What was IROC?

The IROC series is reasonably well known in the US but probably not so well known outside it. The idea was to invite champions from a variety of series (mainly US series it must be admitted) to race equal cars and find a Champion of Champions.

About the Drivers

Between them, the drivers in the inaugural series had won 32 major championships, the Indy 500 six times, the F1 World Championship twice, the Can Am Challenge Cup five times and the NASCAR Grand National seven times.

Al Unser and Mario Andretti were unable to participate due to their Firestone contracts and the IROC series use of Goodyear tyres

About the Cars

Porsche supplied 15 of the just introduced 911 3.0 RS, each in a different colour, for the series. These were somewhere between the 1973 2.8 RSR and the 1974 3.0 RSR in specification. In terms of engine they had the early version of the 3.0 racing engine, the 911/74 which produced 315 bhp and had butterfly throttles. For 1974, the 911/75 was introduced with sliding throttles which boosted power to 330 bhp. In terms of wheels and tyres, the IROC cars had the 9" front and 11" rear as used on the 2.8 RSR which fitted inside the standard 3.0 RS arches. The IROC cars did not have the extra wide arches of the 1974 3.0 RSR. They were initially were fitted with the duck-tail spoiler, however, this was replaced by the whale-tail before the first race.

The cars in the demo are modified versions of the GTL car, in particular to reflect the narrower wheel arches used on the IROC car.

Below is a photo of the first 12 IROC Porsches ready for delivery from the factory. The final 3 were delivered separately.