A secret car, known to a handful of General Motors employees as XP64 and to the inner circle at Chevrolet as "the bug," emerged last week from behind the orange doors of a large, hectic room in Chevrolet's plushy new Engineering Center. Outsiders with an ear to the ground had been expecting an all-out racing sports car, but vital details were missing. SPORTS ILLUSTRATED here presents—along with exclusive photographs—the first full story of the Corvette SS.
The electrifying reality is that the SS (for Super Sport) is the first true racing car to come from Detroit—an epic surprise thrust by Chevrolet at the eleventh hour for this Saturday's world championship sports car race at Sebring, Florida. With only a week to go, the company was dickering with World Champion Driver Juan Manuel Fangio to take the wheel.
Introduced as a research laboratory on wheels, Chevrolet's trail breaker is a stripped sports racer, not a touring-racing combination. Potentially it is the peer of the world's finest and fastest machines of this kind. It is essentially a straightforward car which nevertheless explores new engineering principles. Its great singularity, however, lies not in its machinery but in the fact that nothing remotely like it has come from the U.S. automobile industry since its reorganization from a cluster of individualistic enterprises into a few corporate giants which have made the word Detroit mean the mass production of American passenger cars.
Having come of age last year, the Florida International 12-Hour Grand Prix of Endurance (to give the Sebring race its proper title) is taking another giant step. By far the most significant sports car race in North America, it gives U.S. stay-at-homes their only opportunity to see the renowned drivers and cars which play to an enormous following in Europe; it gains immeasurable new stature from the advent of the SS.
When Chevrolet unveiled a production Corvette with promise of racing success last year, that was considered astonishing enough by those who had commenced to believe Detroit would continue to downgrade sports cars. The promise was fulfilled handsomely enough for Corvette to win many Sports Car Club of America races—and this, in turn, undoubtedly figured in Jaguar's decision to produce a potent new production version of its all-out D-type, also named, like some fine prewar Jaguars, the SS.
Now comes Chevrolet with a car nearly 1,000 pounds lighter than the production Corvette, more powerful and more tractable. The aerodynamic body is of lightweight magnesium alloy; light, strong metals are utilized where applicable. Possibly remembering the abortive comeback of France's famed Bugatti last year, Chevrolet is being sensibly cautious about the car and is prophesying no miracle at Sebring. The Bugatti, as you may recall, made a disappointing showing for 18 laps in the 1956 French Grand Prix and then retired, never to appear again, despite Bugatti's fabulously successful prewar racing history and wealth of racing engineering experience.
Chevrolet has had no such experience, and Sebring, moreover, is a brutally exacting course—part airport runway and part asphalt road—which is a great destroyer of cars. Says Zora Arkus-Duntov, the expatriate Russian engineer who developed the SS for Chevrolet: "We will need enough luck to overthrow the government of Russia and feed all the hungry Chinese. There isn't that much luck in the world."
The grapevine says, however, that initial tests by Driver John Fitch on the course itself have exceeded expectations, especially in the vital matter of handling qualities.
Given certain reservations about Detroit's cloudy future in racing, the SS, even though unproved, remains a lustrous accomplishment. It has been only five years since General Motors Styling produced the first plastic Corvette body shell and asked Chevrolet Engineering to put something inside it; only five months since the SS began to incubate on the drafting boards; only a week since the new baby was assembled in final form, with the briefest of practice periods available before race time. There was no handbook by Dr. Spock, with all the answers, to consult during the lying-in. No one really was certain that all the bugs would have been expunged by 10 a.m. Saturday. There was even a chance, early this week, that the car might not race at all if its preparers felt it could not perform adequately in so short a time. Whatever develops, the SS is a car of fundamental importance and a much-needed shocker to shake U.S. motor racing from the doldrums of isolation and sameness, regardless of the positive engineering advances which may well accrue to Chevrolet.
Here is the car in detail:
1) There is a three-dimensional truss-type space frame of small-diameter chrome molybdenum steel tubing (weighing only 180 pounds) for high rigidity, reminiscent of the best Mercedes-Benz practice.
2) Rear suspension is by a De Dion tube (conventional European practice) positioned by a revolutionary arrangement of four ball-jointed radius rods. Two unitized coil spring-shock absorber assemblies, but no transverse leaf spring, commonly seen with the De Dion arrangement, are utilized on the SS.
3) The drum-type rear brakes of cast iron with finned aluminum muffs are inboard, alongside the differential housing, which is bolted to the frame. As a whole, the rear assembly has these merits: load transfer from one wheel to the other is canceled out, unsprung weight is low, all rear axle control members are relieved of driving and braking strain and road adhesion is considered excellent.
4) Independent front suspension is by nonparallel control arms, linked by coil springs with interior shock absorbers. The nonparallel technique has been experimented with before; Chevrolet believes it has achieved its inherent advantages in cornering stability and at the same time the positive control which has been elusive in this system in the past.
5) The engine, which develops approximately 315 hp at perhaps 6,200 rpm, is based on the standard 283-cubic-inch (4.6 liter) Corvette V-8 block, with a single racing camshaft and pushrods. Aluminum cylinder heads have been designed for higher performance; fuel injection is into the intake ports, as in the standard motor. The oil pan now is of magnesium. Individual exhaust pipes increase horsepower by providing an extractive effect, and engine breathing is considered so good that the compression ratio may be lowered to 9:1, with a resultant safeguard against detonation. No official top speed has been predicted, but there have been whispers that 190 mph is not improbable under ideal conditions. For Sebring the car will not be geared for ultimate speed, rather for a balance between speed and acceleration. It will have the excellent torque characteristic of its production stablemates, an invaluable asset for dig out of Sebring's tight turns.
6) The four-speed synchronized gearbox with hand shift has these ratios: 1st—1.87 to 1; 2nd—1.54 to 1; 3rd—1.22 to 1; 4th—direct.
7) Light materials are used where feasible. Standard engine weight has been reduced by 75 pounds; the magnesium body replaces Corvette's conventional plastic bodywork; the 43-gallon fuel tank is of plastic; the wheels are magnesium; the clutch assembly bell housing, aluminum. Over-all dry weight is 1,850 pounds, compared with 2,800 for the stock Corvette.
8) The radiator system (there is no fan) is an advanced type sometimes seen on speed record cars. Cooling air is taken through an aluminum radiator, which circulates engine oil as well as the coolant, and deflected upward through louvers in the hood. The rearward rush of outside air over the hood creates a vacuum effect; air is sucked through the radiator at a higher than normal rate, with consequent cooling benefits. Cooling air is also deflected directly onto the brakes.
9) Wheelbase is 92 inches, 10 inches less than the production Corvette, but over-all length remains the same, 168 inches. A roll bar is concealed in the rather racy headrest. The plastic bubble shown on page 10 will not be used during the race; it was fitted to conform with Sebring rules on touring equipment. The only visible points of resemblance between the SS and the production models are the grille and the design on the side panels.
10) Brakes are power-assisted, a novelty for a car of this function.
This, then, is the car and, if there are names to remember, they are two: Edward N. Cole and Zora Arkus-Duntov. Cole, Chevrolet general manager, called the signals, and Duntov carried the ball. An energetic and enthusiastic man, Cole began his automotive apprenticeship in a Cadillac laboratory in 1930. As Cadillac's chief engineer in 1949, he designed the industry's first high-compression V-8 engine. Chevrolet tapped him as chief engineer, and he designed the V-8 which helped win back a working sales margin over Ford in 1955 after a very close 1954 race. Last year, at 46, he became boss at Chevrolet. No tyro at "shopping" for body designs at GM Styling, Cole is nonetheless regarded primarily as a "performance" man, and his knack for getting the most out of an engine may be of immense value to Chevrolet this year as Ford and Plymouth capitalize heavily on radical body restyling while Chevrolet must make do with what the industry calls a face-lift. The SS, as a prestige performance package, could hardly have been uncloaked at a more propitious time.
Cole leaves one area of Chevrolet's aspirations for the SS to speculation—the scope of its racing program—which is nothing if not prudent in the somewhat jittery atmosphere occasioned in Detroit when one talks of racing right out loud. The primary goal is engineering research, but it would not be wrong to assume that patriotic hearts would beat faster if the SS showed its exhaust to Europe's best one fine day.
"Testing under the most severe operating conditions," says Cole, "gives the engineers a chance to study the performance and safety characteristics of new developments and features which have been built into this vehicle.
"That is the principle behind the development of the SS. It is a study of new ideas to determine whether they might eventually be refined and offered in regular passenger cars. Instead of substituting these features in test cars on a piecemeal basis, we hand-built a car around them that will provide concentrated results.
"Testing over rough race courses will serve to quickly furnish comparative engineering data that under ordinary circumstances would require long periods of research."
Ed Cole's estimate of the situation differs only in detail from that of an astute observer of racing, John Wyer, who has summed up a lifetime of experience in his recent book, Motor Racing Management (The Bodley Head, London). Wyer, the former team manager of Britain's Aston Martin sports car program, is one of the few frank devotees of racing who admit that racing experience does not, in fact, have as much to do with subsequent passenger cars on a point-for-point basis as is usually claimed, and he says, in effect, "So what?"
"Designers are," Wyer writes, "above all, creative artists. They are, very often, an irritating and contrary race, surprisingly and inexplicably blind to what appears, to the commercial mind, to be the starkest realities of the situation. But, however infuriating they may be, and frequently are, they do possess this almost sublime quality of being able to create, and it is a quality which must be allowed freedom if it is to find its highest expression.
"Designers can, no doubt, and particularly if we pay them enough, be made to obey faithfully the dictates of the sales and production departments even when they know them to be divorced from sound engineering principles. But a designer who is compelled to work to rule will lose the spark of originality...and he will, in time, lose the power to create....
"I suggest [that] the manufacturer who engages in racing, by virtue of the mental stimulus which he will give to his technicians, by virtue of the profound research which all racing demands, and by virtue of a general raising of standards of engineering which must result, will, often almost in spite of the united efforts of his own sales, commercial and production departments, produce a better car than the manufacturer who has never raced at all.... Racing improves the breed of production cars without necessarily having to produce its own likeness in every little production car which scurries off the end of the assembly line."
To which might be added that Cole has given Duntov this kind of freedom and Duntov has produced a potentially superior car.
At 47, Duntov is a silver-haired, courtly man with the somewhat dubious distinction of having swum with Nicolai Bulganin one summer near Yalta as a schoolboy. He made the tiny quota for bourgeois students at a technical school in Leningrad, and eventually slipped out of the U.S.S.R. after being held loosely as a hostage for his parents, who had preceded him. With a recent engineering diploma from the distinguished Charlottenburg Institute in Berlin in hand, he became an apprentice engineer and soon designed a minor part for a generator.
"It was an insignificant thing," he says, "but it was my greatest creative joy. Everything since has been weaker."
Duntov dabbled in motorcycles and middle-distance running in Germany, moved on to France and thence to the U.S. Europe was to see him again, however, most vividly at the Le Mans races of 1954 and 1955, in both of which he co-drove the class-winning 1,100-cc. Porsches. His Ardun cylinder heads (for Arkus-Dimtov) which transformed poky stock engines into fire-eaters earned a lasting place in racing.
It was this varied and useful background that Duntov brought to Chevrolet. It has, obviously, not been wasted.
Following current Detroit practice, Chevrolet has entered the SS at Sebring in the name of Lindsey Hopkins, a successful Indianapolis "500" car owner.
Sebring has not only the SS but a bagful of other attractions. It provides the second act in what bids to be the most gripping sports car duel in years—Maserati vs. Ferrari.
The 1956 champion, Ferrari, won the first round toward the 1957 manufacturers' title in Argentina, but Maserati has developed swiftly and may field the two finest drivers in the world—Argentina's Fangio (if he hasn't decided for the SS) and Britain's Stirling Moss. Maserati, too, will be making another effort with its new and powerful 4.5-liter car, which is tentatively to be driven by Fangio and Moss. Jean Behra, the plucky one-eared French driver, and the Argentine 10-goal polo star Carlos Menditeguy, may share one of Maserati's bread-and-butter three-liter machines. Texas' Carroll Shelby, who smiles from this week's cover (and talks about himself in a story on page 69), and the American expatriate Harry Schell, who lives in Paris, are to co-drive an experimental 2.5-liter Maserati.
Enzo Ferrari, meanwhile, has not been sitting on his hands. For the three works cars of the 1956 Mille Miglia type (SI, Dec. 24) he has these accomplished drivers: blond Peter Collins of Britain, Germany's young Count Berghe von Trips, Luigi Musso and Cesare Perdisa from Italy, and the Spanish hotspur, the Marquis de Portago. The sixth driver would have been Eugenio Castellotti (see box), who was killed last week in Italy. He may be replaced by the French winegrower, Maurice Trintignant. Two of the V-12, 3.5-liter Ferraris will have four overhead camshafts, instead of last year's twin-cam system, to provide more positive valve control at high engine speeds.
Besides Ferrari and Maserati the only other logical contender for the over-all victory is Jaguar. New for Sebring is a 3,800-cc. engine developing 300 hp, basically a larger version of the standard Jaguar 3,442-cc. six-cylinder racing engine, with redesigned combustion chambers and larger valves. Since Jaguar has retired from racing as a firm, three cars are being entered by the North American distributor, Sportsman Briggs Cunningham, who will co-drive one of them. Jaguar's hottest prospect is the D-type, to be driven by Mike Hawthorn and Ivor Bueb of Britain, the team which won the 1955 Le Mans in a similar car.
A MATTER OF STRATEGY
It should be noted that team managers may juggle their drivers at the last minute if they please. The driver nominated as No. 1 is firmly attached to a specific car, but the second drivers may be shifted on paper at will until they actually take the wheel of a car. Then they are committed.
If the heavyweights fail—not an impossibility on the tortuous Sebring layout—the terriers will have their day. Not to be discounted are the two-liter Maseratis and Ferraris and the 1.5-liter Porsches. The basic goal for the smaller cars, however, is a class victory or over-all win on the index of performance (an arbitrary method of judging which car best measured up to its potential, regardless of engine size).
Besides its other superlatives, Sebring constitutes the longest race in the U.S. and the world's most severe test of brakes.
The thoroughgoing fan who for weeks has wallowed in pre-Sebring rumors now has the delectable time of fulfillment at hand. The same amount of time that another man devotes to breakfasting and shaving, putting in a full day's work, dining, dandling the children and catching the Ed Murrow newscast, the fan will be spending on the Sebring grounds—from the moment the starting flag dips at 10 a.m. Saturday and the drivers sprint across the pavement toward the 65 cars, to the moment in darkness, 12 hours later, when the winner receives the checkered flag. If this dedicated enthusiast is not exhausted, the next day he will be able to go right back and watch a three-hour race for the overflow of applicants who missed the main event.
The most extensive radio coverage so far will include live broadcasts by Walter Cronkite and Arthur Peck over CBS from 10:20 to 10:25 a.m., 1:05 to 1:20, 8:45 to 9 o'clock and 10:05 to 10:30 p.m. on race day. There will be CBS bulletins on the hour.
As a searching test of brakes Sebring is so rugged that this factor tends to override other considerations, especially for the larger cars which have the greatest weight to retard at the corners. Ferrari and Maserati have modified their drum brakes; the Jaguars will have new discs by Dunlop. Sebring, thus, will write another chapter in a lively engineering argument—drums vs. discs—the drum brakes having seen long service on family cars as well as racing cars, the more recent discs having been derived from airplanes. (For a graphic look at the latest drum and disc brakes, see drawings, left.)
But let Vittorio Bellentani, Ferrari racing engineer, take the stand:
"Ninety per cent of success at Sebring depends on brakes—specifically on the continuance of braking power despite heat-producing braking efforts. Le Mans and Monaco may be equally severe for hard braking but nowhere except at Sebring is there such a succession of bends which allow the brakes almost no cooling time between one application and the next.
"The problem is not to provide exceptionally powerful brakes, but brakes whose cooling system is such that their power does not diminish through fading."
Well aware that Ferrari's 1956 Sebring victory was won in no small measure because of the lack of competition toward the end, Bellentani concedes, "There was no adversary who could molest us at the finish when our braking power had become immensely limited." Both Maserati and Ferrari have facilitated brake cooling. Instead of fixed shoes pressing against a rotating drum the Jaguars employ steel discs which turn with the wheels and are squeezed by a pair of pads when the brake pedal is depressed. The pads are mounted inside a so-called "caliper," which is fixed in place to bracket part of the disc without retarding its motion until the pads are activated.
It is the terrible strain on brakes (not to mention gearboxes) which gives the highly developed smaller cars a glimmer of hope for the over-all prize. Porsche, for example, with a weight of only 1,166 pounds in its all-out Spyder model, maintains that a recent test in which the brakes were used to decelerate from 120 mph to 30 mph as quickly as possible, 320 times in rapid succession, wore only .04 inch from the brake lining (of secret composition) and caused neither excessive heat nor significant fade.
Important as brakes, foreign cars and drivers are, they must yield center stage to the SS. It is tempting, indeed, to herald the SS as the first concrete symbol of a bold new day for American motor sports and indulge the notion that some time, in the not too distant future, more of the Detroit titans might get their feet wet, too. It could happen. Yet history says the largest manufacturers, with the shining exception of Mercedes-Benz, avoid the hay bales. On the other hand, Detroit, more and more openly, is supporting a large-scale program of stock car racing, and it is precisely this which has lifted stock cars to a major sports level.' Le Mans has announced that three Corvettes and two Ford Thunderbirds will compete in the 24-hours. Chevrolet disclaims any such entry—but make no bets that the SS will not be there, if it proves to be a sound racer.
In any event there will be a bold new Sebring this Saturday; one to encourage hopes that future U.S. racing will be as exhilarating.
MASERATI DRUM BRAKE incorporates special lining (1) on shoes, opposed cylinders (2) to operate the shoes, a bimetallic drum (3) and passages (4) for bleeding hot air past drum fins (5).
Dusk at Sebring, the critical time of half-light, when drivers must adjust to darkness, is frozen here in a photograph by Richard Meek, who also recorded in color some other episodes from last year's race
DEATH OF 'IL BELLO'
As a boy he labored in farm fields near Milan. At 20 he suddenly inherited great wealth and commenced a silken life, ornamented with a Rolls-Royce and fashionable bars. When stern Enzo Ferrari spied him lolling in the Rolls one day, haughtily waiting for the chauffeur to open the door, Ferrari barked, "Come out of your stupor. Wake up and do something." Eugenio Castellotti (see opposite page) did something, in Ferrari racers, with such fury that in six years he broke both his legs and an arm in racing accidents, but he also became the Italian champion. He shared the winning Ferrari at Sebring last year with Fangio, but his supreme victory was in last season's Mille Miglia. Overwhelmed by his good looks, Italian women shouted "Il Bello!" at Castellotti all along the 1,000 miles of open road (SI, May 7, 1956). Last week, at 26, taking time out from Sebring preparations to test a Grand Prix Ferrari, Castellotti missed a vital downshift, veered off the course at Modena, Italy and crashed into a wall. He died at once.