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| www.QV500.com - Porsche 911 (1972-73) Part 5: 911 2.8 Carrera RSR |
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The 2.8 Carrera RSR was Porsche’s Group 4 competition car for the 1973 season. Based on the fabulous 2.7-litre RS homologation specials covered in Part 3, the bigger engined RSR's featured a number of important upgrades for track use. Weighing in at the 900kg class minimum for Group 4 cars, the RSR's suspension geometry had been altered to accommodate special coil springs with fully adjustable dampers, even wider Fuchs alloy wheels and new tyres. Titanium hubs were also used whilst twin circuit brakes with ventilated and perforated discs were sourced from the magical 917 sports prototype. |
Engine-wise, 2.8 RSR's began life running hot Typ 911/72 engines, these units having been specially developed from the Typ 911/83 motors found in the 2.7. The cylinder heads were further apart to facilitate a bore stretch of 2mm, this having been possible thanks to Porsche's use of Nikasil cylinders with aluminium rather than magnesium castings. Displacement was now 2806cc thanks to a bore and stroke of 92 x 70.4mm respectively. New pistons, four bearing racing cams and twin plug cylinder heads were sourced from the 2.5 ST. Output was 308bhp at 8000rpm - an incredible 98bhp up on the 2.7-litre road car, compression having been hiked from 8.5 to 10.5:1. Initially, fairly similar Bosch mechanical fuel injection was used. Capable of around 175mph and 0-60 in under five seconds, it was stunning performance coupled to exceptional reliability that made the RSR such a formidable opponent. More often than not it got the better of Ferrari Daytona Competizione's, De Tomaso's GT4 Pantera's and highly developed cars from Ford and Chevrolet, all of which were considerably more powerful than Stuttgart's little flyer. Although appearing outwardly similar to the Lightweight 2.7, the RSR came with a number of distinctive features that help differentiate it. Most obviously, the wheelarches were flared to accommodate those wider wheels and this left the 2.8 with an even more aggressive stance. |
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More bulbous fenders necessitated some modifications to the stock-looking wraparound bumpers, the front lid commonly being fastened down with leather retaining straps. Oil coolers were located behind each front bumper and fed by a gaping opening, the standard chin spoiler often having been modified by teams looking for a little extra downforce during that 1973 season. The ducktail spoiler remained unchanged. 49 2.8 RSR's were eventually built, the majority of which were completed between March and May of 1973, just a handful of what were predominantly used as ultra fast road cars being manufactured thereafter. |
| Porsche didn't have to wait long for the RSR to start winning, these cars quickly going on to establish themselves as the machines to beat in Group 4 and dominating almost every championship they contested. Of the eight 1973 World Manufacturers Championship events RSR's were entered in, they won five with class victories being secured at the Dijon, Monza and Nurburgring 1000km race's, the Watkins Glen 6 Hours and the Targa Florio. The 2.8's cleaned up in the North American IMSA GT Championship as well with eight wins from ten race's, undoubtedly the most significant of which was when Gregg, Haywood and Helmick took outright victory at the Sebring 12 Hours. Porsche's domination of the European GT Championship was actually a little unhealthy though, often over 90% of the grid having comprised 911's in one specification or another. Six wins from nine race's was the result, just De Tomaso occasionally putting up a fight although the German marque would have been sore at losing out to Lancia in the Tour de France. There were two important wins for RSR's in the SCCA's Trans Am Championship, the 2.8's record in this series having been blighted by the presence of a hot 3-litre RSR prototype for Al Holbert. In Germany's national Rennsport Meistershaft competition, it was the works Capri's that thwarted the 911's, RSR's winning just two of nine rounds at Diepholz and Sauerland. |
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To view the 2.8 RSR's period race record, please click on the appropriate link below where you will be able to find information on the cars, drivers and teams who took part in that '73 season:
1973 World Manufacturers Championship |