McLaren P1 engine revealed

Details of the McLaren P1's engine have emerged ahead of the production car's appearance at the Geneva motor show.

The P1 is driven by a petrol engine and an electric motor. The combustion engine is the 3.8-litre twin-turbo V8 that is in theMcLaren MP4-12C. It has been upgraded to produce 727bhp and 531lb ft of torque at 7500rpm.

McLaren Electronics has developed the electric motor for the P1. It produces 176bhp and delivers its maximum torque of 192lb ft from a standstill. It is mounted directly on to the engine via a new engine block that reduces weight compared with traditional hybrid systems. All the power is delivered through a dual-clutch, seven-speed semi-automatic gearbox to the rear wheels.

The P1's maximum power output is 903bhp and is achieved by the petrol engine and the electric motor working simultaneously.

The batteries are mounted onto the carbon fibre chassis and weigh 96kg. They are kept at the same temperature by the car's cooling system and can be charged by the petrol engine or by plugging the P1 into a socket. The P1 comes with a plug-in charger that can recharge the battery in two hours. The batteries are also charged by regenerative braking using the electric motor.

The McLaren P1 features an all-electric driving mode, E-mode, that can power the car for over six miles with no tailpipe emissions.

McLaren has fitted two features to the P1 that increase performance. The first is the Instant Power Assist System that instantly delivers the electric motor's 176bhp. The second is the Drag Reduction System which is engaged by pressing a button on the steering wheel. When activated the rear wing reduces in angle and lowers the drag of the car by 23%.

The P1 will be shown at Geneva next month, when details regarding pricing, fuel consumption and performance are expected to be released.

By Matthew Burrow