Boat U.S. - January 2008 - (Page 23) While good fuel economy and hybrid vehicles seem to be mentioned in the same sentence with increasing frequency, hybrids, with few exceptions (see sidebar), are not suitable for towing. Many aren’t recommended for towing at all or if they are, have capacities of just 1,500 pounds. However, currently available alternative technology that provides for excellent towing capacity and improved economy does exist in the form of electronically controlled, diesel engines. That’s right, diesel power is not just for boats anymore. With Ultra Low-Sulfur Diesel (ULSD) fuel now at the pumps, manufacturers can meet the stricter air quality standards that will apply in the coming years through advances in emission control technologies that would have been hampered by highersulfur fuel. Diesel engines, once reserved for heavy-duty trucks, will make a lot more sense in light-duty applications such as mid- to full-sized SUVs and light pickups. “Light-duty diesels are likely to have the towing capacity of a one-ton ‘Dually’ of 10 years ago, with much better fuel economy,” With ample torque at low rpm to pull a heavy boat up the ramp, diesel-equipped tow vehicles offer better fuel economy and increased towing capacity compared to those with gas engines. The Jeep Grand Cherokee CDR (left) can tow up to 7,400 pounds, while the Chevrolet Silverado 2500 HD (below) can tow up to 16,500 pounds when properly equipped. says Nick Cappa, technology spokesman at Chrysler. “Dually” refers to the four-rear-tire configuration, two on each side, used on some heavy-duty pickups to help support heavier loads. Jeep already offers the Grand Cherokee with a three-liter, six-cylinder diesel engine that produces 215-hp and 376 lb.-ft. of torque. All that power makes the Grand Cherokee capable of towing as much as 7,400 pounds. And unlike gas engines which tend to produce high torque at high rpm, the Chrysler power plant reaches full torque at just 1,600 rpm. So the strength to pull a heavy boat up a steep ramp rests just a touch above idle. Diesel power plants offer more fuel efficiency in two ways. First, there is simply more energy in a gallon of diesel fuel than in a gallon of gas. While the numbers vary slightly according to blends, a gallon of diesel contains around 139,000 British Thermal Units (Btu) of energy compared to 124,000 Btu for gasoline, roughly 12% more energy. E10 gas, a blend of 90% gasoline and 10% ethanol, contains less than 121,000 Btu. Secondly, diesel engines run at very high compression ratios, typically around 18:1 compared with gas engines that run at 8:1 or 9:1, though high-performance gas engines can run at higher ratios. Diesel engines can extract and use more of the available energy in diesel fuel, thanks to the higher compression. Put simply, diesels use more air and less fuel compared to gas engines of equivalent displacement. These advantages add up to more miles per gallon. The 5.7-liter V8-equipped Grand Cherokee gets an EPA-rated 15 mpg in the city, 20 on the highway, while the same vehicle with the 3-liter diesel gets 18 and 23 mpg, respectively. That’s a 20% improvement in city mileage. Jeep says the Grand Cherokee can go 450 miles on a tank of diesel. Cappa, who has driven both the Chrysler 300 equipped with the V6 diesel available in Europe and the V8 Hemi model available in the U.S., says the diesel offers exceptional acceleration. “It’s a different type of driving,” says Cappa. “The power is not in the high-end rpm, the power is there in low- to mid-range. The torque is the same or better with the 3-liter V6 than with the Hemi 5.7 V8.” More smaller-displacement, light-duty diesels will begin coming to the U.S. market in the ’09 and ’10 model years as the federal and state emissions standards unify. California and seven other states adopted more stringent standards a year ahead of the federal standards, which meant that automakers either had to meet the new standards ahead of schedule to sell in those states or simply not sell noncompliant vehicles in those states. Such vehicles are known as “42-state” diesels. Chrysler offers the Jeep Grand Cherokee in 42 states, but their Dodge brand offers a 6.7-liter Cummins diesel in the Ram 2500 and 3500 HD pickup truck models that already meets 2010 requirements in all 50 states. BoatU.S. Magazine January 2008 23
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.