The speed of the engine was reduced to a maximum of 4,680rpm in daily driving use and the power was delivered to the wheels via a lightly modified automatic gearbox. The engine could burn any fuel, including diesel, kerosene, alcohol, or vegetable fat.
Wankel’s rotary engine had a single, shallow, lozenge-shaped combustion chamber in which a near-triangular rotary “piston” spun eccentrically.
Wankel first envisaged rotary engines in 1924, and NSU became interested in his research and patents to boost performance of its racing motorcycles. Prototype engines were running by 1958 and the partners worked closely to resolve design issues.
By putting the engine into small-scale production in a specialized sports car, its reliability could be assessed without jeopardizing NSU’s profitability.
The Spider hit the headlines in September 1963, and production starting the following year. The tiny Wankel engine was mounted under the trunk floor at the back: with a single rotor, the Spider could almost reach 100mph (161kph). What it lacked in torque it made up for in free-revving smoothness, spinning happily to 8,000rpm. Critics praised its power delivery and handling, but the Spider, like all early rotaries, needed plentiful fuel and maintenance. Dr. Wankel, though, never experienced the thrill of driving it on open roads—he never had a driver’s license.
“The odd thing about the Wankel is that it gets progressively smoother as its speed builds up, with no vibration periods, valve bounce, or the like to impose limits on it.”
Road Test Of The Spider In Road & Track Magazine, 1965
Video: Model of the car Nsu Wankel Spider
Specification: Model of the car Nsu Wankel Spider
YEAR REVEALED: 1963
PLACE OF ORIGIN: Neckarsulm, West Germany
HISTORICAL STATUS: production car
ENGINE: single-rotor rotary, 30ci (497cc)
MAXIMUM POWER: 50bhp
LAYOUT: rear-mounted engine driving the rear wheels
BODYWORK: two-door, two-seater roadster
TOP SPEED: 97mph (156kph)
NUMBER BUILT: 2,375