Rudolf Diesel What You're Missing

those big engines that went pocketa-pocketa and got together at the local truck stop have joined the smart set

Herewith we ponder the diesel engine, and why a lot of people who should know are telling us it is our automotive salvation of the future. You, of course, remember the diesel. It is the source of all the noise and black smoke that spews from the innards of 18-wheel tractor trailers. It is what rumbles in the night when a freight train rolls through town. It is the power plant that the Germans, in a fit of chauvinistic zeal, used to power everything from battle cruisers to transport planes to light reconnaissance vehicles to zeppelins before World War Two. Even today, they remain as their countryman Rudolf Diesel's (1858--1913) most ardent supporters, with two large auto makers, Mercedes-Benz and Volkswagen, as well as dozens of other industrial concerns, firmly committed to the engine that the late, lamented inventor and former refrigeration engineer developed as the Rational Heat Motor in 1897. But their enthusiasm, long latent in the realm of passenger automobiles, is spreading away from Germanic pockets of industry such as Wolfsburg and Stuttgart and settling in such unlikely locales as Detroit. This begs the questions, Why diesels? And why diesels now?

Students of current events and recent history will, of course, recall a troublesome economic curiosity known as Diesel (continued from page 160) sedan enjoys a hard core of loyal owners, thanks to its practically bulletproof reliability and its solid fuel economy, which borders on 28 mpg (four-speed manual) under city conditions. Peugeot, like Mercedes-Benz, has been committed to the diesel principle for a number of years and now is beginning to reap the fruits of what for a long time seemed a lonely and rather unpromising technical preoccupation. It is no longer alone, by any means. In the past year, more and more manufacturers have entered the diesel wars and rumors abound that others are on the verge. The industry was shaken in mid-1978 when Cadillac--long known for its silky, large-displacement gas engines--arrived in the market place with its diesel Seville sedan. This model carried the Oldsmobile 350 V8 diesel, as did a pair of other General Motors models, the Chevrolet C-10 light pickups and their G.M.C. C-series counterparts.

Other American manufacturers are testing the waters with light utility vehicles as well. International Harvester is offering a version of its popular fourwheel-drive Scout with an 81-hp in-line six-cylinder diesel manufactured by Nissan, the parent company of Datsun. Dodge has a variety of its two- and fourwheel-drive pickups available with a 103-hp six-cylinder diesel made by Mitsubishi, the Japanese conglomerate that produces Arrows, Sapporos, Colts, Challengers and the new Champs for Chrysler.

Does driving a diesel require any special skills? Does one have to be an over the-road truck driver, capable of jamming 13-speed Road Ranger gearboxes, in order to operate a diesel Rabbit or Oldsmobile? Hardly. In fact, after a few minor adjustments, the average motorist will have a difficult time telling whether he is behind the wheel of a diesel or of a gasoline-powered car. The biggest difference is evident during the first few moments in the automobile. Because diesels have no sparkplugs, the starting cycle is slightly different. "Glow plugs" must be activated in the cylinder combustion chambers, or precombustion chambers, in order to preheat the initial charge of air and fuel entering the engine. Depending on the ambient temperature, that procedure can take up to a minute, which is timed by a light on the instrument panel. Before starting a diesel, the driver must wait until the dash warning light indicates that the glow plugs have reached operating temperature. In warm climates, that is practically instantaneous. In temperatures below zero, the time can stretch to nearly a minute and generally must be augmented by a 110-volt "plug-in" engine-block heater, which keeps the oil warm and thin enough to permit the engine to turn over. (Because of the high compression ratios, diesels are particularly difficult to start in extremely cold temperatures. Many commercial and military diesel vehicles are kept running constantly in arctic conditions because of this problem.)

Novice diesel drivers will also notice a somewhat unpleasant noise emitting from their hoods during the first few moments of cold running. Because of the unusual combustion characteristics and different bearing tolerances in diesels, they produce an unholy death rattle upon being started. Thumps and clatters roll out of the engines, prompting the uninitiated to believe that his new engine--which has been touted as practically unbreakable--is about to come apart like a cheap wrist watch. However, as soon as the diesel reaches operating temperature, this awesome cacophony disappears. But even then, the diesel fails to attain the satiny behavior of the best gasoline power plants, though rapid leaps in diesel combustion-chamber design, fuel-injection advances, vibration damping and sound insulation in late-model cars are minimizing the difference.

That leaves performance on the highway as the only significant differential that requires adjustment by the new diesel driver. Unless he is behind the wheel of the new Mercedes-Benz Turbo Diesel, which has performance characteristics equal to its gasoline-powered stablemates, blinding speed simply must be eliminated from his highway repertoire. Diesels are slower than comparable gasoline-powered cars in all departments--acceleration, passing power and top speed--and adjustments in driving style must be made. While the rest of the world is leaving him at stop lights or whistling away down the interstate, the diesel driver must content himself with the knowledge that he, like the fabled tortoise, will be the winner in the end.

But will he? Is the diesel clearly cheaper to operate? Acknowledging that it will provide lower operating costs on a per-mile basis, we must still inject other factors into the equation before reaching a conclusion (or, more correctly, trying to reach a conclusion, because the evidence is inconclusive). As a limitation to the diesel's over-all economy, we have the higher initial cost, simply because the engine must be more heavily constructed and demands a high-precision fuel-injection system in place of carburetors. For example, an Olds or Seville diesel will cost about $287 more than the gas version, while a diesel Rabbit is $300 more expensive than the conventional model. Coupled to this is the frequently higher incidence of mandatory oil and oil-filter changes--which may run to a difference of 2000 miles or more--which also adds to the operating expense. These shortcomings (combined with the added noise and vibration, lower performance, cold-weather starting problems) are partially offset by the fact that a diesel engine is 10--15 percent cheaper to operate on a per-day basis, discounting purchase price and maintenance. Because of the general reliability of the engine, the more miles one drives, the more feasible a diesel becomes (which is why it has been the favored power plant for the long-distance trucker for so long), meaning that savings might be substantial for a 50,000-mile-a-year salesman but would be essentially meaningless for a suburban housewife puttering around town.

Diesels are what might be called steady-state power plants. They are at their best running for long periods of time at relatively constant rpms, which is why they work so nicely in power-generating plants, locomotives and ships. Because of their bulky reciprocating parts, they are not as adept at quick accelerations and decelerations as gas engines, which places them at a disadvantage in automobiles. Therefore, they work at maximum efficiency in situations where they can run at constant speeds (as on interstate highways) for hours on end, while the stop-start environment of city streets emphasizes their deficiencies. Ironically, the traveling salesmen of America are not embracing the diesel as tightly as are the suburbanites, who invest the engine with a certain cachet that it does not deserve. Much of their fascination centers on a conviction that the diesel is more ecologically responsible than a gas engine. That is only partly true. The Government regulates only three pollutants emitted by internal-combustion engines--hydrocarbons, carbon monoxide and oxides of nitrogen. Because of its peculiar combustion process and the great excess of air used in relation to raw fuel burned, the diesel produces very little in the way of hydrocarbons and carbon monoxide. However, it is a sinful supplier of NOx, or oxides of nitrogen. Moreover, it pollutes in terms of particulates (tech-speak for filthy black smoke), noise and putrid odors--all of which are ignored in the Clean Air Act, which controls automotive emissions. Admittedly, the latter three are merely irritants, as opposed to threats to the public good, but the NOx situation may pose a serious threat to the future of the diesel. It is a complicated situation dealing with Congressional politics and industrial capabilities, but it can be summarized by the energy crisis. This ingenious ploy, in which a claque of supposedly simple Middle Eastern tentfolk brought almost all of Western civilization to its knees by shutting off the oil-well spiggots, transmitted a number of unpleasant political and economic messages to a complacent American citizenry. Most have been repeated to the point of tedium, but the salient aspect of the oil embargo--cum--energy crisis to this discourse is that it heightened everybody's awareness of our critical need to reduce consumption of that popular petroleum distillate known as gasoline. The energy crisis sent all available technical hands in the automobile industry thundering off in search of alternate power sources. Everything from propane to hydrogen to peanut oil to methane generated by goat dung was crammed into gas tanks in hopes of kicking the gasoline habit. Electric cars were touted. Steam was trumpeted as the new salvation. Inventors rhapsodized. Patent attorneys profited. Hard-nosed businessmen scowled. Nothing worked. Early optimism that the beloved, gasoline-powered internal-combustion engine would be swept out of the market place like so much household dust faded in the face of hard reality.

In the midst of this technological zephyr, the aged, much-maligned diesel continued to chug along in the gloom of semioblivion. To be sure, Daimler-Benz AG had successfully marketed a diesel passenger car in 1936, and sales of continuing models by its successor, Mercedes-Benz were thriving, but even the updated M-B versions were sluggish, dull and proletarian--somehow better suited to the needs of senior Albanian bureaucrats than to the speed- and convenience-crazed American motoring public. But slowly, as the euphoria surrounding the goat-dung miracles and the steam choochoo extravaganzas dribbled away, the mundane old diesel came into focus.

Yes, upon hard examination, there are some endearing qualities about diesel automobile engines. To begin with, they are as simple and reliable as anvils. No cockamamie ignition gadgetry, no points to stick, no coils and condensers to fail, no sparkplugs to foul. Thanks to the wondrous mind of Rudolf Diesel, all of this effluvia has been eliminated and instead of the fuel's being ignited by an electric spark, as in conventional engines, the combustion comes after a charge of air has been heated (simply by having its molecules crammed together under great pressure) to a point where it ignites a blast of liquid fuel.

Wonderfully elemental. A splendid system in theory. Moreover, the diesel is, in the arcane context of pure physics and thermodynamics, quite fuel efficient. This means that an engineer can mathematically prove that it will produce more work per gallon of fuel than a gasoline-powered counterpart. This advantage is generally pinpointed in the 20--25 percent range for engines of equivalent output. Add to this that a gallon of diesel fuel requires much less raw energy to refine than a gallon of gasoline, and the over-all advantages of this power plant in a resources-conscious time become clearer.

The attraction of the diesel to the average American motorist is simple: It produces more miles per gallon than its gasoline counterpart at a cheaper per-gallon cost. For example, the four-speed manual Volkswagen Rabbit Diesel, rated by the Environmental Protection Agency at 40 mpg in city driving, will consume an average of $225 per year in fuel (again according to the EPA), while its gas-powered sister (25 mpg) will use an average of $420 in unleaded regular. There are mitigating factors in what appears to be an overwhelming advantage for the diesel (lower performance, a $300 higher sticker price, etc.), but the direct, instant gratification of lower expenditures at the gas station appears to blot out these subtle shortcomings. The rush to diesels is on, in all sizes and shapes of automobiles, even in the traditional gas-guzzling ranks of big American cars. In 1977, Oldsmobile introduced a Delta 88 four-door powered by a diesel version of its popular 350-cubic-inch V8. The big car was an instant hit, averaging 21 mpg in city driving, while providing solid performance, and it appears to be the forerunner of a whole phalanx of diesels from Detroit. General Motors, in particular, is enthusiastic about the diesel because it views the engine as a potential salvation for the so-called family-sized car (Oldsmobile has it available on 19 of its 26 models and Cadillac has it as an option for its Seville and Eldorado).

By 1985, all manufacturers selling cars in America must have a line-up of automobiles that average 27.5 mpg. That can be accomplished by simply eliminating large cars--the much-denounced gas guzzlers--or by saving them with a massive increase in their efficiency. It appears that the simplest way to achieve this is to convert them to diesel power, which means a major alteration in the make-up of the domestic automotive scene. Whether or not that happens depends on a number of unresolved variables involving Government policies, consumer enthusiasm for diesels, the state of the economy, the development of other power sources, etc., but the fact remains that diesels are on the rise, both here and abroad. That certainly must provide great satisfaction for Mercedes-Benz, considering its tenure as a diesel manufacturer and its continued pioneering efforts in diesel technology. It presently imports four diesel cars into the United States, all of which are distinctive engineering expressions, if not classic examples of inexpensive motoring. The 62-hp, four-cylinder 240D sedan is the lowest-priced Mercedes presently available in America--if a $14,245 tag can in any way be construed as low-priced. In addition to the slow, workaday 240D, the company exports the 300D sedan, which features the world's only five-cylinder diesel engine and reasonably adequate performance, for a base price of $19,904. Recently added to this lineup are the sporty 300CD Coupe ($22,481) and a smashing new diesel turbo model, the 300SD. Called the Turbo Diesel, the car is based on the large Mercedes S class sedans from which the 450SEL and the 280SE also come. It carries the 300D's five-cylinder diesel with an exotic turbo-charger added that increases everything--horsepower, fuel mileage, acceleration, reliability, etc.--while reducing emissions. There is no question that the turbo-charger is the perfect adjunct to a diesel engine, simply because it adds to performance without any penalties, but it is tricky to design and expensive to manufacture (the car goes for $25,000). Nevertheless, Mercedes-Benz's pioneering with the first passenger-car turbo-diesel engine is bound to collect a mass of imitators in the near future.

Mercedes-Benz has long been the leader in diesel production, but its German associate Volkswagen is hard on its heels in all departments, and Detroit expects to overtake the Germans this year. After quietly introducing its diesel-powered Rabbit in March 1977, Volkswagen witnessed a sales boom that company officials regard simply as phenomenal. Within a year of introduction, nearly 20,000 diesel Rabbits were sold in the U.S.A. and that number was severely limited by production shortages. This year, the company projects that 25--30 percent of Rabbits, sold will be diesels. The appeal of the diesel Rabbit appears to lie solely in its outstanding mileage. Of course, the diesel is slower--nearly five seconds deficient in 0--60 acceleration and with a six-mph-slower top speed--when compared with its gasoline-powered counterpart, but the lure of cheap operation and durability seems to outweigh those shortcomings in the minds of many buyers. Like the Oldsmobile's, the Rabbit diesel is a direct adaptation of the four-cylinder overhead-camshaft power plant that has been so instrumental in making the boxy little German front-drive sedan such a lively yet economical performer. Knowing a good thing when it sees one, Volkswagen is now offering the diesel as a Dasher option.

While the Peugeot 504D, with its 71-hp four-cylinder engine, cannot be ranked as one of the performance superstars of the American highway, this $9432 four-door (continued on page 164)noting that unless the present law governing NOx emissions is modified, manufacturers will not be able to meet future Government standards and diesels may cease to be manufactured in the U.S.A. However, compromises are in sight and many car makers are vocally optimistic about the diesel's prospects.

But not everybody. The Ford Motor Company is notably cool toward diesels and then-president Lee Iacocca publicly stated that he saw only limited application in America's automotive milieu. Not so with General Motors, which is producing the aforementioned Oldsmobiles and Sevilles and is unveiling a smaller, 260-cubic-inch V8 diesel in 1979 that will eventually appear in the Seville, as well as in Chevy and G.M.C. pickups. Beyond that, G.M. is said to be working on a number of small diesels, including a 1.8-liter four-cylinder for use in its new generation of front drives due in 1981 and a 2.5-liter four (in turbocharged form) for Pontiac. Moreover, Chrysler is working on a small, 2.2-liter four-cylinder diesel that may be introduced in 1981 or 1982. Add to that the widespread diesel research and development going on in Europe and Japan and it becomes clear that poor old Rudolf Diesel may have acted prematurely when he disappeared from the steamship Dresden in 1913. Tormented by financial problems and the gloomy notion that his engine was a failure, Diesel died 14 years before another German, Robert Bosch, perfected a fuel-injection system that made the diesel a practical power plant for automobiles. Now, as we trundle toward the Eighties, the engine seems to enable us to take the first step in moving away from an almost total automotive dependence on gasoline.

How far will the drive to diesels go? It is impossible to predict, based on the variables of petroleum pricing and availability, Government policies and public acceptance of the new engine. All that can be said is that the potential is promising--potential as evidenced by an experimental version of the Volkswagen diesel Rabbit. Called the IRVW--the Integrated Research Volkswagen--the car is a test platform for both advanced engine and safety concepts. In addition to being able to protect its four occupants in 40-mph crashes, the IRVW's turbocharged engine has 22 more horsepower than the production diesel Rabbit, which gives it comparable performance to the gasoline-powered Rabbit. That means strong low-speed acceleration, good passing power, 100 mph top speed and 60 miles per gallon (composite). In fact, at a steady 30 mph, the IRVW has recorded over 80 miles per gallon!

Go ahead, ye of little faith, try that on a tankful of unleaded.

"Diesels are at their best running for long periods of time at relatively constant rpms."