For Sale: 1981 Porsche 935 in Scotts Valley, California

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1981 Porsche 935 K4
VIN: K4/02

One of only two K4 chassis built by Kremer Racing
Complete 100-point concours restoration by Canepa Motorsports
Driven by Ted Field and Danny Ongais
800+ horsepower 3.2-liter twin-turbo flat six engine, 4-speed manual transmission
Heavily influenced by Porsche's own 935 "Moby Dick" design
Eligible for the most important historic racing events worldwide
One of the most powerful 935s ever created

During the mid-70s the Porsche factory reigned supreme with dominant performances from their rugged turbo-powered production racecars. By 1979 the factory began to switch its efforts to the new 936, 956, and 962 prototype, non-production based racing cars. This change spelt the end for the factory Porsche 935, but demand still existed for the continued development of the ferocious 935.

Fortunately some years earlier Porsche had given its blessing to a number of racing teams with close ties to the factory to purchase components and drivetrains, who then designed and produced their own upgraded chassis and bodywork. This included German racing outfit Kremer, based in Cologne, Germany. While these newly constructed vehicles were still generally referred to as Porsche 935s, in reality, they were entirely new designs that engineered the 935 concept to a new level of speed and sophistication. The pinnacle of these independent efforts was the overall win at the 24 Hours of Le Mans in 1979 by the Kremer 935 K3, the last production based car ever to win overall at Le Mans.

The Kremer Brothers had enjoyed a close relationship with the factory since 1970, and were allowed to proceed independently with further development of many models of racing Porsches. They built their first variant of the 935, the K1, in 1976. By 1981, Kremer was ready to produce its fourth version of the Porsche 935, the K4, heavily influenced by the factory Moby Dick 935 produced by Porsche in 1978. In fact, the factory gave the Kremers the drawings, parts, and the Moby Dick car itself on commission to build their new K4 racecar.

K4/02 is the second of only two K4s produced, and as a result of Kremer's constant development, bore little resemblance to an early factory 935. The K4 had evolved into a totally different vehicle, built on a full aluminum tubular chassis, with only a roof and windshield being supplied by the Porsche factory. 02 was delivered to Interscope Racing, Ted Field and Danny Ongais, by Kremer Racing during the 1981 IMSA season. K4/02 would end up being driven and tested by Interscope Racing, but the newest Lola T600 prototypes were chosen in favor of the new developing field of prototype racers.

Vasek Polak acquired the car in the 1983 where the car remained in storage until 1997. At this point the K4 was prepared to race in historic racing, where it was owned by Marshall Field, Ted Field's nephew, for a short period of time. Almost two decades later, the K4 became publicly available for the first time and Canepa acquired the car in 2018, with a clear vision for the Kremer-built 935.

Canepa has had ample experience in restoring not just legendary Porsche 935s, but also 935s built by Kremer. Within a 5 year span, Canepa restored not only the 1979 Daytona-winning Porsche 935 campaigned by Interscope Racing, but also restored the 1979 24 Hours of Le Mans-winning Porsche 935 K3 campaigned by the Whittington Brothers. Upon acquiring Kremer's final hurrah of the 935 platform, Bruce and the Canepa Motorsports team took their time to create a solid action plan of returning the K4 to its former original as-delivered specification in 1981.

Canepa's restoration began with the disassembly and cataloging of all components of the K4 to determine the best course of action to restore and preserve it to its absolute original state. The original K4 bodywork was removed revealing the aluminum tube-frame chassis, and all other components were removed from the chassis until nothing was left except for bare aluminum, which is when the real restoration began.

The aluminum-tubed chassis was an artwork of triangulation, Kremer's interpretation of engineering the most performance out of the 935 platform. Canepa's restoration department was charged with a laborious challenge: refinishing each and every individual aluminum chassis tube until they appeared as new.

While the chassis was getting restored, the mechanical side of the K4's restoration was already well underway. All hardware down the smallest bolts and washers were restored and replated, or replaced as necessary, and all mechanical systems were addressed. The 935 engine was completely rebuilt, resulting in an engine capable of 800+ horsepower. All suspension components were addressed and were rebuilt and restored. BBS wheels centers were refinished and installed with new hardware, and shod with original period Goodyear racing slicks for display. A new aluminum undertray was fabricated, as well as new aluminum interior panels, and installed. A new fuel cell was installed, along with fuel pumps, fuel and oil lines, and brake lines. Brake calipers were rebuilt, and the racing seat was fitted. Once completed, the 935 was mechanically as perfect as when it left Cologne.

Some of the K4's most defining features are its aggressive exterior bodywork and aesthetics, and Canepa spent a significant amount of time perfecting the flowing bodywork. The bodywork was completely gone over by Canepa's bodymen, fixing minute details and ensuring that the fiberglass bodywork would be flawless once painted. Primed and then painted in Interscope Racing's iconic black, the K4 has a menacing presence when fully assembled. Once bodywork was painted and fitted, many hours were spent on historic image research to ensure that the livery of the K4 was perfect, with each decal scaled and placed in their exact location.

Completed, the K4 is a stunning racecar to behold. With a historic lineage from Porsche, Kremer, and Interscope Racing, this 935 is one of the most aggressive 935s ever built. It was revealed for the first time publicly since its restoration at the 2026 Air | Water show in Costa Mesa, CA, and was a sight to be seen by all.

It's rare to be able to be the caretaker for a piece of Porsche history that only 2 examples were ever made, even more rare owned by one of the most iconic private racing teams of all time. With Interscope Racing taking delivery of this car in its iconic colors, it is one of the best looking 935s and one of the best performing 935s of all time. With over 800 horsepower, a complete restoration by Canepa Motorsports to exacting standards, and with only 2 ever made, is a real piece of automotive history that can leave most historic racers in its dust. Available for the first time in 8 years, this 1981 Porsche 935 K4 is not a piece of history that you want to miss out on!