The group s rallycars pt 1

1y ago

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No 1 seat ibiza bimotor

(Original article by Jay Auger) The new Group S formula draft gave Spanish car maker SEAT, which was freshly out of the Fiat group, the perfect opportunity to have a presence in international rallying. However, at the time, there was economic and political unrest in Spain which gave SEAT very little budget to develop a top class rally car. Four wheel drive transmissions, which had become the norm in top rallying, were relatively new and expensive technologies to develop. Hence, two Spanish brothers (the Serivàs) privately came up with a cheaper solution to giving a rally car four wheel drive: use two engines! The “Bimotor” idea was born. It was presented to SEAT Sport which gave it the thumbs up.

The normal SEAT Ibiza itself was a new front wheel drive supermini introduced at the 1984 Paris Motor Show. One interesting feature is that the engine and drivetrain was designed in collaboration with Porsche which, after paying royalties, SEAT could market the car under the “System Porsche” moniker. Furthermore, the bodywork was signed by Italdesign and manufactured by German coach builder Karmann. All of which was to give the new car much credibility, publicity, and boost sales. It was thus logical to use this particular car in the Bimotor concept.

To simplify things, the brothers used two front sections of the Ibiza and joined them together hidden under the bodywork. The “twin” theme continued with the engine, transmission, and suspension. The instrument cluster also contained two of every gauge. The engines were twin 1461 cc “System Porsche” units tuned to produce around 125 HP each, making in theory a total of 250 HP. Adding the two displacements netted a 2922 cc total figure which would put the car in a favorable engine class if the car ever could enter Group B.

There was obviously some difficulties at synchronizing both systems together. One of those was that the front engine would run 1500~2000 rpms higher than the rear one due to inertia. The other main issue was to find a way for the front and rear transmission linkage to work perfectly in synch. Cooling of the rear engine was achieved by installing the radiator in front of the engine in between the bulkhead which was fed cool air by two ducts mounted in the side windows.

The bodywork itself was left relatively unchanged and remained steel for the most part. Only the hood/bonnet, rear hatch, and arch extensions were made out of lightweight fiberglass. This is a far cry from other Group S prototypes that used very expensive exotic materials and polymers all around. However, the Ibiza was a small and lightweight car to begin with and even if fitted with two engines the claimed weight was a respectable 1001 kg (2207 lbs).

By the time the Ibiza Bimotor project was fully completed, Group B and Group S had already been cancelled. However, the car was tested sparingly from 1986 through 1988 in Spanish national rallies with moderate success. A late “evolution” of the car was reportedly performed that boosted each engine’s power to 150 for a total of 300 HP. The final “nail in the coffin” for the Bimotor came when the plan to revive Group S did not materialize within the FISA. The project was abandoned with the car never competing outside of Spanish dirt. The car would not be seen again until it made an appearance at the 2011 Goodwood Festival of Speed hill climb.

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Comments (2)
  • Nice article! I'm amazed to read that the car weighs just 1001 kg considering it has two engines. I know it is a racingcar but still.

    11 months ago

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