Working in partnership with the Renault Sport Formula One Team, Infiniti has developed an automotive first – a high-tech dual-hybrid powertrain. Words: Dean Slavnich.
TECH INSIDER INFINITI PROJECT BLACK S
Dual in the Crown
Among all the shiny, stylish concepts on display at the 2018 Paris Motor Show – most of which were laying claim to some form of autonomous drive capability that the public won’t actually experience on real-world roads any time soon – it was Infiniti that showcased arguably one of the most relevant cars; relevant at least in a realistic engineering sense, insomuch as the powertrain technology within the stunning Project Black S is not far off from making it to vehicle production.
Based on the Infiniti Q60 coupe, and co-developed with the Renault Sport Formula One Team, Project Black S is the first automotive example of a high-tech, dual-hybrid powertrain. The development prototype essentially lifts the advanced powertrain tech from Renault’s F1 racer and dumps it into a road-going application. “The Project Black S engineering prototype is the first indication of how cutting-edge motorsport powertrains could be used to create thrilling hybrid cars,” says Jérôme Stoll, Renault Sport Formula One Team president.
Off the back of announcing it has developed – and will launch later in 2019 – the industry’s crown first variable compression engine, code-named VC-T, the powertrain engineering drive within Infiniti shows no signs of slowing down.
The world’s first dual-hybrid powertrain for automotive application represents a true F1-to-road- car technology transfer. Infiniti also says Project Black S reaffirms its commitment to developing exciting high-performance electrified powertrains, having announced in mid-2017 that the brand will ‘go electric’ in 2021.
Sharing the same name as the Geneva 2017 design study car, the Paris Project Black S prototype made huge engineering strides forward thanks to its rapid 18-month development program.
Infiniti’s VR30 twin-turbo V6 with 405ps is used in combination with two F1-derived heat energy harvesting systems – MGU-H (motor generator unit – heat) – that develop electricity under acceleration. In what’s being seen as a real technical highlight, the VR30’s twin-turbos are actually fitted with the two MGU-H units, which harvest the heat energy from the exhaust gases, enabling the powertrain to generate electrical power under both braking and acceleration.
That VR30 MGU-H setup is paired with a kinetic harvesting system – MGU-K (motor generator unit – kinetic) – that essentially generates additional electricity under braking. The electrical energy created by the three MGUs is stored in a high-rate discharge 4.4kWh lithium-ion battery pack located at the rear of the Project Black S. Mirroring the F1 setup, the power recovered by the MGUs and stored in the battery pack is deployed in two ways. Firstly, it acts as an electrically assisted anti-lag system, spooling up the turbine blades within both e-turbos more quickly and rapidly increasing the amount of air recirculated back into the engine to boost overall power. Secondly, energy stored in the pack can be used to power the MGU-K, feeding some 120kW of additional electric power directly into the drivetrain.
For this development prototype version of the Project Black S, the extra power is applied to the rear axle through a newly designed final drive assembly on the rear, which also integrates the MGU-K. In total, the new powertrain adds a hefty 200kg to the vehicle, which now tips the scales at 1,775kg.
The V6’s initial 405ps output is hugely bettered by the dual-hybrid powertrain, with Project Black S offering 420kW in total – the equivalent to 571ps. That huge jump represents a 41% power increase from the standard Q60 donor car. Project Black S produces more power and accelerates more quickly – the 0-100km/h (0-62mph) sprint time is under four seconds – than any Infiniti road car to date.
The dual-hybrid system also uses the MGU-K to provide a high-response electrically assisted launch control function, with a helical gear limited-slip diff managing power delivery to the rear wheels.
Additional technical highlights include full drive-by-wire controls and a new brake-by-wire regen braking system.
Space invader
Packaging all the different powertrain elements in a car originally designed for just a performance V6 engine caused the Project Black S team a number of considerable engineering challenges.
Placing the MGU-K and battery pack at the rear, along with all the ancillary components and subsystems, meant big technical changes needed to be made to the car’s architecture. This included modifying the rear suspension crossmember to take on the MGU-K, while a new cooling system was also installed, placing the radiator core beneath the rear floor and channeling air through the center diffuser. For this, advanced CFD work enabled the team to make a number of alterations to the design of the vehicle’s undercarriage, enabling the diffuser and cooling duct to work in parallel with the rear wing to aid cooling and airflow.
Matters were just as complicated at the front, where there was initially no room for the two MGU-H units or the independent hybrid cooling circuits. In the current Q60 engine bay, the VR30 3.0 motor fits its compartment with tight precision with literally no more space available. Infiniti engineers had to move and repackage the existing engine cooling system, and install a high-efficiency radiator. A small section of the body has also been cut out in order to accommodate the MGU-H systems.
Fast movers
Infiniti teams in Hong Kong; London; and Atsugi, Japan, worked with their counterparts in Enstone, UK, and Viry-Chatillion, France (Renault Sport Formula One and Renault Sport Racing respectively), to create the tech demonstrator in a very quick timeframe.
“Working with Renault Sport Formula One meant we could operate on incredibly short development cycles,” explains Infiniti’s motorsport group director, Tommaso Volpe. “In just 18 months, an agile cohort of designers and engineers from Infiniti and the Renault Sport Formula One Team has turned a design study into a working demo car.”
In particular, Renault’s rich experience with thermal management simulations proved to be critical in validating the durability and performance of the dual-hybrid system in its journey from track to road.
“Given the compressed timescales for delivery of the Project Black S, we have used predictive computer modeling to validate how to marry the car’s design, aerodynamics, powertrain and dynamics together,” says Volpe. “Having a small, responsive team of experts involved in developing the prototype has meant we were able to make changes quicker than going through a traditional testing and validation process.”
As for what’s next for the Project Black S program: unlike many of those glitzy self-driving concepts at the Paris Motor Show, this tech demonstrator has real-world ambitions, with feasibility and performance testing to continue well into 2019, shifting from digital and dyno assessments to track and real driving conditions.
Project Black S pairs a high-performance V6 IC engine with two energy recovery systems derived from Formula One.
The dual-hybrid powertrain adds 200kg to the vehicle, but engineers turned to exotic materials to save weight elsewhere, replacing the steel hood, trunk lid, fenders and roof of the standard car with lighter carbon-fiber panels.
