CONTENTS., May 1925
CONTENTS. Editorial Notes ... ••• • • • ••• Secrets of Engine Balance. By F.…
Attempting to sort out the sports car racing scene has grown increasingly complex over the years. In the 1950s we had cars that were recognisable as relatives to their roadgoing counterparts “progressing” into pure racing machinery that still had a relevance to the road, such as the Jaguars. Even in the 1960s the big manufacturers were interested enough to spend millions on the production of a project like the GT40, followed by those fabulous 25-off production runs of 5-litre Ferrari 512 and Porsche 917 models which could record 160 m.p.h. plus laps at Monza and Spa.
Most people I have talked to in the sports car world, including Eric Broadley at Lola and Manfred Jantke at Porsche, pinpoint the gradual wane of this racing class to 1976’s chaotic separate series for Group 5 (“Silhouette”/World Championship of Makes) and Group 6 (World Championship of Sports Cars) as beginning with the restriction to 3-litres in 1972. That resulted in Ferrari’s steamroller assault on the World Championship with the F1 flat-12-powered 312Ps and subsequent domination from the Matra V12 sports-car team. Last season’s surprise defeat of the nimble, 495 b.h.p. Alpine-Renaults by Alfa Romeo’s 33TT12s with 3-litre flat-12s completed a great year for the Italians in World Championship competition—both Formula One titles (Ferrari), World Rally Championship ,(Lancia) and the sports car title for Alfa Romeo.
The CSI in Paris obviously decided the Italians were having it much too easy, and that the Germans looked like scoring rather heavily in any kind of endurance racing this season. The result was a positive barrage of rule changes, coupled with some embarrassing late amendments on the question of rim width restrictions, which have left the two hours minimum/four hours maximum of the emasculated Group 6 Sports Car Championship events with a somewhat depleted entry, and considerable public wrangling between Alpine-Renault and Porsche.
Opening round of this season’s sports car series was at Nurburgring in early April and there were arguments over virtually every aspect of the revised regulations, neatly complementing Depailler’s first lap attempt to become the first man on the moon with a Renault.
What were they arguing about? Primarily the interpretation put on the CSI’s vague definitions covering rim and tyre width. Porsche had originally developed their 936 prototype to run 15-in, rim widths and 16-in. wide Goodyears. Alpine Renault, working with radial ply Michelins had 16-in, rims and 17.5-in, tread width!
Pierre Ugeux, president of the CSI, sent out a telex to the Press and contestants of this opening sports car round just one week before Nurburgring, which effectively cancelled the 16-in. rim width restriction! The message from the CSI president included some glorious new British phrases—”I wish to recall that the role of the CSI principally concerns the valorisation of these World and European Championships… I will ensure the respect of the current stability rules in all areas, in full agreement with the constructors (BPICA) to ensure the normal running of following events.
“The constructors who have made the effort to be ready in time should not feel prejudiced by an exceptional decision, made on purely sporting grounds.”
At first sight one would feel that this might be a reasonable demand, over a genuine mistake. . . but put yourself in Porsche’s shoes. I cannot recall all the significant occasions on which they have been barred, or suffered sudden rule changes, because they are so successful in their chosen branches of the sport (since F1). However, even with a limited memory to aid me, think how Porsche suffered in the States, their ultimate turbocharged 917 Spyder developments, driven. by Follmer and Donohue, eventually conquering not only the previously unbeatable McLarens, but also the entire establishment’s efforts to handicap them out of the running, before they were just banned out of the SCCA’s Can-Am series. This year they’ve found that their Turbo was banned from SCCA touring car events (that’s the 911 style Turbo RSR) and they have also suffered continual harassment in their pursuit of long-distance honours, such as the domination of the 917 by the 3-litre limit.
When the FIA finally decided that they would run Championships for both Sports Cars and Silhouette, Porsche (and BMW, with Ford in the German background, if they get an adequate budget to do anything next season) agreed that they would contest the longer, 6 to 12-hour duration, events that formed part of a scheduled 10-round Silhouette series, catering for Groups 1-5. Thus Porsche’s main effort, directed through the research and engineering centre at Weissach, was to race a development of the KKK turbocharged 911 bodystyle . . . though by the time large wheelarches and aerodynamic aids have been added, it’s barely recognisable as anything but a high speed blob.
Known as the Martini Porsche 935, the ensuing Porsche represents over two years concentrated development work and has simply annihilated the limited opposition in the new Silhouette series. That it weighs close to 970 kg. (a ton equals 1,016 kg.) and has at least 590 reliable horsepower, present at 7,900 r.p.m., is of less consequence than the fact that it, in the two races covered at press time, has proved completely dependable hi every way. The short wheelbase, wide track, and threat of turbo lag, all made the team a little apprehensive before the opening Mugello round of the series. Porsche felt that they might not be competitive with the BMW prepared 480 b.h.p., fuel-injected, 3.5-litre six in bulky 1,030 kg. CSL coupes.
As Porsche’s regular pairings, Jacky Ickx/ Jochen Mass, pulverised any semblance of opposition to the Martini Porsche, team manager Manfred Jantke felt confident enough to pledge a return to the production Porsche nose in subsequent races, rather than the restyled “not-in-the-spirit-of-the-regs” nosepiece installed at Mugello. The “standard” nose didn’t reduce speed, but the 19-in, diameter rear Dunlops (the best opposition were on Goodyear, who are making a much bigger effort in touring cars these days) and the provision of a driver-operated boost control are both significant features.
We have talked about the Group 5 opposition, but what does it amount to? From the Cologne-based Kremer brothers, private Porsche dealers for the last 15 years, there is an outwardly disimilar, but inwardly copied Porsche Carrera turbo, which finished second at Mugello. Some of the more expensive details have been omitted, like the factory’s all-917 based braking system for the Kremer model, but there’s certainly over 500 b.h.p. from the KKK turbocharged six, which is of works capacity at 2.8-litres . . the same as used to be used for the Herbert Mueller/Gijs van Lennep Martini car in 1974.
At those opening rounds, BMW Motorsport GMBH kept faith with Silhouette racing by preparing three of their winged CSLs for Alpina-Faltz, Schnitzer and the British Hermetite team of John Fitzpatrick/Tom Walkinshaw.
For Silverstone’s round of this championship, 9th May, it is expected that a works CSL (possibly with turbocharger and anything up to 1300 b.h.p.!) will join the fray, driven by Hans Stuck/Ronnie Peterson. Also at Silverstone should be the promising 2.4litre turbo Stratos V6, for Carlo Facetti and Vittorio Brambilla, with close to 490 b.h.p., developed from an engine that has two valves per cylinder. More power, toward 600 b.h.p., is expected if the four-valve-per-cylinder heads -as used by Carlo Facetti last season-can be incorporated with the turbo on the trusty former Ferrari Dino V6 motor. Developed by Mike Parkes at the Turin competitions centre, the Stratus qualified third fastest at Vallelunga, but whether it will realise its potential depends entirely on the continuing success of Lancia’s rallying programme. If the rough stuff falters, Parkes has to forget racing and concentrate on rallying.
So, Porsche must be reasonably happy with Silhouette, especially as there are some of the 485 b.h.p. turbos (worth about £20,000 apiece), designated RSR930/75s, arc also in customer hands in Group 4 trim, eligible to take part in Silhouette events. Incidentally the 930/75 replaces the previous 3-litre Carrera RSRs that used to contest the European Grand Touring Championship, because the CSI made the normally aspirated car illegal through rule changes! Pictures of the Zuffenhausen-manufactured 930/75 appear in colour on page 522 of this issue.
Despite the fact that they were ruled ineligible to participate in the main prize fund, some of these 1,120 kg./2,470 lb. turbo RSRs appeared in the Nurburgring opening round of the Sports Car Championship: in fact Toine Hezemans took second place in just such a car, but had to settle for a share in the Group 4 (European Grand Touring Championship) fund, rather than the ADAC’s richer overall rewards.
This superb result for a production customer model reflects the low ebb of the Group 6 scene at the moment, though it should he pointed out that, for the immediate future, there are more competitive cars than in Group 5’s Championship. At Nurburgring it was a case of Alpine-Renault A442s pitching their turbocharged V6 power against Porsche’s 936 stop-gap machine, with Porsche also smarting heavily under sundry scruffneering issues, including the rim width business.
Porsche obviously felt very strongly about the last-minute CSI decision, their pre-event release referring to items such as “an error by the team of Renault and their tyre partner, Michelin, who developed their Group 6 racing cars with tyres too wide . . . In order to give the favourite French team a chance to enter the event, the CSI took this startling step… of course we have considered withdrawing from the event because there is little sense in a competition with unequal weapons . . .” That Porsche did enter was probably only due to the fact that this was the only Group 6 round scheduled for Germany this season.
The Porsche 936, which is a concoction of a newly developed version of the 908 space frame, and the production two valve per cylinder, single camshaft per bank fiat six, is a definite candidate for Le Mans this year, and they may also go to Spa, where it is thought that Alpine-Renault drivers will not attend. Although Porsche are a little embarrassed about the 936, because they (like the other German makers) believe totally in the concept of Silhouette racing, and events that last over four hours are proving something to the public, the car should not be as ill-sorted as some of the weekly reports imply.
Porsche’s 2,142-cc. flat-six (in sports cars you multiply by 1.4 to get the regulation turbocharged capacity under which you will race: in F1 the factor is 2.0) is giving a reported 520 b.h.p. at 8,000 r.p.m. on a compression ratio of 6.5 to 1. The I,997-c.c. CHS Renault-Gordini V6 (86 mm. bore, 57.3 mm. stroke) has a c.r. of 7.5 to 1 and a quoted 500 to 505 b.h.p. at 9,900 revs., with the capability of withstanding 11,000 r.p.m. Since the steel block Renault V6 has twin overhead camshafts on each cylinder bank, and four valves per cylinder, one conjectures that the turbo boost on the Porsche must be comparatively high to that employed by Renault, but then Porsche and KKK have been working in this field with great success for longer than anyone else.
The minimum weight limit has been increased to 700 kg. this year—that is for Group 6 3-litre cars, for, as in Group 2, 4 and 5, the CSI have a sliding scale of minimum weights (with the car dry of fuel at the end of a race) based on cubic capacity. Thus the top contestants should come to the line weighing about the same. This was never checked, as the Nurburgring scrutineers were too bothered by listening to the allegations about Renault Alpine’s tall airboxes, rear wing height, and even detail quibble over their (non)installation of an external cut-off switch to activate the fire extinguisher.
Looking at the future rounds of the series, in addition to the regular participation of Renault Alpine there is the promising March 76S-DFV V8 (driven by Guy Edwards at Nurburgring) and the delayed Alfa Romeo challenge to look forward to. Quite which Alfa will be used initially is a question of labour disputes in Italy, but they have last year’s space frame, 3-litre, flat-12 33TT12 to fall back on, a monocoque design that can take the flat-12 in 3-litre form (33SC12), and their ultimate objective, a 2,140-c.c. turbo version of the 12, currently under development as the 33SC3.
As F1 goes from commercial strength to strength, we have the spectacle of ever-weakening, ever-multiplying European touring/sports car championships. Naturally there is a body of opinion that says the CSI should lump all the poorly supported series for Group 4 (EGT), Group 5 (Championship of Makes) and Group 6 (Championship of Sports Cars) together. The European Touring Car Championship, scene of Jaguar’s now postponed (to May 2nd, Mugello, Italy) return is not under immediate threat, but it is a weak series as well at present. The German contingent, principally Porsche and BMW, are totally opposed to amalgamation as they are convinced Group 5 will grow into the Championship for European car factories to contest. Jantke of Porsche, and Neerpasch at BMW, know that this season could be grim, but they are sure Alpine-Renault, Lancia, Alfa Romeo and Jaguar will all be out to play in 1977’s Silhouette series, leaving the sports cars, which are of little interest to the car makers, to die and long distance racing to make a partial return to the days when it meant something to win.
Excellent logic . . . but will the customers pay through the interim?—J.W.
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