New racing rules set by the CSI beginning in 1976 affected Groups 3, 4 and 5; the classes with which Porsche was primarily concerned.
In 1974 Porsche had introduced the 930 Turbo which would be the basis for its 1976 racing program. The Group 4 variant would be known as the '934' and would be sold to private entrants, while the Group 5 variant would be known as the '935'.
The 934 had to remain close to the 930 Turbo specifications to qualify for Group 4 competition. The minimum weight limit was such that the 934 was often raced with electric window lifts - an unheard of luxury in a race car - and ballast located in the nose. Aside from the stiffness provided by the roll cage, only a cross-bar was added under the front bonnet to obtain race-winning chassis stiffness.
The engine differs from the standard 930 Turbo in its details - horizontal cooling fan, aggressive camshafts, larger intake and exhaust ports, and high capacity K-Jetronic fuel injection. Output was rated at 485bhp. The 934 was the first racing Porsche to use water cooling for its cylinder heads.
Porsche's legendary handling gave the 934 the agility it needed to beat the competition. The 934 also used brakes from the famous 917 Le Mans winner and BBS wheels since Porsche didn't have 16" wheels of its own production.
Racing within the limitations of the Group 4 rules, Porsches 934 was invincible throughout the 1976 and 1977 seasons, winning race after race. It also proved to be one of Porsche's most important, privately entered, racers with some 400 cars being produced. Competing at Le Mans, the greatest challenge in racing, produced GT class victories for the 934 in 1977 and 1979 when a 934 took victory in the GT class at the 24-hour French classic.
