Opel Kadett D 400 – Group B Prototype

Published on: Mar 3, 2017 @ 19:43
(C) Jay Auger - website owner & author
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Opel Kadett 400 Prototype


Around the same time that the Manta B 400 was being finalised as the Group B replacement for the Ascona B 400, Opel Motorsport manager Tony Fall considered an alternative for the future: use the proven chassis and mechanicals of the B 400 and throw them under a much more compact and lighter body – the Kadett 400 idea was born. The project is said to have been outsourced to German specialist Matter.



1983 Kadett D GTE.JPG
1983 Opel Kadett 1.8 GTE

Starting life as a normal Kadett D in GTE trim, the car was then carved about considerably and was “grafted” onto a Manta B 400 floorpan. This effectively turned the little Kadett from an under-powered front wheel drive hatchback to a fierce rear wheel drive rally weapon. This “silhouette” procedure was completely allowed under the Group B regulations.


Compared to the Manta platform, the engine in the Kadett was able to be positioned about 5 cms (2 inches) further to the rear of the front axle to slightly improve weight bias and rear traction potential. The normally aspirated 2.4L “phase 2” engine was upgraded to produce around 220 horsepower.


The exterior featured a wide arch kit made out of composite panels and polycarbonate windows. The resulting car was said to weigh about a metric tonne, which was about the same as the Manta, but that most likely could have been improved with further development and replacement of steel parts.

The conversion process for the Kadett D 400 turned out to be very time consuming so only a total of three cars are rumoured to have been built, all sporting slight differences in their specifications and exterior panels (two had square arch extensions, one had round ones).

At the time, not many countries and events allowed for such prototypes to compete and roam around freely. As such, the cars were sent to South Africa for extensive testing (where the Kadett model was coincidentally very popular). One particular car was entered in the country’s 1984 Nissan Int’l Rally driven by Tony Pond. The car showed promise, running in second place with three best stage times out of nine, until Pond was forced to retire due to an oil pump failure.


The Kadett D model was soon to be replaced by a new generation so the “400” project in itself was only a stepping-stone / proof of concept to the next phase of Tony Fall’s master plan. By this time the face of the World Rally Championship (WRC) was quickly evolving with fiercer four wheel drive machinery and the Manta B 400 had already been “decommissioned” out of the international rally scene. As such, Opel’s team manager knew all too well that something even more extreme was needed – ultimately giving one last pitch to the GM executives: the Kadett E 4S project.


In 1986, a Kadett D 400 was subsequently purchased by Malcolm Wilson to be entered in the British Rally Championship. However, the aluminium roll cage that the car was equipped with was no longer being accepted. Wilson had it changed to a steel one and sold the car off. The car would subsequently participate in many rallies both in Britain and Ireland with a few podium finishes.

Murray Grierson

Murray Grierson would campaign a Kadett D 400 from 1986 to 1989 in both the UK and Scotland Rally Championships to good effect by clinching regular podiums. Co-driven by Roger Anderson, Murray Grierson won the 1987 Scottish title outright and came in as a runner-up in the 1988 British National series. Grierson would swap his Kadett D 400 for a MG Metro 6R4 after finishing a disappointing third in 1989.

NOTE: The 1986 timing for the return of these cars to Europe sometimes makes them be incorrectly labelled as being Group S prototypes, of which they are clearly not. Two of the three prototype cars are known to still exist today with a fourth recently built as a tribute replica. The latter was shown at the 2014 Eifel Rallye Festival in Germany.

Opel Kadett 400 replica


Group/Class PROTOTYPE # built: 3
Conception / Production 1983~1984
Type 4S unit with Cosworth “crossflow” cylinder head, I-4, DOHC 16v, gas located front longitudinal
Displacement 2410 cc WRC: 2410 cc
Compression ratio 11.2:1 (presumed)
Output power – torque 220 HP @ 7000 rpm – lb-ft (- Nm) @ – rpm
Materials block: cast iron cylinder head: aluminium
  • natural / normal
  • 2 x Weber carburetors
Ignition electronic, firing order 1-3-4-2
Cooling system water-cooled
Lubrication system dry sump with oil cooler
Type rear wheel drive Getrag 5 speed gearbox
Gearbox ratios (presumed) constant input: 1.652
1st: 3.717
2nd: 2.403
3rd: 1.766
4th: 1.263
5th: 1.000
R: 4.230
constant input: 1.038
1st: 2.337
2nd: 1.671
3rd: 1.355
4th: 1.163
5th: 1.000
R: 2.650
Differential ratio 4.55 ZF hypoid bevel gears, 75% limited slip rear differential
Clutch dry – double disc
Type Kadett D steel monocoque chassis paired with Manta B floorpan. 3 door hatchback.
Front suspension (presumed) McPherson type, independent, telescopic gas shock absorbers and anti-roll bar
Rear suspension (presumed) live axle with 4 longitudinal links, panhard rod, coil springs and telescopic gas shock absorbers
Steering system rack and pinion N/A
Brakes Front and Rear Discs Dual circuit with servo, adjustable ratio split front to rear
length: 3898 mm (157.4 in) width: – mm (- in) height: 1380 mm (54.3 in)
wheelbase: 2520 mm (99.2 in) front track: – mm (- in) rear track: – mm (- in)
Rims – tires N/A N/A
Dry/Unladen Weight 1000 kg (2200 lb)* approx
Weight/power 4.5 kg/HP (10 lb/HP)
Fuel tank N/A



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

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