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Diesel vs Gasoline

14958 Views 21 Replies 12 Participants Last post by  zoomie


In my quest to educate myself and make the best decision for my family, this is what I've come to understand. I'm no expert and this is not intended as a be all end all. I'm learning and I'm positive there are others as well. My hope is that this can become a tool to those who choose to venture to the 'dark side'.

One figured bandied about is 30%, as in Diesel can offer up to 30% gains in efficiency. If you compare the EcoDiesels 22 MPG combined figure with the HEMI's 17 MPG combined number we see a difference of 25.64%, the theory holds water. But WHY?

Well for one its the fuel itself, with 15% more energy density per gallon of diesel vs gasoline the fuel itself inherently carries more work potential.

Adding to the efficiencies are higher compression ratios, ostensibly the higher the compression ratio the more power is extracted from the fuel itself, which adds an extra punch of performance as well as maximizing efficiencies. Of course gains are not limited to simply the fuel itself.

Diesel engines themselves enjoy mechanical advantages over their gasoline propelled counterparts. Variable vane Turbo's are a major one, allowing the boost to modulate which in turn delivers torque in a more linear fashion than one big GOB. From what I understand diesels also lack a throttle plate which eliminate pumping loses gasoline cars suffer from.

As I said above, by no means is this a be all end all, but simply a jumping off point for discussion and education.
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Wonder how old that pic is.....haven't seen that in years! Not sure what a real life hemi average is, but my ed with just over 1000 miles is at 24.9. That's per evic and by hand it's 24.97.......
I think a lot of people are dissuaded by the higher price of diesel fuel, but they don't understand the details of diesel fuel with how much energy comes out of it and such.
Don't come to California, the governor (not mine) has signed into law a new tax to be levied 1 January 2015 on each gallon of fuel. Projected to be between 15 and 76 cents per gallon. His excuse is Federal government cap and trade. We got to clean up this air. Huh? Pretty clean air here in San Diego. Moving to Texas or northern Michigan next year. Currently diesel fuel in my area is $3.93 per u.s. gallon.

David
Your figures are conservative. I have two friends with Hemi's in 1500's. Under the same reasonable driving conditions, no tow, the differences are closer to 50%. Under tow it's higher than that as the gasser reaches deep into the tank for a big drink.


Your conclusion is conservative/correct.
Diesel averages between 10-20 cents more in this area. My ED is averaging around 24 city, and close to 29 highway. Most gas burning trucks of any size can't touch this.
yea people like to cite the higher diesel pump cost, do some cost per mile calcs and come back ;):D
Even with the increase in price of the diesel fuel I am saving between $100-120 per month in fuel cost. I am also only paying about $0.18 more per gallon for diesel than for gasoline. Currently getting 26+ mpg with combined driving. Awesome!
I have a jetta with a 2.0l turbo gas engine that needs premium fuel and a jeep liberty with a 3.7l gas engine that takes regular.

It's an interesting comparison because premium fuel costs more than regular, just like diesel in your area and the jetta gets better mpg than the liberty, just like the relationship between the hemi and the 3.0l diesel. (also the car that gets better mpg uses the more expensive fuel)

For me to make sense of which car I should drive for given trip, I started measuring cost per 100 miles along with mpg. If you are collecting Gallons, and Miles for your mpg calculation it's not much more to collect the Dollars spent on that tank so you can calculate $/100miles.

This calculation takes into consideration all fluctuations in fuel prices for both fuels. Im in Canada so I told this story with Miles but my math uses kilometers.

The Liberty costs me between $14 and $22 per 100 kilometers ( as high as $24 when I tow my 3000lb boat) and the jetta costs me between $10 and $14 per 100 kilometers.

In my area it makes sense for me to drive the jetta, even though the fuel is more expensive the cost per mile is cheaper.

So, since I'm still (still) waiting for my ED, can someone post their $/100 miles, and someone else to the same thing for the pentistar and the hemi? (it would be fun to see the numbers for the ford EB too but I think I have to ask on another forum).
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First, I would love to pay 2.399 /gallon! Currently its $3.75 to $3.89 here in south florida.

Valvale, Also there is a 'thottle plate' or correctly termed butterfly valve. This is needed in conjunction of the EGR valve otherwise cooled exhaust gasses cannot be redirected back into the intake when the turbo is spooled up for normal light acceleration and constant speeds. Also the valve is fully opened when the DPF regeneration process occurs.

btw: the lowest I paid for diesel with my first diesel 2500, was just over $1/gallon.
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Don't come to California, the governor (not mine) has signed into law a new tax to be levied 1 January 2015 on each gallon of fuel. Projected to be between 15 and 76 cents per gallon. His excuse is Federal government cap and trade. We got to clean up this air. Huh? Pretty clean air here in San Diego. Moving to Texas or northern Michigan next year. Currently diesel fuel in my area is $3.93 per u.s. gallon.

David
That is brutal. But after cali implementing that, just how much longer could it possibly spread into other locations across the nation.
It's about Obamas war on oil and coal for that matter. He wants to power Los Angeles and other cities on wind and solar. Los Angeles metro area has 10 million people and seems like most of them are on the freeways at the same time. You can't heat LA and power their cars on wind and solar. Before I retired I drove 124 miles round trip per day to my work. Not sure how the working folks will manage. But I digress, don't mean to get political.

David
San Diego
It's about Obamas war on oil and coal for that matter. He wants to power Los Angeles and other cities on wind and solar. Los Angeles metro area has 10 million people and seems like most of them are on the freeways at the same time. You can't heat LA and power their cars on wind and solar. Before I retired I drove 124 miles round trip per day to my work. Not sure how the working folks will manage. But I digress, don't mean to get political.

David
San Diego
By all means, I hear you. This is why the EV movement is a compelte FARCE, especially in Cal. More than 50% of the electricity produced in Cal is coal or gas fired, so yea they took hydrocarbons out of the consumers hand and hid them behind a socket. But don't you worry we're saving the world. ;)

Obama's war is a war on perception. Simplify things to a binary answer and watch opinion crumble, this is why we can't have a legitimate discussion about social rights or environmental issues. If you speak out against EV you're a Luddite and clearly hate the environment, if you speak out against encroaching social programs you're obviously an old white boy conservative.

Someone certainly created one beauty of a playbook.

FUQ...
Guess that describes me, old, white and conservative. Born in the late 40s and grew up in 50s Detroit. I'm conservative because that's how I was raised and makes sense to me. Very well traveled and realize how good we have it in this country but that's changing. Think I'm wrong? Look around, Detroit looks like downtown Mogadishu, and Chicago is almost as deadly. My generation is becoming dinosaurs, becoming extinct. Back to fuel prices before moderator canx my post. Yes, the rest of america is headed fuel price wise to where California is headed. Hey moderator we need a sub forum for political speak, no?

I bought my ecodiesel because I need a half ton diesel and I'm true to Ram brand, not to clean up the air. And of course the great fuel economy is great.

David
San Diego
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By all means, I hear you. This is why the EV movement is a compelte FARCE, especially in Cal. More than 50% of the electricity produced in Cal is coal or gas fired, so yea they took hydrocarbons out of the consumers hand and hid them behind a socket. But don't you worry we're saving the world. ;)

Obama's war is a war on perception. Simplify things to a binary answer and watch opinion crumble, this is why we can't have a legitimate discussion about social rights or environmental issues. If you speak out against EV you're a Luddite and clearly hate the environment, if you speak out against encroaching social programs you're obviously an old white boy conservative.

Someone certainly created one beauty of a playbook.

FUQ...
To add to the farce, lets not forget strip mining mountain sides and digging large open pit mines to extract lithium and cobalt. Large amounts of energy is used in the extraction, refining processes. Then you have the Gallium, arsenic, and rare earth metals used in electronics to monitor all those cells and environmental pollution caused by its manufacturing. EVs surely gives a false sense of cleaning up the environment.

I dont think that this has to do with White Conservatism, it is because most majority of Americans today cannot think rationally, logically, and be critical. In fact, in regards to being critical, I find that most people cannot take criticism and get personally offended.

Dont get me wrong but, I do believe we have some sort of climate change going on. Our local weather today is different than it was in the 70's. But then again, there is climate change occurring on Mars! Sun Blamed for Warming of Earth and Other Worlds
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To add to the farce, lets not forget strip mining mountain sides and digging large open pit mines to extract lithium and cobalt. Large amounts of energy is used in the extraction, refining processes. Then you have the Gallium, arsenic, and rare earth metals used in electronics to monitor all those cells and environmental pollution caused by its manufacturing. EVs surely gives a false sense of cleaning up the environment.

I dont think that this has to do with White Conservatism, it is because most majority of Americans today cannot think rationally, logically, and be critical. In fact, in regards to being critical, I find that most people cannot take criticism and get personally offended.

Dont get me wrong but, I do believe we have some sort of climate change going on. Our local weather today is different than it was in the 70's. But then again, there is climate change occurring on Mars! Sun Blamed for Warming of Earth and Other Worlds
Oh forsure, but thats what I mean by the binary nature of our culture now. Yes there is climate change happening but the discussion can never be fruitful because of black and white thinking. If you believe in global warming you're branded ultra liberal, if you speak out against the narrative you obviously don't care about the environment. There is absolutely no place for grey which holds with the destruction of logic and rationality. Its much easier to take up one of the two offered positions and be done with it.

A book called Propaganda: The Formation of Mens Attitudes by Jacques Ellul completely ruined the world for me ;) its a beautiful break down of the psychological measures needed to create this type of binary culture. I would recommend it to anyone, seriously!
Guess that describes me, old, white and conservative. Born in the late 40s and grew up in 50s Detroit. I'm conservative because that's how I was raised and makes sense to me. Very well traveled and realize how good we have it in this country but that's changing. Think I'm wrong? Look around, Detroit looks like downtown Mogadishu, and Chicago is almost as deadly. My generation is becoming dinosaurs, becoming extinct. Back to fuel prices before moderator canx my post. Yes, the rest of america is headed fuel price wise to where California is headed. Hey moderator we need a sub forum for political speak, no?

I bought my ecodiesel because I need a half ton diesel and I'm true to Ram brand, not to clean up the air. And of course the great fuel economy is great.

David
San Diego
I was just using conservatism as an example of the black and white thinking. I dont think white conservatism or insular liberalism are exclusively the root of our issues, but I do believe that our issues are because in this country it can only be one or the other. Its the inability to cross pollinate and expand thinking that has run us into the ground. It all starts with a world class education system.

>:)
First, I would love to pay 2.399 /gallon! Currently its $3.75 to $3.89 here in south florida.

Valvale, Also there is a 'thottle plate' or correctly termed butterfly valve. This is needed in conjunction of the EGR valve otherwise cooled exhaust gasses cannot be redirected back into the intake when the turbo is spooled up for normal light acceleration and constant speeds. Also the valve is fully opened when the DPF regeneration process occurs.

btw: the lowest I paid for diesel with my first diesel 2500, was just over $1/gallon.
Ok that makes sense then, If I'm understanding correctly it needs to remain open to suck the gasses back through? Basically acting like a vacuum, is that the same case with DPF regen as well?
At the root of our problems are the politicians that forget they draw their power from the people. I have a saying, "Dope 'em up, (legal MJ), dumb 'em down (state of public education) and give 'em free stuff (you fill in the blank) and they'll keep you in office." America is changing and if you don't believe ask a WWII vet next time you see one. Back to the topic at hand, I believe in clean air, lakes, rivers, streams and such but I don't need some snot nose 40 something politician in Sacramento or D.C. for that matter telling me how to live my life. Yes there is warming on Mars and I blame all the Winnebago motor homes burning diesel fuel on Mars for that. Global warming? Maybe but if memory serves me the world came out if the last ice age in the 1600s before the earth was industrialized. ****, the 6 pm news weatherman can't even predict the weather correctly half the time. All that said I would live no other place than America, now if we can just get rid of the lying, self serving career politicians we'd be a **** of a lot better off. Ok, off my soap box.

David
San Diego
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Ok that makes sense then, If I'm understanding correctly it needs to remain open to suck the gasses back through? Basically acting like a vacuum, is that the same case with DPF regen as well?
The butterfly is upstream to where the EGR ties into the intake and is closed down when the EGR is opened. Closure of the valve like on a gas engine creates suction for pulling in the EGR gasses.

Tim
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