The story of the speed record set 71 years ago, when a Porsche with a 1.5 liter engine ran at top speed for 3 days straight

71 years ago, in 1951, Porsche was still in its infancy, and the engines that powered the creations of that time were modest in size. Porsche 356 SL, for example, had an engine of only 1.1 liters initially, then a 1.3 liter one appeared and only later a 1.5 liter one. There was still a time when the German company moved its headquarters from Austria to Germany and still produced cars in Austria, and in Germany it did so on the basis of a contract with a factory in Stuttgart. And with all this incipient logistics, Porsche engineering already had the claim to break records.

Ambitious minds at Porsche had already proposed to participate in Le Mans, to demonstrate to the world their reliability and performance. But when the 4-cylinder boxer they had on the Porsche 356 appeared in 1.5-liter guise, there was an enthusiast named Richard von Frankenberg, who set out to break a world speed record in the engine class of 1.5 liters.

That version of the Porsche 356 SL had an experimental 1,488cc air-cooled boxer engine, obviously. The engine had inner cylinder walls made of a special alloy, and the valves were coated with sodium, for better heat dissipation. Two Solex 40 carburetors ensured the mixture of air and gasoline for combustion. Thanks to this engineering, that Porsche engine develops 72 hp at 5,100 rpm. This experimental version was later followed by a series one, with 60 hp.

At the end of September 1951, however, Richard von Frankenberg had come with his team and those from Porsche to the Montlhery circuit near Paris, to set the speed record. Twocars tried to achieve records in different classes — one with a 1.3-liter engine and one with the new 1.5-liter engine.

The 1.3 liter Porsche broke two less notorious records in its segment. But the real revelation came from the 1.5 liter Porsche, driven by Richard von Frankenberg and his team of replacement drivers, consisting of Walter Glockler, Fritz Huschke von Hanstein, Petermax Müller and Hermann Ramelow. To be able to hope for a record, the car had to run continuously for 72 hours, with short stops only for refueling and changing drivers. The circuit favored high speeds, as the corners had an inclined route, so that there was no need for heavy braking to pass them. Each lap was 2.54 km long, and at one point a pace of 57 seconds per lap had been reached.

Twice an engine belt broke and had to be quickly replaced. And towards the end, the gearbox also broke down, refusing the couplings in motion. This made the drivers drive towards the end only in 3rd gear, revving the engine to the maximum.

On October 2, 1951, after 72 hours of almost non-stop driving, the Porsche covered 10,987 km at an average speed of 152.34 km/h. This average also includes stops for small repairs, and driver changes, and refueling, and on the circuit, in the straight line segments, the car constantly reached over 200 km/h. The average speed of a tour, without taking breaks into account, was over 160 km/h.

And all this with an engine of only 1.5 liters, built 71 years ago!