In 1951, Volkswagen prototyped a 1.3 litre diesel engine, given project number 508. Volkswagen made only 2 air-cooled boxer diesel engines that were not turbocharged, and installed one engine in a Type 1 and another in a Type 2. It even provided vital strength data for Porsches own 1.3/1.5 crankcase, but it would be 1981 before the public learned of this decidedly different VW engine. The occasion for reconstructing a workable compression-ignition engine was Porsche's own 50th anniversary. Development boss Helmuth Bott was searching his firms vast book of past projects for possible runners to celebrate that first half-century, and particularly for non racing designs to showcase Porsche's many other facets.
With diesels all the rage today, especially those cloned off some gasoline engine, this 1951-53 project was a natural. So he called in Robert Binder, head of engine design in modern Weissach, and allotted him DM 50,000 to recreate the diesel Beetle. Binder was no random choice. His own first task upon joining Porsche in 1951 had been to design that same diesel Beetle engine, although he wasn't a specialist in such technology. Wolfsburg had provided a contract, however, and firms like Bosch could always help the tiny staff of three or four engine men, working in Porsche's wooden barracks under Papa Rabe. In any case, solving the unexpected was routine for young Porsche people then. To repeat the task today took more men and a computer but proved almost as tricky. No test reports had survived and there were very few drawings. Binder drew largely on various memories and the shop skills of their development men. The two engines of that day had long since been scrapped, but at least Bosch found a proper injection pump in its own museum and Mahle cast some 22:1 pistons.
Porsche uncovered a three-piece crankcase at a dealer, since its stronger bottom end as used for the 356 had been developed for this diesel Beetle, too. That gave beefier bearings. Otherwise they needed prechamber heads and new seals but VW cooling proved sufficient for even diesel thermics. The first time around Binder had also drawn on a Gmund project. This was a two-stroke, air-cooled, diesel twin later used in their tractor. But it was conceived to fit a Beetle, if necessary.
Impetus for their original contract came from the very low diesel fuel prices of 1951, as well as Korea-war related shortages of gasoline. Then VW chief Heinz Nordhoff visited the U.S. and returned convinced Americans would never drive automobiles, which rattled on, idle while producing little perceptible power. Project 508 became another of those many, many Porsche designs for VW, which fell into a back drawer. Before that, however, they had fitted one to a Beetle and another to the VW van with which young Bott used to run engineering errands. This pair covered perhaps 15,500 miles apiece in everyday use and provided great glee for drivers who could pull up to the diesel pump and watch the attendants jaw drop. There was a considerable consumption plus too. Bott recalls about 36-40 mpg when a contemporary Beetle did 29-34. Since these test engines displaced 1290 cc (74.5 x 74 mm), Porsche could extract 23 hp initially and 25 at 3100 rpm by the end of the project with a rev maximum of 3300 and weight penalty of only 45-55 lb. Such power was hardly dashing; but then, the everyday Beetle wasn't all that much peppier. Even so, their diesel was slower enough that Porsche engineers still wonder what the person thought who stole the world's only diesel Beetle from a downtown parking slot. Despite a long wait for pre-warming and curious fuel needs, the thief drove it all the way to Switzerland before abandoning his smokey, noisy and obviously odd steed.
It is equally curious that the story is this different VW never became common. Apparently motor magazines and industrial espionage were as rudimentary as design facilities of the time. When some bystander did hear a difference he usually asked if a cylinder had failed. When I drove the car on Nurburgring recently-Porsche put its reincarnated engine into a Beetle of appropriate age from the works collection-both smoke and nose were all too evident, if not overwhelming. Lets just say that few would have been tempted to spend money on a radio with all that air-cooled clatter in the back. Nor was performance neck-snapping on the Rings upgrades where first was a must with two aboard. Absolute maximum speeds of around 15-30-45 mph in the gears go with a top of perhaps 68 if the wind is with you. Porsche quotes an even 60 seconds for 0 to 60. I fully believe them. Cheered on by spectators for an old-timer event, we may even hold the slow-lap record for the Rings short course-truly, a new nostalgia high. Now, if we could just get Porsche to recreate some more projects-the inline six for instance, or an intriguing, air-cooled flat three maybe? Their impeccably turned-out diesel Beetle drew more attention than an everyday 936 Le Mans winner after all. You must wonder how many other recently invented auto ideas were already tucked into a lost file at Porsche decades ago.