From the listing for this 1976 Porsche Le Mans raced car for sale:

Introduced in 1976, the Porsche 934 was essentially a Group 4 GT race version of the Porsche 930 Turbo road car. Having qualified for Group 4 by building a minimum of four hundred 930 Turbos in two consecutive model years, Porsche then built thirty-one 934 race cars. Taking a standard, galvanized 930 bodyshell the 934 was built-up with an aluminium roll-cage fitted and the cockpit left bare, except for a single, RSR-type driver’s race-seat with safety harness and some extra gauges for boost pressure. The engine output could be varied between 480 and 560bhp using an adjustable wheel on the dashboard and with a homologation weight of 1120kg, every bhp had only to move 2kg. A disadvantage to the performance was turbo-lag and drivers had to get used to accelerating before the apex using a 4-speed transmission, instead of 5-speed. The car was otherwise similar to its production 930 counterpart and the rules stated that the 934 had to retain the same engine spoiler as the road car and therefore could not be fitted the bulky air-to-air intercooler as used on the works 2.1 Turbo RSR. Instead Porsche devised a clever method for cooling the charged intake gases using water radiators mounted in the front spoiler which fed water back to the engine compartment where two cooler-cores were fitted, above which air came in through a finned plenum-chamber lowering the temperature from 300° F to 120° F.

Chassis 0158 was supplied new by Porsche competition dept. to Erwin and Manfred Kremer in Cologne financed by the privateer German driver, Gerhard Holup from Kaarst. Holup raced the car extensively in national championship races but had an agreement in place with the Kremer Bros. which allowed them to enter the car for other important World and European Championship races with other professional drivers. In 1976, Bob Wollek, Didier Pironi and Marie-Claude Beaumont drove the car for Kremer in the Le Mans 24 hours and Reinhold Joest, Jürgen Barth, and Bob Wollek drove in the 6 hours of