Tim Basaker

AKA The Warden

12/01/00

Diesel Engines and the American Automotive Industry

The vast majority of cars sold today in the United States are powered by an internal combustion engine. Of these, over 99% of the cars sold in America are powered by a gasoline engine. The remaining 1/3 of 1% are primarily pickup trucks. These are powered by a diesel engine. There are diesel-powered cars, as well; for instance the Volkswagen Jetta TDi and the Mercedes-Benz E-300D. However, the diesel engine, which is unknown to many people and disliked by many more, is truly the logical choice for an automotive power plant. This is for three reasons. First, contrary to popular belief, diesel engines are better for the environment than comparable gasoline engines (that is, to say, an engine built for the same purpose in the same vehicle). Second, diesel engines, as a whole, are less expensive to operate than comparable gasoline engines. Third, for their size and economy, many diesel engines have more engine power than comparable gasoline engines.

Diesels and the Environment

When most people hear about diesel engines, one of the first thoughts that pops into many minds is the image of a large 18 wheel tractor-trailer pulling along the highway with a large cloud of black smoke in it’s wake. However, in spite of the visible exhaust smoke, diesels are, in nearly all fields, cleaner-burning than gas engines. The following is from a report by Jake Russell, compiled from an EPA study. Each column shows a factor of which the amount of pollutants produced are decreased between an average gasoline engine and an average diesel engine (for instance, carbon monoxide (listed below) production is over 30 times greater in a gasoline engine as compared to a diesel engine). Numbers with a minus sign in front signify a pollutant where the production rate is increased in an average diesel engine.

Unburnt Hydrocarbon: 5.8

Carbon Monoxide: 36.7

Nitrous Oxide (NOx): -0.9

Butadiene: 20.6

Benzene: 13.9

Formaldehyde: -0.7

Acetaldehyde: -0.9

Ethene: 4.5

Propene: 11.2

Isobutane: 3.2

Toulene: 16.6

Ozone : 8.8

Each one of these pollutants is potentially dangerous to humans. And, except for NOx, formaldehyde, and acetaldehyde, each one of these is reduced drastically in diesel engines. And the three that are increased are increased in a very minuscule amount. Furthermore, on average, a diesel engine will consume less fuel per mile driven than a similar gasoline engine. For instance, the 6.9 litre (420 ci) V-8 diesel engine that is in the van I drive can go approximately 15 miles for every gallon burned. On the other hand, a typical 6.6 litre (400 ci) V-8 gasoline engine will only go 8 to 10 miles for every gallon of fuel burned. Diesels consume fewer natural resources, and burn the natural resources it does take in more efficiently, with a lesser environmental impact.

Diesels and Price

There are two reasons that diesel engines cost less to operate than gasoline engines. One is the simple fact that diesels are more fuel-efficient than similar gasoline engines. Volkswagen makes a 4-cylinder diesel that is available in the Jetta, Golf, and the new version of the venerable Beetle. They also have a 4-cylinder gasoline engine that is a similar engine displacement size (the gasoline engine is 2.0 litres (121 ci) and the diesel engine is 1.9 litres (116 ci)). The VW gasoline engine has an EPA estimated fuel economy rating of 24 miles to a gallon in town, and 31 miles to a gallon on the highway. The VW diesel engine has an EPA estimated fuel economy rating of 42 miles to a gallon in town, and 49 miles to a gallon on the highway. (6) This is a considerable savings, considering that, under normal circumstances, diesel fuel is less expensive than the low-grade gasoline (it is interesting to note that diesel fuel is actually a by-product of the production of gasoline). The second is that diesel engines are built more robustly (heavy-duty internal parts), have fewer moving parts (primarily due to the absence of an ignition system), and are therefore less likely to break down than similar gasoline engines. A typical gasoline engine will run for between 100,000 and 150,000 miles without any major engine work. On the other hand, the 5.9 litre (359 ci) Cummins turbo diesel engine can go an average of 300,000 miles before any major engine work. (5) Furthermore, I have spoken with people who claim to have put over 1 million miles on their diesel engines without any major engine work. Diesels have always been known for their longevity. According to people I’ve spoken to who drive large trucks for a living, this is in fact the primary reason (along with fuel economy) that large tractor-trailers use diesel engines. A gasoline engine could pull the load, were the engine big enough. However, it would consume a lot of gasoline and would not last past 100,000 miles. Large truck diesels routinely last over 500,000 miles without major engine work, according to people I’ve spoken with.

Diesels and Power

Diesel engines have always been known as "stump pullers" (that is to say, able to put a lot of pulling power into a situation). While horsepower numbers may not show this well, overall, diesels are more powerful than similarly sized gasoline engines. According to a brochure from Dodge, the 5.9 litre (360 ci) gasoline engine puts out a maximum of 245 horse power, and 335 ft-lbs of torque. The Cummins 5.9 litre (359 ci) diesel, on the other hand, puts out 245 horsepower as well, but puts out 505 ft-lbs of torque. Both these engines are available in Dodge’s line of ¾ ton and 1 ton trucks. The same brochure gives maximum gross combination weight ratings (the weight of the truck and a trailer together). For a 1-ton truck, the maximum GCWR is 15,000 pounds with the 5.9 litre gasoline engine. With the 5.9 litre Cummins diesel, however, the GCWR is raised to 21,500 pounds. Other than the different engines, the trucks are similar. (11) Ford is very much similar. According to their brochure, as well as their website, the 5.4 litre gasoline engine puts out 260 horsepower and 350 ft-lbs of torque. The 7.3 litre (444 ci) "Powerstroke" diesel puts out 235 horsepower and 500 ft-lbs of torque. As with Dodge, these engines are both available in Ford’s line of ¾ and 1-ton trucks. With a 1-ton truck and the 5.4 litre gasoline engine, the maximum trailer weight (different from the GCWR because it does not include the weight of the truck itself) is 9,300 pounds. With the 7.3 litre diesel, the maximum trailer weight is raised up to 13,600 pounds. (7)(8) That difference may seem relatively small, given how big the initial numbers are, but 4,000 pounds can make a big difference when pulling trailers.

Diesels and Critics

There are three groups of people who are against diesel engines. One group believes that diesel engines are bad for the environment. The California Air Resource Board (CARB) is part of this group. According to a Volkswagen dealer, they have even forced Volkswagen as well as Mercedes Benz to cease importing diesel-powered cars into the state of California for this reason. In one context, it could be thought that diesels are bad for the environment. However, compared to the primary alternative (gasoline), diesels are considerably cleaner. Except for nitrous oxide, formaldehyde, and acetaldehyde, diesels put out far fewer pollutants than gasoline engines. Gasoline engines put out 5.8 times as much hydrocarbons, 8.8 times as much ozone, and a staggering 36.7 times as much carbon monoxide as diesel engines. (4) Furthermore, diesel engines consume less fuel as a whole than gasoline engines do. (4)(6)

A second group says that diesel exhaust is carcinogenic. Again, the CARB is at the forefront of this group, and, in fact, the CARB originated the belief that diesel exhaust creates a serious cancer risk. However, the EPA doesn’t agree with the CARB’s findings completely. As Dieselnet News states, "The EPA’s position on quantitative cancer risk assessment is in contradiction to the findings of the California Air Resources Board (ARB), which has established unit risk estimates for cancer from diesel exhaust particulates. The ARB estimates are based on some old railroad worker studies, which were later found unsuitable for such purpose by the EPA." The article continues to say that "no specific cancer unit risk estimate for diesel exhaust is adopted or recommended in the EPA assessment." (3) In short, contrary to the CARB’s statement that diesel exhaust is a cause for lung cancer, the EPA doesn’t have enough information to make that claim.

The third group is primarily made up of individual consumers who have either had a bad experience with diesel engines or prefer the performance factor of gasoline engines. It is true that gasoline engines are able to accelerate vehicles at a much higher rate than diesel engines. This is from personal experience. The likelihood of that changing is small. However, the people who have had bad experiences with diesel engines happened to be unlucky. In the late 1970’s and early 1980’s, car manufacturers, most notable General Motors, experimented with diesel engines. GM went so far as to take their 5.7 litre (350 ci) gas engine and convert it to diesel. (1) The results were disastrous. The engine was not designed to handle the extra stress associated with diesel engines, and failures were exceedingly common. Cylinder head gaskets would fail often, and sometimes even internal parts, such as crankshafts and piston connecting rods, would break. Many people, after buying one of these "350 diesel" powered cars, swore to never buy diesel, or General Motors, or both, again. This engine, which was an embarrassing fluke, almost single-handedly ruined the diesel reputation in America. I have spoken to many people who have owned this engine and feel this way about it. It is sad to say that, for many of these people, the "350 diesel" was the only experience they have ever had with the diesel engine. People should understand that not all diesels are like the "350 diesel" was, and give the diesel engine another chance. Europe was fortunately spared the embarrassment of a fluke like this. As shown in Jake Russell’s report, diesel cars have grown to command almost half of the automotive market in some European countries, such as France. (4)

Diesel engines are better for the environment, have more power for their relative size, and are more reliable as compared to gasoline engines. In theory, everyone should see that and be rushing out to get one. However, between false assumptions and bad experiences, people in the United States still tend to shy away. The time has come for a change. A change to a machine that’s cleaner, more reliable, and more powerful. Hopefully, people in the United States will see this soon.

 

 

 

End Notes

1. Grosser, Morton; "Diesel: The Man and the Engine" 1978

2. Patterson, D.J.; and Henein, N.A.; "Emissions from Combustion Engines and Their Control" 1972

3. Unknown author; "EPA Health Assessment Document for Diesel Exhaust approved by the CASAC panel" October 19th, 2000 http://www.dieselnet.com/news/0010epa.html

4. Russell, Jake; "Americans Should Invest in Light-Duty Diesels More" 1998 (est.) http://www.chesco.com/~rosenberry/diesel/diesel1.htm

5. Daimler-Chrysler; "Dodge Ram Power – Cummins Turbo" 2000 http://www.4adodge.com/ram-truck/power/feature2.html

6. Volkswagen; "Volkswagen Comparator" 2000 http://www.vw.com/compare/index.htm

7. Ford Motor Company; "Ford Motor Company – Home Page" 2000 http://www.ford.com

8. Ford Motor Company; "2001 RV & Trailer Towing Guide" 2000 (brochure)

9. Ford Motor Company; "Power Stroke Diesel V8" 2000 (brochure)

10. Ford Motor Company; "2001 F-150, F-250/350, Ranger, E-Series" 2000 (brochure)

11. Daimler-Chrysler; "2001 Ram" 2000 (brochure)