Porsche brought a handful of 924 Carrera GTs to compete in the GTP class in the 1980 Le Mans 24 hour race, with the best car finishing sixth overall. Further development of the Carrera GT platform led to even more homologation specials, culminating in 1981 with the wild 924 Carrera GTR. Ferociously quick, the 924 Carrera GTR was the strongest and fastest—barring only the GTR Le Mans and GTP—of Porsche’s first-generation water-cooled racing cars.
In 1979, Porsche began developing its 924 Turbo as a Group 4 GT entry for the 1980 24 Hours of Le Mans. The new coupe was fitted with a full alloy roll cage and an additional cross-brace beneath the hood. Body panels included aluminum, lightweight urethane and fiberglass. Disc brakes and axles came from the 935 parts bin; a larger intercooler was fitted in the nose; an uprated dog-leg five-speed transmission with limited-slip and its own cooler mounted at the rear gave the chassis exceptional balance. The suspension was fully adjustable, with titanium springs and Bilstein coil-overs front and rear. The dry-sump 2.0-liter inline four developed a startling 375 horsepower with almost 300 pound-feet of torque, giving the 2,050-pound GTR brilliant a 180-mph top speed.
After a trio of 924s made a successful debut in 1980, Porsche came back to Le Mans in 1981. In 1981 Porsche entered a 924 Carrera GTP and a 944 LM, both of which used the new 2.5L engine later used in the 924S and 944. In 1982 924s were entered only by privateers, including two cars entered by BF Goodrich using road tyres. The 924 won the IMSA GTO class in 1981 and the IMSA GT class in 1982, but overall never bettered the Porsche works results, despite the customer cars having more power than the original works cars. After 1980 Porsche focused on mid-engined cars for the new Group C regulations for 1982, dominating the class and ending factory development of the GTR.