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08/07/2013
MCLAREN P1, AN ASPIRATIONAL HYBRID

FROM THE ENGINE TO THE WHEELS
900HP and CO2 emissions of less than 200 grams per kilometre? Science fiction? No, advanced McLaren technology

Nicodemo Angì

WHAT CAN I SAY ABOUT MCLAREN? It is a brand that is firmly established on the Olympus of extreme supercars thanks to a DNA derived directly from top-level motorsport competitions.
Could a brand like this make a “normal” hybrid car? The answer is obvious: the P1 has batteries and an electric motor but that’s where the similarity with other hybrids ends. The numbers are those of the purest sports car because the petrol engine is a 3.8-litre V8 turbo (and certainly poles apart from the smaller offspring of downsizing) that is capable of 727 HP at 7,500 rpm – high for a road turbo.
The turbo gives the engine a good boost even starting from mid revs, given that the relevant maximum torque of 720 Nm is available from 4000 revs.  Acceleration is impressive: going from 0 to 100 km/h takes less than 3 seconds, 200 is achieved in less than 7 seconds and the astronomical speed of 300 km an hour in 17 seconds.
The management of such extreme dynamics demands an appropriate braking system and in fact the P1 has powerful carbon-ceramic discs.

A song for two voices
Developed in-house by McLaren Electronics, the electric motor produces 176 HP with 260 Nm torque already available at 0 revs, which is typical of electric motors. The hybrid powertrain will give a total power output of  903 HP and 900 Nm torque, figures that are impressive.
The lively electric motor also allowed McLaren to use the Instant Power Assist System (IPAS) for instant acceleration boost. Which totally eliminates the irritating “delay” that made the first turbocharged engines fairly unmanageable and cantankerous and is still noticeable in today’s modern motors. Let’s be clear: the P1’s response to the accelerator pedal will certainly be aggressive, but its declared linear power delivery is identical to that of a "naturally aspirated engine".
The presence of the electric motor also enabled the IC engine to be optimized as a function of maximum power, given that low revs are refined by the electric unit. Engine power is transferred to an advanced seven speed dual-clutch transmission, whose speed of action is increased by the intervention of the omnipresent electric motor and sophisticated electronic controls. When changing up to a higher gear the IC engine must reduce its revs, which is easily verified on the road. This adaptation of IC engine revolutions is performed by the electric motor, which instantly and precisely "brakes" the IC engine so that the higher gear can be engaged with maximum speed.

A motor that does everything
This has confirmed a trend that uses electric motors not just for hybrid driving but also to "refine" the behaviour of transmissions and internal combustion engines.
The electric motor is also used to recover braking energy and recharge the batteries through IC engine operation: it is still a hybrid even though the numbers tend to put this characteristic in second place. Although small (declared range in E-Mode is about 10 kilometres and it will recharge at home in about two hours), the battery pack is a good exercise in technology.
Even if they don’t tell us what technology is used, the manufacturer places emphasis on innovative water cooling  – which is necessary given the "violent"  delivery demanded by the IPAS –  that optimizes operating conditions cell by cell. Battery pack weight  – 96 kg is a good figure – is limited by the very energetically “dense” cells and their location in a structure integrated with the Formula 1 grade carbon fibre monocoque, which eliminates the heavy safety housing that would be necessary otherwise.
The P1 will be everything but inexpensive and massed produced, so it can allow itself a very refined construction: the electric motor, for example, is housed directly in the engine block to optimize weight and bulk. This "obsessive" search for lightness (the word is McLaren’s) is an important ingredient in considerable performance in terms of emissions (less than 200 grams/km) from the McLaren P1.
Project modernity is expressed in other details, like the large display on the dashboard: it is easy to imagine that it can be used to display navigation maps, multimedia files and web connection services. The instruments also have displays, which makes them extensively configurable and packed with information.

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