Here you can learn about the rules and regulations that governed Group B car creation!
Group B had no restrictions on car design, exterior or interior dimensions, material composition of chassis or bodywork, drivetrain layout, engine type or size, or power output, but these general rules applied;
- The cabin had to fit two seats (side by side) and could not be open roofed.
- Respect a minimum race weight calculated via engine size (x 1.4 for forced induction – see list below).
- Run a maximum tire width combination calculated via engine size (x 1.4 for forced induction – see list below).
- All of the rest was mostly free minus specific basic safety requirements.
It is notable to mention that Group A & N had a minimum interior space requirement for homologation and if that figure wasn’t met the car was transferred into Group B. This rule can be credited with the forceful Group B homologation of low-powered cars with high production numbers such as the Peugeot 504 Pickup and other supermini models that had very small cabins.
CLASS SPECIFIC REGULATIONS
Group B cars were divided into 4 different classes pertaining to their “final / adjusted” engine displacement;
- B-12: 2000 cc +
- B-11: 1600~1999 cc
- B-10: 1300~1599 cc
- B-9: 1299 cc or less
The FISA (FIA) mandated that forced induction engines (with a turbo or supercharger) would get a multiplication factor of 1.4 to calculate their “final” engine displacement figure. Meaning that, in example, a twin-charged Lancia Delta S4, although it had a 1759 cc engine, would get a final cc rating of 2463 cc. The adjusted figure was used to determine minimum weight requirements and maximal tire width for the particular model.
Race minimum weights;
- ~1000 cc = 590 kg (1300 lb)
- 1001~1299 cc = 675 kg (1490 lb)
- 1300 ~1599 cc = 750 kg (1650 lb)
- 1600~1999 cc = 820 kg (1810 lb)
- 2000~2499 cc = 890 kg (1960 lb)
- 2500~2999 cc = 960 kg (2115 lb)
- 3000~3999 cc = 1100 kg (2425 lb)
- 4000~4999 cc = 1235 kg (2725 lb)
- 5000+ cc = 1300 kg (2865 lb)
Maximal tire width combinations (for one side of the vehicle – staggered setups allowed);
- ~1000 cc = 16″
- 1001~1299 cc = 17″
- 1300 ~1599 cc = 18″
- 1600~1999 cc = 20″
- 2000~2999 cc = 22″
- 3000~3999 cc = 24″
- 4000~4999 cc = 26″
- 5000+ cc = 28″
As such, when building the cars, Group B engineers had to approximate the race weight of their designs in harmony with the engine choice to properly set the cars up for the specific weight and tire classes. The best way to maximize a Group B car was to run the largest displacement engine possible (taking into account the 1.4 forced induction multiplier) and make the weight as close to the minimum requirement of that class. The rest of the chassis and suspension could therefore be set up to run the properly sized tires within the class limits. Not doing this correctly would handicap the car in one way or the other.
You can view the complete FIA “Appendix J” by choosing either of these options (Group B regulations were identical from 1982 to 1985, limitations to aerodynamic overhangs were implemented for 1986);
For a Group B car to be accepted in official competition, manufacturers had to produce a minimum of 200 units within a 12 month period. Many of the homologation road cars were built by the rally teams themselves and not by the manufacturer. Thus, most cars were roughly finished, somewhat unreliable, and unpractical for daily use. After completion, FISA officials would then be invited to physically count the cars. While some manufacturers were very proud of showing off their cars by lining up the 200 units side by side, others were rumored to have used trickery with various double-counting schemes.
In addition to the one-time batch of 200 homologation cars, the FISA introduced a totally new feature that was called “evolution” (ET). This would allow an additional 10% of the total number of cars produced to receive special modifications specifically for racing. If this was something the manufacturer was interested in doing they needed to build a minimum of 20 more cars to homologate any “evolution” models into competition. A new batch of 20 more evolution cars would be needed each subsequent year to homologate any major changes.
The new evolution rules were meant to somewhat replace the old “VF/VO” (parts manufacturer variant / parts option variant) rules that the manufacturers exploited in Group 4 to greatly enhance the performance of a normal production road car. It had allowed them to produce special racing parts and use them on the rally cars by masquerading them as dealership “optional parts”. In Group B, this was still permitted but the big change was that if these parts were used the car automatically became an “evolution” model, to which the regulations stated that the production of the car model used for homologation had to be terminated.
The rules for these special cars also mandated that the cabin section had to remain identical to the homologated road car. The fore and aft sections could subsequently be modified at will as long as the main homologated components would remain intact. On each subsequent anniversary of the homologation date, 20 more (or 10% of the total produced) “evolution” cars could be built to homologate any changes such as; modified engine displacement, aspiration, exterior dimensions, and aerodynamic add-ons. However, any major changes to key components such as; drivetrain layout, engine position, and main cabin structure would require a totally new homologation batch of 200 cars.
For the FISA, the termination rule was seen as enough of a dissuasive measure for the manufacturers to reconsider using the evolution feature. However, it turned out that the FISA was deadly wrong as most manufacturers simply worked around it by producing 200 homologation cars that were branded as a different model than the normal production car. For the most well funded teams, this meant designing and producing a car built entirely from scratch to win rallies, and they exploited the loophole to the maximum – something that the FISA had not quite planned for…
In the latter stages of Group B, leeway from the FISA officials allowed the competition “evolution” cars to be homologated before the actual completion of the road cars, thus providing manufacturers with more opportunities to fake production numbers and present the same units with different identification numbers. A common trickery was also to use normal homologation models to build the evolution cars and refitting them with new identification plates. Other manufacturers of the latter homologation models did not reach the required 200 units as when news of the cancellation of Group B hit they simply stopped making them. All of these factors makes the Group B “homologation specials” very rare and coveted today.
GROUP 4 TRANSITION PERIOD
In May of 1981, some of the finer details of the Group B rallying category were still not yet set in stone, making members of the FISA doubt that there wouldn’t be enough of a field of cars for its planned debut which was less than seven months away. As such, it was voted to let the previous Group 2 and 4 cars compete for the various 1982 rally championships and allow time for manufacturers to develop a car under the new regulations while still having a model that could compete in the interim. This transition feature also allowed privateers to continue competing with the cars they already owned. Another rule was that by 1983 manufacturers would have to run Group B homologated cars with their seeded drivers to be able to score points.
However, most manufacturers were still not ready to fully embrace the new regulations and invest large sums of money to design new rally cars without some sort of guarantee that the FISA wouldn’t just change the rules again. To put that fear to rest, the FISA added a 5-year “stability” clause to ensure that the regulations would not change until December 31st 1987, and would not be cancelled unless a 2-year notice. Furthermore, manufacturers with Group 4 homologated cars of which the expiration date was not yet reached (5 years after the last year of production) would be allowed to apply for a “transfer” into Group B (even if their rally cars would be identical to the previous version) and be eligible for points. This would temporarily circumvent the true purpose of the expiration deadline (to develop a new model) and allow the car to continue competing for a longer period of time.
For the complete Group B homologation list and papers, CLICK HERE!
(C) Article by Jay Auger – website owner & author
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- All “Appendix J” documents are the property of the Fédération Internationale de l’Automobile (FIA): SOURCE