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| Technical Focus: The Loeb Machine |
By: Martin Sharp |
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Saxo supremacy in Super 1600 - a technical issue? |
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Then Sebastien Loeb blew away the opposition, blasting his Citroen Saxo to the winning posts of the first three of this year's six Super 1600-contending world rallies. The series was beginning to look like a one-horse race. Measures have been taken to level the playing field, to bridle the Citroen to performance parity with its Fiat, Ford and Peugeot competitors. But will they work? Let's look at the facts: For the 2001 Super 1600 Championship, "VK-S1600" restrictions were added to the technical regulations for 1.6-litre Group A Kit Cars, which included a car cost ceiling of US$100,000. Interim modifications are allowed to aid the transition in 2001 of 1.6-litre Kit Cars homologated before January 1, 2001 to Super 1600 specification. This means all cars currently contesting the world S1600 championship except the Peugeot 206. In 2002 every Super 1600 car must comply with the category regulations without exception. Citroen Sport is the only manufacturer to exploit this opportunity to the full. This year, talented 27 year-old Frenchman Sebastien Loeb has driven a Super 1600 version of the Saxo Kit Car to victory on each of the three rounds of the S1600 Championship so far.
Immediately Loeb demonstrated the Super 1600 Saxo's pace on the first S1600 round, the Catalonia, Rally, rival teams and manufacturers voiced opinions that the "freedoms" incorporated by Citroen in this first S1600 year meant that the playing field was tilted in favour of the Saxo. Specifically, discussions majored on the size of inlet restrictor laid down by the regulations. Cars homologated after January 2001, and all cars from January 2002, must have a single-valve inlet manifold with a maximum venturi diameter of 60mm at the throttle valve opening, which must derive from a large-scale series production car. However, this year only, 1.6-litre Kit Cars homologated prior to January 2001 which have multi-valve intake manifolds may retain such an intake arrangement, providing at least 3mm length of the section of each inlet tract between the throttle butterfly and the cylinder head does not exceed 34mm diameter; the restriction for 1600cc kit car engines was 38mm. Citroen alone opted to take this route, retaining the Saxo's four-throttle arrangement, and introducing Super 1600-specification 34mm restrictors in each intake tract. The regulations also allowed pre-2001 1.6-litre kit cars to retain a 150mm diameter clutch until next year, when 184mm is the minimum clutch diameter for Super 1600. Citroen Sport also chose this option, gaining a further dispensation to use this clutch with its existing flywheel, which is lighter than the S1600 minimum weight of 2600g. In its "Restrictions for ŒSuper 1600' Kit Variants," the FIA reserves the right to modify the engine intake restriction rule for pre-2001 cars "at any moment". After Loeb took the Saxo S1600 to its second straight win in Greece, the FIA invoked this right, decreeing that the Citroen must also be fitted with the common 60mm restricted single throttle after the third 2001 Super 1600 round in Finland, which Loeb also won. This regulation therefore comes into force effectively from the Sanremo Rally. Will it affect the Saxo's chances? Indeed, was the regulation parity askew? First, some background: Citroen Sport was forced out of rally-raids in 1998. An admirable record of 36 victories out of 42 rally-raids contested came to an end when a change in the FIA cross-country technical regulations effectively excluded its ZX Rallye-Raid prototypes. Indeed, the French company was not able to contest the 1997 Paris-Dakar event in its swan-song year, as the Dakar organisers had introduced technical regulations which mirrored the 1998 FIA rules one year early. However, while Dakar '97 was running, Citroen Sport was planning its future. One project was to capitalise on the then-new kit car regulations to build a competitive, customer-oriented, rally car from the new Saxo road car, which was launched internationally in February 1996. The Saxo is based on the AX platform, which the team already had some experience of turning into a rally chassis. Additionally, when the Saxo was introduced, passenger car crash test legislation was less stringent than today, hence its mainstream engineering designers could develop a volume production bodyshell with comparatively less weight and more torsional rigidity than that available to engineers today. The result was a 1600cc Kit Car which could be built to meet the regulation 920kg minimum weight. The minimum weight for Super 1600 cars has been raised to 950kg, so the Saxo requires ballast . In contrast for example, the Punto, homologated into Group A in November 1999, is developed from a volume production bodyshell designed to meet later crash test legislation, and teams have difficulty in getting the weight of a Punto Super 1600 much below 1040kg. Homologated into Group A in March '97, the Saxo Kit Car took Patrick Magaud to runner-up in the 1997 French Rally Championship. Essentially a Citroen Sport customer car, the specification of the Saxo continually improved through subsequent years of healthy entries in Saxo Kit Car Trophies, which ran within the French Championship. Other small hatchback production cars enjoy base specifications with more competitive potential than the Saxo in some areas, particularly in rear suspension design. However, in March 1998, French motor sport magazine Echappement described the stage time performance of the winner of the A6 class and fourth overall of the Vins de Champagne Rally as: "astounding, comparable with those of the three leaders". The car? A customer specification Saxo Kit Car. The crew? Sebastien Loeb and Daniel Elena in their first-ever national category French rally. Loeb had just turned 24 years of age. Three years of refinement later, that kit car became Citroen's Super 1600 contender. When preparing to convert the Saxo from kit to S1600 spec, Citroen Sport admits it was not entirely confident about the future of the new formula, plus it had to take account of the fixed specification and parts stocks for its customer Saxo kit cars. It was decided to do the minimum possible to turn the customer version of the kit Saxo into a Super 1600.
Guillois quotes power from the 4x34mm Saxo S1600 engine at 207bhp, estimating that other single-throttle S1600 cars have "maybe a little more, maybe a little less". First official dynamometer tests of the Saxo engine fitted with a 60mm diameter restrictor showed a bhp deficit compared to the four-throttle engine of, "Between three to four percent". It is understood that; "a little less torque" was seen on the dyno, "but the difference is not so high". Some perspective: in 1998 Loeb/Elena finished just three rounds of the French Championship-based Saxo Kit Car Trophy. They won each round they finished. In 1999 Loeb, again with Elena, won that Trophy, including one first, one second, and one third overall result in nine rallies. In a 1600cc Citroen Saxo Kit Car. Is it any wonder that the same combination of highly refined rally car and and highly talented crew are leading Super 1600 after three rallies? For a 1.6-litre Kit Car engine, comparatively the Saxo has never lacked for a useful torque spread. It is doubtful that a six brake horsepower deficit will be sufficient to upset such ideal balance. The recent FIA dispensation to allow Loeb to drive a works Citroen Xsara in the Sanremo Rally and not contest the Super 1600 category on that rally means the only registered S1600 driver competing in a Saxo will be Irish driver Niall McShea. He has 18 months' experience of a full-kit Saxo on British and Irish rallies, scoring numerous category wins; often finishing just behind World Rally Cars and ahead of Group A and Group N four-wheel-drive turbo cars. In Super 1600 this year McShea switched from the Ford Puma to a Willy Lux-run Saxo from the Rally Finland, where, after second fastest on the first stage, he was running fourth when a broken driveshaft on the sixth special stage ended his run. Testing of the single-throttle S1600 Saxo engined installed in the car was under way as this was written. Lux fully expected a little less power compared to the four-throttle engine, similar to the dyno tests, but he was hopeful that a marginally improved torque output would result from this more realistic appraisal. McShea describes the Willy Lux-prepared S1600 Saxo as: "Something special." McShea's specialisation is tarmac rallies. His second round in the Saxo is the Sanremo Rally. It would seem unlikely that the aforementioned balance will be unduly upset by Loeb's absence from the Saxo cockpit in Italy. |
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Independent, unbiased reporting - all the spins without the spin. |
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