McLaren F1

The **McLaren F1** is a sports car designed and manufactured by British automobile manufacturer McLaren Cars and powered by the BMW S70/2 V12 engine. The original concept was conceived by Gordon Murray, who successfully convinced Ron Dennis to back the project and hired car designer Peter Stevens to design the exterior and interior of the car. On 31 March 1998, the XP5 prototype with a modified rev limiter set the Guinness World Record for the world's fastest production car, reaching 240.1 mph (386.4 km/h), surpassing the modified Jaguar XJ220's 217.1 mph (349 km/h) record from 1993.

The car features numerous proprietary designs and technologies; it is lighter and has a more streamlined structure than many modern sports cars, despite having one seat more than most similar sports cars, with the driver's seat located in the centre (and slightly forward) of two passengers' seating positions, providing driver visibility superior to that of a conventional seating layout. It was conceived as an exercise in creating what its designers hoped would be considered the ultimate road car. Despite not having been designed as a track machine, a modified race car edition of the vehicle won several races, including the 1995 24 Hours of Le Mans, where it faced purpose-built prototype race cars. Production began in 1992 and ended in 1998. In all, 106 cars were manufactured, with some variations in the design.

In 1994, the British car magazine *Autocar* stated in a road test regarding the F1, "The McLaren F1 is the finest driving machine yet built for the public road." They further stated, "The F1 will be remembered as one of the great events in the history of the car, and it may possibly be the fastest production road car the world will ever see." In 2005, Channel4 placed the car at number one on their list of the 100 greatest cars, calling it "the greatest automotive achievement of all time". In popular culture, the McLaren F1 has earned its spot as 'The greatest automobile ever created' and 'The Most Excellent Sports Car of All Time' amongst a wide variety of car enthusiasts and lovers. Notable past and present McLaren F1 owners include Lewis Hamilton, Elon Musk, Rowan Atkinson, Jay Leno, George Harrison, Ralph Lauren, Nick Mason, and the Sultan of Brunei. In the April 2017 issue of *Top Gear Magazine*, the McLaren F1 was listed as one of the fastest naturally aspirated cars currently available in the world, and in the same league as more modern vehicles such as the Ferrari Enzo and Aston Martin One-77 despite being produced and engineered 10 years prior to the Ferrari Enzo and 17 years prior to the Aston Martin One-77.

## Design and Implementation

Chief engineer Gordon Murray's design concept was a common one among designers of high-performance cars: low weight and high power. This was achieved through the use of high-tech and expensive materials such as carbon fibre, titanium, kevlar, magnesium and gold. The F1 was the first production car to use a carbon-fibre monocoque chassis.

Gordon Murray had been thinking of a three-seat sports car since his youth. When Murray was waiting for a flight home from the Italian Grand Prix in 1988, he drew a sketch of a three-seater sports car and proposed it to Ron Dennis. He pitched the idea of creating *the ultimate road car*, a concept that would be heavily influenced by the company's Formula One experience and technology and thus reflect that skill and knowledge through the McLaren F1.

Murray declared that "During this time, we were able to visit Honda's Tochigi Research Centre with Ayrton Senna. The visit related to the fact that at the time, Honda powered McLaren's F1 Grand Prix chassis. Although it's true I had thought it would have been better to put a larger engine, the moment I drove the Honda NSX, all the benchmark cars—Ferrari, Porsche, Lamborghini—I had been using as references in the development of my car vanished from my mind. Of course, the car we would create, the McLaren F1, needed to be faster than the NSX, but the NSX's ride quality and handling would become our new design target. Being a fan of Honda engines, I later went to Honda's Tochigi Research Centre on two occasions and requested that they consider building for the McLaren F1 a 4.5-litre V10 or V12. I asked, I tried to persuade them, but in the end could not convince them to do it, and the McLaren F1 ended up equipped with a BMW engine."

A pair of Ultima MK3 kit cars, chassis numbers 12 and 13, "Albert" and "Edward", the last two MK3s, were used as "mules" to test various components and concepts before the first cars were built. Number 12 was used to test the gearbox with a 7.4-litre Chevrolet V8, plus various other components such as the seats and the brakes. Number 13 was the test of the V12, plus the exhaust and cooling system. When McLaren was done with the cars they destroyed both of them to keep away the specialist magazines and because they did not want the car to be associated with "kit cars".

The car was first unveiled at a launch show, on 28 May 1992, at The Sporting Club in Monaco. The production version remained the same as the original prototype (XP1) except for the wing mirror which, on the XP1, was mounted at the top of the A-pillar. This car was deemed not road legal as it had no indicators at the front; McLaren was forced to make changes to the car as a result (some cars, including Ralph Lauren's, were sent back to McLaren and fitted with the prototype mirrors). The original wing mirrors also incorporated a pair of indicators which other car manufacturers would adopt several years later.

The car's safety levels were first proved when during a testing in Namibia in April 1993, a test driver wearing just shorts and a T-shirt hit a rock and rolled the first prototype car several times. The driver managed to escape unscathed. Later in the year, the second prototype (XP2) was specially built for crash testing and passed with the front wheel arch untouched.

### Engine

#### History

Gordon Murray insisted that the engine for this car be naturally aspirated to increase reliability and driver control. Turbochargers and superchargers increase power but they increase complexity and can decrease reliability as well as introduce an additional aspect of latency and loss of feedback. The ability of the driver to maintain maximum control of the engine is thus compromised. Murray initially approached Honda for a power plant rated at 410 kW (550 hp; 557 PS), with 600 mm (23.6 in) of block length and a total weight of 250 kg (551 lb), it was required to be derived from the Formula One power plant in the then-dominating McLaren/Honda cars. When Honda refused, Isuzu, then planning an entry into Formula One, had a 3.5-litre V12 engine being tested in a Lotus chassis. The company was very interested in having the engine fitted into the F1. However, the designers wanted an engine with a proven design and a racing pedigree.

#### Specifications

Gordon Murray then approached BMW, which took an interest, and the motorsport division BMW M headed by engine expert Paul Rosche designed and built Murray a 6,064 cc (6.1 L; 370.0 cu in) 60º V12 engine called the BMW S70/2. At 461 kW (618 hp; 627 PS) and 266 kg (586 lb) the BMW engine ended up 14% more powerful and 16 kg (35 lb) heavier than Gordon Murray's original specifications, with the same block length.

It has an aluminium alloy block and heads, with bore x stroke of 86 mm × 87 mm (3.39 in × 3.43 in) DOHC with variable valve timing (a relatively new and unproven technology for the time) for maximum flexibility of control over the 4 valves per cylinder, and a chain drive for the camshafts.

The engine uses a dry sump oil lubrication system. The carbon fibre body panels and monocoque required significant thermal insulation in the engine compartment, so Murray's solution was to line the engine bay with a highly efficient heat-reflector: gold foil. Approximately 16 g (0.56 ounce) of gold was used in each car.

The road version of the engine used a compression ratio of 11:1 to produce a maximum power output of 461 kW (618 hp; 627 PS) at 7,400 rpm and 650 N⋅m (479 lb⋅ft) of torque at 5,600 rpm. The engine's rev limiter is set at 7,500 rpm. In contrast to raw engine power, a car's power-to-weight ratio is a better method of quantifying acceleration performance than the peak output of the vehicle's power plant. The standard F1 achieves 550 hp/ton (403 kW/tonne), or just 0.27 hp/lb.

The cam carriers, covers, oil sump, dry sump, and housings for the camshaft control are made of magnesium castings. The intake control features twelve individual butterfly valves, and the exhaust system has four Inconel catalysts with individual Lambda-Sondion controls. The camshafts are continuously variable for increased performance, using a system very closely based on BMW's VANOS variable valve timing system for the BMW M3; it is a hydraulically actuated phasing mechanism which retards the inlet cam relative to the exhaust cam at low revs, which reduces the valve overlap and provides for increased idle stability and increased low-speed torque. At higher rpm the valve overlap is increased by computer control to 42 degrees (compare to 25 degrees on the M3) for increased airflow into the cylinders and thus increased performance.

To allow the fuel to atomise fully, the engine uses two Lucas injectors per cylinder, with the first injector located close to the inlet valve – operating at low engine rpm – while the second is located higher up the inlet tract – operating at higher rpm. The dynamic transition between the two devices is controlled by the ECU. Each cylinder has its own miniature ignition coil. The closed-loop fuel injection is sequential. The engine has no knock sensor as the predicted combustion conditions would not cause this to be a problem. The pistons are forged in aluminium.

Every cylinder bore has a Nikasil coating giving it a high degree of wear resistance. From 1998 to 2000, the Le Mans–winning BMW V12 LMR sports car used a similar S70/2 engine. The engine was given a short development time, causing the BMW design team to use only trusted technology from prior design and implementation experience. The engine does not use titanium valves or connecting rods. Variable intake geometry was considered but rejected on grounds of unnecessary complication. As for fuel consumption, the engine achieves on average 15.2 mpg (15 L/100 km), at worst 9.3 mpg (25 L/100 km) and at best 23.4 mpg (10 L/100 km).

It was later revealed that BMW had used an E34 M5 Touring as a test mule in order to test the engine. The existence of such a test mule was revealed when David Clark, the director of McLaren road and race cars from 1994–1998 disclosed this fact to motoring journalist Chris Harris in a podcast. Clark also revealed that the prototype was kept out of the public eye and that BMW is still in possession of the prototype where it has been kept in their top-secret prototype storage facility.

### Chassis and body

The McLaren F1 was an early example of a production road car using a complete carbon fibre reinforced polymer (CFRP) monocoque chassis structure. Aluminium and magnesium were used for attachment points for the suspension system, inserted directly into the CFRP.

The car features a central driving position – the driver's seat is located in the middle, ahead of the fuel tank and ahead of the engine, with a passenger seat slightly behind and on each side. The vehicle doors move up and out when opened and are thus of the *butterfly* or dihedral type. Gordon Murray's design for the doors was inspired by the Toyota Sera.

The engine produces high temperatures under full application and thus causes a high temperature variation in the engine bay from no operation to normal and full operation. CFRP becomes mechanically stressed over time from high heat transfer effects and thus the engine bay was not constructed from CFRP.

### Aerodynamics

The overall drag coefficient on the standard McLaren F1 is *Cd*=0.32, compared with *Cd*=0.36 for the faster Bugatti Veyron, and *Cd*=0.357 for the SSC Ultimate Aero TT, which was the fastest production car from 2007 to 2010. The vehicle's frontal area is *C*dA=1.79 square metres (19.3 sq ft) and the S·Cd figure is 0.57. Because the McLaren F1 features *active* aerodynamics these are the figures presented in the most streamlined configuration.

The standard McLaren F1 road car features no fixed wing to produce downforce (compare to the LM and GTR editions); however, the overall design of the underbody of the McLaren F1 in addition to a rear diffuser exploits ground effect to improve downforce which is increased through the use of two electric Kevlar fans to further decrease the pressure under the car. A "high downforce mode" can be turned on and off by the driver. At the top of the vehicle, there is an air intake to direct high pressure air to the engine with a low pressure exit point at the top of the very rear. Under each door is a small air intake to provide cooling for the oil tank and some of the electronics. The airflow created by the electric fans not only increases downforce, but the airflow that is created is further exploited through design, by being directed through the engine bay to provide additional cooling for the engine and the ECU. At the front, there are ducts assisted by a Kevlar electric suction fan for cooling the front brakes.

There is a small dynamic rear spoiler on the tail of the vehicle, which will adjust dynamically and automatically attempt to balance the centre of gravity of the car under braking – which will be shifted forward when the brakes are applied. Upon activation of the spoiler, a high pressure zone is created in front of the flap, and this high pressure zone is exploited—two air intakes are revealed upon application that will allow the high pressure airflow to enter ducts that route air to aid in cooling the rear brakes. The spoiler increases the overall drag coefficient from *Cd*=0.32 to *Cd*=0.39 and is activated at speeds equal to or above 40 mph (64 km/h) by brake line pressure.

### Suspension

Steve Randle, who was the car's dynamicist, was appointed responsible for the design of the suspension system of the McLaren F1. It was decided that the ride should be comfortable yet performance-oriented, but not as stiff and low as that of a true *track machine*, as that would imply a reduction in practical use and comfort as well as increasing noise and vibration, which would be a contradictory design choice in relation to the former set premise – the goal of creating the *ultimate road car*.

From inception, the design of the F1 had a strong focus on weight distribution by extensive manipulation of placement of, among other things, the engine, fuel and driver, allowing for a low polar moment of inertia in yaw. The F1 has 42% of its weight at the front and 58% at the rear, this figure changes less than 1% with the fuel load.

The distance between the mass centroid of the car and the suspension roll centre was designed to be the same front and rear to avoid unwanted weight transfer effects. Computer controlled dynamic suspension was considered but not applied due to the inherent increase in weight, complexity and loss of predictability of the vehicle.

**Damper and spring specifications**: 90 mm (3.5 in) bump, 80 mm (3.1 in) rebound with bounce frequency at 1.43 Hz at the front and 1.80 Hz at the rear. Despite being sports oriented, these figures imply a soft ride and inherently decrease track performance. As can be seen from the McLaren F1 LM and the McLaren F1 GTR track variants, the track performance potential is much higher than that in the standard F1 road car due to the fact that the car should be comfortable and usable in everyday conditions.

The suspension is a double wishbone system with an unusual design. Longitudinal wheel compliance is included without loss of wheel control, which allows the wheel to travel backwards when it hits a bump – increasing the comfort of the ride.

Caster wind-off at the front during braking is handled by McLaren's proprietary *Ground Plane Shear Centre* – the wishbones on either side in the subframe are fixed in rigid plane bearings and connected to the body by four independent bushings which are 25 times more stiff radially than axially. This solution provides for a caster wind-off measured to 1.02 degrees per g of braking deceleration. Compare the Honda NSX at 2.91 degrees per g, the Porsche 928 S at 3.60 degrees per g and the Jaguar XJ6 at 4.30 degrees per g respectively. The difference in toe and camber values is also very small under lateral force application. The *Inclined Shear Axis* is used at the rear of the machine and provides measurements of 0.04 degrees per g of change in toe-in under braking and 0.08 degrees per g of toe-out under traction.

When developing the suspension system, the facility of electro-hydraulic kinematics and compliance at AB Dynamics was employed to measure the performance of the suspension on a Jaguar XJR16, a Porsche 928 S and a Honda NSX to use as references.

Steering knuckles and the top wishbone/bell crank are also specially manufactured in an aluminium alloy. The wishbones are machined from a solid aluminium alloy with CNC machines.

### Tyres

The McLaren F1 uses 235/45ZR17 front tyres and 315/45ZR17 rear tyres. These are specially designed and developed solely for the McLaren F1 by Goodyear, Michelin, Avon and Pirelli. The tyres are mounted on 17 by 9 in (431.8 by 228.6 mm) front, and 17 by 11.5 in (431.8 by 292.1 mm) rear five-spoke cast magnesium wheels, coated with a protective paint and secured by magnesium retention pins.

The turning circle from kerb to kerb is 13 m (42.7 ft), allowing the driver 2.8 turns from lock to lock.

### Brakes

The F1 features unassisted, vented and cross-drilled brake discs made by Brembo. The Front size is 332 mm (13.1 in) and the rear 305 mm (12.0 in). The calipers are all four-pot, opposed piston types, and are made of aluminium. The rear brake calipers do not feature any handbrake functionality, however there is a mechanically actuated, fist-type calipers which is computer controlled and thus serve as a handbrake.

To increase caliper stiffness, the calipers are machined from a single solid piece of metal (in contrast to the more common being bolted together from two halves). Pedal travel is slightly over one inch. Activation of the rear spoiler will allow the air pressure generated at the back of the vehicle to force air into the cooling ducts located at either end of the spoiler which become uncovered upon application of it.

Servo-assisted ABS brakes were ruled out as they would imply increased mass, complexity and reduced brake feel; however, at the cost of increasing the required skill of the driver.

Gordon Murray attempted to utilise carbon brakes for the F1, but found the technology to be not advanced enough at the time; with one of the major culprits being that of a proportional relationship between brake disc temperature and friction—i.e. stopping power—thus resulting in relatively poor brake performance without an initial warm-up of the brakes before use. Since carbon brakes have a more simplified application envelope in pure racing environments, this allows for the racing edition of the car, the *F1 GTR*, to feature ceramic carbon brakes.

### Gearbox and powertrain

The standard McLaren F1 has a transverse 6-speed manual gearbox with an AP carbon triple-plate clutch contained in an aluminium housing. The gearbox was developed in collaboration with Weismann transmissions in California. The second generation GTR edition has a magnesium housing. Both the standard edition and the 'McLaren F1 LM' have the following gear ratios: 3.23:1, 2.19:1, 1.71:1, 1.39:1, 1.16:1, 0.93:1, with a final drive of 2.37:1, although the final gear is offset from the side of the clutch. The Torsen Limited Slip Differential has a 40% lock. The sixth gear ratio allows for a longer cruise at 53 km/h (33 mph) per 1000 rpm.

The McLaren F1 has an aluminium flywheel that has only the dimensions and mass absolutely needed to allow the torque from the engine to be transmitted. This is done in order to decrease rotational inertia and increase the responsiveness of the drivetrain, resulting in faster gear changes and better throttle feedback. This is possible due to the F1 engine lacking secondary vibrational couples and featuring a torsional vibration damper by BMW.

### Interior and Equipment

Standard equipment for the McLaren F1 includes full cabin air conditioning, a rarity on most sports cars and a system design which Murray again credited to the Honda NSX, a car he had owned and driven himself for 7 years without ever needing to change the AC automatic setting. Further comfort features included SeKurit electric defrost/demist windscreen and side glass, electric window lifts, remote central locking, Kenwood 10-disc CD stereo system, cabin access release for opening panels, cabin storage compartment, four-lamp high performance headlight system, rear fog and reversing lights, courtesy lights in all compartments, map reading lights and a gold-plated Facom titanium tool kit and first aid kit (both stored in the car). In addition, tailored, proprietary luggage bags specially designed to fit the vehicle's carpeted storage compartments, including a tailored golf bag, were standard equipment. Airbags are not present in the car. Each customer was given a special edition TAG Heuer 6000 Chronometer wristwatch with its serial number scripted below the centre stem.

All features of the F1 were, according to Gordon Murray, obsessed over, including the interior. The metal plates fitted to improve the aesthetics of the cockpit are claimed to be 20 thousandths of an inch (0.5 mm) thick to save weight. The driver's seat of the McLaren F1 is custom fitted to the specifications desired by the customer for optimal fit and comfort; the seats are handmade from CFRP and covered in light Connolly leather. By design, the F1 steering column cannot be adjusted; however, prior to production each customer specifies the exact preferred position of the steering wheel and thus the steering column is tailored by default to those owner settings. The same holds true for the pedals, which are not adjustable after the car has left the factory but are tailored to each specific customer.

During its pre-production stage, McLaren commissioned Kenwood, the team's supplier of radio equipment, to create a lightweight car audio system for the car; Kenwood, between 1992 and 1998 used the F1 to promote its products in print advertisements, calendars and brochure covers. Each car's audio system was specially designed to tailor to an individual's listening taste; however, radio was omitted because Murray felt it wasn't necessary.

### Purchase and maintenance

Only 106 cars were manufactured: 5 prototypes (XP1, XP2, XP3, XP4, XP5), 64 road versions (F1), 1 tuned developmental prototype (XP1 LM), 5 tuned versions (LM), 1 longtail developmental prototype (XPGT), 2 longtail versions (GT), and 28 racecars (GTR). Production began in 1989 and ended in 1998. At the time of production, each car took around three and a half months to make.

Although production stopped in 1998, McLaren still maintains an extensive support and service network for the F1. Every standard F1 has a modem which allows customer care to remotely fetch information from the ECU of the car in order to assist the customer in the event of a mechanical vehicle failure. There are eight authorised service centres throughout the world, and McLaren will on occasion fly a specialised technician to the owner of the car or the service centre. All of the technicians have undergone dedicated training in service of the McLaren F1. In cases where major structural damage has occurred, the car can be returned to McLaren directly for repair.

### Performance

The F1 remains one of the fastest production cars ever made; as of October 2018, it is outmatched by very few cars, including the Bugatti Veyron and the Bugatti Chiron.

However, all of the higher top speed machines use forced induction to reach their respective top speeds, whereas the McLaren F1 is naturally aspirated. To date the F1 holds the record for fastest naturally aspirated production car, a record it has held for almost 30 years.

## Prototypes

Prior to the sale of the first McLaren F1s, five prototypes were built, carrying the numbers XP1 through XP5. These cars carried minor subtle differences between each other as well as between the production road cars. Contrary to common misunderstanding, XP1, the first ever running prototype, was never publicly unveiled. The XP1 was never painted (with a bare carbon fibre exterior) and was later destroyed in an accident in Namibia. The car unveiled at the Monaco 1992 event was actually a "Clinic Model", aesthetically convincing but without a powertrain. XP2 was used for crash testing (sporting a blue colour during the test) and also destroyed. As it was a crash test car, it didn't have full interior equipment or a powertrain. XP3 did durability testing, XP4 stress tested the gearbox system and XP5 was a publicity car. The XP3 used to be owned by Gordon Murray before being sold to a private buyer. XP4 was seen by viewers of *Top Gear* when reviewed by Tiff Needell in the mid-1990s and later on sold to a private owner, while XP5 went on to be used in McLaren's famous top speed run and is still owned by McLaren.