Porsche 911 SC/RS

Porsche produced in 1983 a racing version of the 911 SC : the SC/RS. To homologuate it, 20 exemplars had to be produced. 5 get to Rothmans for racing and the 15 others were sold as street version.

The 911 SC/RS is mainly based on the 930 and particularly on its body and chassis. Indeed, it retakes the wide body, the wheels, the tyres, the brakes and the suspensions of the 911 turbo. In fact, the servobrake wasn't utilized but the braking power was adjustable between front and rear sets. The street legal car is just fitted with larger torsion bars : 22 mm front and 27.5 mm rear ( instead of 19 mm and 26 mm respectively).

To lighten the car, the measures used on the RS and RSR models were applied : no more rear seats, soundproofing materials nor heating system (replaced by a heating system feed by fuel on street version) , utilisation of thin glass on all glasses, aluminium on body pannels (front and rear lid, doors and front wings), fiberglass on front and rear bumpers. Of course, the interior was treated as well with the installation of light bucket seats, removal of the watch, thin door panels opened by a simple strip and no electric equipment at all. With all these actions, the 911 only weight 980 kg.

The engine was of course an evolution of the SC 3.0 and retake its dimension. Nevertheless, the engine received large modifications in racing views. The K-Jetronic mechanical injection has been replaced by a six pistons Kugelfisher pump. The compression ratio has been raised from 9.8:1 to 10.3:1 with the utilisation of new forged pistons. New overhead camshafts and valve settings ensure a great rev rising. As a result, the engine type 930/18 developped 255 hp @ 7,000 rpm and 26 mkg @ 6,500 rpm with the street legal exhaust system. On street version, the engine received an air pump, like on the 911 SC model to improve the quality of exhausted gas. The oil cooler of the 911, positionned in the front right wing was enlarged and placed in the front spoiler. The gearbox type 915 also receive an additionnal oil cooler (as on the Carrera 3.2) to support the important torque developped by the engine. The gearbox ratios were different than standard ones, and come as specified in the following table :

The SC/RS is also fitted with a 40% locking factor anti-slip differential and a reinforced clutch. On the road, even in street version, the car is very performant : until 160 kph, it accelerates faster than a 300 hp 911 turbo ! But high speed is lower than on the Carrera 3.2, due to the bad front surface of the wide body and the shorter gear ratios. Here are the measures obtained by Auto, Motor und Sport, compared with the 1983 911 turbo :

Some info about racing with the SC/RS
In the early eighties, the sponsor in racing of Porsche was Rothmans, essentially in endurance races. But in 1983, a rallycar would carry Rothmans colors : the 911 SC/RS. In this time, rallying was a technological race without limits : the Group B rallycars used rare materials and great engineering to produce 500 hp in an ultra perfectionned body.

The performances of these famous cars were absolutely astonishing as their prices. Lancia 037, Peugeot 205 Turbo 16, Audi Quattro, Toyota Celica Turbo...Very performant cars and not a Porsche to fight against. The Group B at Porsche was planned for 1983 with engagement in rally in 1985. So there wasn't any rally programm. At that time, Rothmans was engaged with Opel but results were late to come and as relations were good between the cigarette manufacturer and Porsche, they asked the factory to produce a rallycar for the 1984 season. The program was clear : European Championship because a 911 was still competitive in this kind of races.

In fact, in some races, the 911 was still competitive provided a good driver was at the wheel. In the last three years, private clients won great victories like the Tour de Corse (1981 - Thérier and Vial) and even the European drivers Championship (1981 - Zanini), the swiss championship (1983 - Ferreux) and the belgian championship (1983 - Snyers), all on 911 SC. So Porsche began to produce what would be known as 911 SC/RS. It was homologuated as an evolution of the 911 SC model and 20 have been produced, 5 of which for Rothmans; the other ones have been sold as street version for DM 188,100. The Carrera 3.2 wasn't retained as a base for the rally car because its larger engine put it in the upper class of cubic capacity, heavier. For the scope of the modifications, check the street version document but the racing version was again improved.

From the beginning, to improve the behaviour of the car and its capacity of reception after jumps, Porsche planned to install helicoidal coil springs. Unfortunately, as the 911 SC wasn't fitted with such equipments, Porsche had to wait 1985 to homologuate it. So, for the 1984 season, the car received larger torsion bars : 22 mm front and 27.5 mm rear ( instead of 19 mm and 26 mm respectively).

The 911 also receive high performances racing shock absorbers and a reinforced engine cross bar. The cockpit is equiped with an aluminium roll cage. If the street legal version is fitted with a 8:31 final drive ratio, two shorter (8:35 and 7:37) were homologuated on the racing version. The transmission is also improved by the utilisation of a competition disc clutch. As an end, the exhaust system is a "Rallye" model which is optimized for the engine settings. It allows the SC/RS to provide 280 hp @ 7,000 rpm and 29.6 mkg @ 5,500 rpm with no less than 26 mkg between 3,500 and 7 ,500 rpm. Porsche produced the car, Rothmans sponsorized it and the DRA team (future Prodrive) used to engage it on tracks.

The car would run for the European Championship but also in the Middle East one with Saeed Al Harji. In Europe, Rothmans engaged a great driver who already had driven for Rothmans with opel. The problem is that this pilot was so great that even Lancia engaged it for the World Championship on the fabulous Lancia 037. But Henri Toivonen was ready to drive both cars. The first part of the Championship was a little bit disapointing for the team as the car showed little wickness but it was very performant on dry tracks. The first victory came in Sardaigne at the middle of the season, followed by victory in Belgium and on the "Milles pistes" rally, in the south of France. Some other great places allowed the team to win the European Championship but some problems with Toivonen lead to a second place overall, which is a great result.

After this episode, Toivonen was fired. On the races, the 911 SC/RS is a very agile car with great motricity, on every fields. It is due to the weight distribution, more pronounced on the rear that the production 911s. It was a great advantage during the season. In the Middle East Championship, where sand and rocks are roads, Al Harji and the 911 were the best with a lot of victories and won the Championship.

For 1985, the car received reinforced chassis and transmission and improved oil ducts.The programm was the same as before with two new pilots for the European Championship : Bill Coleman and Bernard Beguin. The races were hard, competiting with the Group B cars. But the SC/RS obtained great places like third and fourth in the Rallye of Corsica, vicory in Ireland and second places in the "Tour de France" and in Alsace. But concurrence was rude and with the disparition of the Group B cars (fatal accident of Toivonen on Lancia), the racing 959 project was given up. As a result, Porsche and Rothmans stopped rallying to concentrate their minds to the sport prototypes championship. Until 1987, the 911 SC/RS obtained great results in the Middle East but then ... the 911 was obsolete facing the new 4WD rally cars. The end of an area.