The International Race of Champions (IROC) was an invitation-only US competition series, which saw some of the best drivers from various motorsport disciplines come together to compete in identically-prepared control cars. For the debut season in 1974, this consisted of the Carrera RSR 3.0 in a bespoke IROC specification. Just 15 cars were built by Porsche to compete in the racing event.
This car is a striking tribute to those original 15 cars, using a 1979 model year 911 SC as the foundation, and rebuilding it to 1974-style RSR specification to meet FIA Appendix K regulations for historic motorsport. It is approved in the Competition GT Car category to FIA class IR/1, for the 911 RS/RSR type under homologation number 3053. Its current FIA Historic Technical Passport (HTP) is valid until 31 December 2030.
Its original 911 SC chassis has been upgraded with RSR steel trailing arms, aluminium torsion bars, and Bilstein coilover suspension with adjustable dampers and Raceservice4u custom anti-roll bars.
The engine is modified with high-butterfly throttle bodies and RSR sprint camshafts, with valve springs that are robust to 9,000rpm. It has mechanical fuel injection, a twin plug Magneti Marelli distributor and 8-pin Bosch CDI boxes. There is also a 42mm exhaust manifold with ceramic coating. The car retains the correct 915 gearbox, and has a mechanically driven oil pump to circulate the fluid through an oil cooler and back into the transmission. It has also been upgraded with a 225mm Sachs Power Clutch kit, and drives the rear wheels through a ZF limited-slip differential. All of the pipes for the oils and fluids are braided stainless steel lines.
The brakes have been upgraded to the items from a 3.3-litre 930 Turbo. Behind the pedal are two brake cylinders; one for the front wheels and one for the rear wheels, which enables a brake balance adjustment controller. Its fuel tank has been replaced with an FIA specification tank with a 60-litre capacity. Two pumps feed the petrol to a catch tank, while the third is a high-pressure pump to the injection system. The wiring harness has been rebuilt, with many unnecessary connectors removed, and with renewed wiring linings throughout.
The exterior has been transformed with wide front and rear wings, and RSR style front and rear bumpers in polyester – as per the original racing cars. The front boot lid and engine lid are both fabricated from the same material in the RSR style, and it retains steel doors. As it has been raced extensively over the last six years in particular, it has had minor bumps and scrapes as you would expect, but these have all been carefully repaired as-and-when needed. The paintwork is described as being in fair condition.
Inside, the top of the dashboard has been largely retained, but everything else has been stripped out, and with all of the insulating and sound-deadening material removed. An FIA specification roll cage has been installed, along with lightweight door cards. There is a single Sparco bucket seat for the driver, a three-spoke Sparco steering wheel, and a gear lever with a shortened stroke. The handbrake has also been upgraded to the RSR style unit. Its instrument gauges are largely original, though the rev counter has been upgraded to an Auto Meter item marked to 10,000rpm. A plumbed-in fire extinguisher system is also installed.
Over the last six years, this 911 Carrera RSR 3.0 IROC Replica has been managed by TwinSpark Racing – a leading Porsche specialist in the Netherlands, which also handles sales and maintenance of Singer-restored 911s for the Benelux region. During the most recent ownership, the gearbox has been overhauled, new rocker arms and bushes have been fitted, and it has received a new set of wide alloy wheels. The wheels are fitted with slicks that have only been used for two races, and it comes with two extra sets – one with rain tyres.
This Porsche 911 Carrera RSR 3.0 IROC Replica is a striking recreation of one of the most exciting 1970s competitors, which has been prepared to a very high standard, and which is a proven race-winning machine. The vendor reports that it is surprisingly easy to start and drive, but it delivers thrilling performance on track. A genuine RSR 3.0 IROC will come with a price tag of more than $1 million, so this represents a superb race-ready 911 for a fraction of the cost.
Over the last five years, this 911 has won races at the following events: