McLaren F1, 1993

McLaren F1, 1993

 

 

 The McLaren F1 is a sports car designed and manufactured by Gordon Murray and McLaren Automotive. On March 31, 1998, it set the record for the fastest production car in the world, 240 mph (391 km/h). As of April 2009, the McLaren F1 is succeeded by three faster cars in sheer top speed, but is still the fastest naturally aspirated production car.

The car features numerous proprietary designs and technologies. It is lighter and has a more streamlined structure than even most of its modern rivals and competitors despite having one seat more than most similar sports cars, with the driver's seat located in the middle. It features a powerful engine and is somewhat track oriented, but not to the degree that it compromises everyday usability and comfort. 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 24 Hours of Le Mans in 1995, 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.

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 use of high-tech and expensive materials like carbon fibre, titanium, gold, magnesium and kevlar. The McLaren F1 was the first production car to use a carbon-fibre monocoque chassis.

The idea was first conceived when Murray was waiting for a flight home from the fateful Italian Grand Prix in 1988; Murray drew a sketch of a three seater sports car and proposed it to Ron Dennis, pitched as the idea of creating the ultimate road car, a concept that would be heavily influenced by the Formula One experience and technology of the company and thus reflect that skill and knowledge through the McLaren F1.

Engine
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 introducing an additional aspect of latency and loss of feedback, the ability of the driver to maintain maximum control of the engine is thus decreased. Murray initially approached Honda for an NA powerplant with 550 bhp (410 kW; 560 PS), 600 mm (23.6 in) block length and a total weight of 250 kg (551 lb), it should be derived from the Formula One powerplant in the then-dominating McLaren/Honda cars.

When Honda refused, Isuzu, then planning an entry into Formula One, had a 3.5 V12 engine being tested in a Lotus chassis. The company was very interested in having the engine fitted into the McLaren F1. However, the designers wanted an engine with a proven design and a racing pedigree.

The final result is a custom-built 6.1 L (6064 cc) 60-degree V12 with an aluminium alloy block and head, 86 mm (3.4 in) x 87 mm (3.4 in) bore/stroke, quad overhead camshafts for maximum flexibility of control over the four valves per cylinder and a chain drive for the camshafts for maximum reliability, the engine is dry sump. At 266 kg (586 lb), the resulting engine was slightly heavier than Murray's original maximum specification weight of 250 kg (551 lb) but was also considerably more powerful than he had specified. The bespoke engineered engine for the McLaren F1 is called the BMW S70/2.

The carbon fibre body panels and monocoque required significant heat insulation in the engine compartment, so Murray's solution was to line the engine bay with a highly efficient heat-reflector: gold foil. Approximately 25 g (0.8 ounce) of gold was used in each car.

The road version used a compression ratio of 11:1 to produce 627 hp (468 kW; 636 PS) at 7400 rpm—considerably more than Murray's specification of 550 horsepower (404 kW). Torque output of 480 ft·lb (651 N·m) at 5600 rpm. The engine has a redline rev limiter set at 7500 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 powerplant. The standard McLaren F1 achieves 550 hp/ton (403 kW/tonne), or just 3.6 lb/hp. Compare with the Ferrari Enzo at 434 hp/ton (314 kW/tonne) (4.6 lb/hp), the Bugatti Veyron at 530.2 hp/ton (395 kW/tonne) (4.1 lb/hp), and the SSC Ultimate Aero TT with an alleged 1003 hp/ton (747.9 kW/tonne) (2 lb/hp).

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-Sond controls. The camshafts are continuously variable for increased performance, using a system very closely based on BMW's VANOS variable 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 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 engine computer.

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.

Chassis and body
The McLaren F1 was the first production road car to use a complete carbon fiber reinforced plastic (CFRP) monocoque chassis structure. Aluminium and magnesium was 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 either side. The doors on the vehicle move up and out when opened, and are thus of the type butterfly doors.

The engine produces high temperatures under full application and thus cause 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 decided to not be constructed from CFRP.

Aerodynamics
The overall drag coefficient on the standard McLaren F1 is 0.32, compared with 0.36 for the faster Bugatti Veyron, and 0.357 for the current holder of the fastest car world record (as of 2008) - the SSC Ultimate Aero TT (in terms of top speed). The vehicle's frontal area is 1.79 square meters and the total Cx is 0.57. Due to the fact that the machine features active aerodynamics these are the figures presented in the most streamlined configuration.

The normal McLaren F1 features no wings to produce downforce (compare 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 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 increase 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 an electric suction fan for cooling of the front brakes.

Suspension
Steve Randle who was the car's dynamicist was appointed responsible for the design of the suspension system of the McLaren F1 machine. It was decided that the ride should be comfortable yet performance oriented, however not as stiff and low as that of a true track machine, as that would imply 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 scratch the design of the McLaren F1 vehicle had strong focus on centering the mass of the car as near the middle as possible by extensive manipulation of placement of i.a. the engine, fuel and driver, allowing for a low polar moment of inertia in yaw. The McLaren 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 were designed to be the same front and rear to avoid unwanted weight transfer effects. Computer controlled dynamic suspension were considered but not applied due to the inherent increase in weight, increased 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 front and 1.80 Hz at the rear, despite being sports oriented these figures imply the rather soft ride and will inherently decrease track performance, but again, the McLaren F1 is not in concept nor implementation a track machine. As can be seen from the McLaren F1 LM, McLaren F1 GTR et al., the track performance potential is much higher than that in the stock McLaren F1 due to fact that car should be comfortable and usable in everyday conditions.

The suspension is a double wishbone system with an interesting design, i.a. that 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.

Castor 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 bushes which are 25 times more stiff radially than axially. This solution provides for a castor 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 are also of very small under lateral force application. Inclined Shear Axis is used at the rear of the machine 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 Anthony Best Dynamics was employed to measure the performance of the suspension on a Jaguar XL16, a Porsche 928S 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 and Michelin. The tyres are mounted on 17x9 inches and 17x11.5 inches cast magnesium wheels, protected by a tough protective paint. The five-spoke wheels are secured with magnesium retention pins.

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

Brakes
The McLaren F1 features unassisted, vented and crossdrilled brake discs made by Brembo. Front size is 332 mm (13.1 in) and at 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 caliper which is computer controlled and thus serves as a handbrake.

To increase caliper stiffness the calipers are machined from one single solid piece (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 utilize carbon brakes for the McLaren F1, but found the technology not mature 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 prior to use. As carbon brakes have a more simplified application envelope in pure racing environments this allows for the racing edition of the machine, the McLaren F1 GTR, to feature ceramic carbon brakes.

Gearbox and miscellaneous
The standard McLaren F1 has a transverse 6-speed manual gearbox with an AP carbon triple-plate clutch contained in an aluminium housing. 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, the final gear is offset from the side of the clutch. The gearbox is proprietary and was developed by Weismann. The Torsen LSD (Limited Slip Differential) has a 40% lock.

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 responsiveness of the system, resulting in faster gear changes and better throttle feedback. This is possible due to the McLaren F1 engine lacking secondary vibrational couples and featuring a torsional vibration damper by BMW.

Interior and equipment
Standard equipment on the stock 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, according to the official McLaren F1 website, 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 department, 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.

All features of the McLaren F1 were according to Gordon Murray obsessed over, which included the interior. The metal plates fitted to improve aesthetics of the cockpit are claimed to be 20/1000s of an inch 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 hand made from CFRP and covered in light Connolly leather. By design the F1 steering column can not 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 like the steering column the pedals are also tailored to each specific customer.

During its pre-production stage, McLaren commissioned Kenwood to create a lightweight car audio system for the car; Kenwood, between 1992 and 1998 used the McLaren F1 to promote its products in print advertisements, calendars and brochure covers. Each car audio system was especially designed to tailor to an individual's listening taste, however radio was omitted because Murray never listened to the radio.

Every standard McLaren F1 also has a modem which allows customer care to remotely fetch information from the ECU of the car in order to help aid in the event of a failure of the vehicle.

Purchase and maintenance
Only 106 cars were manufactured, 64 of which were the standard street version (F1), 5 were LMs (tuned versions), 3 were longtail roadcars (GT), 5 prototypes (XP), 28 racecars (GTR), and 1 LM prototype (XP LM). Production began in 1992 and ended in 1998. At the time of production one machine took around 3.5 months to make.

Up until 1998, when McLaren produced and sold the standard McLaren F1 models, they had a price tag of around 970 000 USD. The cars can sell for up to nearly twice that of the original price, due to the performance and exclusivity of the machine. They are expected to further increase in value over time.