Porsche 904

Porsche
Porsche 904 Carrera GTS
904
Sales designation:	Carrera GTS
Production period:	1963-1965
Class :	Sports car
Body versions :	Coupé , roadster
Engines:	Petrol engines : 2.0–2.2 liters (114–198 kW)
Length:	4090-4113 mm
Width:	1540 mm
Height:	1065 mm
Wheelbase :	2300 mm
Empty weight :	570-650 kg
Previous model	Porsche 718
successor	Porsche 906

The Porsche 904 , officially marketed as Carrera GTS , was a racing sports car from Porsche KG . The coupé, which was produced from 1963 to 1965, was approved by the StVZO and was allowed to be driven on public roads as well as on racetracks.

The car was used by the works team in the sports car world championship from 1964 to 1966 and in 1965 as a specially constructed 904 Bergspyder in the European mountain championship . In addition, many private teams also drove the racing car in the two international racing series and in national championships such as the German Automobile Circuit Championship in the 2-liter GT class .

The 904 won the 2-liter GT class in the brand world championship in 1964 and 1965 and also won the prototype class in 1964 .

General

Porsche 904 on a demonstration lap in 1981 on the Nürburgring

In 1963, Porsche developed a successor to the Porsche 718 . The new racing car produced from November 1963 with the internal type number 904 was to start in the GT class of the sports car world championship. According to the FIA regulations, at least 100 904 vehicles had to be produced in order to obtain the homologation required for this. However, the demand from private drivers was so high that after the 100 planned vehicles another 16 were assembled. Even during development, Porsche had paid great attention to producing the car cheaply and sold it at a price of DM 29,700, which was favorable for the time. The rest of the parts for four other cars served as a spare parts store.

Since the 904 was approved for use on public roads as a GT car, it was not allowed to be marketed with the internal number because of the Peugeot naming rights to three-digit numbers with a zero in the middle. The Porsche 904 was therefore sold as the Carrera GTS .

Like the Porsche 911 , Ferdinand Alexander Porsche designed the Porsche 904. It was the last model that contained the four-cylinder boxer engine designed by Ernst Fuhrmann and belonged to the so-called road racing cars. The later successor, the Porsche 906, was, although it could have been approved as a road vehicle, the first sports car from Porsche used almost exclusively as a racing vehicle.

For the company, the 904, built for the first time at Porsche with a steel-plastic construction, was a milestone.

Model development

904 Coupé (1963-1964)

body

With the body of the 904, Porsche made a compromise between technical innovations and low production costs. Instead of a tubular space frame, the body carrier was a conventional, lightweight and inexpensive to produce box frame made of steel, which consisted of two stable longitudinal members, between which several cross struts were welded.

For the outer skin, on the other hand, Porsche used a lightweight plastic, polyester resin reinforced with glass fibers from BASF for the first time . The body made by Heinkel in Speyer was glued to the box frame and also screwed. By gluing the frame and plastic skin of the body of the 904, a high degree of rigidity was achieved.

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  Front view of a Porsche 904

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  Behind the license plate the lid of the small trunk

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  Cockpit of a Porsche 904

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  Minichamps model of Ben Pon and Gerhard Koch's car in the 1000 km race on the Nürburgring in 1964

The two-seater coupe had a mid-engine . Behind the cockpit was the engine in front of the rear axle with the transmission behind it, which drove the rear wheels. For better weight distribution, the petrol tank with a capacity of 110 liters, the oil cooler and the mandatory pre-assembled spare wheel were located in the front under the front hood. The trunk, required by the FIA ​​regulations for GT vehicles, with the minimum dimensions of 65 × 40 × 20 cm, was integrated into the removable trunk lid.

The aerodynamically designed body had a small frontal area. The car was insensitive to cross winds and could be controlled safely even at high speeds. The vehicles were initially all painted silver-gray, later also white and other paintwork.

In the interior there were only the instruments and equipment necessary for sporting use. The bucket seats were firmly attached to the body. On the other hand, the pedals and the steering wheel of the Porsche 904 can be adjusted lengthways in order to allow different drivers an optimal seating position. In the first vehicles produced, the Plexiglas windows in the doors could only be opened by sliding them horizontally. Later cars with retractable panes (crank windows) and small triangular windows in front of them were also manufactured. Larger storage compartments were integrated into the doors.

During the 1964 season of the World Sports Car Championship, Porsche improved some details on the car. Vehicles produced later in 1965 were given a redesigned front with larger air intakes to better cool the brakes. Larger openings were incorporated on the sides behind the doors so that the engine got more air.

landing gear

Porsche 904/6 with enlarged air openings in the front and on the sides

The Porsche 904 had independent suspension all around on inclined double wishbones, which were mounted in rubber bushings. The suspension was taken over by coil springs with internal shock absorbers. Lateral stabilizers at the front and rear reduced the body roll when cornering. The hydraulically operated dual-circuit brake system with disc brakes was adopted from the Porsche 911 and reinforced 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 racing tires with sizes 5.50-15 at the front and 6.00-15 at the rear. The tires were each mounted on 15-inch perforated steel disc wheels with different widths from five to seven inches.

engine and gears

Porsche initially planned to install the six-cylinder boxer engine from the Porsche 911 in the GTS model. However, this idea was discarded and the tried and tested 2-liter four-cylinder boxer engine of the type 587/3 from the Porsche 356 Carrera 2 was used instead . Porsche justified this by stating that the mechanics had to have enough spare parts and maintenance knowledge for a racing car to be sold internationally. This was ensured with the so-called Fuhrmann engine , of which more than 200 pieces were built in the two-liter version.

The engine had air cooling (fan) and dry sump lubrication . In the 904 it was installed as a mid-engine directly behind the driver and - unlike in the Carrera 2 - in front of the transmission. The crankcase, cylinder heads and cylinders were made of light metal. The inside of the cylinder had Ferral running surfaces, which were beneficial for the oil adhesion and lubricating effect. The valves were controlled by two overhead camshafts each with a vertical shaft drive . For the mixture preparation, the engine engineers used two downdraft carburettors from Weber or Solex. The engine had dual ignition with two distributors and two spark plugs per cylinder. The 12-volt ignition system was fed by a 450-watt alternator.

Fuhrmann engine with modified carburettors in the Porsche 904

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

The 904/8 , which only started as a works car, had the 2.2-liter eight-cylinder boxer engine of the type 771, which was first used in the Porsche 718 RS 61 in the 1962 Targa Florio . Two overhead camshafts per cylinder bank, which were driven via vertical shafts, controlled the valves. The engine had a compression ratio of 10.2: 1 and developed a maximum of 198 kW (270 hp) at 8600 rpm.

The 904/6 factory car used for the first time in 1965 featured the air-cooled 2-liter six-cylinder boxer engine of the 901/20 type. The engine taken from the Porsche 911 has been heavily modified for racing and is around 54 kg lighter than the production unit. The crankcase was made of light electron , the cylinder heads and cylinders of light metal. An overhead camshaft per cylinder bank, which was driven by a chain, controlled the valves. The mixture preparation was regulated via a Weber triple downdraft carburetor per cylinder row. With a compression ratio of 10.3: 1, the engine developed 155 kW (210 hp) at 8000 rpm.

904 Bergspyder (1965)

body

Porsche 904 Bergspyder (1965, chassis number: 906-004)

For the European Hill Climb Championship in 1965, Porsche developed a successor to the Porsche 718 RS 61 Spyder, which was still driven in 1964. The 904 Bergspyder was based on the 904/8 Coupé and already received chassis numbers that began with 906. This is why the car is sometimes called 906/8 Bergspyder, although the racing car always started as the 904 Bergspyder and was technically based on the 904 Coupé.

The developers took over the steel box frame from the coupé and placed a light, open plastic body on it. The Bergspyder was not a beauty and visually showed no relationship to the aerodynamic coupé. The car was shorter, especially at the front, and flatter than the standard 904 because of the missing roof and shorter windshield. However, this conversion made the car around 120 kg lighter than the coupé at 570 kg.

During the European Championship season in 1965, the body was changed several times. For example, the windshield on the model with the number 906 004 was further shortened and flattened. Later, the Bergspyder was given a lighter body, rounded at the front and aerodynamically improved.

A total of five copies of the vehicle were produced, three of which were eliminated due to accidents in use. In the hill climb championship, driven by Gerhard Mitter , he could only achieve one overall victory at the Rossfeld hill climb. The 904 Bergspyder was replaced by the Porsche 906 Bergspyder at the Ollon-Villars hill climb at the end of 1965.

landing gear

The chassis and tires were taken from the coupé without any changes. The 904 Bergspyder was very difficult to drive due to its low weight and the chassis not being adapted to it. Because of its restless roadholding and the tendency to hop, it was internally called "kangaroo".

engine and gears

The air-cooled 2-liter eight-cylinder boxer engine of type 771 was installed in the Bergspyder. This engine was first used in 1962 in the Porsche 718 RS 61 and already had a Bosch injection system for mixture preparation. The valves were operated by two overhead camshafts with vertical shaft drives. The engine developed a maximum of 191 kW (260 hp) at 8800 rpm and had a compression ratio of 10.5: 1. With the five-speed manual transmission removed from the 904 Coupé, the car reached a top speed of around 260 km / h.

Racing history

1964 - Victories in the sports car world championship

Porsche 904 in the 1000 km race with Andrea Vianini and Nasif Estéfano at the Nürburgring in 1964

Porsche 904/8 during training for the 1000 km race on the Nürburgring. The car was unable to take part in the race due to an accident during training.

The Porsche 904 was first used at the 12-hour race at Sebring in March 1964. In the race, private drivers Lake Underwood and Briggs Cunningham drove the car, which had started as a prototype due to a lack of homologation, to ninth place and to P3.0 class victory . The works team celebrated their first overall victory with the Carrera GTS at the Targa Florio . Antonio Pucci and Colin Davis drove the car in front of their teammates Gianni Balzarini and Herbert Linge , who finished second, to first place. For Porsche it was the second overall victory in this endurance race after last year's success with the 718 GTR . The 904/8 equipped with an eight-cylinder boxer engine achieved eighth place and P2.0 class victory with Edgar Barth and Umberto Maglioli .

In most races, the 904 was inferior to the larger capacity and more powerful Ferrari racing cars such as the 250 GTO , 275P and 330P and an overall victory was not achievable. In the 2-liter Grand Tourisme class, the 904 was used successfully by private drivers alongside the works team. At the 500 km race in Spa-Francorchamps, Edgar Barth achieved fifth place and the GT2.0 class win. In the 1000 km race on the Nürburgring , Gerhard Koch and Ben Pon from Racing Team Holland took third place overall and won the GT2.0 class. The works drivers Joakim Bonnier and Richie Ginther finished fifth in a 904/8 and won the 2-liter prototype class.

The two 904/8 racing cars with the eight-cylinder engine used by the works team in the Le Mans 24-hour race were very fast on the Hunaudières straight at around 280 km / h, but could not finish the race due to a damaged clutch. In contrast, a Carrera GTS with Robert Buchet and Guy Ligier won the GT2.0 class and came seventh in the overall standings.

In the 12-hour race in Reims, the 904 driven by the Argentines Andrea Vianini and Nasif Estéfano drove to fifth overall and class victory ahead of the works 904 with Gerhard Koch and Gerhard Mitter .

Other overall victories with the 904 were achieved by private teams in the 3-hour race in Monza and the 500 km race in Bridgehampton for 2-liter cars. In Monza, Rob Slotemaker won for Racing Team Holland and in Bridgehampton, Joe Buzzetta and Bill Wuesthoff from Ed Weschler's team won .

Another 2-liter prototype class victory was achieved by Edgar Barth and Colin Davis with a 904/8 at the 1000 km race in Paris .

The Porsche 904, which was actually developed for the circuit, was also very successful in hill climbs , some of which were classified in the sports car world championship, and in rallies. In the Tour de France for automobiles , Robert Buchet and Herbert Linge finished the race from Lille to Nice with the GTS as third and class winners. The two works drivers Günter Klass and Rolf Wütherich finished fourth with their 904s. In the Alpine Rally, Jacques Rey and Jean-Pierre Hanrioud finished third in the overall standings with a Carrera GTS.

In the European Hill Climb Championship, the Swiss Heini Walter won the GT class mountain cup with the 904. European mountain champion was Edgar Barth with a Porsche 718 RS61 .

In the German Automobile Circuit Championship (DARM) in 1964, several private teams started with the 904 and achieved overall victories and in other races in the classification for GT vehicles over 1.6 liters in the races in Trier, at the Nürburgring and in Neubiberg second and third places.

1965 - Dominance in the German Automobile Circuit Championship

Porsche 904/8 at the 1000 km race by Jo Bonnier and Jochen Rindt at the Nürburgring in 1965

In the sports car world championship in 1965, Porsche concentrated increasingly on operations with the prototypes 904/6 and 904/8 and left the 2-liter GT class to the private teams with their Carrera GTS. At the 2000 km race in Daytona, the forerunner of the 24-hour race later held there, only private teams with a 904 competed. There, the Charlie Kolb team drove behind two Ford GT40s and Shelby Cobra Daytona to fifth place and to GT2.0 class victory. In the Sebring 12-hour race, Porsche started with a 904/8 and two series 904s. Lake Underwood and Günter Klass finished the race with a series 904 as GT2.0 class winner in fifth place. Behind it was the second factory production car from Joe Buzzetta and Ben Pon. The 904/8, piloted by Gerhard Mitter and Herbert Linge, finished ninth in the overall standings and P2.0 class winner.

In Monza, the works team decided not to start in the endurance race. The 904 was only represented by private teams. Ben Pon and Rob Slotemaker won the 2-liter GT class ranking in fourth place. In the following Targa Florio, Porsche used three different 904 prototypes in addition to a series 904 in order to be able to compare their stability in a long-distance race. The 904 Bergspyder with Colin Davis and Gerhard Mitter, built for the European Hill Climbing Championship, finished second in the overall standings behind a Ferrari 275P2 . The 904/6, the 904/8 and the 904 followed in third to fifth place. The experience gained prompted Porsche to use the more reliable six-cylinder engine instead of the eight-cylinder engine for long-distance races and the future 906 .

In the next long-distance race at the Nürburgring, Porsche fielded three 904/6 and one 904/8. The 904/8 driven by Joakim Bonnier and Jochen Rindt achieved third place behind two Ferraris and victory in the P2.0 class. The other works cars finished the race in fifth, sixth and ninth place ahead of the privately entered 904s. Porsche competed in the Le Mans 24-hour race with one 904/8, two 904/6 and one 904 alongside three private teams. Only two works cars finished the race. Herbert Linge and Peter Nöcker finished fourth with a 904/6 prototype. Behind them, Gerhard Koch and Anton Fischhaber placed fifth with the 904 in the overall ranking.

In the last race of the 1965 World Championship season, the 500 km race in Bridgehampton for 2 liter cars, the Porsche 904 driven by Herb Wetanson won. This was also the last overall victory that a 904 achieved in this racing series.

In the European Hill Climb Championship, Porsche competed with the 904 Bergspyder specially developed for this racing series. The racing car, which was mainly piloted by Gerhard Mitter, was unable to hold its own against the more powerful Ferrari Dino 206P . The Italian Ludovico Scarfiotti won the 1965 sports car class and the hill climb championship before Mitter. Herbert Müller, on the other hand, secured the mountain trophy in the GT class in a Carrera GTS.

As in the previous year, private drivers started with a 904 in the 2-liter GT class of DARM. Porsche also drove 904 prototypes in several runs to test technical improvements. The 904 regularly prevailed against competitors from Abarth , Lotus and Elva and achieved victories. The 904 production cars and 904 prototypes won eight out of eleven races. One of the most successful 904 pilots was Udo Schütz , who won three runs and finished on a second or third podium in three more runs.

At the Monte Carlo Rally in 1965, Eugen Böhringer and Rolf Wüthrich achieved a respectable success with the Carrera GTS. In the race, which was made more difficult by a hurricane-like snow storm, in which only 22 of the 237 vehicles started reached the finish, the two Porsche works drivers drove their car to second place. Timo Mäkinen and Paul Ester with a Mini Cooper S were the winners .

1966 - The last operations by the factory team

Porsche 904 as a ZDF camera car in the 1000 km race, driven by Paul Frère and Rainer Günzler at the Nürburgring in 1966

In the 1966 brand world championship season, Porsche mainly used the 906. Only at the 24-hour race at Daytona and at the 12-hour race at Sebring were 904 of the works team started alongside the 906. In Daytona the works 904 with Gerhard Mitter and Joe Buzzetta drove behind the 906 to seventh place in the overall standings and to an S2.0 class victory. The second 904 with works drivers Günter Klass and Udo Schütz finished the race in eighth place. The 904 was used by Porsche for the last time in Sebring and was driven by George Follmer and Peter Gregg to victory in the 2-liter sports car class and to seventh place. After that, the 904 was no longer used in any endurance race.

In the European Hill Climb Championship, Michel Weber and Rolf Stommelen drove the Carrera GTS in several races and Rudi Lins in the Sierra Montana hill climb. In the races, the pilots were able to place themselves regularly on ranks four to six.

In the DARM, mostly Peter Ernst and Rolf Stommelen started with the 904 in a few races. Stommelen achieved the best result of the season with second place at the GT race in Hockenheim. After the 1966 season, the 904 was no longer used in the DARM.

1967 - The last appearances in the European Hill Climb Championship

In 1967, the 904 was only used in the mountain championship in the two mountain races Mont Ventoux and Ollon-Villars. In Mont Ventoux, two 904 drivers finished 12th and 22nd. In the Ollon-Villars hill climb, which was also rated in the World Sports Car Championship, Gildo de Guidi finished 15th and Hans Schertenleib 29th place overall .

The results from 1964 to 1967

1964

1965

1966

1967

Technical specifications

The Porsche 904 was produced and used from 1963 to 1965 in the following versions:

Porsche 904:	904 Coupé (street version)	904 coupe	904/6 Coupé	904/8 Coupé	904/8 Bergspyder “Kangaroo”
Engine:	4-cylinder boxer engine (four-stroke)		6-cylinder boxer engine (four-stroke)	8-cylinder boxer engine (four-stroke)
Displacement:	1966 cc		1991 cc	2195 cc	1982 cc
Bore × stroke:	92.0 x 74.0 mm		80.0 x 66.0 mm	80.0 x 54.6 mm	76.0 x 54.6 mm
Performance at 1 / min:	114 kW (155 PS) at 6900	132 kW (180 PS) at 7200	155 kW (210 PS) at 8000	198 kW (270 hp) at 8600	191 kW (260 hp) at 8800
Max. Torque at 1 / min:	169 Nm at 5000	196 Nm at 5000	196 Nm at 6000	230 Nm at 7000	210 Nm at 7100
Compression:	9.8: 1		10.3: 1	10.2: 1	10.5: 1
Valve control:	Two vertical shaft driven overhead camshafts each		One overhead camshaft each, chain-driven	Two vertical shaft driven overhead camshafts each
Cooling:	Air cooling (fan)
Transmission:	5-speed gearbox and limited slip differential; Rear wheel drive
Brakes:	Dual circuit disc brakes
Front suspension:	Inclined double wishbones , stabilizer
Rear suspension:	Inclined double wishbones, stabilizer
Front suspension:	Coil springs, telescopic shock absorbers
Rear suspension:	Coil springs, telescopic shock absorbers
Body:	Plastic body with box frame
Track width front / rear:	1316/1312 mm		1314/1312 mm		1338/1402 mm
Wheelbase :	2300 mm
Tires rim:	VA: 185/70 HR 15 on 7J × 15 HA: 185/70 HR 15 on 7J × 15	VA: 5.50-15 on? J × 15 HA: 6.00-15 on? J × 15
Dimensions L × W × H:	4090 × 1540 × 1065 mm				4113 ×? ×? mm
Empty weight :	approx. 650 kg		approx. 640 kg		approx. 570 kg
Top speed:	250 km / h	263 km / h			260 km / h
Acceleration 0-100 km / h:		5.5 s

literature

• Jürgen Barth, Gustav Büsing: The big book of the Porsche types. Race car. Motorbuch Verlag, Stuttgart 2010, ISBN 978-3-613-03241-5 .
• Jürgen Barth, Patrick Albinet, Bernhard Weigel: Porsche 904 Heel Verlag, Königswinter 2003, ISBN 978-3-898-80115-7
• Peter Schneider: Type compass Porsche. Racing and racing sports cars since 1948. Motorbuch Verlag, Stuttgart 2003, ISBN 3-613-02300-8
• Lothar Boschen, Jürgen Barth: The great book of Porsche types. Motorbuch Verlag, Stuttgart 1994, ISBN 3-613-01284-7
• Stuart Gallagher: Fascination Porsche. Parragon Books, Bath, ISBN 1-4054-8355-5
• Brochure W 222 2M 3.64 Gl from Dr. Ing.hc F. Porsche KG
• auto, motor und sport , various editions 1964
• Programs of the 1000 km Nürburgring 1964 and 1965
• Motor-Revue , annual edition 1980/81, Vereinigte Motor-Verlage, Stuttgart

Web links

Commons : Porsche 904  - Collection of pictures, videos and audio files

Porsche database

• Porsche 904 Carrera GTS Coupé on Porsche.com ( Memento from March 23, 2009 in the Internet Archive )
• Porsche 904/8 Carrera Coupé on Porsche.com ( Memento from March 23, 2009 in the Internet Archive )
• Porsche 906/8 Bergspyder “Kangaroo” on Porsche.com ( Memento from March 23, 2009 in the Internet Archive )

Report on the Internet

• The Porsche 904 on ClassicDriver.de
• Chassis register of the Porsche 904 (English)

Individual evidence

1. ↑ ^{a b c d e} Dr. Ing.hc F. Porsche AG: 1963 - Porsche 904 Carrera GTS Coupé. On: www.porsche.com/germany/ , archived from the original on March 23, 2009 ; Retrieved January 4, 2013 . 
2. ↑ ^{a b c d e f g} Dr. Ing.hc F. Porsche AG: 1965 - Porsche 906/8 Bergspyder “Kangaroo”. On: www.porsche.com/germany/ , archived from the original on March 23, 2009 ; Retrieved January 4, 2013 . 
3. ↑ Classicscars - website: results of the sports car world championship. From: www.classicscars.com , accessed January 8, 2013 . 
4. ^ ^{A b c d e} Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 90.
5. ↑ ^{a b c d e} Stuart Gallagher: Fascination Porsche. P. 156.
6. ^ ^{A b c d e f} Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 98.
7. ^ ^{A b c d e f g h i} Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 99.
8. ↑ Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 105.
9. ^ ^{A b} Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 104.
10. ^ ^{A b c} Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 100.
11. ^ ^{A b c} Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 91.
12. ↑ Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 101.
13. ↑ ^{a b c} Dr. Ing.hc F. Porsche AG: 1964 - Porsche 904/8 Carrera Coupé. On: www.porsche.com/germany/ , archived from the original on March 23, 2009 ; Retrieved January 4, 2013 . 
14. ↑ Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 60.
15. ^ ^{A b c} Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 118.
16. ^ ^{A b c} Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 106.
17. ↑ Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 107.
18. ↑ Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 108.
19. ↑ ^{a b c d e} Euromontagna - website: European Hill-Climb Championship. From: www.euromontagna.com , accessed January 4, 2013 . 
20. ^ ^{A b} Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 112.
21. ↑ Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 62.
22. ↑ Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 130.
23. ↑ ^{a b c d e f g h} Classicscars - website : Racing results of the sports car world championship 1964. From : www.classicscars.com , accessed on January 4, 2013 . 
24. ↑ Classicscars - Internet site: Race results of the sports car world championship 1963. At: www.classicscars.com , accessed on January 4, 2013 . 
25. ↑ Teamdan - website: rally results and overall placements in 1964. (No longer available online.) On: www.teamdan.com , archived from the original on December 24, 2016 ; Retrieved January 4, 2013 . 
26. ↑ ^{a b c} Racing Sports Cars - Internet site: German automobile circuit championship. From: www.racingsportscars.com , accessed January 4, 2013 . 
27. ↑ ^{a b c d e f} Classicscars - Internet site: Race results of the Sports Car World Championship 1965. From : www.classicscars.com , accessed on January 4, 2013 . 
28. ^ Double-declutching - website: Rallye Monte Carlo 1965 - Pat Moss-Carlsson / Nyström and one of the toughest rallies of all time. From: www . Zwischengas.com , January 20, 2011, accessed January 4, 2013 . 
29. ↑ Teamdan - website: rally results and overall placements in 1965. (No longer available online.) On: www.teamdan.com , archived from the original on March 3, 2016 ; Retrieved January 4, 2013 . 
30. ↑ ^{a b} Classicscars - Internet site: Race results of the sports car world championship 1966. From : www.classicscars.com , accessed on January 7, 2013 .