Mazda RX7 (Group B) + Homologation Version

Published on: Jan 19, 2016 @ 15:59
Originally Published in: 2014 (old website)
(C) Jay Auger - website owner & author
Notice: Any form of duplication methods (including but not limited to copy/paste of text and screen capture) of the website's content is strictly forbidden.

In 1984, without much financial backing from Mazda itself, Mazda Rally Team Europe (MRTE) took the jump from Group 2 into Group B with the RX7. It can be seen as a questionable decision since the FB chassis had been around for quite a while. It was also quite evident at the time of its introduction that four wheel drive was now the way to go in top international rallying. However, there was much publicity to be gained, win or not, since Group B had launched the World Rally Championship into a blazing fan craze.

Mazda RX7 FB332

Mazda’s Group B weapon was based on the standard RX7 chassis in series 3 “GSL” trim. The RX7 itself was a mainstream production model contrary to most of the other Group B special homologation cars. With over 470,000 produced in its entire first generation the RX7 far surpassed the 200 units required for Group B homologation. What the FISA (FIA) mandated per the regulations in those instances was that 20 “Evolution” models were built to homologate the car for competition. As unassuming than the normal RX7 looked for a potential rally car, the evolution feature would really bring it to another level.

The rally car features wider fender/wing flares, a large rear spoiler with an oil cooler underneath, upgraded suspension components, and a high revving 13B rotary engine producing around 300 HP.

rx7bv

While they had to manufacture most of their own parts in-house, MRTE still managed an impressive third place finish at the 1985 Acropolis Rally amidst much stronger opposition.

NOTE: The Group B RX7 is not to be confused with special 4×4 version built by Rod Millen in the 1980s for use in North American rallies.

In 1986, MRTE subsequently started work on a Group S RX7 prototype based on the new second FC generation, which also featured four wheel drive, for details CLICK HERE!

***This article is only a quick excerpt / please come back later for page expansion***

SPECIFICATIONS

Group/Class B/12 Homologation number: B-255 (click # to view papers)
Years active 1984~1986 Homologation

  • start: February 1st 1984
  • end: December 31st 1988
Engine
Type 13B RESI, 2 rotors Wankel, gas 2 nodes / 3 lobes
Displacement 1308 x 2.0 = 2615cc
Compression ratio N/A
Output power – torque 300 HP @ 8500 rpm 270 lb-ft @ 7500rpm
Materials block: N/A cylinder head: N/A
Aspiration naturally aspirated MRTE Weber 51 IDA carburetor
Ignition & Injection
  • Bosch L-Jetronic fuel injection
  • 3x high-flow fuel pumps
Cooling system water-cooled
Lubrication system dry sump with trunk mounted reservoir and rear wing mounted cooler
Transmission
Type rear wheel drive MRTE/PBS 5-speed manual transmission with “dogleg” first gear
Gearbox ratios
  • N/A
  • N/A
  • N/A
Diffrential ratios
  • N/A
limited slip rear differential
Clutch dry / twin plate
Chassis-body
Type
  • steel monocoque FB332 chassis with roll-cage
  • 3 door coupe widened fibreglass bodyshell
  • polycarbonate windows
Front suspension Bilstein shock absorbers, improved parallel links
Rear suspension Bilstein shock absorbers, improved parallel links
Steering system rack and pinion N/A
Brakes
  • four-wheel disc brakes
  • MRTE 4 pot front brake calipers
  • Alloy 2 pot rear brake calipers
  • Hydraulic handbrake
dual circuit with servo
Dimensions
length: 4285 mm (169.0 in) width: N/A height: N/A
wheelbase: 2420 mm (95.0 in) front track: N/A rear track: N/A
Rims – tires
  • Enkei 15×6″ alloy wheels
  • Enkei 15×7″ alloy wheels
  • Front: DMG2 195/65R15 gravel tires
  • Rear: DMG2 205/65R15 gravel tires
Dry/Unladen Weight 960 kg (2120 lb)  Bias: F50/R50
Weight/power 3.2 Kg / HP (7.1 HP / lb)
Fuel tank N/A

HOMOLOGATION / PRODUCTION VERSION

MAZDA RX7 GSL SE (series 3)

Widely known as the quirky sports car with a rotary engine and rear wheel drive, the Maxda RX7 was a mainstream production model and is not an homologation special. It is hardly a rare machine with over 470,000 units produced in its entire first generation. However, in early 1984, Mazda did use 200 units out of its production as proof for homologation, which were reportedly all of series 3 “GSL” trim. The owners of these vehicles probably never knew that their cars were used for Group B homologation. It is unknown if a record of the actual VINs used for homologation exist, albeit it wouldn’t change much since there was no actual difference with the other cars of the same batch.

As such, only the 20 “evolution” Group B RX7s built are truly special but these cars were almost exclusively used in competition by the rally teams themselves and never sold to the public. A super rare unused example is known to exist and was put up on auction in 2017.

SPECIFICATIONS

Class Sports RWD coupe
Production 1978~1985 Assembly: Japan
Engine
Type 13B RE-EGI, 2 rotors Wankel, gas
Displacement 1308 x 2.0 = 2615cc
Compression ratio N/A
Output power – torque 135 HP @ – rpm 135 lb-ft (183 Nm) @ – rpm
Materials block: N/A cylinder head: N/A
Aspiration naturally aspirated
Ignition & Injection fuel injection
Cooling system water-cooled
Lubrication system external oil cooler
Transmission
Type rear wheel drive 5-speed manual transmission
Gearbox ratios N/A N/A N/A
Differential ratios N/A Limited Slip
Clutch N/A
Chassis-body
Type steel monocoque FB332 chassis 3 door coupe bodyshell
Front suspension N/A
Rear suspension Live Axle, four link, Watt linkage
Steering system rack and pinion N/A
Brakes 4 wheel disc brakes N/A
Dimensions
length: 4285 mm (169.0″) width: 1675 mm (66.0″) height: 1260 mm (50.0″)
wheelbase: 2420 mm (95.0″) front track: N/A rear track: N/A
Rims – tires N/A N/A
Curb Weight 1050 kg (2315 lb)  bias: 50/50
Weight/power 7.8 Kg / HP (17.1 HP / lb)
Fuel tank N/A

VIDEOS


(C) Articles by Jay Auger – website owner & author

  • Images & videos are the property of their original owners
  • Eifel Rallye Festival Pictures used under permission – McKlein Publishing
  • All homologation papers are the property of the Fédération Internationale de l’Automobile (FIA): SOURCE

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