Gas milage for a diesel / gas engine
Here's my request, I need people that own fifth wheel trailers to let me know about their gas mileage. I presently have a toyota tundra when I'm not towing anything I get about 20 miles to the gallo...
Forum Discussion
One more answer to the OP’s original question:
Pulling the exact same 6000 lb. 10.5’ tall trailer, my 4.6 gas F-150 or 5.4 gas Expedition would get 8.5 mpg. Our 2012 6.7 diesel F-350 got 10.5 mpg. Everything else equal diesel will always get better fuel economy (usually stated at 15 – 30% better) because the engine will be up to 15% more efficient and the fuel contains up to 15% more btu per gallon. But that isn’t the end of the story because torque curve, engine weight, fuel cost, engine cost, mileage before trading on the replacement vehicle, etc. are important too. The diesel/gas comparisons will not be truly valid until someone comes out with a turbo, direct injected, 5.0 gas engine to compare to the on coming turbo, direct injected, 5.0 Cummins diesel engine—then we’ll have a real comparison.
On a quick read I’m not sure that the DEF DPF issue has been truly explained:
Back in the middle of last decade the EPA began to require reduced NOx levels from diesel exhaust. The first approach was EGR and engine tuning including a richer mixture. By 2008 the requirements included eliminating the black soot particles so DPF was added. The first approach to getting rid of the soot plugging up the DPF was to raise the exhaust temperature by injecting extra fuel at some place in the exhaust stream increasing the exhaust temperature in the catalytic converter to literally burn up the soot. For 2011 models the EPA required a further reduction in NOx. This level is extremely difficult to accomplish with EGR and tuning. Navistar just about went out of business trying to accomplish this method on class 8 diesel engines and had to give up. Just about every engine larger than a small car engine went to the DEF method. This method tunes the engine leaner but produces more NOx in the engine. The NOx is then broken down in one stage of the converter by injecting DEF in the presence of certain rare metals. At the same time monitoring of soot in the DPF and improved DPF design has allowed engine control to reduce the amount of fuel needed to burn off soot. Both of these changes have contributed to much better fuel mileage in the current crop of trucks than the 2008 – 2010 models.
EGR—Exhaust Gas Recirculation
DPF—Diesel Particulate Filter
DEF—Diesel Exhaust Fluid
Pulling the exact same 6000 lb. 10.5’ tall trailer, my 4.6 gas F-150 or 5.4 gas Expedition would get 8.5 mpg. Our 2012 6.7 diesel F-350 got 10.5 mpg. Everything else equal diesel will always get better fuel economy (usually stated at 15 – 30% better) because the engine will be up to 15% more efficient and the fuel contains up to 15% more btu per gallon. But that isn’t the end of the story because torque curve, engine weight, fuel cost, engine cost, mileage before trading on the replacement vehicle, etc. are important too. The diesel/gas comparisons will not be truly valid until someone comes out with a turbo, direct injected, 5.0 gas engine to compare to the on coming turbo, direct injected, 5.0 Cummins diesel engine—then we’ll have a real comparison.
On a quick read I’m not sure that the DEF DPF issue has been truly explained:
Back in the middle of last decade the EPA began to require reduced NOx levels from diesel exhaust. The first approach was EGR and engine tuning including a richer mixture. By 2008 the requirements included eliminating the black soot particles so DPF was added. The first approach to getting rid of the soot plugging up the DPF was to raise the exhaust temperature by injecting extra fuel at some place in the exhaust stream increasing the exhaust temperature in the catalytic converter to literally burn up the soot. For 2011 models the EPA required a further reduction in NOx. This level is extremely difficult to accomplish with EGR and tuning. Navistar just about went out of business trying to accomplish this method on class 8 diesel engines and had to give up. Just about every engine larger than a small car engine went to the DEF method. This method tunes the engine leaner but produces more NOx in the engine. The NOx is then broken down in one stage of the converter by injecting DEF in the presence of certain rare metals. At the same time monitoring of soot in the DPF and improved DPF design has allowed engine control to reduce the amount of fuel needed to burn off soot. Both of these changes have contributed to much better fuel mileage in the current crop of trucks than the 2008 – 2010 models.
EGR—Exhaust Gas Recirculation
DPF—Diesel Particulate Filter
DEF—Diesel Exhaust Fluid
