Attention: TDR Forum Junkies I'm confused, I was told by a Cummins cust. service rep that Cummins engineers were looking into the mpg issues to see if there is any way to improve it with the new emissions setup, and then I get this e-mail from Cummins.
Summary: 2004 Dodge MPG
Solution:
Thanks for your Email message.
Since we build the diesel engines for Dodge and they supply all the other components to build the trucks, we are not in a position to speak for Dodge on expected MPG figures on Dodge trucks and we have been advised that Dodge does not publish figures for the diesel powered trucks. Keep in mind that newer model trucks get heavier and a new vehicle will typically not do well in fuel economy tests.
We know how much fuel the engine will burn, under full load, on the engine dynamometer, which is measured in pounds per horsepower hour, but when the engine is installed into a chassis, those figures no longer apply, due to the various chassis components. Cummins is unable to troubleshoot fuel mileage (MPG) problems on Dodge trucks. All Dodge truck warranties are handled by Dodge.
The engine in the new truck is very new and the piston rings have not had a chance to "seat" yet and some cylinder pressure is getting by the rings into the crankcase, which is what we call "blowby". After you get 500 - 1000 or so miles on it, the engine needs to be "worked" to create some cylinder temperature. If the engine is operated with only light loading, it can take up to 30,000 miles to "seat" the piston rings and this will also affect the fuel consumption rate of the engine. "Seated rings improves combustion characteristics in the cylinder and all the fuel is burned more completely.
There are several variables involved that relate to fuel mileage and since the engine is only one part of the equation, it is very difficult to predict mpg on any specific vehicle. There are several factors such as winter fuel blending, rpm, MPH speed, wind, aerodynamics, load, rear axle ratio, tire size, 4x4, driver habits, etc. , that really have more affect on MPG, than the engine. For optimum fuel economy in a diesel powered vehicle, the engine should be operated about midway between rated speed and peak torque rpm and the vehicle speed should 55 to 65 MPH.
Duallies and 4x4 chassis usually have worse MPG than 4x2 single wheel models. The least desirable combination for fuel economy, would be a 4x4 dually with 4. 53 or higher rear axle ratio and automatic transmission, operating in winter conditions. Single wheel models with manual transmission and 3. 73 rear axle ratio (operated between rate and peak torque rpm running 55 or 65 MPH range) will produce the optimum fuel economy. Also, the odometers are sometimes not accurate or the tachometer gearing can be configured wrong. Since we build the engine and ship it to Dodge, we are not in a position to know the affect of all these other factors.
Keep in mind that a new truck, with new wheel bearings, brakes, transmission, driveline, etc. , may not perform as expected, since these components contribute to MPG. We suspect the mileage will improve after the first few thousand miles after all these components "wear in". A slipping automatic transmission for example would be a major contributor or even a defective odometer. The engine RPM should be an indicator of whether the transmission is slipping, however.
We have talked to hundreds of Dodge owners (1998. 5 to 2003 truck engines) and they have told us MPG figures from 8 to 28 mpg, depending on the above variables. The guy getting 8 mpg was very upset that he could not run 80 MPH, with 35,000 pounds gross weight. On the other end of the spectrum, we tend to question 28 mpg, but believe many are getting in the low 20"s (empty). A sudden increase in fuel consumption might indicate a plugged air filter, if there is excessive black smoke or possibly an automatic transmission problem.
From what other customers have told us, a two-wheel drive, single wheel truck could expect mileage to be 15 to 20 mpg (empty/no heavy load) running at normal highway speeds (some models and conditions may do better). Loaded or pulling a trailer, the mileage may drop to the 8 to 15 mpg range. Duallies and 4 wheel drives or running above normal highway speeds or pulling excessive loads can reduce MPG figures significantly.
We defer RAM mpg fuel economy questions to the Daimler-Chrysler folks, since we only make the engine. We can talk about inherent engine efficiency, but tank fuel economy MPG depends on many factors besides the engine. We noted one comment from the recent USA Today article on the new Ram trucks:
How thirsty? Heavy-duty trucks are not required to display fuel economy numbers. During the test drives, a 3500 Quad Cab with single rear wheels and high-output Cummins showed 16. 4 mpg on its fuel economy computer in 'unladen' driving on hilly two-lane roads. The trailer-towing 3500 with high-output diesel got 9. 8 mpg.
The 5. 7- liter gasoline V-8 truck that spent all day demonstrating the off- road course showed 10. 2 mpg on its readout. The 5. 7 V-8 in a two- wheel-drive, regular-cab Ram recorded 15. 5 mpg in 600 highway miles. The V-10 was not tested.
We thank you for your interest in Cummins products. Please let us know if you need assistance in locating the nearest Cummins-authorized Dealer or Distributor Service Provider. For assistance in locating a Service Provider, feel free to use Cummins North America Dealer Locator, which can be found on Cummins website:
Summary: 2004 Dodge MPG
Solution:
Thanks for your Email message.
Since we build the diesel engines for Dodge and they supply all the other components to build the trucks, we are not in a position to speak for Dodge on expected MPG figures on Dodge trucks and we have been advised that Dodge does not publish figures for the diesel powered trucks. Keep in mind that newer model trucks get heavier and a new vehicle will typically not do well in fuel economy tests.
We know how much fuel the engine will burn, under full load, on the engine dynamometer, which is measured in pounds per horsepower hour, but when the engine is installed into a chassis, those figures no longer apply, due to the various chassis components. Cummins is unable to troubleshoot fuel mileage (MPG) problems on Dodge trucks. All Dodge truck warranties are handled by Dodge.
The engine in the new truck is very new and the piston rings have not had a chance to "seat" yet and some cylinder pressure is getting by the rings into the crankcase, which is what we call "blowby". After you get 500 - 1000 or so miles on it, the engine needs to be "worked" to create some cylinder temperature. If the engine is operated with only light loading, it can take up to 30,000 miles to "seat" the piston rings and this will also affect the fuel consumption rate of the engine. "Seated rings improves combustion characteristics in the cylinder and all the fuel is burned more completely.
There are several variables involved that relate to fuel mileage and since the engine is only one part of the equation, it is very difficult to predict mpg on any specific vehicle. There are several factors such as winter fuel blending, rpm, MPH speed, wind, aerodynamics, load, rear axle ratio, tire size, 4x4, driver habits, etc. , that really have more affect on MPG, than the engine. For optimum fuel economy in a diesel powered vehicle, the engine should be operated about midway between rated speed and peak torque rpm and the vehicle speed should 55 to 65 MPH.
Duallies and 4x4 chassis usually have worse MPG than 4x2 single wheel models. The least desirable combination for fuel economy, would be a 4x4 dually with 4. 53 or higher rear axle ratio and automatic transmission, operating in winter conditions. Single wheel models with manual transmission and 3. 73 rear axle ratio (operated between rate and peak torque rpm running 55 or 65 MPH range) will produce the optimum fuel economy. Also, the odometers are sometimes not accurate or the tachometer gearing can be configured wrong. Since we build the engine and ship it to Dodge, we are not in a position to know the affect of all these other factors.
Keep in mind that a new truck, with new wheel bearings, brakes, transmission, driveline, etc. , may not perform as expected, since these components contribute to MPG. We suspect the mileage will improve after the first few thousand miles after all these components "wear in". A slipping automatic transmission for example would be a major contributor or even a defective odometer. The engine RPM should be an indicator of whether the transmission is slipping, however.
We have talked to hundreds of Dodge owners (1998. 5 to 2003 truck engines) and they have told us MPG figures from 8 to 28 mpg, depending on the above variables. The guy getting 8 mpg was very upset that he could not run 80 MPH, with 35,000 pounds gross weight. On the other end of the spectrum, we tend to question 28 mpg, but believe many are getting in the low 20"s (empty). A sudden increase in fuel consumption might indicate a plugged air filter, if there is excessive black smoke or possibly an automatic transmission problem.
From what other customers have told us, a two-wheel drive, single wheel truck could expect mileage to be 15 to 20 mpg (empty/no heavy load) running at normal highway speeds (some models and conditions may do better). Loaded or pulling a trailer, the mileage may drop to the 8 to 15 mpg range. Duallies and 4 wheel drives or running above normal highway speeds or pulling excessive loads can reduce MPG figures significantly.
We defer RAM mpg fuel economy questions to the Daimler-Chrysler folks, since we only make the engine. We can talk about inherent engine efficiency, but tank fuel economy MPG depends on many factors besides the engine. We noted one comment from the recent USA Today article on the new Ram trucks:
How thirsty? Heavy-duty trucks are not required to display fuel economy numbers. During the test drives, a 3500 Quad Cab with single rear wheels and high-output Cummins showed 16. 4 mpg on its fuel economy computer in 'unladen' driving on hilly two-lane roads. The trailer-towing 3500 with high-output diesel got 9. 8 mpg.
The 5. 7- liter gasoline V-8 truck that spent all day demonstrating the off- road course showed 10. 2 mpg on its readout. The 5. 7 V-8 in a two- wheel-drive, regular-cab Ram recorded 15. 5 mpg in 600 highway miles. The V-10 was not tested.
We thank you for your interest in Cummins products. Please let us know if you need assistance in locating the nearest Cummins-authorized Dealer or Distributor Service Provider. For assistance in locating a Service Provider, feel free to use Cummins North America Dealer Locator, which can be found on Cummins website:
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