HIGHLIGHTS 1997 ITALIAN FORMULA 1 WORLD CHAMPIONSHIP RENAULT F1, 1977 1997:THE ITALIAN GRAND PRIX VIEWPOINT... Philippe Chasselut: "Water injection" Irs: the quantity and the temperature of the mixture injected into the engine... To reduce the engine's susceptibility to detonation, we therefore had to find a way of cooling the air in the mixture, which has been forced up when it had been compressed by the turbo. This was the function of the heat exchangers. However, their effectiveness was reduced when the ambient temperature was very high (Brazil) or at Grands Prix run at high altitude (South Africa, Mexico.) In these conditions, the oxygen was rarified and so the mass of air passing through the radiators was less and therefore produced less of a cooling effect. It was as a means of solving this problem, that Jean Pierre Boudy, in charged of the development, had an idea in 1982 of lowering the temperature of the compressed air by injecting water into the inlet system. Once in contact with the hot air, the water vaporised and by thermal exchange, this vaporisation reduced the air temperature. As a consequence of this, the air fuel mixture temperature would also drop when it occured a bit futher along the inlet system. We therefore managed to reduce temperature of the compressed air, which had previously been around sixty degrees, by between 10 and 12 degrees. it was enough to prevent detonation. A 12 litre water tank... At the opening round of the 1983 season, the Brazilian Grand Prix, Renault became the first engine builder to use water injection in F1 to cool the air fuel mixture. The system comprised a 12 litre water tank, fitted into one of the side pods and a control unit installed behind the driver's head. This unit contained an electric pump, a pressure regulator and a pressure sensor. This sensor triggered the system, once the boost pressure exceeded 2.5 bar. Below this pressure it was not needed as there was no risk of detonation. Sucked in by the pump, the water passed through the regulator, which maintained a conatant flow rate, before being injected into the inlet system. This system required us to start every race with 12 litres of water in the side pods. The handicap of this weight lost us about three tenth of a second per lap in the early stages of a race. It was less of a disadvantage than the normal method of preventing detonation on turbo engines fitted to road cars at the time, which was to retard the ignition. That is the Briazilian Grand Prix of 1983. Renault is the first engine manufacturer to use water injection in Formula 1 to cool the compressed air inside the inlet system in order to protect its engine from a particularly destructive phenomenon- detonation. Having solved this problem, Renault can set off on the search for more power.

Philippe Chasselut, in charge of the cylinder head section in Renault Sport's research and department, recalls those days... "In 1982, the Renault V6 turbo developed 585 horsepower, whereas when it was first used in F1, back in 1977, it put out 525, so the increase in power has been minimal. But during those years, we had concentrated on other areas: reliability, smooth power curve and a reduction in throttle response time, Once we has reached our target in there areas, we turned our attention to finding more power and in 1986, the Renault V6 turbo put out 870 horsepower in race trim. Therefore, having found a 60 horsepower increase from 1977 to 1982, we had gained almost 300 from 1982 to 1986. In theory, all one has to do was to increase the boost pressure to increase horse power on a turbo charge engine. However, the engine components had to be able to withstand the extra forces. This was the problem we faced when we started to look for more power, starting in 1982. The first obsticle was detonation. This phenomenon occurs when a large quantity of air fuel mixture enters the cylinder bores and provokes an abnormal combustion. On a road car, detonation, also know as pinking, but does not damage the engine. But in Formula 1 engine, the force of the detonation is such that the piston can be destroyed, through hot gases escaping between the combustion chamber and the sump."