP1-NH by a second per lap. For the Test Day on 3 June, you have reduced the fuel-flow for non-hybrids to 108 kg/h rather than the 110 kg/h with which they raced at Spa. The flow for the hybrid remains at 80 kg/h. Why?

When the EoT was created for the 2014 championship, to keep consistency of the hybrid usage with the other car systems, the hybrid coefficient was multiplied by 55% per kilometre at the shorter circuits compared with Le Mans (where the long straights alter the balance). That rule therefore applied at Spa.

Relative performance of hybrids and non-hybrids differs between Spa and Le Mans. Hybrids are at a relative disadvantage at Le Mans.

We used the data collected during the first two outings to adjust EoT for Le Mans and to close the gap between private and factory teams.  Again, between Spa and Le Mans Test Day, the privateers will have progressed. The ACO and FIA specialists will continue analysing data during and after the Test Day.

Some non-hybrid competitors are worried they’ll have to hold back.

Fuel consumption per lap is a real restriction. It’s difficult to manage if left to the driver. That’s why factories have developed automatic solutions. Encouraging privateers to do the same would involve pointless expense. That’s why the EoT that will apply on Test Day does not specify consumption per lap or per stint. So, there is no reason for drivers of non-hybrids to hold back. All the data collected during Test Day will be analysed by the FIA and the ACO and published for Race Week.

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