A Right Turn to Turbos

Salvation! A performance resurrection is upon us. Just as automotive enthusiasts everywhere were resigning themselves to levels of stimulation heretofore associated with mopeds and single-cylinder garden tractors, a massive revival in the more visceral aspects of motoring has appeared. And it has come almost at the last possible moment. Until recently, it seemed that a ragged cabal of Government agencies, anticar Luddites, environmental zealots and OPEC loonies was succeeding in banishing all inherent excitement in automobiles in the sacred name of its own varied interests. But now we stand in amazed witness at the appearance of a small mechanical talisman that, when attached to an internal-combustion engine, can in a large measure restore the horsepower that because of increasing profits for a varied collection of desert fiefdoms has been squeezed out of engines for the sake of hotly debated improvements in air quality and reduced fuel consumption.

We call it a turbocharger. It is not to be mistaken for a supercharger or any other gadget intended as an energizer for weakhearted power plants. It is a wonderfully ingenious device that has been used for decades on airplanes and various automobile- and boat-racing engines. Now, thanks to a variety of external circumstances mentioned above, this turbocharger thing appears to have a bright future in an everyday world of cars where the search for horsepower has gained Holy Grail dimensions (at least among people who care about maintaining a pace on the highways something in excess of that associated with joggers, oxcarts and municipal buses). The really neat aspects of a turbocharger are as follows: (1) It is light, compact and simple. (2) It can be attached to practically any internal-combustion engine, either gasoline or diesel powered, and generate dazzling increases in horsepower. (3) This multiplication of output comes without seriously affecting drivability or the exhaust-emission standards or radically increasing the fuel-consumption rates.

Imagine the turbocharger as a small pump. Imagine, too, that an internal-combustion engine's horsepower increases in direct relationship to the amount of fuel that can be delivered into its cylinders. Most automobile engines are what we call normally aspirated; i.e., they burn only the amount of fuel that is pushed into them by the earth's atmospheric pressure. It stands to reason that if that fuel volume can be artificially pumped into the engine, the more power it will deliver, just as more coal in a furnace or more wood in a fireplace will generate more heat. Turbochargers and superchargers operate in essentially the same fashion, in that they both force the fuel charge into the engine's combustion chambers under pressure. They were conceived for a similar purpose: that of supplying extra power for aircraft power plants at altitudes at which normal air pressure is reduced to a point where power output drops radically. The difference lies in the manner in which they operate. The supercharger runs via gears or belts from the engine to which it is attached. It therefore is something of a parasite, draining away some of the extra power it helps generate for its own operation. However, the turbocharger is a much more ingenious application of the same principle. It is operated by a little fan--or impeller--that is driven by the exhaust gases as they exit the engine. This is "free" unused energy and the turbocharger therefore can generate bonus amounts of horsepower without any wastes in its own behalf.

If the turbocharger is capable of supplying quantities of virtually no-cost added power, one might reasonably ask why the thing has not been an integral part of all automobile engines from time immemorial. In keeping with that aged wisdom about there being no such thing as a free lunch, it should be noted that there are certain deficiencies in the turbocharger that limit its appeal and its application. First of all, it is expensive out of all proportion to its size. Because the aforementioned impeller spins in excess of 30,000 rpm, exotic metals have to be machined to precise tolerances, which is anything but cheap. Moreover, the turbocharger operates on a sort of closed-loop system whereby the faster the engine runs, the more the exhaust-gas velocity that energizes the turbocharger, which pumps in more fuel, which produces more power, which makes the engine run faster. . . . This means one thing: If a turbocharger is permitted to run free, it will finally pump so much fuel into the engine that self-destruction is the only possible result. The turbocharger will pressurize the internals of an engine to a point where it will literally blow apart. This requires what is called a waste gate--a device to vent excess pressure built up by the turbocharger--which adds both cost and complication. Moreover, if one wants really significant boosts in power from a turbocharger, a specially designed engine is necessary, like those that run at Indianapolis. There turbocharged engines rule the roost but cost $35,000-$40,000 each. Yet consider what a turbocharger does for an Indy engine's output. Normally aspirated, a Drake-Offenhauser four-cylinder or a Cosworth-Ford V8 will produce between 300 and 400 horsepower. With a turbocharger attached, the output jumps to over 900 hp! The same blossoming outputs are also to be found in various Porsche sports-racing-car engines--along with even more prodigious price tags. Turbocharging is a superior way of gaining massive power increases from engines with limited displacement, but it is relatively expensive. Given a choice, engine designers can gain similar results by simply making normally aspirated engines larger. The old saying "There is no substitute for cubic inches" still applies, but when that avenue is closed, turbocharging is the next-best key to horsepower.

That is the reason passenger-car manufacturers are becoming so enamored with turbos. As the demand for smaller, lighter, more fuel-efficient automobiles increases, large-displacement engines are becoming as antiquated as tiller steering and wooden-spoked wheels. They simply gobble too much fuel for normal applications, even in America, where monster V8 engines have been practically as much a part of the culture as hot dogs and gangland killings. At the beginning of this decade, something like 80 percent of all cars made in America carried engines in excess of 300 cubic inches. Today that figure has dipped drastically and by the mid-Eighties, many auto makers are expecting that as many as 60 percent of their products will be powered by small four-cylinder engines. A majority of the remainder will be modestly sized V6s, with nothing being propelled by any engine larger than 350 cubic inches.

This Brave New World of minimotors will be wonderful in the context of fuel conservation, but, as we noted earlier, visions of stop-light drag races between one's automobile and a muscular teenager on a ten-speed cause massive depression among enthusiasts everywhere. They are the ones who are viewing the turbo with such optimism, because it is a device perfectly suited to their needs of injecting performance and excitement back into vehicles of all sizes.

That quite obviously is what Buick Division of General Motors had in mind with its new S-type Riviera. This startling machine, introduced amid much hoopla this year, is a glimpse of the future, at least in terms of what so-called highperformance automobiles will be like perhaps a decade hence. It is a taut, close-coupled four-place American grand touring car, featuring such technical exotica as front-wheel drive, independent four-wheel suspension and front disc brakes, plus a small-displacement V6 engine fitted with a turbocharger. The Riv is a sister car to the General Motors E-Car series, which also includes the Oldsmobile Toronado and the Cadillac Eldorado. They are, beneath their various styling flourishes, identical automobiles, except that Buick has pushed its S type considerably farther down the road to sportiness than the two other makes.

Stiffer springs and shock absorbers combined with heftier antisway bars make the S type a solid handler under all but the most arduous conditions. Its frontdrive layout has eliminated the nasty penchant for radical understeer and a condition called torque steer (feedback through the steering when the wheels are turned under power) often found in such applications. New is a word that is bandied about in the car business in the same fashion in which the news media overuse crisis or sportscasters employ great, but the Riviera truly deserves the label. It obviously began life on a clean sheet of paper and the thoroughness with which its components have been integrated speaks well for the future of automobiles in their increasingly miniaturized configurations.

The Riviera has been around since 1963, when Buick introduced it in the form of a classically sculpted four-seater similar in size to the latest version. Following its exciting birth, the car experienced an unpleasant adolescence. It became bloated and awkward. Worst of all, it was dull. Sales slumped until this year, when the latest version revisited attention on the vehicle that had been lacking since its introduction.

Of course, the car can be loaded with all manner of gimcrackery, including a digital-readout instrument panel featuring a mini-trip computer for frustrated astronauts, power sun roof, optional lights of all descriptions, leather bucket seats, stereo radios, etc.; but the centerpiece of this buffet of gadgetry is the turbocharger. This tiny device, nearly hidden from view in the fiendishly complex maze of pipes, wires and hoses that conceals the engine, is that which boosts the S type's 231-cubic-inch V6 engine from an otherwise stock 115 hp to a rather lusty 185 hp at peak boost. This power plant, revised and radically improved with new intake and exhaust manifolds and redesigned cylinder heads, is the element that adds the needed jigger of clout to what is otherwise an interesting and competent but somewhat pallid machine.

As if the Buick we took under our wing were not gadget-ridden enough, we could not resist adding a few of our own fillips in the name of added performance and individuality. To enhance the already solid road-holding characteristics of the car, we installed a set of the muchrespected, aggressively treaded Pirelli CN-36, 235/60 VR 15 tires. These famed European GT radials firmed up the rather soft ride of the Buick and increased cornering and braking power substantially, especially on wet pavement. Moreover, their slightly smaller diameter lowered the car, which added not only to its handling but also to its already racy appearance.

Inside, we bolted on an exquisite woodrimmed Racemark custom steering wheel, imported by Racemark International of Burnt Hills, New York, which also supplied us with a set of powerful Hella fog lights for really heavy-weather motoring. And, as a final extra, we hooked to the dash an Escort radar detector manufactured by Cincinnati Microwave--generally acknowledged to be the finest, most sensitive, most uncompromising effort at high technology in the field.

However, let it not be mistaken that the S-type Riviera is a fire-breathing, pavement-ripper throwback to the madcap days of the Sixties, when the "muscle (continued on page 194)Turbos(continued from page 186) cars" ruled the road. Rather than trigger comparisons of the Riviera's performance to the best of those thundering machines, the turbo engine merely restores a level of adequacy to the S type's acceleration and top speed. It will run from 0 to 60 in about ten seconds, which is acceptable for an automobile hitting the streets at 3900 pounds but hardly enough to prompt danger of whiplash among the passengers. Moreover, the sleek contours of the car, which suggest a hefty three-digit top speed, are deceiving. While the Buck Rogers model LED speedometer indicates only to 85 mph, then lapses into fussy spasms of blinking, the S type strains to reach a modest terminal velocity of 105 mph.

Some of those limitations in performance are due to Buick's conservative application of the turbo. One of these units can be adjusted in terms of boost; i.e., the amount of pressure applied to the fuel charge as it enters the combustion chambers. The Buick turbo operates at a rather conservative two-to-five-psi boost, which gives satisfactory but hardly stupefying gobs of horsepower. Other production cars--namely, Porsche and Mercedes-Benz--use turbos with more than twice as much boost, but they employ much beefier and more expensive engines to absorb the extra internal pressures created by the turbocharging.

If the Buick employs a modest, even cautious turbo setup, it is Porsche's role in this epic to take the most avant-garde approach in terms of highway automobiles. Its whale-tailed, chunky-tired little 930 coupe is, with its 165-mph top speed, one of the two or three fastest road cars in the world. With a 3.3-liter (201-cu.-in.) engine that pumps 253 hp out of its overhead cam, horizontally opposed six cylinders, the 930 is a hyperbolic automobile from almost all aspects--including its $41,000-plus price tag. Because its engine is a rugged unit capable of racing applications, the 930 turbocharger operates at an eye-popping 12.3 psi, producing absolutely blistering acceleration (0-60 in under five secs!), as well as its incredible top speed.

If Buick is the leader in mass-produced turbocharged engines, then Porsche is surely the pioneer in the application of turbos in the sports/GT cars that have made that smallish Zuffenhausen, Germany, firm world-famous. Not only have its turbocharged cars dominated the great endurance races at places such as Le Mans and Sebring but the 12-cylinder 917/30 that overwhelmed the Can-Am series in the early Seventies in the hands of Mark Donohue has been called the ultimate road-racing car. That streamlined, ground-hugging machine was capable of speeds over 220 mph and developed over 1200 hp in race trim! From technology gained from such competition cars, Porsche was able to produce the spectacular 930, as well as the recently introduced version of the 924 coupe that has a turbo added to its overhead-cam four-cylinder engine. That particular vehicle was originally criticized for being down on power, but with a new turbo, its original 110 hp has been bumped to an impressive 170 hp, producing 0-60 acceleration times in the neighborhood of 7.5 seconds and a top speed nearing 140 mph. However, like all Porsches, the 924 Turbo is not cheap. The projected price is $20,000--a $6000 boost over the normally aspirated version.

Turbochargers are not new in the market place--Corvair and Oldsmobile briefly and somewhat diffidently marketed turbo cars in the mid-Sixties, before Porsche swept in with its incredible Turbo 911 (now called the 930). Then came Saab, the feisty Swedish firm, which appeared in 1976 with a turbocharged version of its odd-shaped, anvil-tough little coupe.

By adapting a turbocharger used in its trucks and military vehicles, Saab was able to add some desired punch to the overhead-cam four-cylinder fuel-injected engine used throughout its line. This year, an improved 900 series has been introduced, featuring improved handling and interior comfort levels inside a mildly restyled exterior. The turbo engine is available in both a sporty three-door coupe and a more luxurious five-door sedan. While the displacement of the Saab engine is identical with that of the 924 Porsche (121 cu. ins.), the conservative boost of the turbo limits horsepower to 135. However, when compared with the normally aspirated version that produces 115 hp, the results are vivid. The Saab is especially effective at low speeds, where (concluded on page 198)Turbos(continued from page 194) its small size, good visibility and short-burst acceleration make it effective in the cut-and-thrust conditions of heavy urban traffic.

Of all the turbocharged cars presently on the market, the Buick S-type Riviera is the only totally new product. However, another car is a recent addition to the American scene and promises to be a forerunner of a whole new concept of automobile. That is the Mercedes-Benz 300SD, a turbocharged diesel version of its famed S-class four-door sedans. The engine is a modified model of its pioneering five-cylinder diesel that startled the world upon its introduction several years ago. The mating of this particular engine and a turbocharger is a marriage made in engineers' heaven. Turbochargers work on diesels like magic: Every aspect of performance improves; horsepower, fuel mileage, reliability. To wit, the 300SD produces over 40 percent more horses (110 vs. 77) and better fuel consumption, never mind better acceleration and top speed (which, at 105 mph, is about equal to the more powerful Riviera's).

Ford Motor Company jumped into the turbo business this year with a 2.3-liter (140-cu.-in.) overhead-cam four-banger that first saw life in the original Pinto. The engine is fitted in both the new Ford Mustang and its sister car, the Mercury Capri. Again, this is a rather mild application of turbocharging--as must be the case when working with low-cost mass-production engines--but the results are impressive. When coupled with the cars' optional handling packages, the turbo Capri and Mustang are not only the lowest-priced turbo cars on the market but among the most responsive and nimble automobiles made in America.

Where will it all end, this turbocharging business? That question cannot be answered, because the trend has barely begun. Several manufacturers, including most of the domestic builders, as well as Peugeot, Volkswagen, Volvo and others, are reported to be poised on the brink of jumping into the market place with turbo cars. Most agree that turbos are the one simple way to tweak small-displacement engines while retaining good fuel mileage (the turbo does not operate at low speeds, meaning fuel consumption remains normal) and acceptable emissions. As we said, the benefits are even greater on diesels, meaning the turbo boom may be even vaster than anyone can imagine at this time. Either way, turbos have given performance drivers a new lease on life, even on older, nonturbo cars (see left), and that alone is worth rejoicing about.

"It is Porsche's role in this epic to take the most avant-garde approach in terms of highway autos."