Ive had my drivers license for about 10 years now. I have noticed over the years that the price of diesel gasoline has always been higher than unleaded, but in recent times, unleaded has surpassed it.
Here where I live, unleaded has spiked to 3.10/gallon, while diesel is at 2.79/gallon. Truck drivers are on the road every single day and drive hundreds of miles across america, so why hasnt diesel risen to what unleaded is (or higher)? If the cost of oil is so high, why are diesel prices lower than unleaded?
Yes, there are a gazillion people that drive with unleaded gasoline each day, but there's also a gigantic amount of truck drivers that drive further than we do and get less mpg than what us unleaded drivers get. It just doesnt make sense to me. Seems like we are getting rammed in the a$$ real hard for someone to make some money, if ya know what i mean.


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Well, First, it takes about a 1/3 less time and effort to refine diesel out of a petroleum base.

Second, Diesel yeilds about 45% more power (when coupled with a forced induction method) over gasoline per litre, and it also burns slower, so you get more MPG. Most Large/semi trucks do get poor fuel economy.. in city. once they hit the highway, though, they have 14-21 gears (please correct me if I'm wrong) and can use them to greater mechanical efficiency than a traditional 5 speed transmission in a car.

There also Isn't as great a demand on diesel as there is on Gasoline... there are only 2-3 cars being sold in the US & Canada for highway use that have a diesel burning engine. There are even long-haul trucks that have gasoline engines... I pity those fools.

The last bit, sure... it's time to pay the piper.





Transeat In Exemplum: Let this stand as the example.

Let's get one thing straight first Diesel is not Gasoline, Diesel is a type of Fuel, like JP-5, JP-8, Jet A1, Kerosene, Methanol, Alcohol, Avgas, and Mogas.

The Light-Duty diesel truck market has exploded in recent years, with both Dodge and Ford reporting something like 75% of F-Series Super Duty and Heavy Duty Ram sales being diesels. However, diesel is a by-product of refining Gasoline, it is almost unrefined crude oil, why do you think Diesels are nicknamed Oil-Burners, the Heating Oil used in your house is the same fuel that is used in a civilain and some military diesel engines.

A diesel engine has much better Fuel Efficiency then a comparable Gasoline Engine. For 3 reasons:
1.)Air-Fuel Ratio, while a Gas engine needs around a 13:1 Air Fuel Ratio, a Diesel can operate satisfactorily at idle with a 100:1 A/F Ratio, and at full load that will move to about 20:1, still much leaner then a gasoline engine. While Fuel is very important to making power in a diesel, you can never run a diesel too lean, a diesel actually runs cooler the leaner you run the engine.
2.)Compression Ratio, this one is simple, the higher the C/R the more power can be created from the same amount of fuel. The lowest C/R I've seen in a diesel engine is 17:1, and I've seen plenty in the 20:1 range.
3.)Heat Value, diesel fuel give off more heat per unit requiring less fuel to produce the same amount of power

There are other reasons for a diesels fuel efficiency, such as the fact that it throttles on fuel and not on air, there is no throttle body on a diesel, air intake is unrestricted and remains constant no matter the load on the engine. The Fuel Injectors on a diesel are much more precise then the ones found in a gasoline engine, diesel Injectors are some of the most precise pieces of equipment on the planet. Finally, only a small portion of the fuel in the injector is actually used for combustion the rest is used to cool the injectors and is then returned to the fuel tank.

In the city a Diesel engine gets pretty bad gas mileage, but a Cummins Ram will still embarass my Hemi in fuel mileage, there are people with the 12V Cummins reporting 20+ mpg in the city and 30 mpg on the highway, even the 24V Cummins still gets over 20 mpg on the highway. Those big rigs do get bad gas mileage compared to a light duty truck, but you show me a 10-18L gasoline engine that is going to get more then 1 mpg and I'll show you my Beach House on the Pacific Ocean in Kansas.




Yella02-I promise I will return to you in one piece and this will stay up until I am safely home

Saint: I guess I was wrong about the mechanical advantage... then again, most VW TDI's aren't lugging around a few tons of cargo




Transeat In Exemplum: Let this stand as the example.

Diesels always been cheeper historicly. You used to ba able to get it for .98 a gallon when I worked for Exxon back in '90 - '92.





Semper Fi SAINT. May you rest in peace.

GAM, my comment about the 1 mpg is in reference to gasoline engines only because a 10-18L Gasoline Engine is only going to get about 1 mpg, especially when hauling loads.

My knowledge of Fuel Economy is from the Cummins ISB 6-cylinder found in the Ram and from the Marine Corps. The Marine Corps tends to drastically underestimate the range of it's gear, the HMMWV for example is rated at a 250 mile range, or appx. 10 mpg, and the LVS is said to have a 300 mile range, or appx. 2 mpg, however I know that these vehicles will get better fuel economy, and have a much greater range then that, the reason for understating the range is to ensure that a vehicle does not run out of fuel and grind a convoy to a halt. Semi-trucks may get better fuel mileage then the Marine Corps' trucks, since we only use Automatic Transmissions with very few gears, and no Overdrive on some of them.




Yella02-I promise I will return to you in one piece and this will stay up until I am safely home

While were on the diesel topic: Does anyone know what the average MPG of a 18 wheeler tractor trailer is? This topic made me wonder....

Good Question.

Saint: thanks I fig'd 1mpg was a little overstated, but then again, I'm not entirely certain of the actual MPG either...



Transeat In Exemplum: Let this stand as the example.

You'd have to ask a Big Rig driver, the government doesn't require Fuel Economy numbers from anything with a GVWR over 8800 lbs. so the manufacturers do not spend the money to do the testing.




Yella02-I promise I will return to you in one piece and this will stay up until I am safely home

UpstateNyZ24 wrote:While were on the diesel topic: Does anyone know what the average MPG of a 18 wheeler tractor trailer is? This topic made me wonder....

My Grandpa used to drive trucks, about 6-7mpg ( highway) normally. It also depends if your loaded or unloaded, loaded of course gets about 1 mpg worse. He did that for over 30 years, so he knows what hes talking about.




- 2004 Cavalier - 124k, owned since new

Thanks man. That's not too bad. I figured it would be somewhere around 5MPG loaded.

Holy smokes...

My Dad's H2 hummer got about 8Mpg...

/me boggles



Transeat In Exemplum: Let this stand as the example.

gas smells cool though



1989 Turbo Trans Am #82, 2007 Cobalt SS G85

racing fuel and nitro smells better.

That explains it...


You're both huffing Gas...




Transeat In Exemplum: Let this stand as the example.

yes but imi huffing gas conservativly, while rodimus, is going at it with and an extremly liberal attitude.

Ahhh... so instead of hourly, you're only doing it 3x a day? That explains a lot.



Transeat In Exemplum: Let this stand as the example.

5-7 mpg may sound bad, but you have to look at the sheer size of those engines. The Marine Corps MTVR, has a 15-ton payload and uses a 12L engine. The smallest engine Cat makes for a truck is 7.2L. A Gasoline engine of that size in the same size vehicle is going to get about 2-3 mpg at the best.




Yella02-I promise I will return to you in one piece and this will stay up until I am safely home

True.. true.



Transeat In Exemplum: Let this stand as the example.

i work in a stone quarry and our triaxle dumps truck average between 3 and 5 miles per gallon, this is an estimate of about 100 different trucks.

Bruce
red03ecotec

Dont forget the army's HEMMIT that thing has a CAT 3208 V-8 diesel with twin ginormous turbos AND an enormous supercharger too. It only gets in the 3-5 mpg
range. But the most non fuel eff. vehicles in the world would have to be a top fuel dragster. They burn thru about 20 gal. of nitro methaine in a 1/4 mile. So that would
mean they get 80 gallons PER MILE !!!! How would you like to feed one of these things?




Semper Fi SAINT. May you rest in peace.

Nitromethane is much cheaper, though...

Personally, if i was going to look at alternative fuels for Callisto, i'd look at an LPG conversion...


Goodbye Callisto & Skaði, Hello Ishara:
2022 Kia Stinger GT2 AWD
The only thing every single person from every single walk of life on earth can truly say
they have in common is that their country is run by a bunch of fargin iceholes.

/\ /\ /\ /\ Are you kidding? You are kidding right? When I worked at Mid Atlantic 4X4 and Speed we sold Nitro. That stuff was like $30.00 a gallon almost 12 years ago so unless someone found a Nitro Methaine fountain somewhere and it just flows from the ground then this stuff is still expensive as hell. And propain is just a by-product of the oil refining process that gives us gasoline. Some can be found naturaly but most is made by us. Or at least thats what I was told back in my Exxon days. I think. Getting older is hell.






Semper Fi SAINT. May you rest in peace.

i may be wrong on the nitromethane being cheaper...

but lpg i know is cheaper.


Goodbye Callisto & Skaði, Hello Ishara:
2022 Kia Stinger GT2 AWD
The only thing every single person from every single walk of life on earth can truly say
they have in common is that their country is run by a bunch of fargin iceholes.

/\ /\ cool no biggie Keeper.




Semper Fi SAINT. May you rest in peace.