The astonishing Renault 5 Turbo

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By any standard the Renault 5 equipped with mid-mounted engine and turbocharging is an extraordinary motor car. Its looks are strongly akin to a Gallic cartoon character car, all flying buttresses and extensions to cover its 160 bhp heart. Then there is the courage of State-owned Renault producing such a car while still fully engaged in Formula 1, and in an atmosphere where the car buyer’s shopping list tends to be topped by price, rather than performance.

This is an unashamed performance car, a fine base on which to build a World Championship rally victor, but also a genuine production car in its own right, rather than a conversion. This month available in France at the July 1st exchange rate equivalent of £11,954.26, predictions are for 1,000 vehicles a year by the close of 1981. Present production rate at the Alpine Dieppe factory is eight a day with homologation of the car into Group 4 (400 vehicles, only available in red or blue for this initial run: each plated with a number on the dashboard) planned for September 1980. Its first outing on a World Championship rally is planned for November 8th /9th Tour de Corse, but we could see it out in France in July on national events in prototype classes, possibly the Tour de France, if that event is held in 1980.

No production is earmarked for Britain at all. The earliest we could have the car would be 1982. Doubtless some entrepreneurs will bring it in in just the same way as the Stratos arrived on our streets in limited numbers at “telephone number” prices!

What do you get

Sharing the 1,397 c.c. pushrod Gordini four cylinder motor, you might expect this to be just another tuned-up tin top. After all, what can 1.4 litres do, In Renault’s Garrett AiResearch turbocharged case it can provide 160 bhp and 155 lb ft of torque instead of Gordini’s 93 bhp and 82 lb ft. Figures that would not shame a three-litre six. Install that in a vehicle of 970 kg 2,139 lb, engineer the lot thoroughly (as Renault have in a near four year development) and the result is simply sensational.

Renault report that a test car of the same vital statistics as the ones we tried returned 0-62 m.p.h. in 6.90; 0-400 metres (roughly equivalent to the drag strip quarter mile) in 15 sec. and had a top speed of 124 m.p.h. The engine capacity of 1.4-litres shows more on the road, than on paper, but it’s still a flyer. Jean Ragnotti emphasised this facet when he took the 160 bhp ‘Customer version’ out for testing on some classic Monte Carlo Rally stages. He returned times 2/3 sec per stage kilometre faster than the works Group 2, front drive Renault 5s, of the type that Ragnotti currently leads the French series in. Such R5s finished second and third overall in the very snowy Monte of 1979.

The true competition R5-Turbo will have 250-260 b.h.p., courtesy of a sized up turbo boosting at 1.4 bar, instead of the production 0.86 bar, equivalent to 12.2 lb/sq in boost. It will also have twin intercoolers, a limited slip differential and a projected 231 lb ft torque at 4,600 rpm. Weight will be 810 kg./I,786 lb, this power to weight ratio carefully selected at the prototype stage. Then Renault also considered the V6 Douvrin engine and the 2.0 unlined four from the same source, but neither could match the 1.4 turbo’s power to weight ratio under international FIA regulations — or provide such a well balanced car where fast rally-style servicing would be possible. As you’d expect most major mechanical jobs will be completed by the expensive but rapid method of pulling out the engine gearbox train as one unit, or by simply changing the rear mounted gearbox. A task that must be easier than on a front engine car, even though they have had so-called quick release bell-housings for machines like the Escort for some seasons now

Development

It was Gerard Larrousse’s predecessor as Renault competitions director, Jean Terramorsi, who Renault credit as the creative spark behind the R5-Turbo. Jean died August 27th, 1976, but by then the theme was being developed.

It was only September 1976 before Renault had completed the first prototype! The programme involved collaboration between Renault subsidiaries Service Produit, Renault Sport, Paris, and the Dieppe factory now called BEREX. The Renault styling department created the look of the car, but the first styling models were created at Bertone in Turin under the supervision of Renault styling staff.

By December 1977 they had got down to details like the hexagonal divisions of the 10-instrument dashboard layout with its unique two spoke wheel.

March 1978 and the Dieppe factory had a running black prototype hunting through the local lanes. This in the hands of the man who did all the test driving, former European 2-litre sports car champion Alan Serpaggi.

A second prototype, but not a runner I suspect, was the red Turbo that marked the official debut at the Paris Show October 1978. The black prototype was retained and we all had a chance to look around it at Paul Ricard (Motor Sport, January 1979). As one could see from that car a lot of running changes were made until the new rear suspension, based on fabricated double A-arms, was finalised along with that extraordinary bodywork. Aerodynamic studies were carried out with the aid of the wind tunnel at St-Cyr, but the final shape is not slippery so much as functional, housing wheels close to eight inches wide at the rear and feeding cooling air to the engine in the middle.

Cooling the engine was one major consideration and the adoption of an interceoler (air to air) helped to reduce the intake charge before the Bosch mechanical K-Jetronic handled it by up to 50°C. Cold air is fed to the intercooler by the top half of the driver’s side rear arch intake: intakes on the other side feed the oil cooler and brakes. One intake (on the driver’s side rear arch) is non-functional on the road cars, but will be needed for competition and has thus been incorporated on the road cars. There is also a thermostatic fan and ducting to cool the engine whenever 90°C is exceeded. Properly designed exits for cooling air are provided in the back of those rear arches.

The other major obsession in development was weight. Multiplied by the FIA factor of 1.4 for turbocharged engines, the 1.4-litre becomes 1,956 cc and the target minimum weight in competition 810 kg.

Thus the already radically altered body went on an intensive and expensive diet. Looking for the loss of 50 kg. the engineers used aluminium for the doors (-14 kg.): substituted the same material for pressed steel again on the hatchback (-4 kg.); pop-riveted in an alloy skin for the roof panel (see any GB Mini club racer!) saving 5 kg. They worked out that using so much plastic for the wings and their extension would, in addition to the special lighter gauge steels, save further 4 kg. They even got down to calculating that 3 mm. glass instead of 4 mm. would save another 5 kg. Another fundamental change, which affects the floor of the 5 as well as improving the centre of gravity, is re install a safety 20.5 gallon fuel tank under the two highly styled seats. The radiator for engine water with attendant electric fan is in the front companment along with a spare (front) wheel. Weight distribution is biased well to the rear (the five Speed R3OTX-derived gearbox and transaxle is mostly well aft of the rear drive shaft line), the figures given as 40% front, 60% rear. A fully detailed specification is appended to explore many more details of this fascinating newcomer. Meanwhile, what is it like to drive?

On Alpine roads. . .

The Renault flotilla of R5 Turbos was assembled in the French Alps for our assessment, but the route covered a fair stretch of motorway so that the set route was not all alpine bend-swinging. However, together with two like-minded rogues, we found ourselves a likely looking mountain road to cover in addition to the main road sections, and so spent much of our time enjoying the car in what seems sure to be its natural habitat.

A Renault 5 retailing at more than £10,000 should be something special in more than just performance, and Renault have followed this line of thought.

The seats look as though they came straight from a motor show styling exercise. 

There are the traditional built-up sides, but the effect is not of a deep bucket competition seat, rather a plush piece of avant garde furniture, its rather hard blue relieved by softer fabric inlay for the seat and back panel.

Clutch and brake are perfectly normal, but the accelerator is huge, which should allow accommodation for any style of heel and toe operation. The radio is rather awkwardly mounted so that its stereo cassette player unit needs feeding vertically, preferably when the gearlever is in neutral. The overall effect is quite light and airy, a million miles from the ‘it-must-be-matt-black-if-it’s-sporty’ syndrome so beloved of American and British saloon car marketing men.

The dashboard is permanently illuminated, emphasising a weakness in legibility and clarity that Renault themselves now acknowledge. Basically there are eight minor instruments, including one for the turbo that has been moved from the right in pre-production to the left (swopping places with the 0-60 kg/cm. oil pressure gauge) according to the press literature. With that many many minor dials there is no room to list all the functions: suffice to say everything is included, though such a forward looking machine might have been the place to use a digital clock or, since it’s expensive anyway, one of the latest on-board computers to work out the average speed, mpg, time of arrival, and so on. There is an oil level indicator (a la Lancia Beta coupe) to save removing the rather cumbersome engine cover every time the oil should be checked. An oil temperature gauge is also supplied.

Both 230 km./h. speedometer and 8,000 r.p.m. tachometer are clearly viewed through the strange steering wheel, the rpm warning line extending from 6,000 to 6,500 r.p.m. All instruments are by Jaeger to uniform style.

Switch-gear is via rather complicated push buttons either side of the steering column housing, and via conventional column controls for flashers, lights and sporting horns.

If there is a manual choke, I did not see it! Just press once on the pedal for an instant start to a sunny mountain morning. Some three hours later I was back having covered 971/2 miles at an average 14.2 mpg, which reflects how much I enjoyed the trip. Colleague Michael Greasley, who now edits Motoring News, covered 89 miles at 16.6 m.p.g., while the chap I spent much of the time travelling in convoy with through the mountains did slightly worse than we as I used him as an air break. Renault figures indicate a range of 22.78 mpg in town use; 28.25 mpg at a constant 75 mph and 37.67 mpg at a constant 56 mph, though why anyone would ever travel at such a low constant speed in this joyful machine defeats the author. The modest size and astonishing acceleration reduce other traffic almost to the role the owner of a powerful motorcycle will be familiar with.

At first the engine seems flat and lifeless, something only to be expected with such a small engine at town speeds. It is perfectly docile, whatever you do, but there is some flame-out from the exhaust under constant hard acceleration and deceleration, just like the real racers, but a momentary flicker instead of a sizzling belch.

Pressing on for the first time, joining a nearby motorway, I discovered that the tachometer and boost gauge were going to rule driving impressions in this car. Using the gear lever to the full you discover gear speeds equivalent to 34 mph in first, 56 mph in second, 84 mph for third and an exhilarating 109 mph in fourth. Now the remaining autoroute stretched empty and inviting before me and 200 km/hr was instantly indicated in top, but no more.

The car felt so secure at this speed that I had no hesitation in leaving it there for a couple of miles, even though that involved a couple of long sweeping curves and the occasional lorry. The stability was outstanding, even when the side wind pressure altered in such circumstances.

It was not particularly noisy at that speed. I did not feel I wanted to cruise that close to the rpm limit: 6,000 rpm is 123 mph on the 20.43 mph tall top gear. Tall that is by 1.4-litre standards, not those of a 160 bhp light car.

Experimentally I backed off to 100 mph. That was a pace I would be happy at, and the car’s temperature gauges agreed with that at sustained 5,000 rpm or so. Coming back to the British legal limit was like stopping dead by comparison, the little Renault feeling notably relaxed at 3,500 revs or so. No wonder Renault offer a full 12 months, unlimited mileage guarantee, as for their other tough, but more mundane products.

In the mountains the car took some learning. The boost gauge has to be kept near maximum on the scale for you to get the performance that the bhp figure points toward. Basically that means the rpm counter is certainly above 4,000 most of the time and really hard drivers may go for a 1,500 rpm band between 5,000 and 6,500. Driven that way the engine note is certainly stimulating, but not in the way of a full blown competition car to risk arrest, The Renault has outstanding brakes for this kind of treatment, just as you would expect with over 10″ ventilated units on all four corners. Also outstanding is the ride provided by the De Carbon gas-damping shock absorbers, firm but not jarring. Bilstein could have a problem. . . .

Just as the brake pedal pressure has been precisely “weighted” by Serpaggi’s painstaking development, the handling is truly outstanding for its comprehension of the fact that there is human at the wheel. It forgives errors in a way that I have not encountered in other mid-engine cars, save the very latest Esprit Turbo. Basically there is a degree of understeer to balance out with the gear lever and throttle. It takes a time to drive with the tail sliding out of line through second and third gear corners, but it can safely be done, which is quite an achievement in my experience of this engine layout.

The car is much more efficient driven smoothly, constant throttle pressure and consistent steering action bringing particular satisfaction on ‘Regie-the-Rebel’. The TRX tyres aid turning-in response particularly so that when you move the wheel the R5-Turbo responds equally deftly.

I could quite happily write another three pages about the ingenious Gallic ploy. One I suspect may bring them the World Rally Championship in the same year as a World Formula 1 title, a test I cannot recall any manufacturer achieving simultaneously.

For the customer I see few snags. The looks are odd and the gearchange occasionally vague. At this price it would be more practical to go for a Porsche 924 turbo, but less fun.

It’s a saucy little car that is going to attract a lot of public sympathy, pitched against the German Audi, Opel and Mercedes teams in the David Goliath 1981 onward rally role. A role pioneered by the Mini-Cooper S.

There are prospects that we will see this exciting little R5 in the British Rally Championship, but the car has only really been developed for tarmac events which have been pace-noted in advance, the opposite to the bulk of the events that make up Britain’s premier home international series at present.

Finally I must stress that my overall memory was of admiration for the engineers who turned this unlikely project into such an enjoyable, apparently rugged, road car. It’s nice to see a motor manufacturer prepared to face tIe challenge of the times we live in rather than lie down and wheeze about old glories. Bravo.  JW.