Lancia battled Peugeot in the final year of Group B in the WRC. Keith Howard examines the technology
If 1994 was F1’s annus horribilis, for world championship rallying it was 1986. On the Portuguese Rally Joaquim Santos lost control of his Ford RS200 and flew into spectators. Four were killed and 31 injured. Then, on the Tour de Corse, championship and event leader Henri Toivonen left the road in his Lancia Delta S4, perishing alongside co-driver Sergio Cresto in a fiery crash.
It was a turning point for rallying and Group B cars in particular. FISA president Jean-Marie Balestre pronounced that Group B, and the planned Group S, would now be banned for 1987.
For Lancia the year’s controversy was not yet over. Peugeot’s 205 T16s were disqualified from the San Remo rally for a scrutineering infringement: at the season’s close Markku Alén thought the drivers’ title his. But 10 days after the final round in the US, FISA overturned Peugeot’s disqualification and annulled the San Remo points, handing the driver’s crown to Juha Kankkunen.
But for all its tragedy and angst, the final flowering of Group B produced cars that were as fascinating as they were fearsome. Lancia adopted four-wheel drive late, but the S4 scored an unexpected 1-2 finish on its first rally (the RAC of 1985) and during ’86 took the fight to Peugeot and the 205 Turbo 16 Evolution 2. What the S4 lacked in handling refinement it made up for with its purpose-built engine, which combined power with lag-free low-rev torque by the breathtaking boldness of utilising both a KKK turbocharger and a Volumex supercharger.
To learn more of that last year’s principal Group B combatants, we spoke first to Andre de Cortanze, who was responsible for creating the Evolution 2 version of the 205 T16, and then to Sergio Limone, designer of the rear-wheel-drive Lancia Rally (better known as the 037) and developer of its Delta S4 successor.
AdC: The original 205 T16 was not easy to work on during service stops. This is one of the reasons why we changed the rear structure from a monocoque to a tubular frame in the Evolution 2. We didn’t really have a torsional stiffness problem with the original car but I’m paranoid about this. We measured the torsional stiffness of both and the increase with the E2 was nearly 30 per cent. We integrated the rollcage at the same time, which is why the stiffness increased so much. The E2 was nearly 35kg lighter so it was underweight for asphalt but overweight with the underside protection fitted for gravel. In the end we kept the same protection on the Tarmac version because it acted as well-distributed ballast.”
SL: “A tubular steel structure is easy to build and easy to repair. You remember when Toivonen hit a car between special stages on the Monte in 1986? Within two hours the mechanics were able to rebuild the damaged part. If we’d had a full monocoque in steel it would have been too heavy. And when you have an engine with a blower and a turbo, you couldn’t fit everything into a monocoque. Access would also be a problem: if you needed to change a turbo during a rally you wouldn’t be able to.”
SL: “The MacPherson strut is a fantastic suspension for road cars. But please, not in a rally car! I think it was the right choice to use double wishbones. You have no hysteresis because of strut bending and better control of wheel camber. We used twin dampers at the rear because you have a better chance to keep them cool. Using two dampers either side of the spring also makes it easy to replace a damper if you have a failure. The father of this idea was my previous chief, Mario Colucci. It worked well, so Ing Messori, designer of the S4, carried the same principle over to the new car.”
AdC: “We developed a system of using engine coolant to control the temperature of the dampers. I had the idea in Sweden and we got a really fantastic improvement. We used it there and on the Monte Carlo wherever the dampers ran particularly cold or particularly hot. Water from the engine was typically between 80 and 90 deg C, so we set the damping for that range of temperature. The system wasn’t to cool or warm the dampers as such, but to ensure that the damping was constant.”
SL: “If you put the engine in the rear of the car it’s impossible to find a safe place for the fuel tanks. You can choose side tanks, like we did in the Lancia Rally and Stratos; front tanks, like the Porsche 911; or tanks underneath the cockpit, which is what we chose for the S4. In my opinion that was the safest possible place but it was not enough. At this level of performance, with this geometry of car, it was impossible to have a high level of safety. I hope never again to see mid-engined cars in rallies. When you hit a tree it is important to have the engine in the front.”
AdC: “I’ve never been a top rally driver but I drove the T16 a lot in testing and I never thought it difficult to handle. I can’t say it was easy to drive a racing car is never easy but it was never vicious. It was always predictable, and that was my main concern. Jean Todt and I always worked as if we were putting a friend behind the wheel of the car. Throughout the evolution of the T16 our aim was to improve the car’s safety. We had huge crashes with the T16 but it never caught fire afterwards. So we were frustrated after the Toivonen accident because we believed we had a safer car. We would have carried on into 1987 with Group B without concerns.”
Overcoming turbo lag
AdC: “Our anti-lag system was called DPV [Dispositif Pre-rotation Variable]. It was a device for letting air through the turbo so that it already had some rotational speed. The drivers were not convinced at first but that is the human reaction. If you feel that the car is brutal, you believe it’s more powerful. If the acceleration is smoother and more constant, you don’t feel that change between off-boost and on-boost. All the data was in favour of DPV but the drivers had to learn how to drive with it, so as to let air into the turbo for pre-rotation even under braking. If they closed the throttle completely so there was no airflow into the engine, DPV made no difference.”
SL: “The switch between supercharging and turbocharging in the S4 was in principle very simple. When the turbo pressure reached a given value, the supercharger was bypassed. The bypass had to be achieved mechanically by a rotary valve. There was a problem during acceleration when changing gear, so we had to introduce a pneumatic damper a calibrated hole that increased the time of delivery of the pressure. It was difficult to achieve good reliability.”
AdC: “We wanted to achieve some downforce and better cooling. We didn’t have a cooling problem with the original car but the E2 had much more power, which meant increased heat transfer to the coolant. The rear wing created a depression at the back which extracted the hot air more effectively from the engine bay. I wouldn’t say that we achieved significant downforce but a little is better than nothing. The dynamics of the car were complicated over jumps because of the rear, transverse position of the engine. With a little more downforce at the back we could keep the back of the car lower than the front on landing.”
SL: “Aerodynamics were not a strong point of the S4. We made the choice to concentrate on getting a good handling balance in the car and didn’t do much aerodynamic development. But the roof-mounted double wing was quite complex. If you watch the road dust in film footage of the S4 it goes up to four metres into the air, so we were moving a lot of air with medium effort. We didn’t have a nose-down problem over jumps like Peugeot, maybe because they had a transverse engine and ours was longitudinal. Our cars always jumped well.”