McLaren has announced that its upcoming P1 supercar will have the combined force of two highly efficient powerplants, to provide what it calls "the optimum mix of superb throttle response, day-to-day driveability and top speed." A mid-mounted 3.8-liter twin-turbo V8 gasoline engine and a highly effective electric motor give a combined output of 903hp and a maximum torque figure of 900Nm, ensuring instantaneous throttle response through the rev range, more akin to a naturally aspirated engine. Emissions of less than 200g/km on the combined cycle are reduced to zero in full electric drive mode, while the Formula 1-derived DRS and IPAS technologies offer an increase in straight-line speed and an instant boost of power.
The V8 is a new version of the familiar M838T unit, that has been significantly upgraded to optimize cooling and durability under the higher loads. The engine block has a unique casting to incorporate the electric motor. The gasoline engine produces 727hp at 7,500rpm, and 720Nm of torque from 4,000rpm.
The electric motor is mounted directly onto the engine, and all drive is channeled through the dual-clutch 7-speed gearbox to drive the rear wheels. Thus, the electric motor and V8 engine work seamlessly together, providing more than just added ultimate power and torque.
A further benefit is that the e-motor can provide faster upshifts. This is achieved through the application of instant negative torque at the point of shift, making the engine revs drop as quickly and efficiently as possible to the required engine speed for the upshift.
In addition to the obsessive weight-saving measures demonstrated throughout the McLaren P1, so too is the optimization of usable energy. When off-throttle the electric motor provides additional drag torque, recovering energy to the battery that would otherwise be lost to the brakes.
The McLaren P1 can be driven in a variety of modes, powered by the engine and electric motor together, or solely by the electric motor. This ensures versatility and ease of transportation, allows use in low emission zones and residential driving is optimized with near-silent running. McLaren says the P1 can travel more than 10km (6.2 miles) with electric-only power – enough for most city journeys. When the battery is empty, the gasoline engine will automatically start to maintain drive and charge the battery.
The power available via the V8 and electric motor is further enhanced on the McLaren P1 through two steering wheel-mounted buttons which activate the DRS (Drag Reduction System) and IPAS (Instant Power Assist System). DRS is a technology similar to that employed on Formula 1 cars. Speed is increased by reducing the amount of drag on the rear wing and, where an F1 car has a movable flap on the rear wing, the P1has a wing that reduces in angle to lower drag by 23%. The system immediately deactivates when the button is released, or if the driver touches the brake pedal.
IPAS is designed to deliver power rapidly for high performance acceleration, and provides 179PS of instant additional power. In developing the IPAS technology for the P1, power delivery was prioritized over energy storage. This is achieved through a lightweight battery pack, which McLaren says offers greater power density than any other automotive battery pack on sale today.
The high power density has been achieved through a combination of high power cells, low pack weight and an innovative cooling system. The battery weighs just 212lbs, and is mounted onto the underbody of the high-strength Formula 1-grade carbon fiber MonoCage chassis, which seals the unit in the vehicle, thus avoiding the added weight of any unnecessary battery packaging.
Due to the amount of power being supplied by the battery, complex cooling is required to guarantee cell performance and reliability. The coolant flow is balanced so each cell is cooled to the same temperature across the entire pack.
In addition to the battery being charged via the engine, the McLaren P1 is also equipped with a plug-in charger which can recharge the battery, from empty, in only two hours. The plug-in charger can be stored in the luggage compartment, although the customer may choose to store it outside the car to save weight.
Further details of the McLaren P1 will be released in the coming weeks, before the production-ready car makes its world debut at the Geneva Motor Show next month.