Porsche Carrera 924 GTS Rallye (Group 4 / B)

Published on: Jul 27, 2022 @ 18:56
(C) Michael Langdon @ Rally Group B Shrine
(C) Jay Auger @ Rally Group B Shrine (edition)
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.

INTRODUCTION

With the public homologation announcement for the 924 Carrera GT in Group 4 came an announcement within the Porsche ranks that an evolution of the GT was in the works. Unlike its siblings in the 924 model range, the GTS was built to be a competition car from the beginning. Designed to meet the FIA’s “Evolution” requirement of just fifty examples, the front-engined, rear-wheel drive GTS was not destined to become a threat to the bespoke competitors of the subsequent Group B-era of the World Rally Championship, even in full rally trim. That task was instead given to the 911 for the international scene, to be replaced by the “Gruppe B” (959) as soon as Porsche could make it happen (but ultimately never did). The 924 GTS Rallye would see a few successes on the national rally stages where it was built to compete, notably in Germany in the hands of legendary rally ace Walter Röhrl.


TABLE OF CONTENTS


HISTORY

One of nine prototypes built, the fifth of the 924 Carrera GTS rally cars was offered to Walter Röhrl in 1980. After his Mercedes contract fell through, and unwilling to gamble on an untested car at Audi, Röhrl entered into talks with Porsche. As of March 10th, 1981, a rally version of the 924 Carrera GTS had been ordered for his use in the German Rally Champsionship.

Walter Röhrl between a production 924 Turbo and his competition 924 Carrera GTS Rallye (1981)

The new 924 Carrera GTS Rallye would utilize nearly all of the design elements of the Club Sport model, the highest tier in the established (albeit limited) GTS production run. Röhrl’s rally car however employed larger wheelarch extensions borrowed from the even rarer 924 Carrera GTR endurance circuit variant, fitted out of factory by body specialist Matter, to accommodate a wider range of rims and tyres. A turbocharged four-cylinder engine from Audi provided the power, developing 245 BHP and maximum torque of 335 Nm at 3000 RPM. With a near 50-50 weight distribution, the 924 Carrera GTS Rallye was well-balanced, and described by Röhrl as being “light and powerful” and “a proper car”.

Porsche 924 Carrera GTR (GTP) – Technical View

With Röhrl at the wheel of the new “Monnet Cognac” gold and black liveried 924 GTS Rallye, Porsche’s full support was placed behind the new team in 1981. After his encouraging second-place finish on the Metz Rally in Germany, the decision was made for the team to contest the full German Rally Championship. The team would claim four of the ten rounds on the 1981 schedule, with bad luck preventing five consecutive wins from June through September. Röhrl was scheduled to drive a 911 SC in the WRC Sanremo Rally, so the GTS team did not go to the final event of the German Rally Championship season, making them unable to take the championship despite accumulating enough points to win.

Beyond the German championship, Röhrl and longtime co-driver Christian Geistdörfer drove the 924 Carrera GTS Rallye in the Rallye d’Antibes, but failed to finish. This event would be the last the car would compete in as a Porsche works-sponsored rally car. Company attentions were directed elsewhere for future seasons. Röhrl left Porsche for Opel in 1982, and the GTS team was dissolved. Outside the works team in Germany, a few private teams found use of the 924 Carrera GTS Rallye in particular events.

In 1982 came the new Group B category in which previously homologated Group 4 cars with active homologations could apply for a transfer to Group B, so did Porsche for the 924 Carrera GT. The striking Boss-liveried Alméras team most famously utilising the updated car in the 1982 Rallye Monte Carlo at the hands of Jürgen Barth and Roland Kussmaul. The pair would finish 10th overall but 2nd in Group B – quite ironically the event being won by eventual 1982 WRC champion Walter Röhrl with the Opel Ascona.

(C) Foto Bobo

Another GTS Rallye to compete in the year was Walter Röhrl’s four-time winner in the German Rally Championship, which was repainted blue for the Gitanes cigarette company and driven in Belgium’s Boucles de Spa Monopole rally by F1 driver Jacky Ickx. The car ultimately retired with suspension issues.

(C) Georges Renaux

Although Walter Röhrl proved that the Porsche 924 Carrera GTS Rallye could be competitive at the time of its use, with only a handful of cars were known to have appeared in smaller rally teams throughout the years, it was quickly overshadowed by the quickly-developing and more powerful, bespoke Group B competition that came to dominate the national rally scenes.

REUNION AFTER 40 YEARS

(C) Porsche AG

In 2021, for the 40th anniversary of the 924 Carrera GTS Rallye entering competition in the hands of Walter Röhrl, Porsche secretly restored the rally car to its original condition, gifting it to an elated Röhrl for his 74th birthday on March 7th of that year. The full story and picture gallery are available HERE (click).

(C) Porsche AG

RALLY CAR SPECIFICATIONS

Group/Class
  • 4
  • B/12
Homologations (click # to see papers):

Years Active 1981~1982 Homologation

  • start/end: Jan 2nd 1981 / Jan 1st 1982 (Group 4)
  • start/end: Jan 2nd 1982 / Jan 1st 1988
Engine
Type VAG EA831-based, Inline-4, SOHC 8v, gas front, longitudinal, 40 degree inclinaison
Displacement 1984 cc WRC x 1.4= 2777 cc
Compression Ratio 8.5:1
Output Power – Torque
  • 250 bhp @ 6200 rpm
  • 280 bhp @ – rpm (1982)
247 lb-ft (335 NM @ 3000) rpm
Materials block: cast iron cylinder head: aluminium
Aspiration
  • KKK K26 Turbocharger
  • top-mounted intercooler
  • Bosch Kugelfisher fuel injection
boost: 14.5 psi
Ignition electronic DZV battery
Lubrication System  dry sump rear-mounted ancilliaires
Cooling System water-cooled
Transmission
Type rear-wheel drive Getrag G31, 5-speed manual transaxle
Gearbox Ratios Group 4:

  • 1st: 2.4000
  • 2nd: 1.6315
  • 3rd: 1.2608
  • 4th: 1.0000
  • 5th: 0.7857
  • R: 2.9091
Group B:

  • 1st: 3.1666
  • 2nd: 1.7777
  • 3rd: 1.2174
  • 4th: 0.9310 (0.925)
  • 5th: 0.7858 (0.700)
Differential Ratios
  • 4.1250
  • 4.7414
  • 5.0000
  • limited-slip rear differential
  • external oil cooler
Clutch hydraulic, single plate
Chassis-body
Type “Type-939” steel chassis with aluminium roll cage, polymer GTS/GTR widebody arch panels, polymer doors, polymer front bonnet and intercooler scoop, polyurethane bumpers, fixed headlamps with Perspex covers, rubber rear spoiler, polymer side windows and rear screen, front and rear skid plates
Front Suspension McPherson telescopic struts, coil springs, anti-roll bar, reinforced hubs
Rear Suspension reinforced L&T, reinforced trailing arms, coil springs, antiroll bar, reinforced hubs, laminated axle links (debris protection)
Steering System rack and pinion, hydraulic, reinforced ratio: –
Brakes front:

  • 4-pot calipers (911 Turbo)
  • 282 mm vented discs

rear:

  • 4-pot calipers (911 Turbo)
  • 289 mm vented discs
  • dual circuit with servo
  • adjustable proportioning valve
  • hydraulic hand-brake system
Dimensions
length: 4240 mm (166.9 in) width: 1745 mm (68.7 in) height: 1270 mm (50 in)
wheelbase: 2400 mm (94.5 in) front track: 1477 mm (58.1 in) rear track: 1476 mm (58.1 in)
Rims – Tires central locking system

front:

  • 7Jx16″

rear:

  • 8×16″
front:

  • 205/55 VR16

rear:

  • 225/50 VR16
Dry/Unladen Weight 1050 kg (2,314 lb) Bias: F51/R49 *estimated
Weight/power 3.9~4.2 kg/HP (8.6~9.3 lb/HP)
Fuel Tank rear-mounted, 60 litres tank or 120 litres safety cell
Drag Coefficient 0.34 cd (GT)

HOMOLOGATION VERSION

Beyond the nine prototypes (including the rally variants), just fifty 924 Carrera GTSs were built. Evolutions of the much-praised 924 Carrera GT model, each car was immediately distinguishable from other 924 models by design differences like fixed headlights and wider polymer wheelarches. Each of the fifty cars was left-hand drive, and painted in Guard Red. The base model GTS supplied 245bhp, good for 0-62mph in 6.2 seconds. 16-inch wheels, an option on the GT, were standard on the GTS. With a then price of 110,000 German marks, it was the most expensive production Porsche at the time.

(C) Porsche AG – 924 Carrera GTS Homologation Run

Fifteen of the 924 Carrera GTSs were ordered in so-called “Club Sport” trim. The Club Sport upgrade was intended for teams using the GTS for race or rally events, and offered a power increase to 270 BHP, a 5.2-second 0-62mph time, and a transaxle oil cooler. Club Sports were built to varying specifications; as a result, some include race and rally-specific items such as roll cages, exterior fire extinguisher switches, or sliding windows. Option packages were available for racing and rally, fitted out of factory by German specialist Matter (including a package to fit the car to 1982 Group B specifications), touring, and comfort. Whether Club Sport or base model, the 924 Carrera GTS is an exceedingly rare car, then as now.


ROAD CAR SPECIFICATIONS

Category Sports Coupé 2+2 Homologations (click # to see papers):

Production 1980~1981 (59 units total)

  • prototypes (9)
  • production (50)
  • “Club Sport” conversions (15)
Assembly: Germany
Engine
Type VAG EA831-based, Inline-4, SOHC 8v, gas front, longitudinal, 40-degree inclinaison
Displacement 1984 cc
Compression Ratio 8.5:1
Output Power – Torque
  • 245 bhp @ 6200 rpm (GTS)
  • 270 bhp @ – rpm (Club Sport)
  • 247 lb-ft (335 Nm @ 3000) rpm (GTS)
  • – lb-ft (- Nm) @ – (Club Sport)
Materials block: cast iron cylinder head: aluminium
Aspiration
  • KKK K26 Turbocharger
  • top-mounted intercooler
  • Bosch Kugelfisher fuel injection
boost: –
Ignition electronic DZV battery
Lubrication System
  • wet sump (GTS)
  • dry sump (Club Sport)
Cooling System water-cooled
Transmission
Type rear-wheel drive
  • Getrag G31, 5-speed manual transaxle
Gearbox Ratios  

  • 1st: 2.4000
  • 2nd: 1.6315
  • 3rd: 1.2608
  • 4th: 1.0000
  • 5th: 0.7857
  • R: 2.9091
Differential Ratios 4.1250
  • limited-slip rear differential
  • Oil Cooler (Club Sport)
Clutch hydraulic, single plate
Chassis-body
Type “Type-939” steel chassis with optional aluminium roll cage, polymer GTS widebody panels, polyurethane bumper covers, polymer intercooler bonnet scoop, rubber rear spoiler, fixed headlamps with Perspex covers
Front Suspension McPherson telescopic struts, coil springs, anti-roll bar
Rear Suspension L&T, reinforced trailing arms, coil springs, antiroll bar
Steering System rack and pinion, hydraulic assistance ratio: 22.39:1
Brakes FRONT:

  • single pot 54 mm steel calipers, 282 mm vented discs (GTS)
  • 2-pot 38 mm aluminium calipers, 309 mm vented discs (Club Sport)

REAR:

  • single 36 mm pot steel calipers, 289 mm vented discs (GTS)
  • 2-pot 30 mm aluminium calipers, 309 mm vented discs (Club Sport)
  • dual circuit with servo
  • mechanical hand-brake system
Dimensions
length: 4320 mm (170.1 in) width: 1735 mm (68.3 in) height: 1270 mm (50 in)
wheelbase: 2400 mm (94.5 in) front track: 1477 mm (58.1 in) rear track: 1476 mm (58.1 in)
Rims – Tires front:

  • 7Jx16″

rear:

  • 8×16″
front:

  • 205R55 VR16

rear:

  • 225R50 VR16
Dry/Unladen Weight
  • 1121 kg (2,471 lb)
  • 1060 kg (2,337 lb) Club Sport
Bias: –
Weight/power
  • 4.8 kg/HP (10.1 lb/HP) (GTS)
  • 3.9 kg/HP (8.7 lb/HP) (Club Sport)
Fuel Tank steel, rear-mounted, 84 litres
Drag Coefficient 0.34 cd

VIDEOS


REFERENCES

(free delivery worldwide!)

AWIN Affiliates Program – by purchasing books with the links provided here you are also helping to support the Rally Group B Shrine!*

Group 4 Group 4 – From Stratos to quattro (English)

Gruppe 4 Gruppe 4 – Das Jahrzehnt der Heckschleudern (German)

 Porsche: The Rally Story

Porsche 924/928/944/968: The Complete Story

(C) Articles written by Michael Langdon @ RGBS
(C) Edited and supplemented by Jay Auger – website owner, main author & chief editor

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

WELCOME TO THE ENCYCLOPEDIA OF THE GOLDEN ERA OF RALLYING