Features - Technical

APRIL 7, 1998

Champcar and Formula1 compared


The cars of the two premier single-seater open-wheel racing formula - Formula1 and Champcar - look quite similar to the eye but underneath their sleek, sponsor embellished exteriors they are as different as chalk and cheese.

The cars of the two premier single-seater open-wheel racing formula - Formula1 and Champcar - look quite similar to the eye but underneath their sleek, sponsor embellished exteriors they are as different as chalk and cheese. These differences stem from two factors that have influenced the formulae as they both developed from their roots in motor racing between the two World Wars: circuits and technical regulations.

Formula1 has evolved from Grand Prix racing, fought out between the great European manufacturers on road courses around the world. It has always employed the best automotive technology and attracted the world's best racing drivers. Today it is still the world's major automobile manufacturers who possess the technology and resources to develop the top Formula1 engines, though specialist chassis manufacturers have taken over the build of the cars - my recent article on the British Motorsport Industry described many of the reasons behind this evolution. During the emergence of the specialist chassis constructors, engines developed by complementary specialist manufacturers, such as Coventry-Climax and Cosworth, gained temporary ascendancy due to better integration with the chassis, but they were never the most powerful engines. It was the demanding nature of the road courses that put the emphasis on chassis and aerodynamics rather than outright power.

The roots of Champcar racing in the USA, lie in the wood-board ovals of the 1920's. Post World War1, American racing embraced the technology of European GP cars (the 1913 Ernest Henry Peugeot in particular) and put on a spectacular show of power and speed. It quickly became a form of racing that was closed to the Europeans until the 1960's, when the British chassis constructors (Lola and Lotus) brought their rear engine technology to Indianapolis and transformed American oval racing. Anyone interested in this fascinating era, when the exquisite Millers and Deusenbergs dominated, should read Griffiths Borgeson's book "The Golden Age of the American Racing Car", published by the SAE. It is a book full of historical and technical detail and well illustrated with archive photographs.

Oval racing, epitomised since 1911 by the Indianapolis Speedway, puts its main demand on the engine. High speeds and the provision of multiple racing lines thanks to the banked corners, have satisfied the American appetite for "show". Oval racing is still at the heart of Champcar, and CART - the sanctioning body of Champcar - has carefully evolved the regulations to maintain the show element. However the inclusion of road courses into the series has broadened the appeal and enabled a closer comparison with Formula1 to be made.

Champcars come in two guises - either configured for road courses, with maximum aerodynamic downforce, or for ovals with medium wings and low drag body package. On Super-Speedways (Homestead, Montegi and Gateway) the wing configuration and underbody diffusers are limited by the regulations. Bigger differences lie below the skin and are the product of Technical Regulations that have been carefully evolved by CART and the teams to produce safe cars and to control speed and cost.


Champcars Formula1

· Type 4-stroke, turbocharged 4-stroke, NA

(40ins Hg max = 1.36bar)

· Capacity 2.65 litre 3.0 litre

· No. of cylinders 8 max 12 max

· Valves 4 max 5 max

(no pneumatic valve springs)

· Throttles Mechanical Drive-by-wire

· Control systems No VG-turbo No VG exhaust



· Fuel Methanol Petrol

· Power (bhp) 850+ at 14,000+rpm 750+ at 18,000+rpm

By evolving the regulations to encourage engines that generate their power through turbocharging rather than the sky-high revs of Formula1, CART has ensured an adequate supply of engines at a reasonable cost. They have also given themselves the means of controlling power and hence speeds on the ovals. Maximum boost pressure is controlled by a CART blow-off valve and, if speeds rise too fast, the maximum setting can be altered in the regulations. Doing this does not obsolete the existing engines, as reducing their capacity would do.

Methanol is used as the fuel because of two particular properties: firstly it has a higher Octane Rating than petrol, and so is less likely to cause detonation at high sustained power; secondly, it has a higher latent heat of evaporation for cooling the intake charge after it has been compressed by the turbocharger. Intercoolers do the same job, but are banned by CART. However the heat energy in methanol is much lower than petrol, and so volumetric fuel consumption is much higher. It also corrodes many metals, so fuel systems have to be designed accordingly. Methanol burns with an almost invisible flame, leading to extra precautions to avoid fires. Fuel tanks are protected by anti-ballistic blankets and the rubber bladders are so reinforced that to insert them into the fuel tank requires a hatch in the rear of the monocoque that is almost the size of the engine bulkhead. Refuelling is by gravity only.

Engine manufacturers must supply a minimum of 5 teams consisting of at least 7 cars. However, to encourage new manufacturers they may supply a single team initially, until the engine is developed sufficiently to meet the definition "Competition Proven". After that they must supply at least 5 cars for a year, prior to becoming a fully fledged supplier.

To avoid the supply of special or qualifying engines to favoured teams, there is a cost ceiling on engines, equal to 110% of the average cost of all engines the previous year.

Size and Weight:

Champcars Formula1

· Weight Ovals and road 693kg exc. driver 600kg inc. driver

Super-Speedways 704.5 kg exc driver @ 530kg ex. driver

· O/A length 4.82-4.98m Free

· Width 1.97-1.99m 1.8m max

· Body width 1.60 max 1.4m max

· Height (excl. roll over hoop) 0.81m to ref. plane 0.95m to ref. plane

(The odd dimensions in the CART regulations are because I have converted them from Imperial units used by CART, to SI units.)

Champcars are slightly bigger and considerably heavier than Formula1 cars. Although the overall length of Formula1 cars is not regulated, the overhangs are. As the optimum wheelbase is a function of the track widths, which are regulated, the overall length comes out, typically, at about 4.5m. The approximately 160kg extra weight comes from the banning of the use of composites (other than for the monocoque, bodywork and wings) and other very exotic materials, and from the detailed chassis construction regulations set down to ensure a very high degree of driver protection in the event of hitting the concrete wall at high speed. As a consequence of setting a high minimum weight limit, the chassis constructors do not strive to pare down the weight to the last kilogram, helping to keep the cost of cars down.

The extra weight of a Champcar is the equivalent of driving a Formula1 car with over 200 litres of fuel on board. The cars are less nervous and less responsive, particularly in oval trim when the aerodynamic downforce is minimised.


Designers in both types of racing have attempted to utilise wing and underbody aerodynamics to the full, and the regulators have had to constrain them in the interests of controlling cornering speeds. CART sets out a complicated list of wing regulations with different, more restrictive limitations for Super-Speedways. Both the size and the number of elements in the wings are regulated, with only single element wings permitted on the Super-Speedways. Overall, the dimensions and heights of the wings are not so different from Formula1. Far bigger and more significant differences lie underneath the cars.

While Formula1 has a 50mm stepped flat bottom between the axles, with limited diffusers, Champcars are permitted to use venturis, albeit also stepped up 2 inches (50.8mm) from the bottom of the monocoque reference plane. The size of the diffuser exit is regulated to 6ins (152mm) high x 35ins (889mm) wide for ovals and road courses, and 6ins (152mm) high x 20ins (508) wide for the Super-Speedways. No skirts of any sort are permitted, and strict measurements of the deflection of edges of the sidepods are carried out to ensure that the gap to the road surface does not narrow with speed. The allowance of true but limited ground effect aerodynamics takes away the dependence on the front wing from which Formula1 cars suffer. The design of the front wing and nose reflects this, there being no great need to generate as much downforce as possible from the front wing and less emphasis on the airflow under the centre of the car. The reason that CART has stayed with venturis is that it was found that slipstreaming cars were less unbalanced by running in the turbulent wake of the car ahead, if they had venturis. With enough front axle downforce being developed by the underbody, and hence less dependence on the front wing, loss of front wing downforce changes the balance of the car by a much smaller amount. With so much slipstreaming taking place in oval racing, this was a wise decision.

Wheels and Tyres:

Formula1 has overtaken Champcars in the restriction of tyre sizes and the number of tyres available to a competitor during an event.

Champcars Formula1

· Wheels F 381mmf x 254mm 330mmf x 380mm

R 381mmf x 356mm 330mmf x 380mm

· Tyres F 648mmf x 305mm 660mmf x 380mm max.

305mm min.

R 686mmf x 406mm 660mmf x 380mm max.

365mm min.

· Tyre treads Slicks Grooved

· Heaters No Yes

· Number of tyres 500mile 60

per event: 300 mile 36

Other 28 28

Apart from the grooved tyres used in Formula1 from this year, the biggest differences are a result of the sizes of the wheels. In Champcar, the larger diameter but narrower wheels mean that the tyre constructions are completely different from Formula1. Wide tyres on narrow wheels give the short sidewalls a difficult task in laterally stabilising the tyre, and so are very stiff. As a result the overall stiffness of the tyres is much greater than the relatively soft Formula1 tyres. Because of the sustained high speeds on the ovals, tyre pressures are run higher, and are so critical that tyre pressure monitoring sensors are standard equipment, warning the drivers of any loss of pressure.


Carbon brakes are only allowed in Champcar for 500 mile races. While braking has little performance effect on ovals, the use of ferrous brakes on the road courses, and the heavy weight of Champcars, results in much longer braking distances than in Formula1, providing significantly more overtaking opportunities.


As with Formula1, 4-WD is not permitted in Champcar. Gearboxes must have manual gearchange mechanisms, which is not a penalty on ovals where the gearbox is only used for pit stops. Differentials must be purely mechanical, and must be replaced by spools (i.e. no differential) on ovals. Traction control is as strictly banned as in Formula1.

Suspension and Steering:

The only differences between Formula1 and Champcar here, are that power steering is banned and suspension members must be steel for Champcars only. No form of active or adaptive suspension is permitted.

CART has worked hard on retaining the wheels during an impact with the wall, specifying the strength of critical suspension members.


The specification of sensors used in the data systems of Champcars is restricted. The logical reasoning behind this regulation is that if certain parameters are not measured, they cannot be used to control a function of the car that is not permitted.


The FIA and CART have maintained close contacts concerning safety measures and so it is not surprising that the test requirements are very similar. There are differences in the type of accident common in the two types of racing, and so there are variations in how the regulations have developed. In Formula1, many of the corners have a gravel run-off area and tyre barriers, whereas on Champcar's oval circuits, the outside of the bends are concrete walls, with no run-off. In general, the walls close to the racing line ensure that most of the impact velocity is along the wall, and the car can rub off speed sliding along it. However, when cars do impact with a high perpendicular component of velocity, the energy to be dissipated is large and the deceleration g-levels high. The car can be pointing in any direction when it hits, and CART has ensured that the survival cell in which the driver sits is massively strong. All around the cell, energy absorbing structure is mandated and tests are carried out to ensure that they have adequate performance, even during multiple impacts.

The FIA has made no regulations concerning how the cars are constructed, leaving it up to the teams to use the latest and best materials and techniques. Instead it stipulates impact and structural proof tests to ensure that cars meet the safety criteria. CART, while stipulating very similar tests, also sets down minimum construction details for the monocoque, based on the state of the art and hard won experience.


Champcar racing has two restrictions on fuel quantities: a maximum tank size of 132litres and a maximum fuel quantity to be used in a race, equating to a consumption of 127litres/100km. At 380kph (an average speed possible on ovals) the engine is consuming methanol at a rate of 8litres/minute. Formula1 has no restrictions on total quantity nor tank capacity, and so refuelling strategies are somewhat different. Fuel economy of the engine is a critical performance parameter, and the engine's mixture setting is under constant review by both driver and team during the race. They attempt to maintain maximum power (rich setting) while avoiding an extra fuel stop.

The largest single effect of the CART regulations is to discourage, indeed prohibit major new technologies. As a result it is not cost effective for teams to design, construct and develop their own cars. The exception to this is Penske, who attempts to gain the best of both worlds by designing and building their cars at their factory in Poole, England and flying completed cars to the American based race team who are solely responsible for developing them into race winning form and then racing them. The other teams purchase chassis from one of three suppliers and engines from one of four engine manufacturers. With the 4 chassis: Penske, Reynard, Swift, Lola, and 4 engines: Mercedes (Illmor), Ford (Cosworth), Honda and Toyota, and both Goodyear and Firestone (Bridgestone) supplying tyres, there are 32 possible combinations for teams to choose from. In 1998, only 11 combinations have been put together for racing, with Reynard/Cosworth/Firestone, Reynard/Mercedes/Firestone and Reynard/Honda/Firestone the most popular with three teams each. This tends to indicate that Reynard and Firestone are "must-have's", but choices tend to be based on what worked in the previous year, and nothing in racing remains the same for long. It is too early to judge which is the best combination in 1998, but it already looks as if Reynard, Swift and Penske are all well matched, and there is not much difference between Honda, Mercedes and Cosworth, nor the two makes of tyres.

In contrast, Formula1 currently has 11 chassis, 8 engines and the same two tyre suppliers as in Champcar. While minor, and even some major teams in Formula1 struggle to develop the highly sophisticated machines that are necessary to be competitive, and some only achieve reliability and approach the potential of their cars by mid-season, in Champcar anyone can purchase and compete with a proven competitive car/engine/tyre combination. This creates a very different role for the racing team that enters the car.

Because the technologies that have emerged in Formula1 in the last 10 years: semi-automatic gearbox, control systems, proliferation of composites for many components other than the monocoques and bodywork, and pneumatic valve springs, have been banned in Champcar, the cars and engines tend to have similar performance, having reached the plateaux of the technologies permitted. Teams can purchase a reasonably known and proven package, and freed from the task of designing, building and developing it, can concentrate on racing. In this way the teams are much more like those in F3000 and F3, but much bigger and more professional.

Engineering departments are led by the race engineers who strive to bring their cars to the pinnacle of performance for the different types of circuit. They work mainly on aerodynamic, suspension and damper set-ups. The relationship between the race engineer and his driver can make all the difference to competitiveness - Alex Zanardi and his engineer Maurice Nunn showed in 1997 just how effective a good combination can be.

Because of the fuel tank size restriction and the limited total fuel allocation, pit stop strategy can totally dominate a race result. The frequent practice of sending out the Pace Car under Yellow lights, when an incident or accident occurs, puts wild cards in the hands of each team. The timing of pit stops for fuel and tyres is absolutely critical and some teams, Chip Ganassi's in particular, have shown mastery of the art.

The net result of having a field of 30 or more pretty closely matched cars, driven by drivers whose skill and experience can vary widely, coupled with the strategic demands of racing long distances with a limited supply of fuel and tyres, makes for a certain unpredictability in the outcome. The racing is nearly always close, full of incidents and often undecided until the last corner. And yet, lacking the high technology and super-heroes of Formula1 it does not hold such a strong appeal around the world.

As Formula1 attempts to regain a foothold in the USA and Champcar spreads outside that continent with ovals being built in other countries, the battle for TV viewers and spectators and hence for sponsors will become more intense. One day these cars may race against each other again, as they did in the pioneering motor racing period of 1910-1920 when the Europeans took their GP cars to Indianapolis. Now that would be something to look forward to!