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From the archives: The supercharged and turbocharged Group B rally car from Lancia is ugly, loud, and incredible.
It’s no beauty, and at speed the noise level is rather high. But neither fact is important. Not with the boost gauge pegged and all 250 bhp twisting its way to the fat Pirellis at each corner. Not when you’re whistling down the autostrada at 140 mph, unworried that the road is bending and the pavement is darkening with splotches of dampness. Not when every control in the car—from gearshift, to steering wheel, to the drilled metal pedals—reacts quickly and positively to your inputs. Then, beauty isn’t particularly important at all.
We could argue about the definition of the word “exotic” as it applies to automobiles, and some might contend that automobiles such as the Lancia Delta S4 are not the most exotic in the world. Ferraris, Lamborghinis, Lotuses, etc. are much better-looking and certainly have a higher level of amenities. And if your purpose in owning an exotic car is as much amorous as automotive, by all means stay with these. But from the standpoint of rarity and technical interest, the S4 and its FISA Group B brethren outdistance them all.
This story originally appeared in the 1986 Exotic Cars: 4 issue of Road & Track.
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On the matter of rarity, the international racing rules say any automaker that wants to compete in the Group B rally class must build 200 of the model to homologate it. Twenty more can be created as “evolution” models, that is, competition cars. The constant changing of rules and regulations means the chances of a manufacturer making more than 200 of these fascinating cars to sell to the public are slim. What technical advances will an automaker need to make in order to remain competitive in two years? Enough to assure that you have built-in rarity with the present models.
Before we check out the technically interesting Lancia Delta S4, remember there’s another Lancia Delta: a nice transverse-engine. front-drive sedan with a Giugiaro-designed steel body, room for four and all the expected comfort of a standard production car. Lancia makes this Delta by the thousands. In fact, the Delta S4 shares with the production car the name, a similar front grille and the fact they both have 4-cylinder engines. That’s about it.
Though the S4 is a "production” car, it’s produced with hand labor, starting with the engine. In rather typical Italian fashion, the S4's engine is special, though it’s not apparent when you lift the tail section of the car. That view of the engine is nothing extraordinary, because all you see are two great horizontal intercoolers.
But those intercoolers indicate, of course, that the engine is turbocharged, which is what all the automakers (except Austin Rover with its MG Metro 6R4) figure is the logical answer in this rally class. The rules allow a 900- to 1000-kg car—considered by Lancia the best weight for both lightness and safety—with one of two engines: a normally aspirated powerplant up to 2.5 liters or a turbocharged engine up to 1.76 liters. The potential horsepower from the former displacement would be around 350, while the latter should be able to produce more than 400, which pretty well settles the route to take.
Abarth, which does race and rally design and development for all Fiat’s subsidiaries, created an entirely new engine for the S4. It's a 4-cylinder monobloc design, so it has no detachable head. Inside the block are aluminum cylinder liners, which are treated with a nickel-based coating. Naturally, the engine is dry sump and has twin camshafts and four valves per cylinder. Displacement is 1759cc . . . but that's all the simple stuff.
Though turbocharging is almost a given on an engine of this type today, it wasn’t quite enough for Lancia. While the turbo provides the power needed at high rpm, the S4’s designers wanted more punch lower in the rev range, because rallying requires wide-ranging power. So they added a belt-driven supercharger, using a Roots-type unit, akin to one already offered on several production models.
Here’s how the 2-blower system works: The air is drawn into the KKK turbocharger, compressed and sent directly into the first intercooler. From there it passes into the Volumex supercharger, is compressed again and goes into the second intercooler. Out again, past the throttle and into the intake manifold. Or so the system works until the boost reaches 2.5 bar. At that point, a bypass valve opens, and the intake air is routed around the supercharger, and the turbo does all the compressing. “Idling," the Volumex uses 3-4 bhp compared with 30-40 when working. Let the boost drop below 2.5 bar, and the supercharger starts to work again. Close the throttle, and a shunt pipe ahead of the throttle plate routes the supercharged air back to the turbo to keep things spinning as long as possible, minimizing turbo lag when the throttle is opened again. Incidentally, the mixture going into the first intercooler is around 200 degrees Celsius and drops to 40-50 degrees by the time it’s at the throttle.
Fuel injection and ignition are the dual responsibilities of a Marelli-Weber digital electronic system. These two companies, owned by Fiat, jointly developed the speed/density device. The rally car uses one fuel injector per cylinder. It is, however, a very expensive injector, so the production S4 has a pair of less expensive injectors for each cylinder. There’s one spark plug for each cylinder.
Put it all together, it spells “ power,” with 250 bhp at 6750 rpm and 215 lb-ft of torque at 4500 rpm for the street machine. Add the competition changes—larger turbo, higher boost, etc—and the power goes to 400 at 8000 and torque to 289 lb-ft at 5000 rpm.
To make the best use of that power, the S4 has 4-wheel drive, which is a must in international rallying these days. Hewland, the gearbox firm, worked on the development of the system and produces the version for the rally cars. The rear differential has a 25-percent limited slip, with no limit in front. The center differential is a viscous type from Ferguson, while the gearbox is a 5-speed Abarth design. While the production transmission is all-synchro and encased in an aluminum housing, the competition type uses dog-face gears in a magnesium case. The engine is placed longitudinally in the chassis, but facing rearward with the transmission pointing toward the front so it can mesh directly with the center diff. Front-to-rear power split in the production car is 30/70 percent; in the competition versions, it can range from 75/25 to 60/40, and the settings are mechanically done—not actuated by the driver flipping a lever.
Round- and square-section tubing are used to create the S4’s structure. Ahead of the front axle is a pair of aluminum tubes designed to absorb energy in case of an accident. Although composites are considered necessary for a Grand Prix car chassis, Lancia stayed with a tube roll cage frame for three reasons. First, easy access to components is critical with a rally car; second, the tube structure is easier to get around; and, last, the cage is also simpler to repair. Lancia knows what can happen—the flexing and bending—in an accident.
Production S4s use a fiberglass body, and none of the panels is stressed. Rally S4 bodies have carbon fiber and Kevlar added for lightness and strength. Both ends of the body lift to expose the engine or suspension. Considering the smooth, svelte shapes that usually emerge from wind tunnels these days, it seems almost ludicrous to mention the S4 body was developed in Fiat’s tunnel. Or that the coefficient of drag is 0.60-0.70, versus 0.30-0.40 for a 4-door sedan. And that Lancia considers this a logical, successful aerodynamic design. For though rally cars look as though they are going like the hounds of hell, their average speed is relatively low, in the 50-55-mph range. But consider the conditions and application. There’s all that horsepower in back, demanding gobs of air to cool the engine, and the big brakes require quick cooling too. In both street and rally versions, the side intakes send air to the intercoolers. A rooftop scoop on the competition car takes in air for the oil cooler, engine intake and rear brakes.
Front and rear suspensions of both models of the S4 are quite similar to each other and to that of the mid-engine Lancia Rally the S4 replaces. That means unequal-length upper and lower A-arms and plenty of adjustment for various road surfaces. As Dott Ing Claudio Lombardi, Abarth’s director of experimental programs, puts it, a rally car’s suspension needs two basic ingredients: wheel travel and strength. The S4 has both.
Steering is by rack and pinion, the street editions having vacuum assist. Using engine vacuum stored in a reservoir, this system has the advantage of being light, inexpensive and easy on the engine. Lancia feels it might be a good alternative to hydraulic power-assisted steering on future small production cars. Brakes are vented discs at all four wheels. Giorgio Pianta. Lancia’s legendary development driver who has been responsible for such cars as the Fulvia HF, Stratos and A37 Rally, has tried an anti-lock system on a rally car but feels it still isn’t right for competition. Ing Lombardi adds, however, that with less need to toss a car and spin its wheels with 4wd systems, a combination of anti-lock/anti-spin under acceleration might be the answer in the future.
Abarth and Pirelli developed a new tire for the production S4s. It's really meant to be three tires in one. Called the “PZero Corsa,” the tire has a vee pattern on the inside of the tread, grooved rain channels in the middle and a slick surface on the outside. The rubber compound is also different for each portion of the tire. Pirelli feels that at speed on dry roads the car goes faster and rolls more, using that outer slick part of the tire. Under wet conditions, roll is minimal and the car can take advantage of the inner gatorback tread.
On the road, the production Delta S4 package, from twin blowers to 3-pattern tires, has a curb weight of around 2640 lb. Lancia claims the S4 will do 0-100 km/h (62 mph) in 6.0 seconds flat . . . no turbo lag. That’s with a top speed of 140mph, to which I can personally attest from the driver’s seat.
And it's a very comfortable seat to be in. Just because this is a homologation special doesn’t mean the Lancia is a crude machine. You do have to climb over the high-angled sill formed by the roll cage frame, but then you drop into a high-sided, very nicely done seat. There’s not only full upholstery and carpeting, but even an anti-theft system. A trip computer too . . . all the better for keeping track of the average speed. Naturally, the instrumentation is complete, but so is the ventilation system. There are even electric remote-control mirrors. Two sure hints you’re in something special: the drilled metal pedals and horizontally sliding plastic windows.
You also know you’re in something out of the ordinary when you grasp the stubby shift lever. Shifting is quick and direct. As promised, there is no turbo lag, just solid power from naught to top speed. Our route led to the damp autostrada for high-speed runs, then to a snowy Alpine pass. There is initial understeer, and those who have driven the car in the dry say that understeer eventually leads to a nice neutral attitude . . . at much higher speeds.
The Delta S4s must handle reasonably well at speed, because Henri Toivonen and Markku Alen finished 1-2 in the 1985 RAC Rally in England. Last major rally of the year, the RAC was the S4’s debut in serious competition. To win under such circumstances in the rough world of rallying is downright impressive.
All this Delta S4 performance, and now fame, can be yours for a mere 100,000,000 lire if you want the road version or 250,000,000 for the race/rally edition. At today’s exchange rate, that comes to $57,142 and $142,857, respectively. Lancia points out, however, that a prepared Peugeot competition rally car runs to 320.000.000 lire or $182,857.
Perhaps you could get bank financing.