The Elden PRH 12 is a Formula 3 car with a clean-sheet monocoque design using the Cosworth BDA 1600cc engine.

Changes from the Mk 9 include: an all new monocoque chassis from Arch Motors, wheelbase increased from 84 inches (Mk 8 Formula Ford standard) to 87 inches and a new bulge on the side to accommodate regulation ‘bag’ fuel tanks and their surrounding deformable structure (foam filler covered in aluminium).

Three chassis were ordered from Arch Motors in August 1972, however they required a minimum order of six. So Elden upped the order to six, but requested slow delivery. Three were used for the Mk 12 and then subsequently two for the Mk 15 and one for the Mk 16.

The new bodywork originally came above and over, covering the roll bar. To reduce wind buffeting of the driver, holes were drilled to allow the air to flow more smoothly. Later regulation changes limited the bodywork height, so this was reduced to just below the roll bar maximum height.

The Mk 12 was also used as a test-bed with Piper to produce a hydrogen powered racing car. The chassis was modified to accept hydrogen storage cylinders whilst Piper worked on engine development. Piper had issues with hydrogen’s high flame speed: the valves couldn’t close quickly enough to stop the flame from returning back to the carbeuretor. Their solution was to mix incoming air with cooled exhaust gases which solved the problem. However the end result was an engine that could only produce 20 horsepower. The unwieldy water-cooling required to cool the exhaust to make the solution would made the car impractical and so efforts were discontinued.

Mk 12 cars that went to the USA were sold as and raced in Formula Atlantic and Formula B categories.

Works Team, sponsored by Mitford: Ken Appleby (Owned Mitford, a transport business), Mike Catlow (Later an F3, Formula Atlantic and Group C driver), Andy Sutcliffe (Later an F1 driver for March)

Lee Fjellanger (Winner of ICSCC CSR Championship in 2007, 2008 and 2009 with the Mk 12)

Ted Wentz (Wella Formula Ford Championship winner in 1973).

Won ICSCC CSR Championship in 2007, 2008 and 2009 after conversion to Sports Racer. Driven by Lee Fjellanger.