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Despite the fact that diesel engines are currently found mostly in full-size trucks and commercial rigs, that may soon change due to some recent developments in technology and fuel emission standards. While many people think of diesel-powered vehicles as noisy, smelly and slow, the latest generation of diesel engines is changing that perception.
Oil-burners have a lot to offer. Their longevity is legendary, and they can chug right along with small throttle inputs and miserly fuel consumption, unperturbed by steep grades. Not only that, when a diesel is towing a trailer, this torquemeister hardly even knows what's back there.
Drawbacks? | Back To Top
What about the traditional drawbacks, though? New diesel engine technology is helping to overcome the excessive clatter and cumbersome performance. Two other factors will also help to change the public's negative view: the skyrocketing price of fuel and higher emission standards.
Diesel engines are the odds-on favorite to win the melee with alternative fuels and hybrids currently battling it out to meet the 2007 emission standards, and to offset gasoline prices that have been escalating beyond belief. Automotive organizations such as JD Power and Associates, the Society of Automotive Engineers (SAE) and the Specialty Equipment Marketing Association (SEMA) have already declared diesel the wave of the near future.
Sounds promising, but what led up to this swelling demand? To answer that, we should cover a bit of background on diesel vehicles and the latest developments in the marketplace.
Tech Aspects | Back To Top
For those unfamiliar with the tech aspects of diesels, here's the bottom line: First, diesel fuel is heavier, oilier, evaporates more slowly and has a higher energy density (17 percent higher) than gasoline. That's where part of the "more efficient" comes into play. Diesel fuel produces more energy per volume, which means more miles per gallon.
The diesel's compression chamber is smaller in order to allow the piston to super-compress the air. This relatively small compression chamber results in a much higher compression ratio and thus more torque. Example: the Ford F-350's 6-liter Power Stroke diesel's compression ratio is 17:1 compared to the 9:1 ratio in Ford's 6.8-liter V-10 gas-powered engine. The diesel is designed for high torque; the gas engine is designed for horsepower, basically, the measure of extended energy.
That's why in the past, diesels have been found in only the heavier 3/4- and 1-ton trucks. Ford is said to be looking for a suitable diesel for its 1/2-ton F-150, but there's an even smaller diesel-powered off-road rig that's ready right now, right at the crest of this sea of change.
Common-Rail Injection | Back To Top
For 2005, DaimlerChrysler is rolling out a Jeep Liberty with an optional 2.8-liter, common-rail turbodiesel engine. Aside from the uniqueness of this engine option for this market segment, the common-rail injection system has other virtues that will resonate with consumers. It's able to maintain pressure independent of engine speed and to achieve high injection pressures, which in turn creates small fuel droplets introduced into the combustion chamber at high velocities. The result: fuel is completely burned for maximum horsepower and minimum emissions. We've driven a pre-production model both on- and off-road, and it's smooth, quiet and quick—attributes that we wouldn't have dreamed of a decade ago.
Another important aspect of the diesel Liberty is its estimated 160 horsepower and 295 lb.-ft. of torque at 1,800 rpm, along with a 25 percent improvement in fuel economy. By comparison, the larger displacement Liberty engine, the 3.7-liter V-6, delivers 210 horsepower at 5,200 rpm and 235 lb.-ft. of torque at 4,000 rpm. What's significant about these differences in outputs? "A lot of times people think horsepower but they really mean torque," explains Brian Roth of BD Power, a diesel product manufacturer in British Columbia. "Torque is where you get the acceleration," or that pin-to-your-seat feeling when you hit the gas pedal.
In addition to strong specs, the Liberty is getting strong reviews, focusing equally on the economy and the performance of the Mercedes-built diesel engine. Only 5,000 diesel-powered Jeep Liberty's will be available in the States and, according to a recent article in "SEMA News," DaimlerChrysler has already had 14,000 inquiries.
Perceptions | Back To Top
It may take a little education to convince the American market that diesels are "cool." But good money is on the Liberty radically changing those images of diesels as only for lumbering trucks. This plucky SUV is by no means sluggish, yet without the fuel penalty of excessive fuel consumption. It's been described as having the economy of a four-cylinder engine, the torque of a V-8, and the performance of a V-6.
The Liberty is not the only excitement in the diesel arena. A bold statement is being made now by performance legend Gale Banks Engineering. Banks, in conjunction with Robert Bosch Corp., Garrett Turbochargers and General Motors, has developed the Banks Sidewinder DMAX Type-R race truck. The Sidewinder, a totally modified GMC Sierra, cranks out 650+ horsepower and 1,000 lb.-ft. of torque and will run at selected National Auto Sport Association endurance races.
Two years ago, Banks' diesel-powered Sidewinder Dodge Dakota set the truck speed record at Bonneville Salt Flats. Performance technology traditionally starts on the track before making its way into consumer consciousness. While efficiency and economy aren't exactly the most effective buzzwords for the American auto industry, the kind of performance Banks has achieved with diesel upgrades should catch American consumer attention.
Fuel Choices | Back To Top
Fuel selection is clearly affected by societal issues. Diesel-powered vehicles got a surge of popularity in the United States in the mid-1970s when gasoline shortages created around-the-block lines at gas stations and designated fill-up days. Even then, however, the economy of the diesel never quite overcame the downsides in the minds of American consumers. Diesels back then were heavier, slower and the higher internal pressures meant more noise, vibration and harshness, such a recurring diesel problem that the trio rates its own acronym, NVH.
By 1994, however, the big three American auto manufacturers had solved the NVH problems. They all had their own approach to the solution, but the result was a demand for diesel engines in the larger displacement light trucks. Today, diesels, despite the extra cost, account for roughly 50 percent of sales in 3/4-ton-and-up truck models. Manufacturers and distributors of diesel aftermarket products also indicate a significant increase in sales over the last three to five years.
Diesel Redux | Back To Top
In the process of designing diesel engines that produced more horsepower, Ford, Dodge and GM also reduced emissions. By nature, diesels only produce small amounts of three of the five major emissions: carbon monoxide, hydrocarbons and carbon dioxide. According to the Diesel Technology Forum, the industry has made serious dents in the remaining two, particulate matter and nitrogen oxides. The mandate for low-sulfur diesel fuel kicks in 2007, with the more environmentally friendly fuel available June 1, 2006.
So, with all these pluses, will the diesel take over the light truck market? The answer from those who should know is "probably." JD Power and Associates predicts that diesel-powered vehicles will reach 15 percent of overall sales by 2014, up from 3.9 percent currently.
SEMA is conducting a Diesel Market Study focused on the performance side, including competitive and hard-core recreational off-road applications. According to SEMA's research department, the tougher 2007 emissions standards put the impetus in the direction of diesel, "It's just a matter of time, the manufacturers have to go there," says James Spoonhower.
Brian Roth of BD Power anticipates a rapid growth in the diesel market over the next three years. "Hybrids are 10 to 15 years away," he says, while diesel technology and infrastructure are here now. "I can see the diesels taking over the light truck market."
Allen Shaeffer, executive director of the Diesel Technology Forum, is a little more cautiously optimistic. "We'll see four new diesel vehicles introduced in 2005, but does that mean there will be another 10 new diesel models in 2007? Will there be heightened consumer interest and will people be willing to pay more for diesel engines? In part the manufacturers are asking that question with the model introductions next year."
Aftermarket Influence | Back To Top
One factor that can help with wider acceptance of diesels comes from the aftermarket, which allows consumers to tailor their vehicles to specific performance needs. For details on this aspect of diesel developments, see Diesels and the Aftermarket, part 2 of this article.
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