BMW bares details of M Hybrid V8’s P66/3 hybrid turbo engine

The 24 Hours of Daytona/24 Hours of Le Mans-bound BMW M Hybrid V8 is set to enter an intensive period of testing in the next coming weeks in preparation for the upcoming endurance races. But before that, the German automotive brand shares specific details of how it managed to build a powerful hybrid mill. 

“The project had already reached a key milestone before the rollout: The successful fire-up of the hybrid drive system after installation in the test vehicle at the end of June,” BMW said in a recent press release.

Coming up with a suitable powerplant for the LMDh prototype was no walk in the park though.

Head of Drivetrain Design at BMW M Motorsport Ulrich Schulz and his group initiated an evaluation to determine which race engine would be best suited for conversion into a high-performance hybrid drive system.

“During the evaluation phase, we also took a look at the P48 four-cylinder turbo engine from the BMW M4 DTM and the P63 eight-cylinder turbo engine from the BMW M8 GTE, but potential problems with the durability of the P48 and the heavy weight of the P63 were negative considerations,” said Schulz.

Ultimately, it was the P66/1 eight-cylinder engine (shown above) used in the 2017 and 2018 seasons in the BMW M4 DTM that proved to be the best option.

BMW also adds that the eight-cylinder P66/3 turbo engine with supplementary electric drive had undergone two phases of reconstruction to meet the stringent requirements of the LMDh hybrid drive system.

“Converting the normally aspirated P66/1 engine into a bi-turbo and then working with the electric drivetrain colleagues to turn it into a hybrid drive system was very complex. Thanks to the expertise, the great collaboration, and the high level of motivation of all departments, we managed to complete the fire-up of the complete drive unit just a few weeks ago. We now feel that nothing is standing in the way of testing,” Schulz explained.

For the first phase, the normally aspirated P66/1 DTM engine was converted into an intermediate engine and was later named P66/2, primarily by adapting two turbochargers and adjusting the crank drive.

During this time, the P66/2 was put through its paces by subjecting it to various tests including complete racetrack simulations on the test bench.

Phase two saw the creation of the P66/3 race engine (shown below), including a twin-turbo version, adjustments to the specific requirements of the Dallara chassis, final exhaust system, oil tank, cabling, and integration of the high-voltage environment.

The cylinder block and cylinder heads were recast in the BMW Group foundry in Landshut in Germany and the injection system was rebuilt for direct injection.

At the same time, engineers who already boasted plenty of experience with electric drive systems from the Formula E project were also testing and integrating the electric motor. The unit that forms the hybrid drive system in the car consists of the e-motor, the inverter, and the high-voltage battery.

A separator clutch, between the electric and combustion engines, enables fully electric driving.

The M Hybrid V8’s P66/3 hybrid turbo engine has a regulated maximum power output of around 640 horses with a maximum torque of approximately 650Nm.

Photos from BMW

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