1970 Porsche 911 ST

The Porsche 911 was introduced in 1964 and was engineered with features that allowed it to be highly competitive racers straight from the showroom floor, and its legacy is filled with numerous accomplishments on the track. Competition versions in various configurations were constructed throughout the 1960s as the German manufacturers perfected designs that would be successful in international events while complying with homologation requirements. In many cases, Porsche offered conversion kits rather than complete racing cars, allowing customers to convert road cars to specifications that met their needs and intended racing purposes. Occasionally, Porsche would introduce specific variants of the 911 built at the factory for competition purposes and with specifications that were unavailable through the ordering of Sport Purpose options alone.

Competition-sped standard accouterments bestowed upon the 911 include the dry-sump oiling system and four-wheel disc brakes, and they could easily be accentuated with Sport Purpose options such as exhaust systems, oil coolers, and roll bars.

The Porsche 911 R and T/R versions had been very successful in rally and racing competition during 1969 and were followed in 1970 by what was known internally as the ST. FIA Regulations allowed significant changes to production-based sports cars and GTs for the 1970 season, and Porsche's competition manager, Rico Steinemann, realized that homologating the new 911 S at a low weight would yield a huge advantage. Non-essential materials within the 911S were removed including soundproofing and undercoating material, and numerous lightweight features were installed, including mesh engine-grilles, rubber deck lid hold-downs instead of release cables, thin-gauge sheet metal, aluminum doors, a fiberglass hood and engine lids, plexiglass windows, and pull-strap door releases. Design specifications varied, including a range of fuel tank sizes. The performance was further enhanced by the widening of the track, allowing much wider wheels and tires to be installed. In its most potent configuration, the 911 ST 2.3 weighed a mere 840 kg.

A modified version of the 2.2-liter flat-six available in the road cars was used to power the 911 ST, and as rules allowed only the bore to be increased, the 2.3-liter competition engine was much smaller than the 2.5-liter for the class in which it was due to compete. With the help of a pair of triple-choke Weber carburetors and high-compression pistons, the engine developed over 230 horsepower. Some examples were equipped with the standard 911 gearbox while others used the sturdier five-speed Type 915 gearbox. Some examples received special gear ratios, a forty-percent limited-slip differential, and rally exhaust.

Production of the 911 ST lasted from 1970 to 1971 with approximately thirty-six examples built with the lightweight shell and configuration. As they were built to customer specifications, each example is unique, with many being upgraded to the ST 2.5 specification (2.5-liter).

The Porsche 911 ST was raced by the factory and privateers. It won its racing debut event at the Monte Carlo Rally of January 1970, won several GT class victories at international events including the 24 Hours of LeMans, and by the end of the season, Porsche was crowned the International Rally Championship.

The racing success of the 911 ST encouraged Porsche to build a series production competition version for the 1973 season, known as the Carrera RSR.

by Daniel Vaughan | Mar 2021