Analysis: McLaren P1

mclaren-p1

The McLaren P1 is one of the defining cars of the 21st Century so far. It’s much more than a supercar – it’s a new realm of speed brought to the road. Along with the Ferrari LaFerrari and Porsche 918, the P1’s release has further bridged the gap between road and race car performance, helped by the fact that all of these cars electric hybrids (albeit in different ways) to help boost power and driveability. The powertrain figures for this car are mind blowing: 531 lb ft of torque, 904bhp, 0-60mph in 2.8 seconds and a top speed limited to 218mph. All from a 3.8 litre twin turbo V8 paired to an electric motor.

When I had work experience at McLaren GT a couple of years ago I spent a lot of time around a host of different P1s and even the P1 GTR test mule (it had the cool testing camouflage at the time) so I got to know the ins and outs of the cars fairly well, particularly on the engine side.

McLaren design and manufacture their cars in house except for the engine and gearbox. The 7-speed dual clutch gearbox in the P1 is made by Oerlikon Graziano in Italy and the engine is produced by a UK company called Ricardo (who have a very rich and interesting history, so have a Google for them). These parts arrive at McLaren almost fully assembled but the mechanics will then take them apart for upgrading, particularly the engine. All of the cars McLaren make (12C, 650S, 675LT, 570S, 540C) are based around the same 3.8 litre twin turbo. However a lot of resources are put in to improving its performance, especially for the P1.

Various components will be machined, reinforced or replaced entirely by McLaren-designed parts to increase power output, such as the piston heads, turbochargers and even the block. Top level componentry is then added to further bump up power output, such as bespoke spark plugs from Bosch – the German company have been a key developer in F1’s hybrid era and have helped Mercedes achieve their recent dominance. Software engineers are then let loose on all of these bits to eek out even more horses.

Despite having two smaller turbochargers in place of one large unit, turbo lag is still an issue in this current era of motoring, so the internal combustion engine is paired to McLaren’s Instant Power Assist System (IPAS) which provides instant power at low rpm as the turbos spool up (a process known as ‘torque filling’), or it can be activated manually as a power boost. The motor produces ~175bhp and weighs just 26kg, with the large battery (that allows the car to run in fully electric mode for 19 miles) mounted directly behind the driver to keep improve the centre of mass position.

The P1 chassis is a carbon monocell with machined aluminium front and rear subframes used to mount the suspension components. This is extremely stiff and lightweight (~90kg), which allows the car to accelerate/decelerate rapidly and give the driver plenty of feedback in the corners. Huge carbon ceramic brakes are supplied by long-term racing partner, Akebono and, unlike many of the lower McLaren models, the P1 is equipped with interlinked electronic suspension to cope with the extreme aerodynamic loads on the tyres. In ‘race mode’ the P1 sits just 65mm above the ground, lowering the centre of gravity and maximising the aerodynamic potential of the car through ground effect. This therefore creates a much higher load on the tyre during a corner, so much so that even a current high performance car’s suspension system couldn’t handle it. For the P1 McLaren developed a very clever and responsive system that allowed this load to be spread across each tyre for even the most extreme load cases by using sensors and actuators to push fluid between the four dampers, providing stiffness to one side/corner of the car and softening the other to increase grip levels. This sort of technology is only really seen in F1, but even in F1 it works passively rather than a fully fledged electronic system.

Aerodynamically the P1 is a class leader: in race mode the car produces over 600kg of downforce thanks to its protruding splitter, smooth underbody and whopping diffuser. The two element rear wing can be stalled by the driver (i.e. DRS in F1) to reduce drag by 23%, and has active air braking to reduce stopping distances and increase rear stability. To have these sorts of stats on a road car is actually quite mind blowing, although most of it can’t be exploited on public roads. Despite this, McLaren have still recognised the importance of providing the average driver with a consistent platform: rather than going for peak downforce figures, McLaren have designed the aero package to help make the car easier to drive by producing good downforce at lower speeds, with the active elements of the car optimising the airflow as speed builds.

So there you have it, a very brief overview of s remarkable machine. Can we go even faster on the roads? Leave a comment with your thoughts.

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