fuel economy, who has the best?

[devildogadam]

We liked to do runs with sledge hammers and tanker bars. Then stop when someone falls out and do some for of work out until they caught up.... then just keep running until it happened again. It was always fun

 

[bdemutis]

Well I put 7 gallons in and it said I got half a tank I drove it till it was at e or the gauge read e well anyway my calculation I'm only pulling 12mpg that dosnt seem right at all I do mostly town driving and back roads that are 45. 12 mpg for my 95 2500 shortbed 6.5 with 265 tire and lift kit seems really low. My lifted dodge 2500 with Mopar chip and lift kit and 33" tires got 12mpg and that was a gasser.

 

[devildogadam]

Bdemutis a lot can depend on the right foot... and if your chasing down problems with the turbo among other things all will add up to poor fuel economy even if the engine seems to be running smooth. A big one would be those wore out injectors. Replace them with some STOCK bosh injectors and your sure to gain some mpg. Lift kit will never help mpg. But I sure you can squeeze some better mileage out of her if you do some much needed maintenance.

 

[bdemutis]

Bdemutis a lot can depend on the right foot... and if your chasing down problems with the turbo among other things all will add up to poor fuel economy even if the engine seems to be running smooth. A big one would be those wore out injectors. Replace them with some STOCK bosh injectors and your sure to gain some mpg. Lift kit will never help mpg. But I sure you can squeeze some better mileage out of her if you do some much needed maintenance.

Going to do injector soon I'm not even sure my fuel gauge works because 7 gals shouldn't be half a tank if the tank is 34 gallons.

 

[WarWagon]

Round town I get 10. It just doesn't lock the converter till 45MPH and anything slower simply sucks fuel. Modern gas engines in 1/2 tons unloaded will kick a 3/4 ton MPG around the block. But the 1/2 ton isn't as much truck.

 

[WarWagon]

Going to do injector soon I'm not even sure my fuel gauge works because 7 gals shouldn't be half a tank if the tank is 34 gallons.

Likely the fuel lever sensor doesn't work. Get a modern bombproof one from Leroy.

 

[bdemutis]

Likely the fuel lever sensor doesn't work. Get a modern bombproof one from Leroy.

I will when it warms up I don't want to drop the tank in a freezing pole barn. I'm waiting for it to get a little warmer for injectors also. I don't see it on leroys website.

 

[hookedup50]

On the subject of MPG, how much does adding cetane improvers, improve mileage at all. I loked online and found almost nothing that wasn't company sponsered. It is hard to know what you are even buying at the pump as ratings are not required. I called gulf /cumberland farms and they admitted 40 or the minimum. The few Hess stations state 43 cetane. When I get fuel at sunoco I pay more for fuel, but get almost 2mpg improvement on winter blend. But probably not worth the extra money. If this is hijacking thread I will make new thread, but it seems to me cetane has an effect on mileage as mine is all over the place depending on fill up location. Anyone with thought or real world data.

 

[JayTheCPA]

On the subject of MPG, how much does adding cetane improvers, improve mileage at all. . . . Anyone with thought or real world data.

IIRC, the target minimum is 40 cetane. Just did a search and the only corporate hit that quickly came up was Exxon / Mobile where they state they have minimum 40 cetane. Only authoritative source I could find regarding minimum ratings was from Diesel Power Mag (http://www.dieselpowermag.com/news/1209dp_what_is_cetane/) where the ratings were:
- United States Petroleum-Based Ultra-Low-Sulfur Diesel- 40 (minimum)
- Biodiesel (B100)- 47 (minimum)
- Biodiesel (B20)- 40 (minimum)


Agree that the theory of using cetane additives will get better mileage, but just cannot tell from my own experience as I simply do not see a noticeable difference. When I do add cetane additive, I limit the 'boost' to ~3 points. Sometimes in the winter if it is cold enough (20* F or less), I will boost to just help the motor out a bit. Only other times I boost cetane are when I tow to get a better burn out of the fuel and not try to get better mileage.

In doing the math, cannot justify the cost of adding cetane booster just to hopefully get better mileage.

Given the choice of two stations near each other where the fuel cost is the same, I will buy from the one with a posted higher cetane number (as long as it looks like the pump gets regular use). If the station with the lower cetane is significantly lower in cost, I will go with the lower cost. Where I am, most stations do not post the cetane number, so I buy based off of price and known high volume of the station.

 

[great white]

Iirc, the mandated minimum is 40 cetane rating.

However, very few manufacturers actually attain that number. Its usually in the 34 range when randomly tested.

Now, the good news.

A higher cetne rating than specified from the OEM is kind of like running a higher octane in a gasser. It gets you nothing more than a lighter wallet.

Seeing how our trucks were manufactured so long ago, the cetane requirements are likey lower than 40 (never seen a gm recommendation, but I've never looked either). So even if they're getting below minimum cetane ratings out the door, there's probably no real detrimental effect on our old hacks. It all comes down to the characteristics of those precombustion chambers and how they work. The recardo chambers were designed to work in a time when system operating pressure were low by today's standards and diesel fuel quality was....ahem....somewhat "questionable". The Ricardo's give you lots of "fudge room" for cetane fluctuations.

Besides, there are many other fuel quality factors that are as (if not more) important than just a cetane number.

 

[hookedup50]

Im just wondering, cause I did an empty run(250 miles) to New Jersey and got 15.5 mpg with a heavy foot with gulf Fuel. On way back with a thousand pounds of equipment and same heavy foot, I got 16.5 mpg with Sunoco fuel. I with fuel was as cheap in Mass as NJ. I've not noticed cetane improvers paying for themselves like stated on bottle.

 

[Will L.]

To really understand it, you need a chemical engineer, and a lawyer:
Specifications for No. 1-D and No. 2-D Diesel Fuel (ASTM D-975).

All No.1-D diesel fuel and No. 2-D diesel fuel shall meet the requirements of the following specifications, when tested in accordance with the latest version of the American Society for Testing and Materials Methods of Tests:

A. Cloud Point (ASTM D-2500)—-7°C (20°F) maximum.

B. Flash Point (ASTM D-93).

(1) No. 1-D Diesel—38°C (100°F) minimum.

(2) No. 2-D Diesel.

(a) 52°C (125°F) minimum (May, June, July, August, September, October).

(b) 43°C (110°F) minimum (November, December, January, February, March, April).

C. Viscosity (ASTM D-445).

(1) No. 1-D Diesel.

(a) Kinematic at 40°C, 1.3 centistokes minimum, 2.4 centistokes maximum.

(b) Kinematic at 100°F, 1.4 centistokes minimum, 2.5 centistokes maximum.

(2) No. 2-D Diesel.

(a) Kinematic at 40°C, 1.9 centistokes minimum, 4.1 centistokes maximum.

(b) Kinematic at 100°F, 2.0 centistokes minimum, 4.3 centistokes maximum.

D. Visible water and sediment (ASTM D-1796)—0.05 percent maximum by volume.

E. Carbon Residue on 10 percent Residuum (ASTM D-524).

(1) No. 1-D Diesel, 0.15 percent, maximum.

(2) No. 2-D Diesel, 0.35 percent, maximum.

F. Ash (ASTM D-482)—0.01 percent, maximum.

G. Cetane.

(1) Number method (ASTM D-613) 40, minimum.

(2) Index method (ASTM D-976) 40, minimum.

H. Distillation (ASTM D-86).

(1) No. 1-D Diesel—90 percent point, 288°C (550°F) maximum.

(2) No. 2-D Diesel—90 percent point:

(a) 282°C (540°F) minimum*;

(b) 338°C (640°F) maximum.

* When cloud point less than -12°C (10°F) is specified, the minimum viscosity shall be 1.7 cSt (or mm2/s) and the 90 percent point shall be waived.

I. Corrosion (ASTM D-130). Copper Strip, 3 hours at 50°C (122°F), No. 3 maximum.

J. Sulfur (ASTM D-4045).

(1) On-highway use—0.05 percent by mass, maximum.

(2) All other non-highway uses—0.30 percent by mass, maximum.

K. Color.

(1) On-highway diesel fuel may not contain any dyes or coloring agents.

(2) Non-highway diesel fuel shall be dyed with Solvent Red 164 at the concentration spectrally equivalent to at least 3.9 pounds of the solid dye Standard Red 26 per 1,000 barrels in accordance with the mandate of the US EPA and Internal Revenue Service (IRS). It may not be used in any vehicle designed for on-highway use.

Like Great White mentioned, it is a variable.
If you pour in anything this is a "cetane booster" you will move: the flash point, ash rate and volume, cloud point, biactive soot count, and of coarse all the out gasses like nox,co2,etc. Feel free to play chemist with it, as the real results are simple- if it sounds smoother and doesn't give a noticeable increase in power you are fine. If you start to notice any seat of the pants increase in power, be careful... If you start to notice any mpg gain above 5%, be careful...

Diesel fuel is not an energy efficient system. The hydrocarbon count per btu used is low, because it is a long chain molecule. The only reason it is used is abundance. Adding a lot of power to any fuel sounds like a good idea, until you carry it to it's end. Nitromethane is a really good additive for any internal combustion engine, and will get the most out of it until you add 1 drop too many. Then you get EVERYTHING out of the engine.

I have spent many a year working with fuel engineers, testing new and improved fuels and additives. I add no booster to my fuel, only lubricants. A second fuel entering the chamber that is 1/8th - 1/10th the molecular weight is the only way to "boost" without creating nightmare issues. ie: propane for diesels, nos for gasoline, nitromethane for alcohol. That way the ratio can be exactly controlled without creating a yaw in the fuel graph.

 

[schiker]

On the subject of MPG, how much does adding cetane improvers, improve mileage at all. I loked online and found almost nothing that wasn't company sponsered. It is hard to know what you are even buying at the pump as ratings are not required. I called gulf /cumberland farms and they admitted 40 or the minimum. The few Hess stations state 43 cetane. When I get fuel at sunoco I pay more for fuel, but get almost 2mpg improvement on winter blend. But probably not worth the extra money. If this is hijacking thread I will make new thread, but it seems to me cetane has an effect on mileage as mine is all over the place depending on fill up location. Anyone with thought or real world data.

I can tell an appreciable difference in launch smoothness (manual transmission) due to some fuel station variation. I don't think it is Cetane but all the other factors like age, lubricity, and viscosity etc. Some Cetane additives will appreciably vary the diesel puff on launch (and starting puff) from my experience. None of the additives I have used seem to make an appreciable difference in mileage or power. Just differences in smoke and launch and smoke differences on starting. I think additives are useful in a maintenance role of the fuel system more than anything.

I wouldn't try to distinguish slight mileage variation over 1 or 2 tanks of fuel as there are too many variables: head wind, air temperature, elevation, humidity, pavement smoothness, RPM, foot, moon????