Features - Technical
JANUARY 12, 1999
Formula1 and road cars compared
BY PETER WRIGHT
Apart from the fact that both are 4-wheeled land vehicles used for conveying people, and powered by petrol-fuelled piston engines, there is very little similarity between a Formula1 car and a road car.
Road cars come in many guises from small town cars right up to the super-cars like the McLaren F1 and Ferrari F50, which themselves have been derived from racing technology. However, here we are concerned with comparing a Formula1 car with the sort of road car the average person might buy for everyday transport e.g. a 1.6 litre saloon car such as a Toyota Corolla. If Mr Average was to turn to his favourite motoring magazine to compare the data on new models and, by some extraordinary chance, there happened to be the data on a Formula1 car included in the tables, what differences in specification and performance characteristics would he find?
1.6l saloon Formula1
Body type 5-seater, 4/5-door Single-seater, open-cockpit, open-wheels.
Engine 4 cyl., in-line, 1.6l V-10, 3.0l
Power 109bhp @ 6,000rpm 800+bhp @ 18,000rpm
Power/litre 68 270
Empty weight 1150kg 530kg
Power/weight 0.06bhp/kg 1.5bhp/kg
0-100kph 8.9secs 2.4secs
Top speed 190 kph 350kph
Fuel consumption
(average) 8 litres/100km 80 litres/100km
Price $23,000 $500,000+
If he or she was good at mental arithmetic they would realise that they could have a car, albeit for one person instead of 4 or 5, that had 3.7 times the acceleration from 0-100kph, 1.8 times the top speed, but 10 times the fuel consumption. To achieve this the engine is only 1.9 times the size but has nearly 4 times the power per litre, giving 7.3 times the power in total. In a car less than half the empty weight this equates to 16 times the power to weight ratio, so it would be exciting to drive. The price of the Formula1 car, over 20 times that of the road car, might dampen the prospective purchaser's enthusiasm and the news that it could not be driven on the road would probably bring him back down to earth with a bump!
[Note! These numbers will probably need changing for a Japanese-market Corolla]
It was in the 1970's that both Formula1 and road cars began to feel the affect of regulations. For safety reasons and to curtail the rise in performance brought about by sponsor funded technical development in the case of Formula1; and due to the public's awareness of safety and environmental issues in the case of road cars. Until that time, the design of both types of car was driven entirely by what they needed to do. Racing cars were designed purely for speed around a closed circuit and they only had to keep running long enough to complete the race. Road cars however, had to compete for a share of the market for everyday transport. Factors such as cost, cost of ownership, cost per kilometre, interior space, safety, comfort, tank range, life span, accessories to make journeys less tedious, style, and the pleasure of ownership mattered at least as much as performance. For a start, a car that only carries one person, who gets wet when it rains, and the wheels of which would not only throw up sheets of spray and road dirt, but would also tangle with the wheels of other similar cars, would not be a popular arrangement for a road car!
The regulations in Formula1 mandate that the open-cockpit, open-wheeled arrangement must be used. Performance, through engine, aerodynamic and tyre development and the use of exotic materials, has become so potentially high that every aspect is controlled to a level at which their operation on circuits can be made practically safe. The remainder of the regulations govern safety aspects of the construction and systems, and both are tested and checked by the governing body, the FIA.
Road cars are also regulated for safety reasons. Not only is the construction tested for its performance in crashes, but the ability to see and be seen is also controlled. The environmental impact, in terms of noise, noxious emissions, and in some countries even fuel consumption, is governed by ever tighter regulations. What is largely unregulated is performance, although various countries have ways of discouraging the use of high top speeds, even if the cars are capable of them.
With such varied requirements and regulations to be met, it is not surprising that the two types of vehicle are so different, both visually and in their specification.
Body/chassis structures.
The chassis arrangement of a Formula1 car evolved over 20 years at Lotus. Colin Chapman first built an aluminium monocoque (T25) in 1962. With the 1967 T49, he bolted the Cosworth DFV engine to the rear of the cockpit and used it and the gearbox as part of the chassis. In 1978, the T79 had a single fuel tank between cockpit and engine, forming that part of the structure connecting the two. The arrangement was completed in 1981, by replacing the aluminium sheet metal skins with CFRP, resulting in the basic layout and specification still in use today, albeit with considerable further refinement and benefiting from CAD/CAE and the latest materials and processes. Suspension loads are fed directly into the CFRP honeycomb-sandwich skins at the front, and into the engine/gearbox assembly at the rear. The requirements for this structure are high stiffness, low weight and the ability to protect the driver in a crash. Fuel tankage is sufficient to complete half a race minimum (160 km) i.e. 130-150 litres. The monocoque itself forms part of the body surface and CFRP panels cover the engine and gearbox.
A 5-door saloon car body has been described as a series of load concentrations connected by holes. The need to provide the structure that connects together the suspension and drive train load input points, with access and vision apertures (doors, windows, bonnet, boot) has meant that welded steel is used almost universally to construct the body/chassis unit. Aluminium has been used (Audi A8, Honda NSX, Lotus Elise) and is under intense development in the quest for lower weight; however, it is expensive. Even more expensive, due to labour intensive processes, are composites. Steel provides the best compromise between strength/weight and cost. Impact absorption is built into the structure, steel again being ideal for this purpose.
Steel corrodes and so must be treated and painted to prevent rust over the life of the vehicle. Buyers of road cars are choosy about the colour and finish of their purchases and a wide variety of high-gloss colours, including metallic and special finishes, is available. Formula1 cars are painted too and use the same high-gloss, chip-resistant paints as road cars. Colour schemes are much wilder, incorporating the corporate colours and logos of the sponsors. These are either applied using the artistic skills of air-brush painters or using computer-controlled, laser-cut decals.
The fuel tank in a road car is mounted within the structure, and moulded in plastic. Typically, the capacity is sufficient to give a range of around 600-700km.
Aerodynamics.
The generation and control of aerodynamic downforce, with the minimum drag penalty, occupies a very large part of the R&D budget of Formula1 teams. The performance of the car, i.e. top speed, acceleration, braking and cornering, depend on it. Every detail of the exterior shape and internal ducting is refined in the quest for downforce. Wings, borrowed from aerospace, are added to extract the last gram of downforce from the air flowing past the car.
Road cars do not need the ultimate in performance, and the speeds are generally too low most of the time to generate any significant downforce in relation to their mass. Drag however, is important - it dominates motorway fuel consumption and that all important marketing feature, top speed. A saloon car body generates lift and this generates drag. Road car aerodynamicists have learnt from their racing car counterparts and apply some ground effect aerodynamics to cancel out the upper-body lift, and so reduce drag. The distribution of lift/downforce is important for stability and sometimes the inclusion of nose spoilers and vestigial rear wings may fine tune this on the faster models, but tend to be more of a styling feature. Cross wind stability has become a problem with the low-drag shapes of the last few decades, and it took a while for some designers to master it.
Engines.
It is in the engines of the two cars that we find the greatest similarity in configuration, but one of the greatest differences in performance. Both have petrol-fuelled, 4-stroke, piston engines with twin overhead camshafts operating 4-valves/cylinder, and electronic fuel injection. The swept volumes of each cylinder are similar - 300cc for the Formula1 car, 400cc for the road car. So why does the Formula1 engine produce nearly four times the power per litre compared to the road car engine? 75% of the answer is "rpm". The road car engine produces its peak power at 6,000rpm, which limits the amount of air, and hence fuel for combustion, that can be passed through the engine per minute. This in turn limits the amount of energy that can be released per minute. The Formula1 engine turns at three times that rate and so can release three times the energy to produce three times the power. The other 25% increase in power/litre comes from optimising the breathing and combustion in the engine.
Much of the development of racing engines is involved with designing and developing the moving parts so that they survive the high inertial loads associated with high rpm. High speeds also result in friction and pumping losses and therefore inefficiency. The use of exotic materials to lighten reciprocating parts, the short period between overhauls, the low life of components, and the inefficiency of high engine speeds would not be tolerable in a road car, and so rpm is generally limited to 6000, except for sporty models.
Racing engines do not need a broad power band, the driver being able to operate the engine within a narrow rpm band i.e. around 10-15% of the peak figure. Some road car users drive everywhere in top gear and the manufacturers must provide an engine that does not protest too much at this treatment. The Formula1 engine designer can choose a bore to stroke ratio, valve timing, intake and exhaust pipe lengths etc. optimised for power within this narrow rpm band. It is this freedom to optimise for a narrow operating range that brings the last 25% increase in specific power.
Apart from power, the Formula1 engine is designed for low weight, structural stiffness (it is part of the chassis) and small size. To lower the engine as much as possible it is dry-sumped, using multiple scavenge oil pumps to ensure losses are not incurred by churning oil around inside the crankcase. Road car engines are becoming lighter too, with increased use of aluminium and plastics. However, it is hard to make an engine quiet if it is too light and refinement is a big selling point. The engine in a road car is not part of the chassis structure, being mounted on rubber isolators to ensure the minimum transfer of vibration to the resonant body structure.
Both types of engine are computer-controlled, the techniques having been first developed by the road car industry to control emissions and subsequently used in racing. Ignition, fuel, airflow, temperatures and pressures, rpm etc. are all monitored by a central computer and the operation of the engine optimised to the driver's commands. While the control laws used in the Formula1 engine are targeted at giving the driver maximum power under all conditions, the road car's are heavily influenced by the need to control the emissions and to optimise the fuel consumption, while providing a smooth, driveable engine at all times, even when it is cold.
Transmissions.
Racing cars have their engines mounted just ahead of and driving the rear wheels, for pure performance reasons. Small to medium saloon cars have it mounted between and driving the front wheels for driveability, cost and packaging reasons. The means of transmitting engine torque to the driven wheels is determined by the arrangement, but at the heart of each type of transmission are similar sets of gears and shafts. Road cars are equipped with either a manual, H-pattern, synchromesh gear shift (4 or five gears) and foot-operated clutch, or a torque-converter and automatic gearbox. Formula1 cars have electro-hydraulic gear-change (sequential, dog-clutch engagement) and clutch mechanisms (6 or occasionally, 7 gears), commanded by driver-operated paddle-switches behind the steering wheel. Gear-changes are completed in under 30milliseconds for minimum loss of acceleration. Full automatic operation is not now permitted, but would be very straightforward to implement. This type of gearbox, with manual and automatic options, is beginning to appear in road cars. Offering the best of both fast, simple manual and fully automatic operation, the arrangement is more efficient than a classic automatic and can be fully integrated with the engine.
Differentials in road cars tend to be of the open type, though viscous differentials are fitted to high performance FWD road cars. Formula1 cars have been fitted with a variety of limited-slip differentials, but computer controlled systems are now most common.
Suspensions.
Formula1 suspensions hardly move! They are set up very stiff (maybe 10 times stiffer than a road car's) so that the body of the car moves as little as possible relative to the road when subjected to high aerodynamic downforce and inertial loads. As a result, racing circuits have to be incredibly smooth, otherwise the drivers complain. Suspension linkage arrangements are dictated entirely by the need to control the geometry very precisely and there are no rubber bushes in the suspension. Links are made of CFRP. Coil or torsion-bar springs are used and dampers are adjustable for tuning.
Road car suspension systems are dictated by cost and packaging constraints, rather than precise geometry requirements. The McPherson strut is commonly used at the front and a variety of arrangements are used at the rear, selected so that they do not intrude into the passenger or trunk space. Coil springs and fixed characteristic dampers are most common. Virtually all the inboard linkage pivots are rubber bushes to absorb the road irregularities and prevent them being heard inside the car.
Wheels and tyres.
Formula1 cars are fitted with forged magnesium wheels for optimum stiffness/weight. Most road cars have pressed-steel wheels, but cast aluminium options are available for most models or as after-market items. Formula1 front wheels are over twice as wide as those on a 1.6l saloon, and nearly 3 times as wide at the rear.
Racing tyres are designed for the best possible traction and cornering and are only expected to last around 100-150kilometres before being worn out. Inflated to 1-1.5 bar, they operate best at a tread temperature of 100-130 degrees C. Such is the degree of optimisation that different designs are needed if the track is wet: construction, treads design and rubber compound are all different. The coefficient of friction of dry weather racing tyres is around 1.7.
Road car tyres must work under all conditions - hot, cold, dry, wet, even snow and ice. They must also be quiet, not transmit road irregularities to the car, contribute to a low fuel consumption, last around 50,000kms if treated carefully, and not cost too much. Their coefficient of friction on a dry road is around 1.0.
In spite of these great differences, there is no doubt that the tyre companies in Formula1 learn a great deal that is useful to the development of road tyres.
Brakes.
Formula1 brakes employ discs and pads made of carbon fibre reinforced carbon, and run at temperatures in excess of 600degrees C. Cooling them adequately to deal with repeated stops from over 300kph is critical. A set of discs and pads can easily be worn out during a 300kilometre race.
Running a road car's cast-iron discs and synthetic pads at these temperatures would destroy them. A more critical situation for road car brakes is that they must work the instant they are applied, even if they are cold and wet, as they might well be prior to an emergency stop on a motorway. The rest of the braking system is quite similar, though Formula1 cars are not permitted to be fitted with power assistance nor ABS, both of which are common on road cars.
Cockpit, controls and displays.
The Formula1 driver experiences accelerations of over 4g and must be able to control his car while being subjected to these loads. His seat and all his controls are tailored to him personally and he is strapped in using a 6-point harness. Without heating or air-conditioning, cockpit temperatures can exceed 50 degrees C, and when it rains he gets cold and wet.
Most Formula1 cars have only two pedals - a throttle pedal and a brake pedal that can be operated by either foot. Gear-changing paddle-switches are behind the small diameter steering wheel, as is another paddle for operating the clutch for starting (it is automatic during gear changes). There are a minimum of instruments, instead warning lights indicate the need to change gear, or that some temperature for pressure is out of limits. A small LCD display in the centre of the steering wheel then tells him which system is faulty. It can also display other information of interest, such as the time for the last lap. There is no speedometer.
A number of dials and switches on the steering wheel and around the cockpit allows the driver to adjust certain engine and chassis parameters, while buttons enable him to make radio contact with his Pit, have water pumped into is mouth, or select neutral. Each car has a different arrangement, developed to suit the individual driver.
In contrast, road cars attempt to make the driver as comfortable as possible, to make the control of the car as easy as possible, and to keep the driver informed and even entertained. The range of displays, switches and accessory controls is so great that many drivers never learn how to operate everything. Cockpit temperature can be controlled automatically to a set level; controls are so light that the car can be driven with one hand; and the noise level so low that sophisticated sounds systems are able to provide music to almost the same quality as in the home.
More and more active control systems are being developed to assist the road car driver with the driving task. Fitted mainly to the more expensive road cars, they are now appearing as options are the more popular models. ABS, traction control, anti-skid etc. will soon be standard fit on most cars. None of these systems, even though some were developed on Formula1 cars, are now allowed in Formula1, being classed as "driver-aids".
Computers, control systems and data systems.
Formula1 cars are moving towards having a single, central computer, networked to nodes distributed around the car. However, due to separate makers of the chassis and engine, it is more common at the moment for there to be a chassis computer and an engine computer, still networked together to minimise the wiring loom. Gearbox, data system, steering wheel, dashboard, and all other control systems will be linked to the network. There may be as many as 100 or more sensors connected to the network, either inputting to one of the systems or for data collection. Data is transmitted by telemetry to the Pits, or stored on-board for downloading when the car is stationary.
An FIA accident data recorder is fitted to the cars, and also connected to the network, to gather information about crashes and their cause.
A central hydraulic system provides power to operate many of the control systems, including the drive-by-wire, gear-change, clutch, differential and power-steering systems.
Road cars also have a number of computers, but only some of the more expensive cars have networked systems, where the number and complexity of the accessories makes this worthwhile. Engine, automatic gearbox, ABS, heating/air conditioning, air-bags, music systems and navigation aids are just some of the systems under microprocessor control.
Hydraulic power is used for power-steering and ABS brakes, but they are not integrated. There is a move to get rid of hydraulics on small cars, and electric steering is gaining ground.
Data systems store information about failures, for uploading by the service garage. Before too long, accident recorders, integrated with air-bag systems, will provide legal evidence about crashes.
Safety.
Formula1 drivers are expected to drive at the limit and therefore sometimes have accidents. The protective cell of the monocoque is surrounded, front, rear and sides, by energy absorbing structures. When combined with circuit run-off areas and barriers, and the protective clothing worn by the drivers, there is a very low risk of injury in the event of an accident.
The first safety objective for road users is to avoid having an accident. Rules and regulations attempt to ensure that drivers do not drive near the limit and lose control. However, road car drivers are not professionals and may be subjected to many distractions as well as suffering impairment due to health, drugs or alcohol. Protecting the occupants of a road car is accomplished in approximately the same way as a Formula1 car - the passengers ride in a rigid survival cell surrounded by energy absorbing structures. In addition, the driver and passengers are encouraged to wear seat belts and, in ever-increasing numbers, are protected by air-bag systems. In spite of all these precautions, there is less likelihood of injury during a crash in a Formula1 car than in an equivalent accident in a road car.
Environmental impact.
The only concession to the environment that is imposed on Formula1 cars is the specification of the fuel used. A few years ago, fuel was more loosely regulated and some fairly noxious substances were being emitted; now they use what is virtually pump petrol. However, no emission regulations are in force and they do not run with catalysts. A lack of silencers means that the noise levels are well beyond what is allowed in areas where people live or work.
Road cars however, are so closely controlled concerning what they may emit that the gas coming out of the exhaust is often cleaner than the air entering the engine! Noise is subject to strict standards. Levels of re-cycling are increasing all the time with more and more responsibility being put on the manufacturers to dispose of there products when they come to the end of their useful life.
Maintenance and life.
Formula1 cars are completely stripped and rebuilt, often with new components, possibly every 300-500kilometres. This includes engine and gearbox, many of the components of which will have used up their life over this short distance. The cost of parts for such a service may be $100K or more. If we include the cost of tyres and labour, the total cost can easily rise to over $500 per kilometre. Formula1 cars tend to be obsolete after one year and an individual car may only run 5,000km in that year before it is put onto the show-car circuit.
A 1.6 litre saloon car owner would not expect to pay more than around $0.4 per kilometre for services, nor to have to go to the bother of taking it to a garage more often than every 15,000km. He would also not expect to have any major components replaced during the first 150,000-200,000km.
Performance.
Let us suppose for a moment that our prospective new car purchaser has researched all these differences between a Formula1 car and the 1.6 litre saloon he had intended to buy. Not put off by the open cockpit and wheels, and having just won the Lottery, he orders a brand-new Formula1 car. Dressed in fire-proof suit and crash helmet, he straps in and starts up. What differences would he experience?
The noise and vibration, even before he moved off, would be pretty awesome. Engaging first gear would only require a quick pull on the gear-change paddle and then he would probably stall the engine as he let in the very sharp clutch, using the other steering wheel paddle - after all, Michael Schumacher did! Anything more than half throttle would spin the rear wheels and probably spin the car. A bit less, and our proud owner would be doing 100kph a couple of seconds later. The gear change lights would be twinkling, telling him to change gear and further gear-changes would be needed every few seconds until he was in 6th, by which time the speed would be climbing towards 300kph.
Assuming he is on a closed track, with only corners and no traffic to contend with, he could stay of the brakes until less than 100 metres before the corner. He would need all his strength to apply the brakes and the 4g that resulted would make his head slump forward and his body strain hard against the straps. Slowing to 150kph for the 3rd gear corner, 3g could easily be maintained around it. Whether he could hold is head up to see where he was going, or hold the steering wheel against the hard kicks it gave him would depend how strong his neck, shoulder and arm muscles were. One or two laps and he would be bruised and aching. Definitely not a 1.6l saloon car. Every control input provokes an instant, almost violent response, and it is easy to over do it and lose control. Road car responses are muted by comparison and built-in stability prevents loss of control except under the most severe control inputs or external influences.
Driving a Formula1 car is an extremely physical experience, even for an very fit racing driver. In two hours of hard racing they can lose 3 or 4kg through dehydration; if not properly prepared they can suffer cramps and exhaustion. But, in spite of the battering it gives it's driver, there is no doubt that driving and mastering such a machine is an experience that can never even be approached in a car designed for road use.