The Opel Ascona and Manta you see here are proof that motorsport success isn’t always the arbiter of popularity, especially when it comes to those models rallied under the World Rally Championship’s Group 4 and Group B eras. While the Ascona found championship success with one Walter Rohrl at the wheel, and while the Manta fought a brave rear-guard action against the might of the Quattro and various other Group B ‘supercars,’ neither pointed the way forward for the WRC.

Yet both remain among the most sought after rally (or rally related) cars from their respective eras, something merely underscored by Retropower having been commissioned to build examples of both over the years. It’s all the excuse we need to take a look back at the respective rally careers of both of Opel’s ‘400s’, and also the challenges we faced when it came to building Retropower ‘tributes’ to both of these iconic homologation heroes.

Ascona 400

The Ascona 400 was actually an evolution of an earlier Group 4 Ascona B-based rally car, and while modestly successful on specialised events, it never had the grunt of a works RS Escort or the handling poise of a Fiat 131 Abarth. Two things transformed the Ascona’s fortunes as the ‘70s gave way to the ‘80s, the launch of the more powerful, 2.4 16v-powered 400 (the motor having been devised by Cosworth), and the decision by Opel to sign up one Walter Rohrl as its lead driver.

Rohrl’s ability to extract ever last shred of performance from a car was among his most valued traits, as was his mechanical nous and skill for car development. These traits played a key role in the transformation of the Ascona from also-ran to championship challenger, Rohrl eventually using the proven 400 to take the 1982 Drivers’ title at the expense of the Audi Quattros of Hannu Mikkola and Michelle Mouton. The Ascona 400 remains the last two-wheel drive car to take a driver to world rallying’s ultimate prize. 

Retropower Ascona

The car you see here was actually built for Curt Pattinson and formed the very first Retropower ground-up build, and one with a close visual link to the Works cars campaigned by Opel Dear Sport in the early ’80s. There are differences between genuine 400s and Curt’s of course, the engine being the most notable. While the 2.4 16v used by Opel was a potent unit in its day, the very fact that they were built for homologation and therefore competition means that there’re now rare and expensive, and in any case, the C20XE ‘Redtop’ we selected for the job now makes far more power than the road-going 400s did.

Other elements are more obviously 400-inspired, most notably the bodykit and wheels. The former is a relatively subtle affair, certainly compared to some we’ve seen in the years since, while the wheels selected themselves, mainly as no 400 replica worth its salt would be seen on anything other than 9x15in Revolutions!

Manta 400

Aware that the shifting sands of the early ’80s World Rally Championship had served to render the Ascona uncompetitive by 1983, Opel opted to press on with work on its successor, the Manta 400. A great deal was carried over from the old car including the 2.4 engine, which, aside from a few minor ancillaries alterations and larger, twin 50 carbs, was pressed back into active service largely unchanged. Power was still routed through a Getrag gearbox to a ZF rear axle, but the sheer pace of progress in rallying at the time meant that, with a few exceptions, the Manta was outclassed by its all-wheel drive, turbocharged opposition.

The most obvious exception to this was the British Open Rally Championship, then the unofficial proving ground for drivers hoping to crack the WRC, and with star studded entry lists as a result. It was in this championship that the Manta was to truly make its mark, with drivers like Jimmy McRae, Russell Brookes, Bertie Fisher and Austin McHale all using 400s to good effect, often beating the Quattros on sealed surface events. A Manta 400 took overall honours in 1985 (McRae) and 1986 (Brookes), results that secured the Opel’s place in the hearts of a generation of British rally fans.

Retropower Manta

We’ve undertaken several Manta builds over the years including a handful of 400 replicas, but none has been as in-depth from an engineering perspective as this one, built for a Retropower customer called Kenny and powered by a Nissan RB25DET. This is of course a far cry from the naturally aspirated four-pot favoured by Opel at the time, but we all thought the prospect of a brutally fast, eminently ‘cruise able’ Manta simply too compelling to resist.

The RB has since been treated to a number of aftermarket parts, including forged pistons, steel rods, a more capable exhaust manifold, and for the turbo system, a Garrett GT35 turbo, Turbosmart wastegate and dump valve. Cooling was entrusted to a sizeable Skyline Front Mounted Intercooler, with a similarly sized oil cooler and radiator. The car also sports DTA S80 management with switchable boost modes – a mere 350bhp in ‘mild’ mode or 450bhp in ‘manic’ mode. It’s hardly in keeping with the Mantas wrestled by Messrs McRae and Brookes, but it’s a damn sight more comfortable to use on long haul trips.

These are both very, very different cars, albeit cars linked by a shared motorsport heritage and cult, near rabid followings. Which one you prefer rather depends on how you like your rally flavoured Opels; naturally aspirated and raucous, or turbocharged and cosseting.

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