Classic Retrofit recreates original 911R ignition system

Original 1967 Porsche 911Rs are few and far between, but a 911R is exactly what Classic Retrofit was asked to look at for its latest “special projects” creation. Having already been brought in to create a period ignition for the exceptional 911R replica being built at EB Motorsport in the UK, the firm was well placed to help the owner of a genuine 911R who sought to remove CDI boxes fitted to the R prototype sometime in the 1970s and replace them with proper spark boxes, as would have been on the car from new.

“CDI technology was not introduced until 1969,” notes Jonny Hart at Classic Retrofit, “so all factory cars prior to this date used earlier ignition systems. In the case of the 911R, the car relied on a Transistor Controlled Ignition (TCI) circuit to manage the ignition coils, running signals from the high-revving distributor through a circuit that stretched the ignition pulse, forcing the ignition coils to charge for longer. This system has a few shortcomings when compared to CDI, which is why most racers switched to CDI soon after it was introduced. However, for an original 911R, TCI amplifiers are correct.

“To recreate the original system, a genuine 911R ignition box was 3D printed and sent to us for reference. We scanned the printed replica and set about having new boxes created. While that was in progress, we created a modern TCI module to fit in the 911R units. Two original Bosch blue coils were sourced to complete the package.

“The finished product is an impeccable recreation of the original Porsche equipment and a perfect example of what our special projects section has been creating for the rarest Porsche factory race cars over our three years in business to date.

“More than 200 CDI+ units are now in circulation and everyone who uses them is wonderfully impressed,” enthuses the Classic Retrofit MD. “Working on unobtanium ignition units for rare race cars, including several Le Mans winners, has been an illuminating spin-off from the exhaustive R&D programme that led to the continued success of CDI+. It’s a special service that we are delighted to offer clients and collectors all over the world.”

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