LSD fuel mileage improvement

[boat_fan1]

Well, I was in a bind earlier this week and had to put 1/2 tank of LSD in the 6.4. I was not too worried about it since I have a smoker anyway and dealer is scheduled to swap DPF as soon as they get one. But here is the interesting part. With LSD I was getting 19 MPG at 70 MPH and 2K RPM in the F250 with 3.73 rears according to the lie-o-meter. It normally reads 17 mpg in the same conditions with ULSD. Go figure. LSD is only supposed to be 1 to 3% better, not over 10%.

[montanafan]

What's really astounding here, is the fact that you watch the computer toy.

[exoval]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: montanafan</div><div class="ubbcode-body">What's really astounding here, is the fact that you watch the computer. </div></div>

The computer is the truck has very useful infomation on it. Why somone would not watch the guages on a truck surprises me. ford spent thousands on the ability to tell us drivers how our truck was performimg.

[montanafan]

You are correct, and the thermometer and compass are relatively accurate. They missed the boat by a country mile on the mileage toy, though. That should be considered to be more of a toy than anything representative of a useful instrument. The "miles to empty" can be pretty accurate at times, though.
We've had hundreds of forum members write about the MPG readout, and most think it is a joke. Furthermore, the error is not consistent.

[jhughd]

The computer on my 03, 6.0 was not accurate at all. My 08 has been consistently within .3 of hand calculated.

JD

[LittleBigRig]

Not regarding the lack of constructive comments....

I find it very interesting that the difference between ULSD and LSD would be that great. It is not supposed to be. Even if you are stepping outside the box and using the instruments/gages/readouts in your truck.
I understand that the factory lie-o-meter is usually wrong when compared to hand figured numbers.
However, common sense should prevail here!
Lets say that you are consistantly seeing 17.0mpg on factory readout for X amount of miles (whether or not that number is gnats ass accurate does not apply). And now you only change 1 variable (ie; LSD vice ULSD) and get a substatial increase in mileage.....I would be asking the same questions also.

Who cares if the factory gage is wrong! For 90% of us the gage IS wrong...but it is a CONSTANT wrong (very little delta).

[FINE69]

I agree with LittleBigRig, whether the factory lie-o-meter is accurate or not is totally irrelevant to this discussion. Its kinda funny how somebody on this board always has to knit-pick someone else's story, or ideas.

[jayhirsch]

I have been using my " lie-ometer" to see if I could spot the mpg degradation when my truck did a regen...Appears I can. With about 85 miles since last reset..my computer told me i had a 15.3 avg mpg , driving empty around town ,,and local freeways. I noticed a regen cycle start..passive, I quess since I was driving at the time. Avg mileage went to 13.6 in 10 additional miles of driving. My conclusion..mileage must be around 5 mpg during a regen?

If I got 15.3 all the time..I would be a happy camper....

[Awl_Bidness]

I have been in the fuels refining business for more years and in more states than I care to recount.

Here is what is going on with ULSD vs LSD: To sell into the commercial pipeline market at 15 ppm Sulfur, and to account for minor contamination in transit, refineries are generally targeting 8 ppm Sulfur from the Hydro Desulfurization units. In the last 5 years, refining has had to spend billions of dollars to "turn gasoline into gasoline" (drop S from 100 ppm to 30 ppm) and "turn diesel into diesel (drop S from 500 ppm to 15 ppm). In addition to the billions in capital cost, the operating costs increase and the production volumes decrease.....additional processing steps inevitably crack some materials to LPG and fuel gas which has a lower value.

LSD is typically heavier (higher distillation end point) than ULSD, and tends to be at a higher cetane value. Bottom line, the ULSD with a lower distillation curve will contain fewer BTU's per pound and thermodynamically will deliver less energy to the wheels. This is why you will usually see better economy with LSD vs ULSD. You will see the same shift in mileage from summer to winter in northern climates....when the cloud point has to shift below 20F in September or so for the winter season, the practical way to do that is to shift some kerosene to diesel in the fractionation processess. It keeps the fuel from clouding/gelling, but it also delivers less energy per pound of fuel.

[Kimminau2]

Yeah, what he said!

[montanafan]

I think you are correct in most of your statement. The refinery I just retired from produces 7 PPM of S, but the ULSD has a natural Cetane number higher than LSD. We marketed LSD with a Cetane number of 43, but the ULSD is 46. The refinery of which I speak runs 100% of Diesel related products through its ULSD hydrotreaters, so they can blend any of those products with any others.
Whatever the arguement, the truth is that any mileage changes because of the difference should be very minimal and hard to even detect. Winter blend can, and probably will, show a difference in both mileage and performance.