Whereas once Audi Sport and Porsche Motorsport shared virtually nothing between their R18 and 919 LMP1 programs, the modern era of LMDh prototype development ahead of the 2003 racing season will see the two Volkswagen Group marques (and possibly a third likely Bentley or Lamborghini) share chassis construction and engine. Since Porsche Motorsport has begun to reveal details of their version of the project, much of what is shared confirms details for Audi racing fans as well.
Porsche Penske Motorsport has begun testing the Porsche LMDh rather publicly, and a wave of video, photos and details have followed. Key amongst them is confirmation of the engine being a much rumored biturbo V8. “We were spoiled for choice with the engine for our LMDh prototype, because the product range offers several promising baseline units,” said Porsche Motorsport VP Thomas Laudenbach. “We decided on the V8-biturbo, which we feel offers the best combination of performance characteristics, weight and costs. The kick-off to the active test program was an important step for the project.”
Porsche hasn’t revealed displacement or origins of the race engine, but rumors in the industry have continued to point toward the 4.0 biturbo V8 used in production. Amongst the photos released by Porsche, it’s clear that the racing engine uses the same “hot V” configuration as the production 4.0 from the RS 6, RS 7 and RS Q8, with exhaust and turbos paced atop the engine and air intakes fed through the side of the heads.
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The vehicle will be fielded in the FIA WEC World Endurance Championship and the North American IMSA WeatherTech SportsCar Championship under the team name Porsche Penske Motorsport. Now, the intensive test programme to prepare for the race debut in January 2023 has started. This premiere will take place at the traditional opening round of the IMSA series – the 24 Hours of Daytona. In selecting the combustion engine to complement the standard hybrid elements, as stipulated by the regulations, Porsche opted for a large-capacity twin-turbo V8 unit. The powerful engine is designed to run on renewable fuels, which means a significant reduction in CO2 emissions. In the race, the system output of the hybrid drive reaches around 500 kW (670 hp).
Urs Kuratle, Overall Project Manager LMDh at Porsche Motorsport: “The rollout of the LMDh racing car was also the first track outing for Porsche Penske Motorsport. The squad worked well together right from the start. This shows a high level of professionalism in all areas. After all, the operational requirements for the safe running of a hybrid vehicle are very high. In the next outings we will focus on going deeper into the required processes and procedures. During these first test days at Weissach, the V8-biturbo impressed us in every respect. We’re convinced that we’ve chosen precisely the right unit.”
Engine regulations allow a great deal of freedom
The engine regulations for the LMDh vehicle class allow a great deal of freedom in terms of displacement, design and number of cylinders. Maximum revs are 10,000 rpm, with the pass-by noise measurement capped at 110 decibels. The engine must weigh a minimum of 180 kilograms, including the air supply and exhaust system as well as the peripheral cooling components. If used, this weight also incorporates the turbocharger/s including the charge air cooling. In line with the regulations, the maximum output lies between 480 and 520 kW (644 hp to 697 hp). This range also allows adjustments to be made within the Balance of Performance (BoP) parameters, which are intended to ensure parity between all competing LMDh racing cars.
The torque curve is also clearly defined. Under racing conditions, the combined power output of the combustion engine and hybrid drive totals 500 kW (670 hp) at the half-shafts. The standard components for the recuperation, storage and delivery of electrical energy are supplied by Williams Advanced Engineering (battery), Bosch (motor-generator unit and control electronics) and Xtrac (transmission).