By Sivan Goren with images by Jan van der Walt

In their September 1989 issue, CAR magazine gushed excitedly about the latest Opel Kadett GSi 16V offering that had just been launched, saying: “In ride and finish, this latest most potent GSi is where the original one really should have been.” This new kid on the block was dubbed the ‘Big Boss’, but the world had not seen anything yet because a year later an even more exciting car came into being – one that would become a South African homologation legend.

When the original Opel Kadett GSi was launched, although it was considered the biggest challenger to other hot hatches like the Golf GTI as far as top speed, the 1.8-litre offering lacked low-rev pulling power and had a tendency to understeer when on the limit. Enter the 2-litre GSi around two years later. But despite an extra 200cc being added which resulted in the GSi competing admirably with the Golf GTi 16V as far as low-down and mid-range grunt, it still lacked grip, particularly as compared to Golf. But that all changed with the arrival of the 16V ‘Big Boss’. CAR magazine’s road test gave this glowing report: “Opel engineers have managed to build what is surely the world’s finest four-cylinder production engine to date, with this new 16-valver how they have managed to give the engine the bottom-end power of a conservatively-crammed eight-valve motor, the mid-range of a turbo and the top-end of a cammy multivalve, without resorting to any variable induction length or cam timing tricks, as other manufacturers have done in the recent past.”

But it wasn’t just on the road where the new arrival made an impression. Up to this point, both the Golf GTI and BMW 325i had been the dominant players in the South African production car formula called Group N, but with the arrival of the Big Boss that came armed with a double overhead camshaft, Cosworth-developed cylinder head and Brospeed exhaust system, suddenly the usual winners started to feel a bit nervous – and rightly so. Headed by Michael Briggs, a group of drivers challenged the Class A BMW 325i and a fierce rivalry soon developed between Briggs and BMW driver Tony Viana, much to the delight of frenzied fans that camped out on the sidelines, waiting for the inevitable on-track melee that would ensue.

But with Opel’s success, BMW SA went on the offensive and began to step up their local motorsport programme. At the time, the only way a manufacturer could make a model eligible to enter Group N racing was to get it homologated, which meant producing a certain number of road vehicles (500) and selling them to the general public. With BMW snapping at their heels, the powers that be at Delta knew that in order to remain competitive in Group N, they would have to go the homologation route – and that is exactly what they did. Rolf Mentzel, the then manager of product engineering and quality assurance at Port Elizabeth-based Delta Motor Corporation (now General Motors), was the man tasked with this project – his brief was to make sure that driver Mike Briggs would retain his ‘A1’ race number for the 1990 season, and so he headed overseas with a plan…

He returned with tuned suspension from Irmscher, updated camshaft profile by Schrick and a performance-management chip courtesy of Promotec. The addition of 5-spoke powder-coated Aluette wheels meant the wheel arches had to be rolled to house these wider wheels, and to accommodate the ride height being dropped by 20mm. Local innovative engineer André Verwey designed a limited slip differential – the first of its kind on a front-wheel-drive production car at the time. It was an 18% torque-biased differential for road-going models but the torque bias was bumped up to 80% for the race car version, which helped to put more power on the track. The exhaust system was also developed locally because German regulations demanded lower noise levels. After hours and hours on the dynamometer, a four-into-one exhaust header was designed, which had an even bigger and noisier bore system than its predecessor.

The Superboss was launched at Tarlton, with press delegates lucky enough to have cracked an invite gleefully dicing one another down the drag strip. One such participant was celeb Michelle Bruce, who some might remember as Miss South Africa 1989. Not just a pretty face, though, as she managed 16-second runs over a quarter mile. But celebs and launch parties aside, the birth of the Superboss was about one thing only – and that was the race track. And being a car that was built to win on the track, niceties like aircon, power steering and electric windows were not included – the opening mechanisms for the rear windows were removed entirely – all in the name of reducing weight. Even the sound deadening material was left off, which amplified every squeak and rattle – and there were lots of those.

But you did get cool stuff like front brake cooling ducts in the spoiler – achieved by removing the front bumper-mounted driving lights and building in air ducting to the front discs – where a run-of-the-mill Kadett would have just had boring old lights. And if you were really lucky you also got a head that was hand ported by Cosworth. I say ‘lucky’ because although Delta Motors claimed that all Superbosses came with hand-ported Cosworth heads, in reality only around 20-50% of the models produced between 1990 and 1992 actually did. The rest received a Kolbenschmidt casting which was possibly not as well finished, but the truth is that only an expert would be able to tell the difference.  But maybe the coolest thing is this: an ‘S’ appears at the end of the string of letters that prefix the chassis number on the VIN plate – proof that this is no ordinary Boss.

Refinement was certainly not a quality of the Superboss. Its hard and rattly ride – even when brand new – became famous. But then again, so did its monster of an engine, not to mention its incredible performance on the track. What it lacked in superior interior build like its German counterparts BMW and VW, it more than made up for in pure guts and tenacity. Despite battling with larger-engined rivals in Group N, the Opel Superboss was extremely competitive. Although smaller in capacity, its superior power-to-weight ratio kept the likes of BMW and Tony Viana on their toes and allowed Michael Briggs to win the championship three years in a row.

Show anyone who grew up watching racing in the ‘90s a picture or video of this feisty little bruiser and their eyes will light up with excitement and then glaze over with pure nostalgia, because this was a car with no equal – the Superboss was simply unstoppable.