The Porsche engineers were tasked with developing a lighter sportier version of their Porsche 356 B 1600. To get this done, they enlisted the help of Carol Abarth, an old Austrian living in Italy and also a close friend of the Porsche family.
Erwin Komenda, Porsche’s head body designer and modelers created the basic body shape. Carol Abarth enlisted several coach-builders in Italy to create the Porsche 356 B 1600 GTL Abarth. This was commonly known as Type 756.
Porsche built 20 Porsche 356 B 1600 GTL Abarth cars for successful racing drivers like Herbert Linge.
In 1962, the Porsche Type 718 GTR was unveiled, another limited production run of a factory-built race car, an evolution of the Porsche 356 B platform.
In 1963, the Porsche Type 356 B 2000GS Carrera GT was unveiled. It was known as the Drelkantschaber or three edge scrapers.
In 1964, Porsche unveiled its next factory-built racer for the FIA Group 3 GT class events, the Porsche Type 904 GTS.
Ferry Porsche’s son Ferdinand Alexander Porsche had left the design school and returned to work in his father’s firm. He was known as Butzi to his family and co-workers.
Butzi joined the design department and followed Erwin Komenda’s mentorship program in early 1958. He watched and assisted the designers and modelers working under Komenda. He was part of the work through variations of the Porsche 356 replacement under studio chief Heinrich Klie.
In the midst of the Porsche 356 replacement development program, came along with the assignment to develop a new Group 3 GT class race car.
Porsche Type 904 was an all-new car and every single element of it represented a new direction.
All the previous Porsche cars were built using tube frames with ultra-thin lightweight aluminum panels or steel shells. The Porsche racing department under the management of Wilhelm Hild and Hubert Mimler had already worked with fiberglass for seating shells, and they realized that they could use fiberglass to make the entire car body for improved weight saving.
Hans Tomala, was put in charge of the fiberglass body development process and led his engineers to develop a platform of two large variable section box members with cross bracing reinforcement. The weight of the new frame was said to be under 50 kg.
Engineers then used double wishbone and coil spring suspension in the front and rear along with rack and pinion steering derived from the Porsche Type 804 Formula One car.
Engineers then mounted the Porsche Type 587 2.0-liter four-cylinder engine ahead of the rear wheels and drove them through a five-speed transaxle. This drivetrain layout was similar to the setup in Porsche 550 Spyders.
Porsche Type 587 delivered a maximum power output of 185hp.
Meanwhile, Ferry Porsche had promoted his son Butzi as the head administrator of design while Komenda remained chief body engineer.
The Porsche 904 shape was revised when Klie and his fellow team of sculptors were working through concepts and suggestions under a limited time frame, and the end result was a more aerodynamically efficient slippery-looking shape.
The Porsche 904 was supposed to be completed within four months, from the first Plasticine model to completion of the first driving prototype, to meet its prospected racing debut.
In November 1963, the car was chosen to compete in the 1964 12 Hours of Sebring.
Porsche enlisted Ernst Heinkel Flugzeugbau, the notorious aircraft manufacturer, to fabricate the fiberglass body panels.
To save weight on the unnecessary gluing and bolting, it was decided to create the body by assembling a handful of body panels rather than assembling a large number of body panels that would require more glue and bolts that could end up in increased weight.
The rear section of the car was finished as a massive single piece, a lift-able rear hatch to allow access to the mechanical components such as the engine, transmission, and rear suspension system. This also eased up the work of mechanics in case of an engine breakdown or accidental damage.
Heinkel’s fiberglass techniques were inconsistent, so the body panels had varied overall weight. The lightest entire body shell is said to weigh barely 110 kg.
The total curb weight of the Porsche 940 was measured at 1433 pounds, and due to the inconsistencies in the Porsche development process and Heinkel’s fiberglass techniques, the overall weight also varied.
The very first 12 Porsche 940 units were sent to the United States for the 12 Hours of Sebring racing event and US-based customers.
By early 1964, Porsche had orders for 102 cars from European, US, and Argentina customers.
At the Sebring, privateers won the 2.0-liter-class by a huge margin behind the wheels of a Porsche 904.
Porsche’s factory team won the first and second places in the Targa Florio event. Many international racing events were dominated by the Porsche 904 in the coming months.
Over the following months, Porsche installed its new racing engine, Type 901/20 six-cylinder engines, and its flat-eight Type 771 engines in a batch of late manufacture cars.
Porsche had developed and produced a total of 109 Porsche 904 four-cylinder equipped cars, including several road-going cars sold to the customers.
Porsche 904 was the first fiberglass-bodied Porsche and its success in terms of performance gave a strong warning to its competitors.