Dodge announces a diesel half-ton...

[Timmy!]

right but who runs the low grade ****? I compare premium \ 87 to diesel when I am looking. but 82 cents is a huge gap... that would be nice.

Me? We don't need mid or premium up here, we don't have any oxygen anyway! LOL! Heck, we only have 85/89/91 here.

[chpthril]

right but who runs the low grade ****? I compare premium \ 87 to diesel when I am looking. but 82 cents is a huge gap... that would be nice.

I run the proper octane fuel and for all my vehicles, its 87 oct. Define what you interpret as "low grade", because the octane rating has nothing to do with the fuels quality. Its not even an indicator to its power potential. 87 and 93 release about the same BTU's once ignited.

[chpthril]

If you buy a diesel just for fuel mileage its going to take a long long time to pay off the premium in buying a diesel. I buy a diesel for how much better they tow/haul things.

Ding ding ding, no more callers please, we have a winner

[IDBoating]

Yes, we've beat that horse...you always leave out the important part about your truck...5 or 6 speed MANUAL!

Sorry, it didn't occur to me to mention that. After all, real men drive manual transmissions!

[Timmy!]

Sorry, it didn't occur to me to mention that. After all, real men drive manual transmissions!

[IDBoating]

If you buy a diesel just for fuel mileage its going to take a long long time to pay off the premium in buying a diesel. I buy a diesel for how much better they tow/haul things.

True. And don't forget some of the other advantages:

1) Their engines (and usually entire drivetrain) last a lot longer. My Cummins with ~80K miles is just getting broken in.

2) They retain far more resale value. Though this isn't really a consideration for me since I usually buy vehicles new, maintain them well, and drive them until end of life. With this Cummins "end of life" may be a couple of decades!

My truck will be about ten years old when my son gets his driver's license. I figure it's the ideal first vehicle for a teenager: big enough to go OVER most accidents, and keep him and his friends safer than if they were in an econobox. Plus, with our snow, he can recover his friends when their econoboxes slide into the ditch!

[IDBoating]

No offence, but until gas and diesel prices are comparative, the fuel mileage argument is null and void. The increase in fuel mileage from a diesel as compared to a comparable gas engine in a similar sized vehicle used in a similar manor, is offset by the price per gallon difference.

If we use the $0.30/gallon difference between regular, 87 octane gasoline and ULS diesel that has been mentioned here, that's about a 7% premium per gallon at prevailing street prices around me at the moment. So the mileage advantage of the diesel need only be 7% greater than the equivalent gasoline vehicle to nullify the fuel cost difference. Anything beyond that is a net savings. Taking barry1me's example above:

My one buddy has a 7klb 24ft enclosed trailer and he gets 7-8mpg towing it, where his 2011 F250 diesel got 11-12mpg towing the same trailer.

...the diesel is delivering a 53% improvement in mileage doing the same work. I'd be interested in hearing other mileage comparisons if anyone has them. Just as a baseline: If your diesel is getting, say, 15 MPG then a gasoline vehicle would have to be getting at least 14 MPG (7% less) to be saving money on fuel.

Is that comparing to a normally aspirated gas engine or forced induction?

It's from a study I read back when I was first considering diesel vs. gas. The numbers were 20% efficiency for gasoline and 40% efficiency for a turbodiesel, with about half that advantage (or 10%) coming from the turbo's recovery of exhaust pipe energy. So if we give maximum advantage to the gasoline engine, and presume the gasoline engine in question did not have forced induction, and further presume its addition would yield roughly the same incremental advantage (33%) to the gasoline engine, then comparing turbo gas to turbo diesel the numbers would be approximately 27% and 40%.

As I said, it may be that once you bolt on all the aftermarket stuff to the gasoline engine to get its efficiency closer to the diesel, you'll have an engine that looks an awful lot LIKE a diesel.

[WakerideN]

I run the proper octane fuel and for all my vehicles, its 87 oct. Define what you interpret as "low grade", because the octane rating has nothing to do with the fuels quality. Its not even an indicator to its power potential. 87 and 93 release about the same BTU's once ignited.

I am talking about price......... nothing more... move along. I would agrue that there is a burn difference given if you read your owners manual on the new models they adjust their computer based on what fuel you put in, and its smart enough to make that adjstment.. but I am sure you can tell me how wrong I am...

page 27.... if my PCM can do it.. I am sure ford, dodge, chevy have it figure out... adapative learn technology... http://www.pcmengines.com/operation/

[Wickedcummins]

True. And don't forget some of the other advantages:

1) Their engines (and usually entire drivetrain) last a lot longer. My Cummins with ~80K miles is just getting broken in.

2) They retain far more resale value. Though this isn't really a consideration for me since I usually buy vehicles new, maintain them well, and drive them until end of life. With this Cummins "end of life" may be a couple of decades!

My truck will be about ten years old when my son gets his driver's license. I figure it's the ideal first vehicle for a teenager: big enough to go OVER most accidents, and keep him and his friends safer than if they were in an econobox. Plus, with our snow, he can recover his friends when their econoboxes slide into the ditch!

ding ding ding... Id never buy a gas powered truck for the simple fact the power SUCKS and the resale sucks even more..Talk about getting gang raped with no lube.. Buy a gas vehicle and put 100k on it then try to get even a 1/4 of what you payed for it

[Ewok]

I run 87 in my boat and tow vehicle. I used to run 93 in my G35 before it got totaled.

[chpthril]

ding ding ding... Id never buy a gas powered truck for the simple fact the power SUCKS and the resale sucks even more..Talk about getting gang raped with no lube.. Buy a gas vehicle and put 100k on it then try to get even a 1/4 of what you payed for it

So is torque and Hp measured differently in gas as it is in diesel? Is gas Hp and torque like .75 of a diesel Hp and torque value? Having a standard unit of measurement like Hp and torque, allow for a fair comparison, right? Now, I will say that a diesel does hit its power range at a lower RPM, and that can be an advantage when towing a load.

[IDBoating]

So is torque and Hp measured differently in gas as it is in diesel?

Side note: This brings up a question that has bothered me for a long time. There does seem to be a difference between "advertised" HP and "technical" HP. For example, the Cummins in my truck is supposed to develop 300-something horsepower. Meanwhile, the Cummins in my loader/backhoe - which weighs almost 20,000 pounds, can lift ~6000 pounds in its front bucket, and can dig with over 14,000 pounds of force - is spec'd to develop just 80-something horsepower. Yet I can promise the truck is definitely NOT 4X as powerful as the loader!

Moreover, when we bought the minivan that preceded the one we have now, it was advertised as having a 335 HP engine. Said so right on the window sticker and every other piece of marketing literature. Because we bought the minivan through a remote dealer and had it trucked directly to us, it arrived in "raw" form and I got to see some paperwork that is normally handled by the dealer. One of those things was the Certificate of Origin, sort of the birth certificate for the vehicle, which lists its VIN and weight and fuel type and other important numbers. One of those numbers was horsepower, and it was listed as 35. That's not a typo - the engine was stated as having thirty-five horsepower, or about 10% of the marketing number.

I don't know what this means. But it does lead me to suspect that there are two rating systems for engine power. One (the lower value) is probably the more technically accurate one, and the other (the higher value) is probably some sort of magical theoretical peak power only achievable on the second Tuesday of a certain week when the moon is full (sort of like "peak power" from audio amps). It also makes me wonder how to compare the HP between my loader and truck... if the 10:1 ratio holds, then my loader really puts out ~800 HP using the same hand-waving number system as the truck. Judging by the work that loader can do, I'd say that "feels" about right!

[chpthril]

I am talking about price......... nothing more... move along. I would agrue that there is a burn difference given if you read your owners manual on the new models they adjust their computer based on what fuel you put in, and its smart enough to make that adjstment.. but I am sure you can tell me how wrong I am...

page 27.... if my PCM can do it.. I am sure ford, dodge, chevy have it figure out... adapative learn technology... http://www.pcmengines.com/operation/

Point, as in temperature, of ignition, yes theres a difference, but not the energy expelled, once ignited.

[chpthril]

If we use the $0.30/gallon difference between regular, 87 octane gasoline and ULS diesel that has been mentioned here, that's about a 7% premium per gallon at prevailing street prices around me at the moment. So the mileage advantage of the diesel need only be 7% greater than the equivalent gasoline vehicle to nullify the fuel cost difference. Anything beyond that is a net savings. Taking barry1me's example above:



...the diesel is delivering a 53% improvement in mileage doing the same work. I'd be interested in hearing other mileage comparisons if anyone has them. Just as a baseline: If your diesel is getting, say, 15 MPG then a gasoline vehicle would have to be getting at least 14 MPG (7% less) to be saving money on fuel.



It's from a study I read back when I was first considering diesel vs. gas. The numbers were 20% efficiency for gasoline and 40% efficiency for a turbodiesel, with about half that advantage (or 10%) coming from the turbo's recovery of exhaust pipe energy. So if we give maximum advantage to the gasoline engine, and presume the gasoline engine in question did not have forced induction, and further presume its addition would yield roughly the same incremental advantage (33%) to the gasoline engine, then comparing turbo gas to turbo diesel the numbers would be approximately 27% and 40%.

As I said, it may be that once you bolt on all the aftermarket stuff to the gasoline engine to get its efficiency closer to the diesel, you'll have an engine that looks an awful lot LIKE a diesel.

dont forget the 8K on the front end for the diesel

[IDBoating]

dont forget the 8K on the front end for the diesel

I completely agree, but I was only responding to your statement:

The increase in fuel mileage from a diesel as compared to a comparable gas engine in a similar sized vehicle used in a similar manor, is offset by the price per gallon difference.

...which is a statement about fuel cost without regard to the up-front adder for a diesel engine. I took your statement to mean that any improvement in mileage was offset by diesel's (your words) "price per gallon difference", and that didn't feel right so I did the math using someone else's posted values to maintain objectivity.

As you note, vehicle purchase price is important. So let's consider that. It's more difficult to calculate because then we need to know total miles over the owned lifetime, but we can at least figure out where the breakeven mileage occurs. barry1me's friend would save $0.15 per mile in fuel costs with the diesel. $8000/0.15 means he would break even at 53,447 miles and save money every mile thereafter for as long as he owned the truck. Better retained value with the diesel would lower that mileage figure even more when you consider the cost-per-mile of depreciation. But even leaving that out of the comparison, if his friend expects to keep the truck for more than ~54K miles he will be money ahead with the diesel. And a diesel will be barely broken in by ~54K miles, be worth more in retained value, and probably have pulled the load more comfortably along the way.