Diesel vs Gasoline

calicamper

Expedition Leader
So if your diesel engine weighs 200lbs more than a gasser but because it gets better gas mileage it has more payload? Can you explain the math? I am aware that gas weighs 8.4 lbs per gallon and diesel weighs 7.
CS if your not carrying another 20 gallons of Gasoline because your stock tank 180- 200 mile range isn’t enough you have less room left for gear in your weight limits. The small Diesel range with no extra fuel is a big reason I would get a mid sized Truck/SUV with small diesel
 
In my Unimog to have my 1400 mile range I have 160 gallons = 1150 lb fuel. With gasoline I’d need at least 250gal = 1650 lb + 100 lb for another tank = 600 lb more. My engine weighs 1200 lb. I doubt I could find a 700 ft-lb gasoline engine that weighs only 600 lb. And where would I put the extra 90 gal?
 

billiebob

Well-known member
If range is what is important we are screwed. The industry and every guy posting here claims a lift and bigger rubber is a must do to get into the club. 40 years later I realize every inch of lift and every inch of bigger rubber equals 1mpg. I went from 33/10.50s to 32/7.50s on a stock suspension and went from a best 17mpg to 22mpg without trying. That gives me another 95miles between gas stations. If I drive 12K miles a year, that saves me 160 gallons of gas a year. OR a 3500 mile trip for free.

Sort of off track but if range is important, throw out the lift and the big tires. You'll get a much better, more controllable ride too.
 

calicamper

Expedition Leader
If range is what is important we are screwed. The industry and every guy posting here claims a lift and bigger rubber is a must do to get into the club. 40 years later I realize every inch of lift and every inch of bigger rubber equals 1mpg. I went from 33/10.50s to 32/7.50s on a stock suspension and went from a best 17mpg to 22mpg without trying. That gives me another 95miles between gas stations. If I drive 12K miles a year, that saves me 160 gallons of gas a year. OR a 3500 mile trip for free.

Sort of off track but if range is important, throw out the lift and the big tires. You'll get a much better, more controllable ride too.
I found 180 mile range a major issue in parts of CA,NV and Washington State. One of the larger reasons I sold my J80. And why my recent 2019 purchase never involved a Toyota truck/SUV. There is a big difference between 400Hp and 21-24mpg trip averages and 300Hp with 15-16mpg trip averages. ?
 

Kaisen

Explorer
Ah, playing the range card...

Modern ULSD has 17-19% more potential energy than pump Gasoline. And the diesel cycle is slightly more efficient at converting that potential. For most emissions-legal trucks, the delta is about 20%. In other words, with engines of similar capability you'll go 20% further on the same volume of fuel with diesel. If the average fuel tank size is 25 gallons, that's perhaps the difference between 500 miles on a tank of diesel versus 415 miles with gasoline. 180 lbs of diesel versus 165 lbs of gasoline. At equal weight, you'd be able to carry 2 more gallons of gasoline, good for only 30-35 additional miles. Of course, the average diesel engine and related added components (DEF tank, intercooler and plumbing, etc) weighs perhaps 175 lbs more than the gasoline engine option (some are WAY more than that -- Cummins 6.7L comes to mind). That's about 27 gallons of gasoline for the same weight.

All told, a diesel truck with 25 gallons of fuel weighs about the same as a gasoline truck with 55 gallons of fuel, give or take. A Cummins 6.7L might get 20 mpg where the same Ram with a 6.4L Hemi may only make 15 mpg.

Equal overall vehicle weight:
25 gals x 20 mpg Diesel = 500 miles of range.
55 gallons x 15 mpg Gasoline = 825 miles of range.

Of course, if a diesel gets 20% more range per gallon, but the gasoline truck can carry 220% more fuel for the same overall vehicle weight, gasoline wins.

Or, if you're looking at VOLUME rather than weight, you'd run 25 gallons of diesel but to achieve the same range you'd need to carry 20% more gasoline, or a total of 30 gallons of gasoline. A gallon is 231 cubic inches. So having to carry 5 additional gallons of gasoline would take up 1,155 cubic inches or 0.668 cubic feet. That's right, less than 1 ft x 1ft x 1 ft... although most people know what a 5 gallon spare gas can looks like.

Of course, the US national average price of regular unleaded gasoline is currently $2.41/gal where pump diesel is currently $2.91/gal (eia.gov 02/10/2020 data). So that 25 gallons of diesel will cost $72.75 and 25 gallons of gasoline will cost $60.25. At 20 mpg diesel, that's $0.15/ mile. At 15 mpg gasoline that's $0.16/ mile.

Weight? Gasoline wins when it comes to overall vehicle weight.
Cost? About equal, but gasoline wins (especially when considering the Cummins option alone is over $10K, and there's still higher maintenance costs, higher repair costs, and DEF to factor in)
VOLUME? Yep, to go the same distance you'd need to carry 20% more gasoline which takes up... not much space

So it depends on which metric is critical to your application, and even the trip planned. Pinning your need for a diesel vehicle on "range" seems really quite silly, but again your particular and specific need may somehow really require that range where carrying a spare 5 gallon can would either push you over your payload limit, or maybe you couldn't possibly find another spot to carry another cubic foot of gear, and what you do carry is more critical than range. Your metrics, your decisions.
 

IdaSHO

IDACAMPER
All reasons point towards why our latest purchase landed a 6.2 Ford, along with an aux fuel tank (integrated into the custom bed)

We have near 50 gallons now and at the very worst a bit more than 400 miles of range, at at the very best 600+, which is just about perfect for our travels and the vast majority of the USA.

Had the truck come with a larger fuel tank, it would have been perfect out of the box. (y)
 

Ninelitetrip

Well-known member
All reasons point towards why our latest purchase landed a 6.2 Ford, along with an aux fuel tank (integrated into the custom bed)

We have near 50 gallons now and at the very worst a bit more than 400 miles of range, at at the very best 600+, which is just about perfect for our travels and the vast majority of the USA.

Had the truck come with a larger fuel tank, it would have been perfect out of the box. (y)



If today you were shopping for a 2020 Super Duty and had a choice of your current drivetrain or going to the 7.3 which is about a $1700 upcharge and the new 10 speed transmission, would you even consider it or stick with the 6.2?
 

Ninelitetrip

Well-known member
Simple video comparing the 2020 Ford 6.7 vs 7.3 under the hood. That 6.7 takes up all the space and then some. Just does not lend itself to easy self done or worse on the trail repair. The 7.3 engine bay seems huge in comparison, lots of room to do your own work.


 

IdaSHO

IDACAMPER
If today you were shopping for a 2020 Super Duty and had a choice of your current drivetrain or going to the 7.3 which is about a $1700 upcharge and the new 10 speed transmission, would you even consider it or stick with the 6.2?

Couldnt be 100% certain.
The 6.2 is a fine motor, as is the 6-speed.
And I tend to NOT jump at brand new tech.

Ask me in a few years, I might have a response for ya ?

If the 7.3 proves to be the motor Ford claims it to be, $1700 seems like pocket change.
Add the 10 speed to the equation, and it all seems better.
The actual architecture of the 7.3 is superior to the 6.2, as is the low end grunt.
And the added gears should negate "need" for a regear running large rubber.

All that said, I do still prefer the looks of the 2011-2016 trucks over new.

Mine is also paid for.
Y'all are nuts for buying brand new trucks.
I love me some 100k mile used ones.... ?
 

IdaSHO

IDACAMPER
Simple video comparing the 2020 Ford 6.7 vs 7.3 under the hood. That 6.7 takes up all the space and then some. Just does not lend itself to easy self done or worse on the trail repair. The 7.3 engine bay seems huge in comparison, lots of room to do your own work.



Both the 6.2 and the 7.3 are easily serviced/repaired.

The PSD typically requires cab-off.

That video also reminds me of all the non-serviceable hoses/connectors on these new motors.
My 6.2 has 'em as well. Not impressed at all about that....
 
Last edited:

Ducstrom

Well-known member
I jumped on a 2019 6.2 because I am leery of 'new' tech as well and wasn't sure if the 6.2 and 6 speed would be available in the 2020 model.
I ve heard a lot of good things about the 6.2 and 6 speed and was burned once already by the dual clutch transmission in the ford focus. Didn't want to be a guinea pig again.
 

Ninelitetrip

Well-known member
Couldnt be 100% certain.
The 6.2 is a fine motor, as is the 6-speed.
And I tend to NOT jump at brand new tech.

Ask me in a few years, I might have a response for ya ?

If the 7.3 proves to be the motor Ford claims it to be, $1700 seems like pocket change.
Add the 10 speed to the equation, and it all seems better.
The actual architecture of the 7.3 is superior to the 6.2, as is the low end grunt.
And the added gears should negate "need" for a regear running large rubber.

All that said, I do still prefer the looks of the 2011-2016 trucks over new.

Mine is also paid for.
Y'all are nuts for buying brand new trucks.
I love me some 100k mile used ones.... ?


:) Yeah but 7.3 man:)

I have always bought used, in this case though with eventually going full time the 2020+ F350 SRW Super Cab with that 7.3 is calling me...

Same thoughts on gearing, especially with say 35's, maybe even 37's max. And maybe a few Carli add on's.
 

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