Editing Group B (section)

== Regulations ==
[[File:Rétromobile 2017 - Peugeot 205 T16 EVO2 - 1986 - 001.jpg|thumb| The [[Transverse engine|transverse]] [[Mid-engine design|mid-engine]] [[Peugeot 205|Peugeot 205 Turbo 16 E2]] won Peugeot the [[1985 World Rally Championship season|1985]] and [[1986 World Rally Championship season|1986]] WRC [[List of World Rally Championship Constructors' Champions|manufacturers' titles]].]]

=== Specific regulations ===
Group B followed Article 252 and 253, which covered such things as [[Roll cage|safety cages]] or parts defining a car, like [[Windshield|windshields]] or [[Side-view mirror|side-view mirrors]].<ref name=":2" /> Article 256 covered regulations specific to Group B, with 5 paragraphs over half a page, and included most of the 7 pages of Article 255 for Group A. The first two paragraphs of 256 covered the definition of "(Sports) Grand Touring Cars" with a minimum of two seats, and their homologation requirements.

The section, "3) Fittings and Modifications Allowed" states, "All those allowed for Group A..." referring to the base rule set of what is allowed to be modified, how it can be modified, and what can be removed from the homologation road cars.
{| class="wikitable"
|+Group B engine capacity, weight, and tyre width limits, 1982<ref name=":5" />
!Maximum engine capacity (cc)
!Minimum weight (kg)
!Maximum tyre width (in)
|-
|1,000
|580
|8
|-
|1,300
|675
|8.5
|-
|1,600
|750
|9
|-
|2,000
|820
|10
|-
|2,500
|890
|11{{Efn|Maximum tyre width was not specified for 2,500 cc, with the 3,000 cc limit being applied instead.}}
|-
|3,000
|960
|11
|-
|4,000
|1,100
|12
|-
|5,000
|1,235
|13
|-
|>5,000
|1,300
|14
|}
If [[forced induction]] is present, restrictions apply as though the engine capacity is 1.4 times its actual value. If the engine is a [[Wankel engine|Wankel rotary]] or similar, then the capacity is considered to be "twice the volume determined between the maximum and minimum capacity of the combustion chamber." The equivalent capacity, <math display="inline">C</math>, for a [[Gas turbine|turbine engine]] is much more complicated, derived with the formula <math display="inline">C = \frac{S(( 3.10 \times T ) - 7.63) }{0.09625}</math> (1982) or <math display="inline">C = \frac{S( 3.10 \times R ) - 7.63}{0.09625}</math> (1986), where <math display="inline">S</math> is the "high pressure nozzle area" (cm<sup>2</sup>), and <math display="inline">T</math>/<math display="inline">R</math> is the "pressure ratio" of the compressor.<ref name=":2" /><ref name=":5" />

=== Resulting builds ===
[[File:Rétromobile 2017 - Ford RS 200 - circa 1985 - 001.jpg|thumb|left|[[Ford RS200]]]]
Ultimately, there were few restrictions on technology, design or materials permitted. For example, [[fiberglass]] bodywork was used in the [[Ford RS200]], a car without a common commercially available counterpart, though [[Silhouette racing car|silhouette race cars]] using space frame chassis were still common even when consumer car equivalents were mass produced, for example in the case of the [[Peugeot 205 T16]] or [[Lancia Delta S4]].<ref>{{Cite web |title=Group B's 5 Weapons Of Wonderment |url=https://www.goodwood.com/grr/event-coverage/festival-of-speed/2016/6/group-bs-5-weapons-of-wonderment/ |access-date=2022-05-24 |website=www.goodwood.com}}</ref> The rules provided for manufacturers who wanted to compete in rallying with [[mid-engine design|mid-engine]] and [[Rear-wheel drive|RWD]] or [[Four-wheel drive|4WD]], but their RWD production models had been gradually replaced by [[Front-wheel drive|FWD]] counterparts. By reducing the homologation minimum from 400 in Group 4 to 200, FISA enabled manufacturers to design specialized RWD or 4WD homologation specials without the financial commitment of producing their production counterparts in such large numbers.<ref>Mad For It, Mike Goodbun, [[Classic Cars]], December 2006</ref>

When the Group N, A, and B rules were decided upon, weight and engine displacement restrictions were thought the only way to control speed. This meant that there were no restrictions on [[Turbocharger|boost]], resulting in power output increasing from the winning cars' 250&nbsp;hp in 1981 to there being at least two cars producing in excess of 500 by 1986, the final year of Group B in rally.<ref>Chrysler Sunbeam Ti_and_Sunbeam_Lotus</ref><ref>Lancia Delta S4</ref> Turbocharged engines were not yet common in road-going cars and had only been introduced in the early 1960s,<ref name=":4" /> but in the early and mid-1980s, engineers learnt how to extract extraordinary amounts of power from turbocharging. Some Group B manufacturers went further; Peugeot, for example, installed a [[Formula One]]-derived [[antilag system]] to their engine, although the technology was new and not very effective,<ref name=":3" /> and Lancia [[Twincharger|twincharged]] their Delta S4. Nowadays, the power output of turbo engines is limited via intake [[Restrictor plate|restrictors]], and in the [[Groups Rally]] hierarchy, each class has an explicit weight/power ratio limit.

[[File:Rétromobile 2017 - Renault Maxi 5 Turbo - circa 1985 - 001.jpg|thumb|[[Renault 5 Turbo]]]]
[[File:Porsche 959 Dakar – IAA 2017 – by Nicolas Völcker.jpg|thumb|[[Porsche 959]]]]
[[File:FerrariGTO.jpg|thumb|Ferrari 288 GTO]]Across Groups N, A, and B, there were 15 classes based on engine displacement, with a 1.4 equivalence factor applied for forced induction engines. Each class had weight and wheel size limits. Notable classes for Group B were the 3000&nbsp;cc class (2142.8&nbsp;cc with forced induction) with a 960&nbsp;kg minimum weight ([[Audi Quattro]], [[Lancia 037]]), and the 2500&nbsp;cc class (1785&nbsp;cc with FI) with a 890&nbsp;kg minimum weight ([[Peugeot 205 Turbo 16 E2|Peugeot 205 T16]], [[Lancia Delta S4]]). The original [[Renault 5 Turbo]] had a turbocharged 1.4&nbsp;L engine, so it was in the 2000&nbsp;cc class. Renault later increased the size of the engine somewhat for the Turbo Maxi to be able to fit larger tires (at the expense of higher weight).<ref name="R5Tcorsa">{{cite web | url = http://www.renault5turbo.it/Renault5/La5DaCorsa.html | archive-url = https://web.archive.org/web/20130129073941/http://www.renault5turbo.it/Renault5/La5DaCorsa.html | archive-date = 2013-01-29 | title = La 5 Turbo da corsa | trans-title = The 5 Turbo competition models | work = Renault5Turbo.it | publisher = MR Electronics | language = it }}</ref> The [[Ferrari 288 GTO]] and the [[Porsche 959]] were in the 4000&nbsp;cc (2857&nbsp;cc with FI), 1100&nbsp;kg class, which would probably have become the normal class for circuit racing if Group B had seen much use there.
{| class="wikitable" style="font-size: 95%;"
|+Group B subclasses<ref>FIA Regulations, Appendix J 1986, Art. 256 – Specific regulations for Sports Cars (Gr. B): http://www.fia.com/resources/documents/991499716__Hist_App_J_86_Art_256_a.pdf {{Webarchive|url=https://web.archive.org/web/20061017130929/http://www.fia.com/resources/documents/991499716__Hist_App_J_86_Art_256_a.pdf#|date=17 October 2006}}</ref>
|-
! colspan=2 | Displacement
! rowspan=2 | Weight
! rowspan=2 | Wheel width <br />(front & back)
! rowspan=2 | Cars
|-
! Naturally-aspirated
! Supercharged or turbocharged
|-
| 4000 cc || 2857 cc || 1100&nbsp;kg || 12" || [[Ferrari 288 GTO]], [[Porsche 959]]
|-
| 3000 cc || 2142.8 cc || 960&nbsp;kg || 11" || [[Audi Quattro]], [[Lancia 037]], [[MG Metro 6R4]], [[Ford RS200]]
|-
| 2500 cc || 1785 cc || 890&nbsp;kg || 11" || [[Peugeot 205 Turbo 16 E2|Peugeot 205 T16]], [[Lancia Delta S4]]
|-
| 2000 cc || 1397 cc || 820&nbsp;kg || 10" || [[Renault 5 Turbo]]
|}