BMW returns to racing in IMSA: here are the secrets of the M Hybrid V8 engine

An intense testing period for the BMW M Hybrid V8car with which BMW M Motorsport will participate in the class IMSA GTP of the WeatherTech SportsCar Championship 2023.

The M Hybrid V8 is powered by the P66 / 3 eight-cylinder turbo engine with an additional electric unit. This is based on unity DTM eight-cylinder P66 / 1 used in the 2017 and 2018 seasons on the BMW M4 which competed in the DTM. The choice fell on this unit as it is completely load-bearing, with the advantage therefore of being able to be used on a monocoque frame without an additional sub-frame.

Added to this, of course, is the fact that it is the one that most closely matches the regulatory requirements after converting to a turbo hybrid engine.

Really, Ulrich Schulzdirector of BMW M Motorsport leading the project, and his team had initiated an evaluation to determine which racing engine was best suited for conversion to a hybrid propulsion system high performance even before the BMW Group Board of Directors gave the green light for BMW M Motorsport to enter the LMDh category in June 2021.

So, given the green light to the sports program, we already knew which engine to use. In fact, given the development time and costs, going back to the drawing board to design a completely new engine and build it from scratch was not feasible.

“During our evaluation exams, we also considered the turbo engine a four-cylinder P48 of the BMW M4 DTM and the turbo engine a eight-cylinder P63 of the BMW M8 GTE, but the potential durability issues of the P48 and the heavy weight of the P63 convinced you to look elsewhere “, Schulz explained the decision to choose the engine P66.

The first phase saw the transformation of the engine P66 / 1 DTM in an “intermediate” engine, called P66 / 2, which, unlike the first, naturally aspirated, used two turbochargers. The designers’ attention was focused on durability, performance increase and engine temperature management. The P66 / 2 has completed numerous tests, including complete simulations of a race carried out on a test bench.

The next step was the creation of the P66 / 3 racing engine, which takes the twin-turbo version and adapts it to the specific requirements of the Dallara chassis. There P66 / 3 it is then equipped with a definitive drainage system, oil tank, wiring and power electronics. In addition, the engine is equipped with direct injection.

The last step concerned the coupling with the electrical unit. The engineers in the “M” department already had a great deal of experience with the systems of electric propulsion thanks to the Formula E project and have tested and integrated the electric motor in parallel.

The unit that makes up the car’s hybrid drive system consists of the electric motor, the inverter and the high voltage battery. Between the electric motor and the combustion motor there is one clutch which allows you to drive in certain conditions exclusively with zero emissions (for example when traveling on the pit lane).

The two steering elements were first linked in the car in late June, with the first ignition of the hybrid system being a success. At the end of July testing will follow a Varano de ‘Melegari and immediately after the intensive testing phase will begin.