Porsche 904
Template:Expand GermanTemplate:Infobox automobile
The Porsche 904 is an automobile which was produced by Porsche in Germany in 1964 and 1965. This coupe, manufactured from 1963 to 1965, was street-legal under road traffic laws, allowing it to be driven not only on race tracks but also on public roads.
The car was used by the factory team in the Sports Car World Championship from 1964 to 1966. Additionally, numerous private teams raced the Porsche 904 in these international series as well as in national championships, such as the German Automobile Circuit Championship, specifically in the 2-liter GT class.
The Porsche 904 achieved significant success, winning the 2-liter GT category in the Manufacturer's World Championship in 1964 and 1965, and it also won the prototype class in 1964.
HistoryEdit
After having withdrawn from Formula One at the end of the 1962 season, Porsche focused again on sportscar racing. The 904 debuted late in 1963, for the 1964 racing season,<ref>Gabbard, Alex. "The Porsche 904 Legacy", in VW & Porsche Magazine, 12/87, p.83.</ref> as a successor to the 718, which had been introduced in 1957. Porsche designed the GTS variant to compete in the FIA-GT class at various international racing events. The street-legal version debuted in 1964 in order to comply with group 3 appendix J<ref name="Gabbard, p.82">Gabbard, p.82.</ref> homologation regulations requiring a minimum of 100 road-going variants be sold by the factory. Porsche produced one-hundred and six 904s at four or five a day<ref name="Gabbard, p.84">Gabbard, p.84.</ref> with a list price of US$7245 (FOB Stuttgart).<ref name="Gabbard, p.83"/> Orders far exceeded the one hundred car requirement to satisfy homologation rules and more cars could have been sold.<ref name="Gabbard, p.84"/> The 904 marked the beginning of a series of sportscars that culminated in the dominant 917.
904 Coupé (1963–1964)Edit
EngineEdit
The 904's mid-engine layout was inherited from the 718RSK series (RennSport = racing, K referring to the torsion bar suspension shape), the factory's leading race car. It was powered by the Template:Convert Type 587/3,<ref name="Gabbard, p.83"/> four-cam flat four-cylinder engine producing 180 hp, "probably the most complex four-cylinder" ever.<ref name="VW&P p.87"/> It drove a five-speed transmission with a standard 4.428:1 final drive, with available 4.605, 4.260, 3.636, and 3.362 ratios.<ref name="Gabbard, p.83"/>
Begun as the Type 547, its development began in 1953, when the previous VW-based Template:Convert flat-four, used in the contemporary 356 and rated at Template:Convert, hit the limit of its potential.<ref name="Gabbard, p.83"/> Porsche realized it needed something all-new.<ref name="Gabbard, p.82"/> The brainchild of Ernst Fuhrmann, later technical director, it was hoped to achieve an "unheard of" Template:Convert per Template:Convert,<ref name="Gabbard, p.83"/> relying on hemispherical combustion chambers and Template:Convert-throat 46IDA2 two-choke<ref>VW & Porsche Magazine, 12/87, p.88</ref> Weber carburetors to generate Template:Convert from the Template:Convert four-cam engine.<ref name="Gabbard, p.83"/> The 1.5 liter weighed Template:Convert dry, eventually producing Template:Convert. A complex design that proved "very taxing" to build and assemble,<ref name="Gabbard, p.83"/> but very durable, it was used in 34 different models, including 550 spyders, 356 Carreras, and F2/1s.<ref name="Gabbard, p.83"/>
ChassisEdit
The 904 was the first Porsche to use a ladder chassis<ref name="VW&P p.87"/> and fibreglass body,<ref name="VW&P p.87">VW & Porsche Magazine, 12/87, p.87.</ref> appearing more like a specialist racing car than the modified sports cars typical at the time,<ref name="Gabbard, p.83">Gabbard, p.83.</ref> and was painted white. The fibreglass body was bonded to its steel chassis for extra rigidity, and achieved a drag coefficient of 0.34.<ref name="Gabbard, p.83"/> While many German race cars had used unpainted aluminium bodies since the famous 1934 Silver Arrows, most 904s were painted silver, the modern German national racing color. Unusually for Porsche, the two-seater bodies were provided by contractors, which would later become standard practice among race car builders.<ref name="Gabbard, p.84"/> The 904's fibreglass body was made by spraying chopped fibreglass into a mold, the amount sprayed often varied in thickness over the shape of the car and as a result the weight of the various cars was somewhat inconsistent. Race-prepared four-cylinder 904s weighed in at approximately 1,443 pounds (655 kg) and the low weight gave the 904 the ability to accelerate to Template:Convert from a standstill in less than six seconds (using the standard rear gear, which was typical at Sebring)<ref name="Gabbard, p.83"/> and to reach a top speed of Template:Convert (with the 3.362 ratio).<ref name="Gabbard, p.84"/> Frontal area was only Template:Convert.<ref name="Gabbard, p.84"/>
SuspensionEdit
The Porsche 904 rode on coil springs (the first Porsche not to use trailing arm front and swing axle rear suspension),<ref name="VW&P p.87"/> with unequal-length A-arms in front.<ref name="VW&P p.87"/> The wheelbase was Template:Convert,<ref name="Gabbard, p.84"/> track front and rear Template:Convert,<ref name="Gabbard, p.84"/> height Template:Convert, and ground clearance of Template:Convert on Template:Convert wheels. Brakes were Template:Convert discs at the front and Template:Convert at the rear.
904/6Edit
To satisfy demand, forty 1965 models were produced, some featuring a variant of the 911's flat-six. Due to the weight issues of the first generation plastic body, the 904's successor, the 1966 906 or "Carrera 6", was developed with a tubular space frame covered with an unstressed, lighter fiberglass body.
904/8Edit
A few factory race cars were fitted with a flat eight-cylinder power plant derived from the 1962 804 F1 car, the Template:Convert Template:Convert Type 771,<ref name="Gabbard, p.83" /> which used Template:Convert-throat downdraft Weber carburetors.<ref name="Gabbard, p.97">Gabbard, p.97.</ref> The Type 771s, however, suffered a "disturbing habit" of making their flywheels explode.<ref name="Gabbard, p.97" />
904 Bergspyder (1965)Edit
BodyEdit
For the European Hill Climb Championship in 1965, Porsche developed a successor to the 1964 Porsche 718 RS 61 Spyder. The 904 Bergspyder, based on the Coupé 904/8,<ref name=":0">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> was given chassis numbers that began with the 906.<ref name=":1">Jürgen Barth, Gustav Büsing: Das große Buch der Porsche-Typen. Rennwagen. S. 106.</ref> Therefore, the car is also sometimes called the 906/8 Bergspyder,<ref name=":0" /> Although the race car was most commonly known as the 904 Bergspyder and was technically based on the 904 coupé.
From the coupé, the developers carried over the steel box frame and put on a light open plastic body. The Bergspyder was not a beauty and visually showed no relationship to the aerodynamic coupé.<ref name=":0" /> The car was flat especially shorter at the front and because of the missing roof and the shorter windshield as the series 904. However, this made the car around 120 kg lighter than the coupé, with a weight of 570 kg.<ref name=":0" />
During the European Championship season 1965, the body was changed several times. For example, the windshield on model number 906 004 was shortened and flattened.<ref>Jürgen Barth, Gustav Büsing: Das große Buch der Porsche-Typen. Rennwagen. S. 107.</ref> Later, the Bergspyder received again a lighter and rounded at the front and aerodynamically improved car body.<ref>Jürgen Barth, Gustav Büsing: Das große Buch der Porsche-Typen. Rennwagen. S. 108.</ref>
A total of five copies were produced, of which three were destroyed in accidents.<ref name=":1" /> In the European Hill Climb Championship, Gerhard Mitter piloted the Bergspyder to an overall victory at the hill climb Rossfeld in 1965.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The 904 Bergspyder was replaced at the end of 1965 at the hill climb Ollon-Villars by the Porsche 906 Spyder Mountain.<ref name=":2">Jürgen Barth, Gustav Büsing: Das große Buch der Porsche-Typen. Rennwagen. S. 112.</ref>
SuspensionEdit
The chassis and suspension were taken over without major changes from the 904 coupé.<ref name=":1" /> Due to the low weight and the unadjusted suspension of the 904, the Bergspyder was very difficult to drive.<ref name=":0" />
Engine and transmissionEdit
The Bergspyder is powered by the air-cooled 2-liter eight-cylinder boxer engine used in the type 771. This engine had its first use in 1962 in the Porsche 718 RS 61 [21] and already had a Bosch injection system for mixture preparation.<ref name=":2" /> The valves were operated by two overhead camshafts with vertical shaft drive.<ref>Jürgen Barth, Gustav Büsing: Das große Buch der Porsche-Typen. Rennwagen. S. 130.</ref> The engine delivered up to 191 kW (260 hp) at 8,800 rpm and had a compression ratio of 10.5: 1. The car had a top speed of around 260 km/h (161 mph).<ref name=":0" />
Technical specificationsEdit
- Engine (904 Coupé)
- Drivetrain layout: mid-engine RWD
- Engine type: flat-four
- Bore × stroke: Template:Convert × Template:Convert
- Displacement, ci/cc: 120/1966
- Compression ratio: 9.8:1
- Max SAE net horsepower: Template:Convert
- Specific output, hp per liter: 100.7
- Weight to power, lbs per hp: 5.4
- Transmission: five-speed manual
PerformanceEdit
- Drag coefficient: 0.34
- 0–Template:Convert: <6 seconds
- Top speed: Template:Convert
Modern day replicasEdit
Modern day replicas of the 904 are currently being produced by a number of companies, including Martin and Walker<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> in the UK and Chuck Beck<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and Dennis Frick at Europa Macchina in the US.
RacingEdit
Making an inauspicious debut at Sebring in 1964, where it suffered clutch trouble,<ref name="Gabbard, p.83"/> "a four-cylinder 904 took an astounding first overall" at the Targa Florio.<ref name="Gabbard, p.83"/> It went on to a third at the Nürburgring and a perfect finish at Le Mans. Both times, all five starters finished, placed in the top twelve overall,<ref name="Gabbard, p.83"/> among many much more powerful cars. 904s showed remarkable durability; they "almost always" finished,<ref name="Gabbard, p.97"/> and at Reims in 1964, a customer car fresh from Stuttgart, driven to the track, went on to win without the need for any spares at all.<ref name="Gabbard, p.84"/> For 1964, 904s racked up a 1–2 at the Targa Florio and class wins at Spa, Sebring (co-driven by Briggs Cunningham and Lake Underwood), the Nürburgring, Le Mans, Watkins Glen, Zandvoort, Canada, and the Paris 1000 Kilometer, in the process taking SCCA's C-Production and E-Sports Racing titles.<ref name="Gabbard, p.97"/> In addition, it won rally events including the Tulip, Munich-Vienna-Budapest, Geneva, and "highly acclaimed" Alpine Rally.<ref name="Gabbard, p.97"/> For 1965, results were "equally impressive", seeing wins at the Spanish, Rossfeld, Hellbronner, and Gaisburg rallies, as well as a class win and second overall in the Monte Carlo Rally which saw just 22 finishers in the points, out of 237 starters.<ref name="Gabbard, p.97"/> In addition, 904s won their class at the Monza 1000 Kilometer, Targa, Spa, Daytona Continental, Le Mans, and Zandvoort, among others, repeating their E-Sports title win and adding an SCCA E-Production championship.<ref name="Gabbard, p.97"/>