Porsche 904 (Carrera GTS)

Sales designation:	Carrera GTS
Production period:	1963-1965
Class :	sports car
Body versions :	Coupe , Roadster
Engines:	Gasoline  : 2.0-2.2 liters (114-198 kW)
Length:	4090-4113 mm
Width:	1540 mm
Height:	1065 mm
Wheelbase :	2300 mm
Curb weight :	570-650 kg
previous model	Porsche 718
successor	Porsche 906

The Porsche 904 , officially distributed as the Carrera GTS , was a racing car by Porsche KG . The coupe produced from 1963 to 1965

History

The Porsche 904  had a share of regulations and which could be on race tracks also on public roads. 

In 1963, Porsche developed a successor to the Porsche 718 . The new racing car with the internal type number 904 produced starting from November 1963 was to start in the GT class of the sports car world championship. In order to obtain the required homologation, at least 100 vehicles of the 904 had to be produced according to FIA regulations. The demand of private driver, however, was so high that were installed after the planned 100 vehicles. Because Porsche had laid out at the design stage remaining parts of four other cars were used as spare parts.

Since the 904 could receive a GT-car approval for public roads, this was not allowed to be marketed with the internal number because of the Peugeot name rights to three-digit numbers with a zero in the middle. The Porsche 904 was therefore marketed as Carrera GTS .

Just like the Porsche 911, Ferdinand Alexander Porsche designed the Porsche 904. This was the last model that contained the constructed by Ernst Fuhrmann four-cylinder boxer engine and was one of the so-called road racing cars. The later successor Porsche 906 was, although he had as a road vehicle to be approved, the first sports car from Porsche almost exclusively used as a racing car.For the company, the 904, which was first built by Porsche with a steel-plastic construction method, was a milestone. 

The car was from 1964 to 1966 by the factory team in the World Sportscar Championship and 1965 as a specially constructed 904 Bergspyder used in the European Hill Climb Championship . In addition, many private teams drove the race car also in the two international racing series and in national championships.The 904 won the World Championship 1964 and 1965, the 2-liter GT classification in 1964 and 1964 also the prototype class . 

904 Coupé (1963-1964) 

In the bodywork of the 904, Porsche made a compromise between technical innovations and low production costs. Body support was rather than a space frame, a conventional lighter and less expensive to be produced box frame made of steel, consisting of two stable longitudinal beams, between which a plurality of cross members were welded. For the outer skin Porsche used for the first time a light plastic , with glass fiber reinforced polyester resin of BASF . The body manufactured by Heinkel in Speyer was glued to the box frame and additionally bolted. By bonding frame and plastic skin of the body of the 904 great rigidity has been achieved.

The two-seat coupe had a mid-engine behind the cockpit of the motor was before the rear axle with behind it the transmission, which drive the rear wheels. For better weight distribution were the gas tank with a capacity of 110 liters, the oil cooler and the prescribed fully assembled spare wheel in the bow under the front hinged front hood. In the removable rear cover of the prescribed by the FIA regulations for GT cars trunk was integrated cm with the minimum dimensions of 65 × 40 × 20.The aerodynamically designed body had a small frontal area. The car was sensitive to dominate against crosswinds and at high speeds safely.  The vehicles were initially all a silver-gray, later white, and other coatings.

In the interior, there were only necessary for sporting use instruments and equipment.  The bucket seats were firmly attached to the body. In contrast, the pedals and the steering wheel of the Porsche 904 could be adjusted in the longitudinal direction to allow different drivers an optimal seating position. The Plexiglas window in the doors could only be opened by horizontally pushing in the first produced vehicles. Later cars were also made with retractable windows (crank windows) and small triangular windows in front of them. larger storage compartments inside were integrated into the doors. During the season 1964 of the sports car world championship Porsche improved some details on the car. Thus, later produced vehicles received in 1965 a revised front with larger air openings to better cool the brakes. On the sides behind the doors, enlarged openings were incorporated to give the engine more air.

The Porsche 904 had all-around independent suspension on sloping double wishbones, which were stored in rubber bushings. The suspension took over coil springs with internal shock absorbers. Transverse stabilizers at the front and rear reduced the lateral inclination in curves.  The hydraulically operated Dual circuit with disc brakes was taken over by the Porsche 911 and amplified for racing. In the GTS version, the car was optionally delivered with two tires. The buyer could opt for 185/70-HR-15 radial tires or race tires with the sizes 5.50-15 front and 6.00-15 rear. The tires were each mounted on 15-inch perforated steel wheels with different widths of five to seven inches. 

Porsche initially planned to install the six-cylinder boxer engine of the Porsche 911 in the GTS model. But this idea was rejected and instead resorted to the proven and race-proven 2-liter four-cylinder boxer engine type 587/3 from the Porsche 356 Carrera 2. Porsche justified this by saying that would have to be present for an international race car sold enough spare parts and maintenance knowledge in mechanics. This was ensured with the so-called Fuhrmann engine , of which more than 200 units were built in the two-liter version. 

The engine had air cooling (blower) and dry sump lubrication . This was in the 904 as a mid-engine immediately behind the driver and - unlike the Carrera 2 - installed in front of the transmission. Crankcase, cylinder heads and cylinders were made of light metal. The cylinder inside had Ferral treads that were favorable for oil adhesion and lubricity. The valves were two overhead camshafts with vertical shaft drive controlled. Engine engineers used two Weber falling-stream carburettors or Solex for mixture preparation. The engine had dual ignition with two ignition distributors and two spark plugs per cylinder. The 12 volt ignition system was powered by a 450 watt alternator. 

In the production version, the 2-liter engine with a compression of 9.8: 1 at a speed of 6900 / min made a maximum of 114 kW (155 hp). For racing use, the performance was increased to 132 kW (180 hp) at 7200 rpm, which could be raised to a maximum of 136 kW (185 hp).  With the newly developed five-speed transmission of type 904 and the ZF limited slip differential reached the production car h a top speed of 252 km / and accelerated from zero to 100 km / h in 5.5 seconds. 

The launching only as Trailer 904/8 had the 2.2-liter eight-cylinder boxer engine of the type 771,  the first time in the Porsche 718 RS 61 in the Targa Florio was used,Two overhead camshafts per cylinder bank, which were driven through shafts, actuated valves. The engine had a compression of 10.2: 1 and made a maximum of 198 kW (270 hp) at 8600 / min.

When first used in 1965 904/6 -Werkswagen the air-cooled 2-liter six-cylinder boxer engine type 901/20 was installed. The removed from the 911 engine has been modified for use in racing and approximately 54 kgs lighter than the standard unit. The crankcase was made of light electron , the cylinder heads and cylinder made of light metal. An overhead camshaft per cylinder bank driven by chain controlled the valves. The mixture preparation was controlled by a Weber triple downdraft carburettor per cylinder row. In a compression ratio of 10.3: 1, the motor 155 kW (210 hp) at 8000 / min. 

PERFORMANCE 904 Carrera GTS

• Engine capacity: 121.80 cu in, 1.996 cu cm
• Fuel consumption: 18.3 m/imp gal. 15.3 m/US gal, 15.4 1 x 100 km
• Max speed: 163.4 mph, 263 km/h
• Max power (SAE): 198 hp at 7,200 rpm
• Max torque (DIN): 145 1b ft, 20 kg m at 5,000 rpm
• Max number of engine rpm: 7,200
• Specific power: 99.2 hp/l
• Power-weight ratio: 7.3 lb/hp, 3.3 kg/hp
• Acceleration: standing 1/4 mile 14.2 sec, O 50 mph (O-80 km/h) 5.1 sec
• Max speeds: 48.5 mph, 78 km/h in 1st gear; 77 mph, 124 km/h in 2nd gear; 99.4 mph, 160 km/h in 3rd gear; 124.2 mph, 200 km/h in 4th gear; 163.4
  mph. 263 km/h in 5th gear

904 Bergspyder (1965) 

For the European mountain championship in 1965 Porsche developed a successor to the 1964 driven Porsche 718 RS 61 Spyder. The 904 Bergspyder was based on the 904/8 coupe and already received chassis numbers that began with 906. Therefore, the car is partially entitled 906/8 Bergspyder,  although the race car always went as a 904 Bergspyder to the start and technically based on the 904 coupe.

From the coupe, the developers took 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 coupe.  The car was specially shorter at the front and because of the missing roof and the shorter windshield flatter than the series 904th However, the car was by this conversion with 570 kg about 120 kg lighter than the coupe.

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.  Later, the Bergspyder received again a lighter and rounded at the front and aerodynamically improved car body. From the vehicle a total of five copies were produced, of which three were eliminated by accidents in use.  In the Mountain Championship  Gerhard Mitter piloted only an overall victory at the hill climb Rossfeld.The 904 Bergspyder was replaced yet the end of 1965 at the hill climb Ollon-Villars by the Porsche 906 Spyder Mountain. 

The suspension and tires were taken over without any changes from the coupe. Due to the low weight and the fact unadjusted suspension of 904 Bergspyder was very difficult to drive. Because of his troubled roadside and the tendency to jump, was internally called "kangaroo". 

In Bergspyder the air-cooled 2-liter eight-cylinder boxer engine of type 771 was installed. This engine had its first mission in 1962 in a Porsche 718 RS 61 and had a Bosch injection system for mixture preparation. The valves were operated by two overhead camshafts with vertical shaft drive.  The engine delivered at 8800 / min up to 191 kW (260 hp) and had a compression ratio of 10.5: 1. The sample taken from the 904 Coupé five-speed manual reached the car a top speed of around 260 km / h.