. it is nice to remember when the purists appeared on Porsche events by the beginning of the 70s wearing shirts with the Real Carreras have 4 Cams logo on them. The Fuhrmann engine caused a lot of passion at its period and still does. I will try to concentrate on the facts rather than on emotions.
The heart of this special car was a race engine after all, the 547/1 roller bearing Spyder powerplant slightly detuned to 100 real hp from its 1498cc. The Carrera cars appeared together with the beginning of the 356A era - there are some exceptions on PreA cars, four Coupes and fourteen Speedsters have been identified.
The 4 cam engine was designed from the start in a very different manner than the normal pushrod engine. While they both had the same opposed four cylinder layout, the normal engine relied on pushrods to open the valves, the 4 cam used bevel gears and shafts. The plugs were fired from twin ignition coils, and a distributor was placed on the end of each intake camshaft to distribute the ignition spark.
A dry sump lubrication system drew oil from a storage tank into the oil pump, returning it to the engine by means of steel braided lines. Lubrication was critical in the 4 cam, as a roller bearing crankshaft manufactured by Hirth was used.
The Hirth crank moved a high-domed piston inside aluminum cylinders with chrome plated walls. Air cooling was, of course, used to help dissipate heat created in the engine; a large, rounded fan tower that was characteristic of the 4 camΆs appearance housed a fan capable of moving over 1000litres of air per second at high rpm.
The cooling system worked quite well, considering the ignition timing was set at 24 degrees before top dead center. This timing advance was necessary to create more horsepower propelling the lightweight Porsches to performance on par with larger displacement sports cars of the day like Ferrari and Jaguars.
A gray Coupe named Ferdinand was the first Carrera, as one of the first Stuttgart built Porsches it was the ProfessorΆs last company car, this car went from the original 1100cc pushrod engine to the first experimental Fuhrmann 4 cam engine with 100 hp. Somebody said: That engine has done pretty well in a Spyder, letΆs see how it goes in a 356. Dr. Fuhrmann had hoped from the beginning that his four cam would find its way into a production 356 body.
Porsche customers were crying for more horsepower, so Porsche installed the 547 engine into a 1949 alloy coupe, that won the Liege-Rome-Liege marathon as Porsche special and won it outright. Ferry then approved a small series of 50 or 100 4 cam cars.
They were designated 1500GS and named Carrera in honor of the Mexican race where Porsche Spyders had done so well. The launch coincided with the A model launch by September 1955, even tough we cannot say there were no PreA 4 Cam cars produced by Porsche.
The sales key were the engine, which would be built to full Spyder standards. The first ones were built with 9:1 with a rev maximum of 7.000 rpms, enough for 125mph. Each engine was run at the bench for several hours at 4.000 rpms plus several minutes at full throttle.
A 356 Carrera Cabriolet, the most expensive of them cost close to US$5.000 then, about the same total capitalization Porsche did 6 years before when founded his company. The original 50 cars had already grow past 700 sales by the 60s. The real competition Carrera came when Porsche divided the 1500GS line in GT and DeLuxe.
The GT was now available as stripped Coupe or Speedster with bucket seats, slide-up plastic windows, lighter bumpers, Spyder front ventilated brake drums, aluminum lids and doors to deal with the extra 10hps like the RS. Factory friends could even get engines with polished parts, higher compression ratios, and special cams.
When the title become 1600GS there was no more roller bearing crank. Engines 692/1,2,3 and 3A just like 587 which was designed first but followed in production, had 4 cams heads but plain bearings all over, they worked as well and moved the Carrera closer to production Porsches requiring less care.
Klaus von Rucker, the design boss then, plainly hated roller bearing cranks and once they had race proven plain bearing cranks he hurried them into the Carrera as a 1600cc, saving the available 2 liter version a while longer. The engine did require more oil cooling now, particularly for racing, so they added 33 feet of tubing to the 692 powered cars, carrying 10.5 qt. Of oil to a pair of coolers under the headlights and back with a thermostat controlling the flow. To prove that plain bearings could take it factory men often went to 8.000rpm in the gears posting 0-60 times at 10.8seconds. The so-called Sebring exhaust returned 15 extra hp to the track machines.
The single-leaf, transverse, camber-compensating spring which were fitted to most Carreras together with the new radial tires reduced oversteer in fast bends so you could drift one with an educated right foot. A works car in the Nurburg 1000 km, in 1959, was the first Porsche to try disc brakes in public but von Rucker noted that pads were gone in only 27 laps or 400 miles and also weighted additional 9 lbs. per wheel than their own drums.
If it werenΆt for competition the Carrera tale would have to end temporally by 1959 when the 356B was introduced without a 4 cam in the catalogue. Porsche soon built a series of some 40 lightweight B coupes for 1960, using 1600 GS GT engines.
The next step was the 2000 GS, that began as a 356B too, the fastest road 356 ever built although its quoted top speed remained the same 125 mph. Actual sales began in April 1962, they were announced at the Frankfurt show in September 1961, and is the car which introduced disc brakes to the general Porsche public.
These brakes were the most confusing feature of the Carrera 2 history. Originally announced as a B with drums it became a road test bed for their own annular discs but was handed around for first press tests in early 1962 with drums after all. It stopped well that way but the pedal was heavy, eventual customer cars had Porsche Dunlop ring discs.
It remained the only road Porsche to use them, and it appears that a certain number of later Carrera 2s in the C body used conventional discs although some may have been conversions, these race-proven discs had the caliper inside the disc for greater leverage, reducing servo need, and smaller brake cylinders. The Porsche design was lighter than other normal disc brakes, racers used an alloy rather than iron calipers and German testers promptly rated them the finest brakes ever.
While they did stop the car short, extreme heat flowed outward to the securing bolts around the periphery of the disc ring and this began cause fractures around the bolt holes, at the end the design proved too costly to perfect. Porsche also toyed with a limited slip differential but confined it to the track cars.
The 1966cc plain bearing four was number 587, first design before Fuhrmann left the factory in 1956 and the first Porsche to use any but the 66mm stroke, at 74mm stroke these engines lead the pistons to a high speed of 53.5ft/s, the torque remained 94 lbs-ft with a wider green tach zone from 2200 to 6200rpm - with the red line band ending at 7000 rpm instead of the 8000 rpm from the first engines - that made this engine more easily mastered at the street use.
The 587 engine was also a bit heavier and an inch wider making even more difficult the plug changes. There was a GT option for the 356C line, generally with alloy doors, plastic windows on straps, close ratio gears and limited slip but Porsche do not recall that any of them had Carrera engines. Outside evidence points to a small series with 160hp engines.
Bellow you can see a very nice article regarding the maintenance of these special engines.
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The hour of truth
The Fuhrmann engine-transmission unit, built from 1953 to 1965, was the forerunner of all the Carrera engines and can still be serviced at Porsche today. Michael Sönke watched the restorer Dieter Wurster at work.
The reputations of some Porsche engines race around the world. The fame extends beyond the engines themselves to the people who carefully tend them. At a bar located a good 10,000 miles from the Porsche factory headquarters, the following conversation was overheard among vintage car fans: “ThereΆs a mechanic in Zuffenhausen who can get any Fuhrmann engine to run. He can do it even when other experts are stumped. WhatΆs his name again...?” Someone else promptly chimes in with “Dieter Wurster.”
Dieter Wurster? We meet the man himself a few days later at a work station in Zuffen-hausenΆs Hall 1. So, Mr. Wurster, what is the secret of your work? “You just have to know what to do,” he replies modestly. Hmm. “I mean, the engine is really complicated.”
How long has he been working on these engines? “IΆve been doing repairs since 1960,” replies Wurster, who came to Porsche as an apprentice back in 1956. With a hint of pride, the 57-year-old runs his broad hand over the gleaming black fan blower of one of the last of those Fuhrmann engines built between 1953 and 1965.
This one was the best, from the 904,” says the man from the Swabian region of Germany, “And the most powerful one of this series had 192 horsepower.” The engine is a delight to behold. Every little screw is highly polished. “All the screws used to be galvanized as white as these ones,” reminisces the expert. “But this type of screw isnΆt made anymore. Nowadays theyΆre only chrome-plated yellow.” So for the restoration work, each screw is sand-blasted individually and its surface is treat-ed. Many other parts, large and small, re-ceive the same treatment because the engines Dieter Wurster restores have to be original down to the last detail.
Klaus Bischof, the director of the Porsche Museum, attests to the brilliant reputation of this man. “If a Carrera engine has been restored by Dieter Wurster, then its value goes up tens of thousands of marks just like that.” In certain circles, the best examples of these four-cylinder engines exchange hands for as much as 150,000 marks.
Given the anonymous designation 547, this engine-transmission unit was noted for the vertical drive of its camshafts, its dual-plug ignition, roller bearings, and double-sided cooling fan. Those in the know also call it the “Schubladenmotor,” or “drawer engine.” The young engineer Ernst Fuhrmann received his doctorate with this design. But not everybody was supposed to know about the unit while it was under construction. And so some of the parts were made under the work bench, so to speak. When certain guests came by, the parts were quickly hidden away in the drawers. Fuhrmann left Porsche for a while, only to return later, becoming Porsche AGΆs first chairman of the board in 1976.
With a capacity of 1498 cubic centime-ters, the original Fuhrmann engine took its first spin on a Zuffenhausen test station on April 2, 1953. Trimmed for racing, the 547 generated 110 horsepower at 6200 rpm. It was installed in the new Porsche racing car, the 550 Spyder. With this car and engine, Hans Herrmann took third place in the over-all rankings for the 1954 Carrera Panamericana. Since then, the name Carrera has played a prominent part in the history of Porsche models. In 1955, Porsche decided to install this air-cooled racing engine in the standard 356 sports cars series as well. The first Carrera had 100 horsepower. By 1956, the Fuhrmann engine was up to 130 horsepower in the 550 A. In one of these cars at the 1956 Targa Florio, Umberto Maglioli celebrated the first overall victory for Porsche in a world championship race. Two years later, the engine was clocked at 164 horsepower. In the Porsche RS 60 of 1960, the capacity grew to 1604 cubic centimeters, and by 1961 to two liters.
If everything goes well, Dieter Wurster is nearly finished with an engine after 150 hours of work. It runs again, just like the engine of a Porsche 904 that was delivered to JordanΆs King Hussein thirty years ago. The monarch later purchased a Carrera 6, and the 904 now belongs to the Porsche Muse-um. But before Dieter Wurster is finished, the engine must successfully undergo a special ordeal, namely a stint at the performance test bank. The noise level at test bank number four in Zuffenhausen is very high. The 904 engine revs up again and again over the course of almost an entire day. A special program drives it for a good three hours, at which Wurster then pushes the accelerator lever forward in a single swift stroke. “Full load,” he yells, and then a few minutes later confides that “no engine unit has to withstand this kind of load on the street.” Is he nervous? “Oh no, I havenΆt felt nervous in ages,” he answers quickly and adds, “I know what IΆm doing, after all.” Later he admits that “before my very first engine was tested, I couldnΆt sleep a wink the whole night.”
Customers occasionally observe the tests. As Wurster notes, “Sometimes the rpm figures just about cause their hair to go gray.”
While the engine spins away itΆs time for some stories. Several decades ago, one of the cars was owned by the Formula driver Carel Godin de Beaufort. “He was hard on the gears, so I was always having to repair his engines,” recalls Wurster. The engines that Beaufort drove were listed as having 164 horsepower, but often they only reached 155. Like every racing driver, the Dutchman wanted more. He promised the mechanics that “if you can get it to 165, IΆll give you a case of beer.” With this prospect before their eyes, the mechanics weakened just a single time. They tinkered with the rpm indicator on the test bench beforehand and Beaufort then watched the dial move to precisely 165 horsepower. Now, however, the mechanics had to be careful that the engine didnΆt die out, because the test bank would still show a performance level of ten horsepower. Beaufort was very pleased and the mechanics got their beer. “IΆve never had such a great machine,” he said at the next race. “And,” smiles Wurster, “he never drove better in his life than with that engine. A driver is faster when he believes in his car.”
Towards the end of our conversation, the question again comes up as to the secret of his work. Now his tongue is loosened. He talks about castor bearings, valve seats, valve actuation, dial gauges, bearing bushings, and asymmetrical shafts. And when no one else at the table can follow him anymore, he looks a bit embarrassed and concludes, “You just have to know how it all fits together.” But isnΆt that hard for a lot of people “Absolutely, says Wurster and grins broadly.Designated the 587, the design reached its climax in the 904 GTS built in 1964. A 904 GTS with Colin Davis and Antonio Pucci led the field at the Targa Florio. Eugen Böhringer and Rolf Wütherich took second place at the 1965 Monte Carlo Rally with a four-cylinder 904. Six and eight-cylinder engines were already being installed in some 904s, and these gradually nudged the Fuhrmann four-cylinders from the racing tracks. The Fuhrmann engine is still highly regarded at vintage races today. Even Dieter Wurster does not know how many Fuhrmann engines have survived. But of the ones that have, he is sure they need careful maintenance. “Then theyΆll give you up to 8000 rpm with no trouble,” he reports. When shifting down, however, the driver should be careful because there is no speed limiter to keep the engine from going out.
Klaus Bischof sends the Carrera engines from his museum cars for a thorough check-up every 10,000 kilometers. He also recommends this to customers. “Service” in this case is of an unusually comprehensive nature. The engine-transmission unit is completely dismantled down to the last screw. Steel and aluminum parts, from the crank shaft to the valves, are examined for cracks using special procedures under ultraviolet
light. Parts that wear down such as gaskets and bearings are replaced. Things start to get difficult if a major part can no longer be repaired. “Generally speaking, these engines can only be maintained with parts from the same era,” explains Klaus Bischof. “Imitations are too expensive.”
So Dieter Wurster gets on the telephone. He knows the true believers who still have parts for this engine. Sometimes he is lucky, but success is always costly. Recently he was offered virtually complete units, but on driving out to inspect the items found “a bunch of junk.” Only the price suggested otherwise. “They wanted 30,000 marks for the stuff.
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