The Lola B12/69 chassis that became the B12/69EV world record holder did not begin its life as an electric vehicle. It was designed and built as an LMP1 endurance racing car, intended for events like the Le Mans 24 Hours, using a bio-ethanol fuelled internal combustion engine. Converting it to all-electric power was not a simple powertrain swap — it was a fundamental reimagining of the car’s engineering architecture.
This post tells the story of that conversion: the decisions that shaped it, the engineering challenges it revealed, and the lessons that the process generated for anyone thinking about the relationship between conventional and electric racing car design.
Starting Point: The Lola B12/69 LMP1 Chassis
The Lola B12/69 was chosen as the basis for the electric record attempt programme for several reasons. Its carbon fibre monocoque provided a rigid, lightweight structural foundation — the starting point for any high-performance vehicle. Its LMP1 aerodynamic package, while optimised for circuit racing rather than straight-line speed, provided a known aerodynamic baseline that could be modified for the record attempt configuration.
Crucially, the car had been designed with significant engineering headroom — the structural and aerodynamic margins of a Le Mans prototype are generous compared to a purpose-built record attempt vehicle, which meant that the conversion programme could work within the existing structure rather than requiring fundamental monocoque modifications.
The performance context of the Lola platform — the Le Mans 24 Hours — is directly relevant to the DRT programme’s credibility. A car that could compete at Le Mans represented a genuine performance baseline against which the electric powertrain’s capabilities could be measured. The record eventually set by the converted car — 204.2 mph at RAF Elvington — validated that the electric powertrain was not a compromise.
The Bio-Ethanol Baseline: What Was Being Replaced
In its original configuration, the Lola B12/69 used a naturally aspirated or turbocharged internal combustion engine running on bio-ethanol — a fuel that offers significantly lower net carbon emissions than conventional petrol or diesel when produced from appropriate feedstocks. DRT’s bio-ethanol programme was itself a demonstration of sustainable racing technology, predating the electric programme and establishing the team’s commitment to low-carbon performance.
The bio-ethanol engine occupied the rear section of the monocoque, with the fuel tank positioned behind the driver — the conventional LMP layout. The engine’s dimensions, weight, and mounting interface defined the architecture of the car’s rear section, which the electric conversion needed to fundamentally reimagine.
The Conversion Architecture: Where Everything Changed
Removing the Internal Combustion System
The first phase of the conversion involved removing the entire internal combustion drivetrain — engine, gearbox, fuel system, cooling system, and exhaust. This revealed the rear monocoque structure in its unloaded state, providing the engineering team with the opportunity to evaluate what modifications were required to accept the electric powertrain.
Battery Pack Integration
The most significant structural change in the conversion was the integration of the battery pack. In the original car, the fuel tank occupied the space between the driver and the engine — now available for battery cells. The battery pack’s dimensions and weight were fundamentally different from the fuel system it replaced: denser in some dimensions, more space-efficient in others, and significantly heavier even after optimisation.
The engineering of the battery pack itself — composite enclosure, thermal management, and cell selection — is detailed in our post on lightweight composite battery packs balancing power density and safety.
Motor and Inverter Mounting
The electric motor — producing 850 kW at peak output — was mounted in the rear of the monocoque, driving the rear axle through a fixed-ratio transmission. Unlike the multi-ratio gearbox of the original car, the electric drivetrain used a single gear ratio — appropriate given the flat torque curve of the electric motor across its operating speed range.
Weight Management: The Central Conversion Challenge
The conversion from internal combustion to electric power is, in mass terms, generally unfavourable. The bio-ethanol engine and associated systems weighed substantially less than the battery pack required to match their energy content. Managing this additional mass — distributing it optimally within the chassis, and compensating for its effect on the car’s dynamic behaviour — was one of the conversion programme’s central engineering challenges.
The solution involved a combination of weight removal from areas of the car not directly affected by the powertrain conversion (bodywork, aerodynamic elements, ancillary systems) and careful positioning of the battery pack to achieve a centre of gravity and weight distribution as close as possible to the original car’s baseline.
What the Conversion Process Taught Us
Converting an existing LMP chassis to electric power, rather than designing an electric racing car from scratch, provides engineering insights that a clean-sheet design cannot. The constraints imposed by the existing structure reveal the trade-offs implicit in conventional racing car architecture — and the ways in which an electric powertrain’s characteristics demand a different structural philosophy. These lessons directly informed the approach taken to the DRT Formula E concept design with Sergio Rinland and the RCA, which was designed from first principles as an electric vehicle rather than adapted from a conventional architecture.
The conversion experience also informs the argument for dedicated electric motorsport categories. The engineering compromises inherent in converting a conventional car to electric power are eliminated when the car is designed electric from the outset — a point with direct relevance to the policy case for competitive low-carbon racing programmes.
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