Le Mans Class 101

By P. Michael Clarke

Two general classes of race cars will be on the starting grid for the 66th running of the 24 Hours of Le Mans: Prototypes and GT racecars. Here's an overview of the differences between the categories. We'll save an overview of the combatants in each class for the next article.

Le Mans Prototype 1 (LMP1)

1998 Registrants: Porsche LMP 198, BMW V12, Courage C51, Ferrari 333 SP, Courage C36, Riley Scott MK3, Courage C41, Kremer K8.

The Prototype 1 class is divided into two categories: LMP 875 (as in 875 kilos minimum weight) and LMP 650. Prototypes are not required to have any production run. The wheel base is unrestricted, while the overall measurements are 465 cm long by 200 cm wide. Height, as measured from the bottom of the car, is 96.5 cm (including the rear wing). Aerodynamic devices such as ground effect tunnels, skirts, diffusers, extractors etc. are forbidden. The rear wing must be fixed onto the body work and may be adjustable, but it cannot exceed the overall width of the car. Carbon brakes are also allowed, but all-wheel drive vehicles are not permitted. Finally, the tires must not exceed 16 inches in width and 28.5 inches in overall diameter in LMP 875 (14 inches in LMP 650).

To encourage the largest possible number of engine configurations and manufacturers, the LMP 875 class is limited to a 6-liter engine displacement for normally aspirated versions and 4-liters for turbo-charged power plants. In the LMP 650 category, two engine configurations are permitted by rule: 3.4-liter and 6-cylinders for normally aspirated engines, 2 liters and 4 cylinders for turbocharged versions. In either case, the fuel capacity must not exceed 80 liters.

Le Mans Prototype 2 (LMP2)

1998 Registrants: Debora LMP2.

This category is to Le Mans Prototype 1 as GT2 is to the Le Mans Grand Tourisme 1 (GT1): slightly less advanced technically, but still very fast. Although the LMP2 cars may not be favored to win the overall title in a long distance race such as the 24 Hours of Le Mans, this category offers smaller manufacturers a chance to enter this prestigious event and reap the benefits of a class win. The dimensions are identical to those of the LMP1 cars, but the weight is limited to 650 kilos and fuel capacity is restricted to 80 liters. Only 6-cylinder 3.5 liter normally aspirated engines are admissible. Carbon brakes are not permitted and driving lights, as in the GT2 category, must be yellow.

WSC

1998 Registrants: None.

The American World Sports cars are still admissible, although they must comply with the LPM 875 for weight and intake restrictors. The maximum engine displacement for the WSC cars is 4 liters for the 4 valve per cylinder versions and 5 liters for the two valve versions. Turbo engines are not admissible.

Le Mans Grand Tourisme 1 (GT1)

1998 Registrants: Porsche 911 GT1, Mercedes CLK LM, Toyota GT One, Panoz GT-R1, Nissan R 390 GT1 and McLaren F1 GTR.

Cars in the GT category must be street-legal with modifications incorporated for race track use. Their dimensions and shape must be identical to those of the homologated model intended for production. For example, the constructor must provide for a "luggage compartment" of 150 liters in capacity. Regardless of restrictions, production models must be made available to the market 12 months at the latest after the homologation date.

GT1 cars can be either open or closed cockpit and have one door on either side with a maximum of four seats. Optional equipment and performance enhancing kits are not permitted. The gear box is a 6-speed plus reverse. Carbon fiber brakes are not acceptable for GT1 unless they are part of the original equipment in the GT2 production line. The wheels must not exceed 14 inches in width and 28 inches in diameter (12" and 28" in GT2).

Minimum weight is situated between 900 and 1300 kilos depending upon engine configuration, displacement and intake restrictors. The engine can be replaced with another power plant of the same make offered in the manufacturer's model line. The restrictions are numerous: the designated engine must keep the same block, heads, valve angles, number and location of the cam shafts - even the same firing order - as the production engine. The maximum displacement is 8 liters and 4 valves per cylinder for normally aspirated engines and 4 liters (2 or 4 valves) for the turbo versions. Fuel capacity is set at 100 liters.

The car's undertray between the front and rear axles must be flat. All racecars, except those built prior to June 1 of this year, must be 200 cm wide at the most (mirrors excluded) to be eligible to run the 24 Hours of Le Mans. Telemetry between a race car and its crew is forbidden during all the track sessions. Finally, the driving lights must be white on GT1 cars and yellow on the GT2 models.

Grand Tourisme 2 (GT2)

1998 Registrants: Porsche 911 GT2, Chrysler Viper.

To be eligible to run in the GT2 category, production models of the race cars must have been available to the public since January 1, 1998. Minimum weight is situated between 900 and 1300 kilos according to the same criteria which govern the GT1 category. The engine must be the same as the production car's. Maximum fuel capacity is set at 100 liters. Only metallic materials are allowed for brake pads, calipers and rotors, except if other materials are homologated and used in the production cars. Maximum wheel width is 12 inches and 28 inches in diameter. The driving lights must project a yellow beam.