1957 Porsche 356A Carrera GS Speedster

This car, Lot 134, sold for $858,832 (€792,500), including buyer’s premium, at RM Sotheby’s Paris, FRA, auction on January 31, 2024.

Your correspondent has written that Porsche 356 Speedsters and all four-cam Carrera-engine 356s would be left standing tall when the generational shift away from the 1948–65 356 hit the marketplace. There were almost 78,000 356s built, but only 4,145 Speedsters and 1,478 four-cam street Carreras of all body types. Recent experience calls those prophecies into question because neither Speedsters nor four-cam Carreras are holding up well right now.

Power, with complexity

After only four years in business, Porsche engineers knew that the horizontal, air-cooled, single-camshaft, 4-cylinder engines were not going to deliver enough horsepower to be competitive in racing applications. Ernst Fuhrmann was put in charge of developing a suitable air-cooled racing engine. Appropriately, he had earned his degree from the Vienna Technical Institute with a dissertation on the design of camshaft systems in high-performance engines.

Introduced in 1953, the twin-plug Type 547 engine Fuhrmann designed had manifold gears and shafts to drive the four overhead camshafts. It used the Hirth multi-piece roller-bearing crankshaft that provided high-revving horsepower in race use. Street use was another matter. Start-and-stop driving led to failures, and in 1959 the change was made to plain-bearing crankshafts. The new engines used an oversquare design (bore larger than stroke), screw-adjusting rocker arms to easily set valve clearances, dry-sump lubrication (external oil tank), high-output double-sided fan, almost hemispherical heads, and sodium-filed exhaust valves for improved cooling. Exhaust systems were designed to maximize output — and make wonderful noises.

Despite being heavier, the four-cam engines improved Porsche’s power-to-weight ratio, and thus performance. All of Porsche’ race cars after the 1952 America Roadster used four-cam engines, including all the Spyders — Types 550, 550A, RSK, RS60 and RS61 — plus the Carrera Abarth, 904, Elva-Porsches and a few “specials.”

At 1,488 cc, the 547/1 produced 110 horsepower, rising to 164–170 for the 547/4. The plain-bearing-crank Type 692 (excepting the 692/0 and 692/2) with 1,587 cc came in late 1958 with 105–135 hp. Last of the line in 1962–65 was the Type 587 with 1,966 cc and 130–185 hp.

For track and street

Fuhrmann designed the four-cam engine to fit into a 356 body, wanting it for his own street car; Porsche put the engines in both racing and street cars. A 356 GS was a street car with a four-cam engine and oil-cooling system, sometimes ordered with brake and suspension upgrades. A 356 GT was a very different car. First offered on the 1957 models, the GTs — both coupes and Speedsters — took out weight to improve performance. They eliminated undercoating and sound deadening and substituted vinyl mats for carpets. An oil tank was mounted in the left rear wheelwell for cooling.

The 1958–59 GTs had aluminum skins rather than steel on both doors and lids — trunk and engine — and added five louvers to each side of the engine-lid grille for additional cooling. Oil cooling was now located up front, with steel lines running back to the engine. The GTs also added 60-mm-wide front drum brakes from the Spyders, with air-catching backing plates for additional cooling. Standard 40-mm brakes continued on the rear. There were 25 “leftover” Speedsters built in 1959 primarily for racing, distinguished by six louvers in each stack on the rear deck lid.

GT coupes were the steed of choice in Europe for hillclimbs, which were prestigious, and for circuit racing. In America, Speedsters were the darlings of the SCCA and SoCal Club racing sets, with either pushrod or four-cam engines. The Speedsters deleted 250 pounds versus coupes, and their removable windshields allowed for low-drag frontal profiles. Bruce “King Carrera” Jennings won the SCCA C-Production National Championship in 1960 and again in 1964 with his stable of four-cam Speedsters, forever enshrining the little beasties as winners.

The Speedster hierarchy

The 1958–59 GT Speedsters are the top of the roster, especially those 1959s built with Type 692 plain-bearing crankshaft engines. Then come the all-steel-bodied 1957 GTs. Next up are all the 1956–59 GS Speedsters. Pre-A Carrera GS Speedsters follow behind, although they are rarer. Carrera Speedster prices peaked in 2015–18 and like all Carreras have trended gently downward since. Then, over $2,000,000 was expected for top-rung 1959 GTs with Type 692 engines and some 1958–59 cars with the Type 547. Race history was important. The days of $1,500,000 for a top-shelf GS are also gone for now.

Production records show 14 four-cam “Pre-A” 1955 Speedsters built, all with Type 547/1 engines. There were 145 four-cam 356A Speedsters, of which 31 were all-steel GTs and 54 were aluminum-paneled GTs. There were an additional eight GTs built with Super 90 pushrod engines for specific race classes. About 77 Carrera GS Speedsters were built. Add in lots of coupes, some cabriolets and a few roadsters/Convertible Ds, and the total for four-cam 356 production is 1,478.

An unknown quantity

The 1957 Carrera GS Speedster that sold at RM Sotheby’s Paris auction is serial number 83492, built in June 1957. It is still in its Kardex-correct silver paint over a black interior. Its original engine was Type 547/1 number 90842. Its engine today is a Type 692/1 number 92002, the second of only 14 built with 1,498 cc and a plain-bearing crankshaft. The scarcity of that unit does not overcome the 15%–20% ding for a non-matching engine. We extend forgiveness to race cars where the engine is a wear item — street GSs, not so much.

Also, this Speedster was assembled with coupe seats but had leather buckets in Paris. If they are reproductions, they are a ding to value. The car is freshly restored and looks to have some reproduction trim and aftermarket wheels. It did have the 1957-specific version of U.S. bumper overrider bars.

We know nothing about metalwork, plastic filler, paint quality, originality of the body panels or originality of the car’s chassis and engine numbers. Those questions highlight our advice: Never buy a four-cam Porsche without a pre-purchase inspection by an expert with the right equipment. There are known fake Carrera Speedsters, one made famous by lawsuits. Insist on a magnetic-resonance test on the cars’ serial-number plate and the digits shown on both doors and both lids. Big money leads to fakes, and the money on these cars has been big for 10 years.

So, is $856,000 fair? The car was well sold, but only if it had no wrecks and had all original panels with excellent paint. Otherwise, it was very well sold. ♦

(Introductory description courtesy of RM Sotheby’s.)