You might think that the 616 horsepower the MP4-12C gets out of McLaren's 3.8-litre twin-turbo V8 is pretty much the limit of what's possible for a car that spends most of its time on public roads. Then comes the P1, and even if you don't count the 176 electric horses behind your back, that same 3.8 V8 suddenly has 727 horsepower. Here's how they work together to make 903 manic horsepower.
The M838T engine was the result of a long evolution process that started somewhere with Tom Walkinshaw Racing's Nissan VRH35 that raced at Le Mans in 1998. With the help of Ricardo, McLaren created something new that only shares its bore of 3.66 inches with Nissan's engine. But for the P1, it had to evolve even further.
This time, the aluminum engine block has a unique casting to incorporate the electric motor, and an upgraded cooling and air charging system to deal with the higher loads. The 727 hp peak power comes at 7,500 rpm, while you get 531 ft-lb of torque at a more economical 4,000 rpm. McLaren promises "instantaneous throttle response through the rev range", just like with a normally aspirated engine. Emissions stay under 200g/km on the combined cycle, while electric-only power gives the P1 a range of more than 6 miles. Handy if you just want to roll down to get some milk.
The electric motor was developed by McLaren Electronics, and produces 176 horsepower as well as 192 ft-lb of torque available right from a standstill. Together with the petrol engine and the Instant Power Assist System boost, the P1 has 903 horsepower and 664 ft-lb to play with. The engine-mounted electric motor also sharpens the seven-speed dual-clutch gearbox by producing negative torque at the point of shift, making the engine revs drop as quickly and efficiently as possible to achieve faster upshifts. Sounds punchy. When off-throttle, the electric motor also provides additional drag torque, recovering energy to the battery.
The P1's power storage is a 212 pound battery built into the carbon fiber chassis itself, thus avoiding the weight of any unnecessary battery packaging. With this much power, cooling becomes a big issue, so McLaren made sure the coolant flow is balanced so that every cell stays at the same temperature. A plug-in charger is also part of the package, which can top up the battery in 2 hours.
Thanks to some quality time spent in Formula 1, the P1 also has a DRS system that reduces the rear wing's angle to lower drag by 23%. The system immediately deactivateswhen the button is released, or if the driver touches the brake. And in a car with more than 600hp/ton, the driver will probably touch it a lot.
Did I just hear Jeremy Clarkson shouting pooweeeeeer?
Photo Credit: McLaren