1973 Chevrolet Corvette XP-897GT

The late 1960s had witnessed a tremendous climb in speed as engines continued to produce more and more horsepower. After safety concerns and stricter emission regulations, coupled with an oil embargo, the industry was forced to change. Some of the cars grew in size, focusing on luxury and amenities. Other vehicles went in another direction, becoming smaller and lighter in hopes of increasing performance.

The Chevy Corvette XP-897 GT was a radical departure from conventional design. It was designed by GM's Experimental Studio and built atop a modified Porsche 914 chassis by Pininfarina. It had a mid-engine layout and a 180 horsepower Wankel engine mounted transversely and mated to a new automatic transaxle. It made its debut in 1973 at the Frankfurt Autoshow.

The rotary-piston Wankel engine had been created by Dr. Felix Wankel at Germany's NSU. It offered several advantages over the common reciprocating piston engine, such as simplicity, compactness, high revolutions per minute, smoothness, low weight, and a high power-to-weight ratio. All the parts rotated consistently in one direction with three power pulses per rotor revolution.

The rotary engine would ultimately prove to be both thirsty and polluting, so the gasoline shortage and strict Federal emission legislation signaled its demise.

Three influential General Motors individuals involved in this project included Zora Arkus Duntov, John Z. DeLorean, and Ed Cole. Duntov began his career in the 1950s and was responsible for most of the Corvette's development. DeLorean was also an engineer and was the youngest head of a GM division - Pontiac. In 1969, he took over at Chevrolet. Ed Cole, an engineer, began his career with General Motors in the 1930s. He was appointed chief engineer in 1946, then in 1967, he became president of GM. His projects included the introduction of the small-block V8 engine in 1955 and the corvette of 1953. Later projects included the air-cooled, rear-engined Corvair.

General Motors agreed to pay $50 million for production rights for the Wankel technology. Aware of the engine's shortcomings, Cole believed the ingenuity and size of GM would be able to resolve the engine's issues. The intent was to have an all-Wankel lineup, with the high-selling Vega one of the first to receive the powerplant.

Duntov's Corvette Group was tasked with creating a compact vehicle to be powered by the Wankel engine. They selected a mid-engine layout and acquired a mid-engined Porsche 914/6. Its wheelbase was shortened a further 6.5-inches and the track was widened by 3 inches at the front and nearly two inches at the rear. They retained some of the Porsche underpinnings including the brakes, and the Porsche strut front and semi-trailing arm rear suspension. With a short deadline, the coachwork was tasked to Pininfarina in Turin. The styling was created by GM.

Although intended to have a low weight, the need for a sturdy chassis to comply with crash regulations crippled the performance of the small engine. Duntov tried to resolve the issue with the four-rotor of 1973 but side-lined the project after it consumed twice as much fuel.

The XP 897 GT Rotor Concept was sporty and exotic, yet it did not look like the traditional Corvette. It was everything a concept should be, but perhaps it was too futuristic. Thankfully, the car has survived for future generations to enjoy.

by Daniel Vaughan | Feb 2019