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Wanting a car that would be competitive in the Wesbank Modifieds Series (at the time, South Africa's premier circuit-racing series), South Africa's Delta Motor Corporation commissioned a one-off Calibra race car. Owen Ashley Auto Developments, based in Cape Town, was contracted to design and build the car in late 1990, with financial backing from DMC. The car was designed around the then-current Class A rule set (broadly similar to that used in the American IMSA GT series). The car was based around an aluminium honeycomb floorpan, to which was secured a chrome-moly steel spaceframe. DMC's brief to Owen Ashley stated that as much of the standard Calibra silhouette as possible had to be retained. To that end, a standard Calibra roof, side body monocoque pressings, doors and rear window were used. All remaining bodywork was moulded in fibreglass. The car was powered by a Buick 3800-derived, 3.5-litre all-aluminium odd-fire V6, similar in specification to that used on the IMSA Corvette GTP. Built in the United States by Ryan Falconer, the engine retained its original single-cam, pushrod-and-rocker, two-valves-per-cylinder layout, but employed a Racetronics engine management system and Garrett turbocharger aspirating through a 52mm restrictor plate. The engine produced approximately 600 BHP (447 kW) in race trim. Power was delivered to a rear-mounted five-speed manual Hewland transaxle through a carbon-fibre propeller shaft. Fuel capacity was 40 litres, and double-wishbone suspension was used at both the front and rear ends of the car. Driven by Michael Briggs, the car was campaigned from 1991 to 1993. A rule change for 1994 that banned turbocharged engines from the series, as well as the rapidly increasing popularity of Group A super touring cars, compelled DMC to retire the Calibra in favour of devoting its motorsport budget and resources to its two-car Astra super touring effort. |
