stanlee1963

Using a driving technique to achieve better fuel mileage is a modification as far as I am concerned. Modifying the driver's performance vs. the equipment. Using this driving technique you described so well is how I routinuely get my 23.5-24.5 mpg with the A/C on. I do watch my boost gauge and try to keep the boost low on flat ground and attempt to keep it at that same low pressure on the hills by gradually backing off the throttle about 1/2 the way up the hill exactly as you described it. You described it better than I could, but it is the way that I drive.

I like this 24v chart. In fact I think it's on my flashdrive. I like BSFC charts and have stared at them since the 1980's for various engines, caterpillar, mack, cummins, detroit series 60. The BSFC is an good indication of the efficiency of a particular engine at full throttle only. BSFC charts can assist one in specing a truck to have proper gearing with a balance of power and economy. Using the proper gearing, an engine designed to have a low BSFC at 2000rpm allows good highway cruise speed while providing its best efficiency. This is especially true while pulling a heavy load. But when you are not fully loaded, please know that traveling at a reduced rpm/speed (such as 54-62 mph) is going to yield a better MPG than setting your cruise so that you are at 2000 rpm. Increased speed, requires more energy. Reduced speed, reduces power demand, reducing fuel usage. No matter if we use my industrial BSFC chart or your 24v chart.

I agree that at 2000 rpm the 5.9 has an efficient bsfc, especially true with the all the 24v and the 6.7s. The EQB210 example I used was a poor choice. To validate your statement, I will say that at 2000 rpm my truck runs 66mph and still gets a high 22 or lower 23 mpg. But of course my truck gets better MPGs with decreased speed irregardless to the BSFC. Referring back to Mopar1973Man's 'secret whitepages' posted on this thread. To increase speed, you have to increase the amount of fuel to overcome the resistance. (Speed is the master key to increasing your fuel mileage. I think about my truck going up a hill like it was me running bleachers. If I walk the bleachers it is no big deal, but if I try to run the bleachers I would get short of breath pretty fast. The more speed you demand out of something, the more fuel is demanded.) Thanks for the conversation and keeping me real about the EQB210... I had used it only because it was of similar power rating to my pu.

1997 clubcab, 2 tone - Drk Chestnut Prl and Driftwood Satin Met. 386K miles, 5spd, 3.54, OEM size rubber, boost gauge, muffler delete. The #11 fuel plate, AFC housing and starwheel all the way forward. 23.5-24.5 mpg with the A/C on 100% of the time.

I like to get good fuel mileage with my truck. I usually get 23.5-24.5 mpg during both the summer and winter. I credit this to using the A/C in the summer and using winterized fuel in the winter. I do see better numbers during the fall and spring sometimes a low to mid-25 mpg. I credit that to not using the A/C as often. Speed is the biggest killer. I usually never drive faster than 62 mph. If I drive 70 mph and pass indiscriminately my mileage drops to 22 mpg. Oversized tires kill your fuel mileage, your power, and your brakes. Tires are basically 4 large flywheels that you have to spin up every time you take off. And taller tires require more brake pressure on the linings to stop the same distance as a OEM tire. There's a mathematical formula that applies to flywheels that looks similar to but not exact, Kinetic Energy = 1/2 mass x radius squared. The point of this is that the kinetic energy and inertia energy applied to spin up the taller "radius" height of the tire is squared (multiplied times itself) This 'spin up energy' could be put to better use to propel you down the road by using a shorter tire. Larger tires increase the frontal area of the vehicle thus creating more drag. There's a mathematical formula for that: Drag= 1/2 frontal area x Velocity squared x the drag coefficiency. The point of this is that as you increase your speed, this factors in much more on the air resistance than whether you have increased the frontal area by installing a leveling kit to the front of your truck. I agree with all the things that Mopar1973Man has presented here. Mostly it is speed, but these are other principles to consider as contributors to the subject, the tires aka flywheel's inertia and kinetic energy and aerodynamics and the brake specific fuel consumption of the engine. http://forum.mopar1973man.com/attachment.php?attachmentid=3070&stc=1 In this example chart for a industrial 5.9L Cummins the fuel curve indicates this engine is most efficient close to 1600-1700 rpm. It just happens that 1650 rpm is just about 54.5 mph in my truck using the factory original tires, if my math skills serve me well. Just adding this to information, but all these things and more have been mentioned already. I believe two things that can help would be having a pyrometer and manifold pressure gauge to monitor. I personally do not have a pyro as of yet, but it will be my next addition. Knowledge is power.

Joe a good place to read to get the horsepower and torque ratings for your truck would be, http://www.allpar.com/mopar/cummins-diesel.html. This hyperlink will give you information not only on your truck but a brief history, current, and future applications using the Cummins diesel in the Dodge Ram. Best of luck, sp