Diesel Myths

Unraveling the Myths About Diesel Engines


Of the Big 3 automakers, General Motors was the first to enter the diesel truck market, offering a 5.7L Oldsmobile diesel in their line of half ton trucks in 1978. The 6.2L naturally aspirated, indirect injection engine later followed, and Ford partnered with International to offer the 6.9L IDI in 1983. Dodge introduced the 5.9L 12v Cummins turbodiesel in 1989. Early diesels were dirty, noisy, purpose built, and lacked the performance that today's diesel engines are capable of. While some of these early engines created a legacy for themselves, they all contributed to the many misconceptions that plague the modern diesel industry.

Based on observation and misunderstanding, these misconceptions are merely myths thanks to the huge breakthroughs in diesel technology.


MYTH: Diesel engines emit more pollutants than gasoline engines.

For many years, diesel engines were not held to the same emissions standards that gasoline burning engines have been. This is no longer the case, as Federal emissions standards for diesel engines have become stricter. Advancements in diesel technology have made the diesel combustion process very clean and efficient. In terms of green house gas emissions, a 3/4 or 1-ton diesel powered truck emits less harmful emissions than a medium sized sedan. Diesel engines burn much cleaner than equally sized gasoline engines. The main concern regarding diesel emissions is the emission of soot, a known cancer causing agent that results from diesel fuel that is not completely burned during combustion. Modern diesels utilize catalytic converters, diesel particulate filters, urea injection, and exhaust gas recirculation to ensure clean emissions. As a result, a modern diesel produces extremely low levels of green house gases and diesel soot (soot emissions have been decreased by approx. 97%). This myth is actually backwards; gasoline engines emit more pollutants than modern diesel engines.


MYTH: Diesel engines are designed strictly for towing.

There is no arguing that a diesel powered truck is built to tow and handle heavy loads. A diesel's broad power band and massive amounts of low RPM torque give it a huge advantage when towing. However, not all diesel engines are built equally. In fact, diesel engines can be used in passenger cars or light duty applications where fuel efficiency is a main concern for consumers. The diesel powered 2010 Volkswagen Jetta TDI, for example, gets an EPA estimated 30 mpg city and 42 mpg highway. The 2.0L, four cylinder diesel engine is capable of 10+ mpg more than its gasoline competitors, and the diesel engine provides for plenty of freeway merging power. Manufacturers have been slow to offer diesel engines in car/light SUV applications for many reasons, including economic woes. Diesels are widely used in passenger cars in Europe, where owners enjoy large increases in performance and fuel economy. Not all diesel engines are built for the purpose of towing.


MYTH: Diesel engines are slow & sluggish.Modern diesels are far from slow. In fact, diesel trucks are very competitive in drag racing. The aftermarket community has made it very easy to unlock performance in diesel trucks. Even in stock form, Cummins, Power Stroke, & Duramax diesel engines are all making more than 300 horsepower and 600 lb-ft of torque. This results in remarkable performance for an otherwise heavy vehicle. To see the true performance potential of diesel engines, take a look at these vehicles created by Banks Power: Banks Diesel Project Vehicles


MYTH: Diesel engines get poor fuel economy.

Wrong, plain and simple. Diesel powered vehicles get better fuel economy due to the increased fuel density, combustion efficiency, and broader power band A modern diesel powered truck can receive up to 20% (estimated) better fuel economy than its gasoline powered counterpart. Also, look at the 2010 Volkswagen Jetta; 30 mpg city, 42 mpg highway. A more primitive example of diesel fuel economy would be the Isuzu powered, Chevrolet Chevette of the early 1980's; know for its 40+ mpg fuel economy, not its tire-burning 50 horsepower...


MYTH: Diesel engines are more expensive to maintain/repair.

While the components of diesel engines can be more expensive, diesel engines are much more cost effective to operate/own than gasoline engines. Service intervals are often longer, the life expectancy of a diesel engine is far greater, and a diesel engine can operate much longer before an overhaul is required. Therefore, while the cost of items may be greater, less maintenance/repair will be required and engine life will be longer.


MYTH: Diesel engines produce a lot of noise.

Another myth that can be traced back to previous generations of diesel engines. Fortunately, manufacturers have found ways to mask that distinct diesel sound, making the engines no louder than a comparable gasoline engine. The modern diesel produces very little noise.


MYTH: Diesel engines are not capable of high horsepower.

Diesel engines are not designed to run at high RPM. Therefore, their horsepower ratings are far less than their torque ratings. This is because horsepower is a measurement of engine power as a function of time. Therefore, a diesel is limited in the amount of horsepower it makes by the maximum RPM it is rated to operate at. However, this does not mean that diesel engines can not make lots of horsepower. Plenty of high performance diesel engines produce a lot of horsepower. It is generally assumed that diesel engines can not produce a lot of horsepower because their horsepower rating is always much less than their torque rating. This is simply a result of the limited maximum RPM that a diesel engine can operate.

















































































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