THE PORSCHE 550 SPYDER
The 550 Spyder put Porsche firmly on the map as a serious competitor on the world’s racing tracks; indeed, the diminutive mid-engined roadster generated the nickname ‘Giant Killer’ for its ability to defeat much more powerful rivals. Introduced at the 1953 Paris Auto Show, the 550 and its second iteration, the 550A, remained in production through February of 1959, and a total of 130 chassis were constructed before the 718 RSK Spyders appeared. A large proportion of 550 production was destined for the United States.
Built on a frame of seamless mild steel tubing, the 550 utilised a front suspension of double trailing arms and transverse-leaf torsion bars. After the first few examples, the rear suspension was redesigned from leading control arms to trailing arms with swing axles and tubular transverse torsion bars. Porsche’s engineers had planned an all-new engine to power the Spyder at the gruelling Carrera Panamericana, but early testing determined that Dr Ernst Fuhrmann’s Type 547 advanced 1.5-litre air-cooled four- cylinder Boxer engine was not quite ready. Thus, the first few chassis were fitted with conventional pushrod Porsche engines. Soon, however, reliability was ensured and the new ‘Four-Cam’ would be installed in all the 550s, 550As, RSKs, 356 Carreras, and 904s that were to follow.
This marvellous but complex engine, called the ‘Drawer motor’ because its engineering drawings were quickly hidden in Fuhrmann’s desk whenever Dr Porsche walked into his office, was an all-alloy unit displacing 1,498 cubic centimetres. Its camshafts were driven off the Hirth-patent built-up roller-bearing crankshaft by a series of shafts and crown wheels. Cam timing took dozens of man-hours to properly establish, but once all the clearances were correctly set, the high- revving motor was very reliable. It featured dry-sump lubrication and two spark plugs per cylinder. With compression of 9.5:1 and breathing through a pair of Weber downdraft carburettors, this engine produced a strong 110 brake horsepower. In a chassis that weighed barely 590 kilograms, 550s were capable of top speeds approaching 210 km/h (140 mph), dependent on gearing. Because these little roadsters were ostensibly required to be street driven, they were fitted with a token canvas tonneau that met the letter of the rulebook but were otherwise better left folded away in the garage.