Renault blew it! The pioneering F1 turbo that failed Prost in title bid

He was definitely in the minority, even at that point Michelin had become so disenchanted with the test miles denied it by Renault unreliability that it had switched its main effort to Ferrari.

Castaing, the original technical director of the project, left during the ’79-80 off-season. Some insight into the intensity of the experience is revealed as he explains why. “Being under the microscope with all the pressure of representing a big company like Renault was very tough. Also, motor racing is such a narrow, focused world. Although it’s good to be focused, at some point it keeps your mind from growing. I told Larrousse that I wanted us to try to win the world championship in 1980 and then was going to do something else.

“I thought winning the title in 1980 was realistic. But I was having arguments in private with Larrousse. We already had Prost under contract and we could have had him replace Jabouille for ’80. I was arguing that keeping Jean-Pierre was attaching a weight to our foot because, although he was adding value, he was not a potential champion in any sense. Larrousse was saying, ‘No, we have time to do that later’, and I became frustrated. I was not convinced he saw the window of opportunity we had. If we didn’t win in 1980, it would be much more difficult when everyone else had their own turbos and our advantage evaporated. I sat down with the senior people at Renault and told them I wanted out; they wanted people for a new project in America. We packed and went that same day.”

Of course the title didn’t come in 1980 and not in the Prost years of ’81-83. The window of opportunity Castaing had spoken of was well and truly closed thereafter as the British teams found turbo engines of their own but only after a core of them had tried to have the whole concept banned from F1. When that initiative failed, the Brits got their heads down and beat the Renaults through engine parity and superior chassis technology.

“The engine was always the main asset,” says Migeot. “We lacked a chassis culture. There were a lot of good people but we weren’t properly equipped. Renault in those days would never have committed to a moving-ground wind tunnel and that’s what was required.”

The intervening years, before the Brits caught up, were lost to poor reliability. Only part of this was down to pioneering the turbo route, as Migeot explains: “In 1982, for example, we lost about eight races for the sake of an electric motor that cost 100 francs. That was because the electronics department was one man, doing everything from electric plugs to the sensors on the fuel injection, and he couldn’t cope. The next year the pieces for the new motor cost 100 times more. It was underevaluated in all sorts of respects.”

Dudot concurs: “We were alone. A new team, with a new concept, new tyre technology from Michelin and doing everything ourselves. Only Ferrari was doing this and they had a big history.”

By the end of ’83 and the lost championship, this core of adventurers had been moulded into a team of hardened racers, with only the conservatism and inertia that is part of any big corporation holding them back preventing them, for example, from retaliating when Brabham made its rocket fuel leap in the second half of the year. But those corporate constraints became tighter, not looser, following the ’83 debacle. It was a development accentuated by the replacement of president Bernard Anot, a racing fan, by Georges Besse, who then nominated production car man Gerard Toth as team chief after Larrousse left at the end of ’84.

It was the beginning of the end. Derek Warwick signed as Prost’s replacement believing he’d made the big time, only to see that dream as well as the original one of Castaing, Boudy and Dudot crumble around him: “There were some super people there in ’84, hard-nosed racing pros. But at the year’s end we lost most of them and they were replaced by people from the production car company who had no knowledge of racing. The ’85 car was diabolical, the whole thing turned to shit.”

But it wasn’t quite the end. The engine would power Ayrton Senna to victories in a Lotus as late as 1986. More importantly, as Dudot points out, “It gave us the possibility of this expertise in the company. The five Renault world titles of the ’90s were built on the school time of the turbo programme.”

It was the late 1960s when Renault first began taking an active interest in motor racing. At that time its competition activities were undertaken by two contracted independent companies Gordini did the engines and Alpine the cars, broadly speaking. Francois Castaing worked for Gordini, where he was later joined by Jean-Pierre Boudy. Over at Alpine in Dieppe, Bernard Dudot worked away.

Castaing and Boudy designed, in 1972, a 2-litre 90-degree V6 for use in European sports-prototype racing. It won the championship in ’74 and later took Jean-Pierre Jabouille and Rene Arnoux to F2 titles. This same motor was the basis for all the Renault turbo F1 engines though such a development was not foreseen at the time of its birth.

“We designed it with a very strong cast-iron block,” says Castaing, “and a very narrow valve angle. The buzzword among engine designers was ‘scavenging’ the oil. It was thought an engine would succeed or fail not because of its specific combustion efficiency but on how effectively the oil in the crankcase could be sucked out within the engine’s pressure cycle. We went cast-iron so we could have a very strong bottom end and ensure good flow to the bearings and so limit the amount of oil needed.

“As for the valve angle, we got some help from Moteur Modeme in designing the camshafts and powertrain.” This was the company largely responsible for the Matra V12 F1 engine which, in its initial 1968 form, featured a very wide valve angle. When combined with the engine’s big bore it made it horribly thirsty. The narrow angles on the Gordini engine was a reaction to that. “In retrospect,” continues Castaing, “we should have made the angle between the port and the valve more open and had more of a Duckworth philosophy of breathing.”

By 1974 Renault had bought out both Alpine and Gordini, combining them to create Renault Sport. Castaing was chief engineer. In the meantime Dudot had been experimenting with turbos. “The first time we tried a turbo was on an Alpine for the Rally of Cevennes in ’73,” he says. “It was just a 1.6 engine from the Renault 16 but Jean-Luc Therier almost won. A stone in the turbo was all that stopped us.”

After winning the 2-litre championship Renault wanted to move up to 1000-kilometre racing to fight with Porsche and Alfa rather than Chevron and Abardi. This category had a 3-litre capacity limit but turbos of up to 2-litres were also allowed. “It was Bernard who was really convinced that the way to attack it would be to use a turbo on the existing engine,” says Castaing. Dudot went to America, then the capital of turbo knowledge, to begin a liaison with Garrett and meet associated suppliers, building up his knowledge of the subject over several months there.

The resultant engine won its first race at Mugello in 1975, with Larrousse/Jabouille, but never repeated the feat until triumph at Le Mans three years later. “It was in late 1975 when Francois Guiter from Elf asked us what we would do if we went to F1,” says Castaing. “Guiter was very keen to get Renault there and the Renault president at the time was a fan of F1. Bernard, Jean-Pierre and I realised this was our big chance. We had two competing ideas. One was to do a W9 3-litre engine using three banks from the V6. In F2 form, the V6 had 310bhp so we figured we’d be starting with 450bhp which was about where the Cosworth DFV was then.

“The other idea was to do a 1.5 version of the 2-litre turbo V6. The convention was that such an engine was not feasible on pump fuel. Forced induction had only been possible in the ’50s and before the war when they were able to use nitro and alcohol-based fuels. Initially I was far less convinced about a turbo with pump fuel than Boudy. But Elf really loved the idea because they could see something so different would make great marketing sense for them. At the same time Jean Piramosi, who was running the Renault Sport programme from the marketing and merchandising side, was very keen on this idea. So we built a couple of prototypes with single Garrett turbos and on its first run on the dyrio it was already giving over 500bhp. Suddenly we all became very excited.”

One of these engines was fitted to an Alpine A442 sports racer and at a cold, deserted Paul Ricard Jabouille tried it for the first time. “It was shit,” he recalls. “On the straight it pushed like hell, harder than anything I’d driven before, but everywhere else there was nothing, just like a normal road car.

I said to Boudy and Dudot, ‘It’s too difficult, I don’t think this is a good way.’ But then they made a few adjustments and immediately it was much better and I thought maybe there was something in it.”

“We tested through the winter of ’76 with a mule single-seater,” says Castaing. “We were only using around 1.7 bar boost and the cold weather didn’t reveal any of the detonation issues we subsequently encountered.”

A pukka car, designed by Herve Guilpin, Marcel Ubers and Jean-Claude Guynard, was revealed in early ’77, together with the formal announcement that Renault was re-entering GP racing after a gap of 70 years. Michelin would be coming with them, marking the F1 debut of the radial tyre.

The engine Jabouille used to qualify 21st at Silverstone in July seemed a pale imitation of the responsive, reliable unit it had been during the winter. “Suddenly we discovered the misery of racing an F1 turbo on pump fuel,” says Castaing. “The stress was very high on pistons, valves, sleeves, rings and bearings,” says Dudot. “The big thing was to educate our suppliers of the special task of these parts in a small, powerful turbo engine. The next big step forward was controlling the temperature of the intake and we did that with a water/ air intercooler. The single turbo was just too slow to respond, so from 1979 on the new wing car we had two smaller turbos and this increased the response vastly. Then for 1983 we got electronic injection which allowed us to adjust the mixture far better and have a good temperature and mixture at the same time.”

“After I left, I read books about the British aircraft engines between 1940 and ’43,” says Castaing. “The reason why the Spitfire went from 1500hp to almost 3000 was that they learned how to control compressions and design pistons and parts that could withstand higher boost pressures. I wish I’d read this in 1977. Also, I never thought about putting additives in the fuel. It was supposed to be pump fuel but I hadn’t realised that pump fuel is very different according to where you go in the world and it would have been quite legal, within the octane limit, to have added some anti-detonation agent that could have helped us.

“I was disappointed at the time, but given that we were so new and what we achieved with a brand new concept — winning our first race 24 months after entering — I’m very proud of what we did.”