1959 Porsche 718 RSK Center-Seat SpyderChassis no. 718-028Engine no. 90220

1959 Porsche 718 RSK Center-Seat SpyderCoachwork by WendlerChassis no. 718-028Engine no. 90220
1,587cc DOHC Flat 4-Cylinder EngineDual Weber 46 IDM1 Carburetors150+bhp at 7,200rpm5-Speed Manual Transaxle4-Wheel Independent Suspension4-Wheel Hydraulic Drum Brakes*OA Winner GP of Leopoldville and 1000 KN Buenos Aires*One of just a handful Center-seat RSKs produced*Highly original example retaining original engine, gearbox and bodywork*Eligible for the most exclusive driving and concours events globallyTHE PORSCHE SPYDERPorsche's Typ 718 RSK Spyder was the culmination of years of competition spyders by Porsche. Each step along the way was more successful than the one before as Porsche refined its approach to small displacement performance.The origins of the RSK trace back to the period just before the outbreak of hostilities in the late Thirties. The German government had fostered development of the "people's car" conceived as the KdF-Wagen (Kraft durch Freude, Strength through Joy), the Volkswagen.With its two-door sedan body and small 985cc, 24 brake horsepower engine competition was the antithesis of the Volkswagen's design but its potential was shown when in 1939 Porsche was asked to build a special streamlined coupe on the VW platform. The Typ 60K10 was intended to compete in a proposed race from Berlin to Rome, symbolically linking the capitals of the Axis. The September 1939 date for the event was rendered redundant by the German invasion of Poland on September 1.Even during the war the Porsche design bureau pursued competition projects in moments that could be slipped in between war contracts. The staff and prototype workshop were moved to rural Austria, away from Allied bombers. After hostilities ceased and postwar administration of Germany and Austria were settled a fortuitous contract was obtained to design a Grand Prix car for Piero Dusio's Cisitalia.In the Cisitalia can be seen the precursor of Porsche's later sports racing spyders: mid-mounted horizontally opposed engine and parallel trailing arm front suspension although with a supercharger, deDion rear axle and provision for 4-wheel drive. While these were noteworthy in the postwar racing car design encyclopedia, they reflected much of what Porsche had done prewar including the fabulous Auto Union Silver Arrows and a wartime project for a potentially game-changing sports car.This was the Typ 114 with a mid-mounted 1,493cc dual overhead camshaft 72-degree V10 with shaft drive to the overhead cams and 4-wheel torsion bar sprung independent suspension with parallel trailing arms at the front and swing axles at the rear. A Typ 114 prototype was never built but the concept lingered in the Porsche design bureau's library of promising technical ideas.It was succeeded by the 1948 Typ 356, numbered according to the succession of Porsche design projects – which had been only 60 barely a decade earlier when it was the design number for the KdF-Wagen – which brought the Porsche sports car into reality. VW-based, it took some inspiration from Piero Dusio's success with his production racing cars, the D46, and sports cars, the brilliantly styled 202, based on production FIAT components.However the original Typ 356 design was not rear-engined. Rather, it used the VW drivetrain and rear suspension with the engine located behind the driver and in front of the rear axle. Clearly Porsche recognized the value of mid-engine location, as seen in the Auto Union Types C and D, Porsche's still-born Typ 114 and the postwar Cisitalia Grand Prix, and intended to use it in a low production Volkswagen sports car.Built on a tubular space frame, the original Typ 356 transplanted the trailing arm torsion bar front suspension directly from a VW. The entire driveline and swing arm rear suspension were simply turned around, the torsion bar trailing arms of the VW now becoming leading arms anchored to a frame extension. The engine, now 1,131cc, was given a performance boost with higher compression ratio, modified cylinder heads and dual carburetors to realize some 40 horsepower. Clothing it was a roadster body penned by Porsche's Irwin Komenda with many features continued on later Porsches. This prototype was the first to bear the family name.The economics, however, of producing an essentially hand-built tube frame automobile were impractical even for the perfectionist Porsche family and their equally demanding staff. The mid-engined 356 roadster was replaced by a new VW-based design called 356/2.But the advantages of mid-engine placement were not forgotten by Porsche even though an aluminum-bodied rear-engined 1.1-liter Porsche coupe won its class at the 1951 Le Mans 24 Hours.The pathway became more clear when in 1952 Porsche created the vaunted 4-cam Typ 547 engine designed by Ernst Fuhrmann. Starting with 1,498cc, Fuhrmann's powerhouse little horizontally opposed four-cylinder had a bore/stroke ratio of 0.78, thoroughly modern in engines built decades later and nearly unprecedented for 1952. The 85mm cylinder bore made relatively huge intake and exhaust valves possible in the hemispherical combustion chambers. Four overhead camshafts were driven by an intricacy of shafts and bevel gears operating the valve stems through interposed fingers that reduced side thrust.The Hirth-built 10-piece crankshaft rotated in three roller bearings. The connecting rods likewise utilized roller bearings. This complexity of moving parts was lubricated by a dry sump system with an external reservoir. The large oil capacity helped cool the engine which, like all Porsches to this point, employed air cooling directed primarily to the cylinder heads. Dual spark plugs with dual coils and distributors initiated combustion.The first Typ 547 4-cam Porsche engine ran in April 1953 and in the following summer it was ready to outfit a thoroughly updated 550 Spyder chassis. Based on a ladder frame with tubular side members that was underslung at the rear, it had the proven torsion bar trailing arm front suspension but a new torsion bar-sprung trailing arm suspension in the rear. The 4-cam 550 Spyder scored a notable class victory in the 1954 Carrera Panamericana driven by Hans Herrmann.The early 550 Spyders were factory-owned and campaigned although frequently sold on to local racers after appearing in a race or two. In late 1954 Porsche began to build "production" Spyders for direct sale to customers, the 1500/RS Spyder. Bodied by Wendler they yet again incorporated detail design, body and mechanical details. These included a ZF-built fully synchronized 4-speed transaxle. The now thoroughly proven Typ 547 4-cam engine, steadily updated for performance and reliability, now delivered a rated 110 brake horsepower at a moderate 6,200 rpm and a maximum of 125 hp at 6,500 revs but was capable of nearly 8,000 rpm for limited periods, horsepower unspecified.Building RS (RennSport) sports-racing cars had turned into a viable and profitable business for Porsche.That was proven by the next iteration of the 550, the 550A, now with a rigid, lightweight space frame chassis of thin wall tubing, advancing the concept first evidenced in the original 356 roadster of 1948. The space frame weighed 95 pounds but was 3x stiffer in torsion and 5x stiffer in bending. Its design eliminated body mounting structures that had been needed for the 550, reducing body weight by 30% from the 550. Its engine now drove the distributors directly from the front of the crankshaft with worm gear drive giving consistent ignition timing. The continuously improved Typ 547 engine now delivered some 135 brake horsepower with Weber carburetors.Rear suspension, always a challenge for Porsche, evolved to a low-pivot design with a lower roll center. Longer trailing arms reduced camber change in cornering with a pronounced beneficial effect on swing axle induced oversteer. A 550A won the Targa Florio in 1956. Another, with slippery coupe bodywork, finished fifth overall and won its class at Le Mans.The time was right for the Spyder's ultimate form, the Typ 718 RSK, with development beginning in 1956.Owing its name, RSK, to the shape of the front suspension torsion bar tubes which on the top sloped down to meet the lower torsion bar tubes at their midpoints, shaping the letter "K", the design, intended to better master camber change in cornering, did not survive testing, but the nickname persisted. Even after parallel torsion bars replaced the "K"-shape the steering box remained at the center of the front track with equal length track rods. A double U-jointed steering column gave Porsche the option of offset or center steering wheel mounting. The body was slimmed and lowered, with a rounded nose. The rear air vents were discovered to be better at admitting air to the engine's intake and the cooling system than they were at exhausting it.While retaining its swing axle concept the rear suspension underwent a notable redesign with a Watt's linkage replacing the historic trailing arm with two radius rods, one leading forward from the bottom of the hub and another back from the top that securely positioned the rear wheels. Porsche's rear torsion bars were succeeded by a pair of tubular shock absorbers with concentric coil springs.The RSK's redesign was sufficient for Porsche to give it a new project number, 718. With Weber carbureted 1,587cc Typ 547/3 engines Jean Behra and Hans Herrmann drove an RSK to an unprecedented third overall at Le Mans in 1958. Later in 1958 Behra finished fourth at Riverside in the Los Angeles Times Grand Prix for sports cars headed only by Chuck Daigh in a Chevrolet-powered Scarab, Dan Gurney in a Ferrari 375 Plus and Bill Krause in a Jaguar D-Type.The success of the Porsche Typ 718 RSK can be measured not only in terms of its race wins but also its adaptability. In 1957 and 1958 the FIA allowed full envelope bodywork in 1.5 litre Formula 2. The center-mounted steering box in the 718 RSK made it supremely adaptable to this formula and...