RX Vauxhall Astra 4S – John Welch

Published on: Jan 17, 2016 @ 20:35
Originally Published in: 2015 (old website)
(C) Jay Auger - website owner & author
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HISTORY

Opel Kadett E 4S Prototype

In 1983, GM’s official motorsport effort in Group B international rallying was with the quite conventional rear wheel drive Opel Manta B 400 which quickly fell out of contention. In 1984, Opel went back to the drawing board while the new “E” generation of the Opel Kadett / Vauxhall Astra model was nearing release. For much more detailed information about the “4S” (4×4) project – CLICK HERE!

Paris-Dakar 4S Prototype

In 1985, there was a total of four “4S” prototypes built: each with a different engine but all equipped with “Xtrac” four wheel drive systems. Two cars were tested in the 1986 Paris-Dakar rally and another under prototype rules in one event of the British Rally Championship. Group B was banned not long after which made the 4S’ official intended use shift to Group S instead. Sadly, the class was stillborn and abruptly ended the cars’ development.

Vauhxall Astra 4S RX – John Welch

In 1987, one of the Paris-Dakar prototypes was purchased by John Welch to compete in the British & European Rallycross series which were now filled with very competitive Group B cars. A few years beforehand, the Xtrac four wheel drive system was brought to fame by Martin Schanche in rallycross which would somewhat make the so-equipped 4S a natural contender for the series.

Welch’s car featured a de-stroked 2.1L Manta B 400 “phase 4” engine turbocharged with a BMW Formula One unit that produced a claimed 650 BHP. In theory, this power figure would be enough to match the fierce and proven Group B cars that he faced in competition. However, the 4S never had completed its prototype phase at Opel and this obviously meant that the car faced a lot of teething troubles.

What is also apparent is that Welch’s car was quite aerodynamically “tame” compared to the competition fully equipped with huge spoilers and other add-on appendages meant to increase the traction potential. However, appearances can always be deceiving, especially if taken from the cover of a book written by fellow competitor Martin Schanche and his factory-looking Ford RS200E. Similarly to Schanche, Welch’s car had its heart under the bonnet.

John Welch would compete with the 4S from 1988 to 1992, forcefully retiring when the Group B based cars were replaced with Group A machinery. His best season finish in five years of competition was a 10th place in the 1988 European Rallycross Championship. Welch then sold off the car to a fellow competitor who stripped the drivetrain to install it in an Audi 90 coupe.

John Welch’s Vauxhall Astra 4S and Václav Farka’s Škoda 130 LR EVO are the only known original Group S prototypes to enter rallycross.


SPECIFICATIONS

Group/Class Formula A / Division 2 Championships: none
Years Active 1988~1992 Best finish: 10th (1988)
Engine
Type B 400 “phase 4” engine, I-4, DOHC 16v, gas located front longitudinal
Displacement 2.1L
Compression ratio N/A
Output power – torque ~650 HP @ – rpm (claimed) 420 lb-ft @ – rpm (claimed)
Materials block: cast iron cylinder head: aluminium
Aspiration
  • turbocharger (BMW F1 unit)
  • air/air intercooler
Ignition electronic, firing order 1-3-4-2
Cooling system water-cooled
Lubrication system dry sump with mid-mounted twin oil coolers
Transmission
Type “Xtrac” four wheel drive 6 speed gearbox
Gearbox ratios N/A N/A
Differential ratio N/A Driver adjustable F/R ratio F28/R72 to F50/R50 hydraulic system
Clutch N/A
Chassis-body
Type T-Platform steel monocoque chassis (middle section only) 2 door coupe with integral roll cage and sump guard. Front and rear spaceframe. Kevlar body panels.
Front suspension N/A
Rear suspension N/A
Steering system rack and pinion N/A
Brakes F & R: Discs Dual circuit with servo, adjustable ratio split front to rear
Dimensions
length: 4256 mm / 167.6 in width: 1760 mm / 69.3 in height: 1393 mm / 54.8 in
wheelbase: 2500 mm / 98.4 in front track: N/A rear track: N/A
Rims – tires N/A N/A
Dry/Unladen Weight 960 kg (2115 lbs)
Weight/power 1.5 kg/HP (3.3 lb/ft)
Fuel tank 25 liters

VIDEOS


REFERENCES

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

SPECIAL THANKS:

  • Hamish Munro (spell-check)

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