Fuel mileage from heavy duty trucks

[mi223]

So I recently ventured on my own starting a little one man plumbing company. I am driving around my old truck I have had for years enjoying the fact that it is a good old truck and it has been paid off for years.


It is an old Chevy 2500hd with the 8.1 liter gas. Before the ladder racks and ladders it would usually run between 10-12 mpg depending on speed and right foot. Now I have a topper with ladder racks and ladders as well as a couple 6inch tubes I use to store materials. Since adding these things I am usually around 8mpg. I am getting close for new tires and I know the tires on it are not helping either.

With the new Biden fuel prices, gassing up every few days is really eating into my profits.

I do a fair amount of towing so I am looking at another 2500 minimum. The one ton trucks with a van body or service body keep catching my eye do to the massive amount of storage they provide.

Would a one ton Diesel dually with one of these service or van bodys improve my fuel mileage at all? I realized the diesel engine is more money up front as well as higher maintenance. So that is surely a factor. But curious if a diesel truck would overcome the poor aerodynamics and weight of a work truck vs something like the big gasser I am currently driving.

Replacing this truck is not urgent but it will not last forever so I am trying to take my time and shop around and find what setup will be best for my uses.

 

[Bender]

The diesels may improve mileage. But you will not get ahead because of maintenance and DEF purchase. I had an 8.1, I wish I had it back. It pulled darn near as good as the diesel with zero maintenance other than oil changes. Driving a truck around that size you’re going to get about the same mileage.When I was a field technician, I had a Ford three-quarter ton with the 6.2 L, it got the same mileage as the 8.1.

 

[Bender]

A truck that is paid for, basically makes the gas free. Are you ready to throw down $50,000 or more on a new truck? And have a $700-$1000 a month payment? You can still buy an awful lot of gas with that amount of money.

 

[Bender]

The 8.1 L will make more torque at 1800 RPM, than a small block anything ever will.

 

[mahlv]

My small biz (plumbing/excavation/hvac) has had several trucks and vans over the years. My current truck is a '15 3500 d-max, about 60k on it, and ive never reset the computer for mileage, it is 12mpg over that 60k miles. It is a double cab with a service body and pipe rack. I've logged a couple trips (200 miles or more) approaching 20mpg with it. We just got a Nissan van and I'm impressed with the power and ergos etc, hoping for nissan reliability as it's been in service just about a year now. Fuck the Ford transit stuff, didn't even look at dodge vans.

 

[Bender]

Those Nissan vans look cool! There is a company in Utah that adds the 4x4 parts from the truck and sells them. Way cool.

 

[waveslayer]

How much are you towing?
I ask because we have a 1ton Chevy it gets about 14 around town and 20 to 22 on highway.
But we use a Sprinter van more than anything. That thing gets 28mph all the time. We have had 4 of them now and it's impressive

 

[mahlv]

We have a gooseneck tilt bed to haul a Cat 305 mini ex, its 7-7.5 tons alone. My 3500 has no problems towing it around, but happened to get a deal on a 2013 d-max dually that I use to move that around, especially out of town jobs. The dually gets 10-12 empty or loaded, I'm guessing it's geared differently than my single tire 1 ton, but I did put a lot of $ into making the service truck more american.

 

[tiNdvenTFHwMdqKW]

A modern diesel will get better highway mileage due to the better transmissions they are using. I traded a 2004 Ford V10 for a new Dodge 3500 HO Diesel this year. Up and down the hills where I live the mileage is about the same - it's on the highway where I see the biggest difference. Of course, the new Dodge also pulls my loaded 14K dump trailer like it is empty. The Ford would not have enjoyed pulling a loaded 14K trailer up my hills. I did buy the Ford used for around 14K and paid a lot more than that for the Dodge - so there's that to consider.

I think the type of driving you do should be a huge influence on your decision.

 

[mi223]

Man I hate the idea of a van but they sure are tempting.

I haul an enclosed trailer quite a bit. Don't really need a 3/4ton for that but I haul a skid steer, dump trailer and 32 ft travel trailer enough to justify the heavier truck

 

[Mister Ridge]

Given how much trucks are selling for right now, I don't see how buying a truck is going to save you money compared to filling up a gas hog. Rumor has it that the vehicle market is going to crash in a few months, so maybe wait a bit?

Also, around here, diesel is more expensive than regular. Might affect the calculations a bit.

PS: is the 8.1l for sale? Lol.

 

[TxWelder35]

Don’t buy a new truck to save one fuel. That’s a fools errand.

There are plenty of other better reasons to want one. More storage, more reliable, less down time due to repairs, pulls better.

I had a 2006 ram 3500 with 280k miles I finally traded into a newer truck 3 years back.

Currently have a 2016 SRW Ram 3500 Laramie and a 2018 SRW Ram 3500 cab and chassis SLT for my weld truck.

The 18 is 11200#s with all the shit on it. It gets roughly 13-14mpg in town and 15-16 on the highway. Pulling my 20’ gooseneck with a total weight of 10k behind me it gets 10-12mpg
3.73 gears

The 16 is just a regular ol truck it gets 14-15 in town and 16-17 on the highway. I’ve gotten as high as 21 when I babied it one time for 350 miles but I drive with a lead foot so it definitely has more potential I just don’t care enough to drive it easy.

If a man drove them easy and the trucks didn’t see WOT multiple times per trip and drove 10mph slower on the highway I bet they would pick up 2-3 mpg.

The new trucks are nice. It really is incredible how well these new trucks pull. I was tired of the issues the old truck was giving me and I’m happy with my decision to upgrade instead of keeping the old paid off truck.

Not sure where you live but look into the DOT laws where you are regarding max gvwr of truck and trailer before you need a cdl and all that nonsense. That’s why I bought single wheels instead of duallys, I can still hook up to a 14k gvwr trailer and still be legal

 

[candyx]

U.S. Secretary of Transportation stated that if you buy electric cars or trucks they is no more cost for fuel, big savings !!!

 

[mi223]

Ok just to be clear, the mpg is not the only driver for truck shopping. It is an old truck (2001) it has 180k and I live in the rust belt. It is a good truck but it's days are coming to an end. It gets me by but it will need replaced in the next year or so. I am just planning my next move.

Thanks for all the responses.

Oh. What did Bender do to get banned now?

 

[fxdwgkd]

I avg 8mpg in this truck. 2018. Majority of my driving is highway and interstate. Highway does much better than interstate. I have 9kw inverter so my truck is either going down the road or idling, never shuts off except when i am done for the day. 16ft box, scales at 17500lb. I imagine a dually with an enclosed trl behind it would do fairly close prob better. The 350 and under have more torque and hp than the 450 and 550.

 

[madppcs]

I just bought a GMC 2500 last year. Duramax with the new Alison 10 speed. My best mileage is 19mpg while doing interstate speed limits with no load. Im in Louisiana so theres no elevation to factor in. I got lucky when I found my current truck, availability on new units were nearly 0%

 

[GreenGO Juan]

Have a couple Hundred thousand miles of experience with the Ford 6.7’s with a company I worked driving all around the country. All completely stock.

The a F-250 lightly loaded would average around 17.5. 2016

The F- 250 with a large topper, stuck up 2 feet over the cab, that would average around 12-14 doing 80-90mph, with 3-4 people and maybe 1500 lbs of gear in the topper.

The F-350 we used for pulling an 8x18 with up to 4 to 5k worth of weight in the trailer, same 3-4 people would get around 8-12 at 80-85 mph.

Def issues only occurred with one truck, the 2012 Can’t remember what failed but I think it was around $1500. One thing with the Ford DEF tanks when you go to fill, fill it all the way up because the system won’t reset if u just add a little. The 2012 also had a map sensor fail. The 2014 and 2016 were solid.

I also worked for SunCoast Converters that specialize in modified torque converter‘s and transmissions for the heavy duty diesel’s. The modified trucks( filter, egr delete, 4” straight pipe) got much better gas mileage at the expensive of noise and emissions. Used to do r&r on transmissions there and got to drive a lot of different trucks at different levels of modification. Side not, Joe Webb had Garmon put a built 12 valve in a 1/2 ton that made 600rwhp 1263 ftlbs of torque. It was around 4500 lbs on the scales, that thing was a blast to drive, boil the tires until u let out, It would never hook with street tires. Sadly he died and his wife sold it. I quit working there soon after.

 

[Hobo Hilton]

This is a great discussion with a lot of first hand experience.... There is no perfect truck.

My hat is off to you for starting your own one man business.. Been there, done that.

I'd focus more on growing the business, getting those "word of mouth" referrals, contractor's license, insurance, etc. Save up your cash "in hand" and start walking around looking at a replacement vehicle. When this economy takes a shit and the field service hands are driving a vehicle that is paid for.... You will be in the Cat Bird's seat..... Best of luck... Merry Christmas

 

[Sniperwannabee]

5.9 Cummins common rail Dodge Ram trucks

 

[TxWelder35]

5.9 Cummins common rail Dodge Ram trucks

Will get pulled in circles by any new 6.7

 

[Twins82]

If you can't pay cash for it you dont need it, and buy the time you have the cash you won't want it. One true fact is that you can not fiance yourself out of debt.

 

[BCP]

I would look for a 1/2 ton or a van.

Most 3/4 ton on up are expensive and get 12-15mpg once you put all the crap you will need on them. Also you are going to fill the thing full of glue and dirt.

 

[Bacarrat]

You really have to look into what you are going to be doing with the vehicle all the time and decide if you really need the older bigger diesel engines. Dealing with work trucks, vans and tractors all day, I have a pretty good grasp on how much these things cost to run and maintain in a fleet. What's nuts is a lot of these manufacturers are putting a lot of 4 cylinder diesels in the 3/4 ton vans. Surprisingly they don't have that many issues with carrying the weight these drivers move around all day. I'm talking about companies like Fedex and Amazon where those vehicle start and start all the time and not unheard of a driver doing 100k per year on those things. I know they will not be fast in anyway but they are durable as hell.

 

[packratt]

I get about 14 in my 2016 f350 dually diesel running 70-75.

My work van is a 2016 ford transit 250. It gets about 18mpg. It has 28' ladder on one side of the roof with a 12' and 8' step ladder on the other with pipe tube in the middle. Inside is probably 3-4000 lbs of tools, boxes and parts. We have about 20 of them. Currently all have between 125000 and 225000 miles with no major issues.

Our Motor pool guys don't want our vans on the auto lifts. They use the lifts for the big box trucks.

 

[turbobrick]

I've been through the gamut over the years, searching for the perfect work truck. Started with a 2wd Chevy Vandura G30 with a 350. I also inherited a huge step van at the same time. The G30 was fine, mileage was poor and it was a nightmare to work on. The step van was a no go from the start, slow, horrible mileage, scary in the wind.

I bought a brand new Dodge Sprinter, and had 220k mostly trouble free miles. It knocked down low 20s MPG and had plenty of power, just sucked in the snow and parts were expensive. Then I got 2 of the Ford E350s with the 6.0 Power Stroke. Initially, they were awesome, good mileage, plenty of space, power all over the place, then one holed a piston out of the blue, and we had repeated injector and FICM troubles with the other, still sucked in the snow. At the same time, got a F350 4x4 SRW with service body and 6,0 PSD. The mileage was ok, but it was great in the snow and organization was awesome with the service body, just repeated problems with injectors and turbos.

Then I got a Ram 4x4 6.7 Cummins and a service body. This thing is a favorite, great mileage (upper teens average), unstoppable in the snow, reliable, easy to work on. We still have the Ram and two 6.0 gasser 4x4 Chevy 2500HDs with service bodies. These things have been great. Mileage is not a strong, but they are reliable, easy to work on, kick ass in the snow, cheaper to buy than a diesel.

Overall, I avoid duallies, the trucks are heavy, but we don't need that much capacity. Service bodies are the only way to go, enclosed if you need to work inside like we do, Diesels are great, but buying them is pricey, and modern emissions stuff makes them costly to run and maintain.

 

[mi223]

My work truck when I left my last job was a 18 GMC 1500 with high side boxes and ladder racks. I was never impressed with the storage and I never got more than 15mpg. I always figured/wondered that a more capable Diesel would get similar mileage but obviously at a higher cost and added maintenance.

 

[mi223]

I've been through the gamut over the years, searching for the perfect work truck. Started with a 2wd Chevy Vandura G30 with a 350. I also inherited a huge step van at the same time. The G30 was fine, mileage was poor and it was a nightmare to work on. The step van was a no go from the start, slow, horrible mileage, scary in the wind.

I bought a brand new Dodge Sprinter, and had 220k mostly trouble free miles. It knocked down low 20s MPG and had plenty of power, just sucked in the snow and parts were expensive. Then I got 2 of the Ford E350s with the 6.0 Power Stroke. Initially, they were awesome, good mileage, plenty of space, power all over the place, then one holed a piston out of the blue, and we had repeated injector and FICM troubles with the other, still sucked in the snow. At the same time, got a F350 4x4 SRW with service body and 6,0 PSD. The mileage was ok, but it was great in the snow and organization was awesome with the service body, just repeated problems with injectors and turbos.

Then I got a Ram 4x4 6.7 Cummins and a service body. This thing is a favorite, great mileage (upper teens average), unstoppable in the snow, reliable, easy to work on. We still have the Ram and two 6.0 gasser 4x4 Chevy 2500HDs with service bodies. These things have been great. Mileage is not a strong, but they are reliable, easy to work on, kick ass in the snow, cheaper to buy than a diesel.

Overall, I avoid duallies, the trucks are heavy, but we don't need that much capacity. Service bodies are the only way to go, enclosed if you need to work inside like we do, Diesels are great, but buying them is pricey, and modern emissions stuff makes them costly to run and maintain.

View attachment 7763194
I avg 8mpg in this truck. 2018. Majority of my driving is highway and interstate. Highway does much better than interstate. I have 9kw inverter so my truck is either going down the road or idling, never shuts off except when i am done for the day. 16ft box, scales at 17500lb. I imagine a dually with an enclosed trl behind it would do fairly close prob better. The 350 and under have more torque and hp than the 450 and 550.

While 8mpg is nothing to write home about, the massive amount of storage would sure help to offset that.

 

[sirhrmechanic]

I have a Unimog. OPEC sends me Christmas cards.

Mileage…. Ah hahhahaha.

Sirhr

 

[BadDogPSD]

My new work truck (2022 F250 4x4 6.2L) gets 15 hwy, 12 city, 8.5 towing. It tows a 6k lb enclosed trailer 90% of the time. Would have preferred the 7.3L gas motor, but couldn't find one...

 

[fxdwgkd]

While 8mpg is nothing to write home about, the massive amount of storage would sure help to offset that.

It would be better but with the truck idling all day that doesnt do it any favors

 

[Sniperwannabee]

Will get pulled in circles by any new 6.7

It will pull anything he has and get better fuel economy without all that def bs

 

[TxWelder35]

It will pull anything he has and get better fuel economy without all that def bs

I specifically got rid of my 5.9 because it pulled like shit. Got same mpg as my new trucks. And new trucks pull circles around it.

I was a 5.9 believer until I got a 6.7

My 5.9 was tuned hot, full billet trans, the whole 9. 500hp/1000ft # and a stock 6.7 still pulls circles around it.

 

[Sniperwannabee]

I specifically got rid of my 5.9 because it pulled like shit. Got same mpg as my new trucks. And new trucks pull circles around it.

I was a 5.9 believer until I got a 6.7

My 5.9 was tuned hot, full billet trans, the whole 9. 500hp/1000ft # and a stock 6.7 still pulls circles around it.

how does your truck have those type of numbers and pull terrible? maybe You had a crap TC..was it a ATS

 

[TxWelder35]

how does your truck have those type of numbers and pull terrible? maybe You had a crap TC..was it a ATS

6.7 just delivers the power completely different. Both of mine have the Aisin trans

5.9 would get hot, trans would get hot, had plenty of power up top but just pulling around it was a dog. Revmax signature series

Everything about these new trucks pull better. Weight handling, power delivery, braking, exhaust brake, everything.

I can leave my foot on the floor for 8 miles up a mountain grade with 14k behind me and know good and well that I’m not going to leave part numbers all down the highway. It’ll do it without hardly raising in temps. That 5.9 would have left a pile of transmission and engine parts down the whole highway.


My 18 cab and chassis has the detuned motor and still pulls better than that truck. Not in acceleration but in overall towing. Brakes better, handles the weight better, having an exhaust brake is awesome. You just don’t feel the weight behind them the way I did in that old 5.9

Def ain’t no big deal. Fill the tank up every like 3-4k miles for $15

 

[Jim Out]

Before the ladder racks and ladders it would usually run between 10-12 mpg depending on speed and right foot. Now I have a topper with ladder racks and ladders as well as a couple 6inch tubes I use to store materials. Since adding these things I am usually around 8mpg.

I do a fair amount of towing shop around and find what setup will be best for my uses.

Fuel mileage from.....​

" heavy duty trucks" ??????​

You really should consider a MDT at least, my Cat 3126B 300hp/800tq 6spd FL60 Freightliner got ~10mpg.

In my Volvo 770 I get 10mpg loaded/unloaded @75mph+ everywhere no matter what the load.

Detroit 14L 575hp/1850tq 18autoshift 1999/2000 pre-emission stuff

Cost less than a dually

Try truckpaper.com

 

[Emerson0311]

I pull a 20K+ 5th wheel with a 6.7 F450. Gross combined weight is 34K or so. It is incredible how easily that driveline pulls that weight. 4.3 rear end. I set the cruise and go. Through the Fraser Canyon in BC, only a couple of the steep hills slowed me to 40 mph. Economy is right around 8mpg US.

 

[Jim Out]

https://www.truckpaper.com/listings/trucks/for-sale/category/267/medium-duty-trucks-service-trucks-utility-trucks-mechanic-trucks

https://www.truckpaper.com/listings/trucks/for-sale/208941229/2011-freightliner-business-class-m2-106

$55,900

 

[Jim Out]

Overall, I avoid duallies, the trucks are heavy, but we don't need that much capacity. Service bodies are the only way to go, enclosed if you need to work inside like we do, Diesels are great, but buying them is pricey, and modern emissions stuff makes them costly to run and maintain.

DOT reg is 26,001 -> CDL on a commercial vehicle everywhere.

Had a buddy lose a rear tire on an SRW towing on the freeway.....

......just saying, that's the concept of redundancy, dually is a thing for a reason, especially if you load a 14k trailer.

Single is only the way to go if you have to do it off-road rough terrain jobsite, so I assume that's your main reason?

https://www.truckpaper.com/listings/trucks/for-sale/209519477/2012-freightliner-business-class-m2-106

2012 FREIGHTLINER BUSINESS CLASS M2 106​

$45,000
Cummins ISB 245HP
39k Miles
Allison Auto
26k GVW Under CDL

 

[BCP]

I had one like this several years ago and sold it for 29k, kinda regret it since it was a beast for work:

https://www.truckpaper.com/listings/trucks/for-sale/209830859/2010-chevrolet-silverado-3500hd?ST=arizona&CTRY=usa

 

[Aftermath]

I bought a Dodge Cummins Diesel 2500 automatic transmission new in 2001. At the time, diesel fuel was a few cents cheaper than regular gasoline and I had a 1974 3/4 ton Chevy with a 5 speed. I hauled tools and building materials everywhere I went, pretty much, so It was loaded all the time. It averaged around 10 mpg and I shifted it maybe a million times a day. I got the automatic because I just got tired of shifting that thing all the time.
The 5.9 24 valve didn't really improve the mileage because 1) it's an auto and 2) I bought it with 4.11 gears. I definitely didn't want a dually and Dodge only made dually 1-tons then. I wanted that Cummins, though and got as heavy duty 3/4 ton as I could assemble. It averaged about the same and I think the best mileage was maybe 14 if I could keep it at about 45 mph. I still have this truck and it's a nearly daily driver. About 10 years ago, I installed an ATS transmission with some other upgrades. SOLID shifts, improved the mileage maybe 1 mpg but maybe not even that. About 2 years ago, I got worried about the factory original turbo and decided to replace it.
Wellllllll, I ended up doing a complete engine rebuild, twin turbos, head studs, cam, injectors, hot rod injector pump, intake, 5" exhaust from the turbos back, low and high fuel controllers. I have not put this on a dyno but that combination of stuff is supposed to give me about 750 hp. The difference is VERY noticeable. I've always been a motorhead. Mostly, I still drive it like I always have but now I can pass someone like I'm on my motorcycle.
Now I say all that to say this...the factory hp was something like 220 and mileage around 10 mpg. I spent about $15,000 on this engine and now have 750 hp...so a little more than 3x. The mileage went from 10 to a solid 18 mpg...so not quite double. Had I realized that improvement, the $15k would have been washed away many years ago, especially when I was buying $6.00/gal fuel around Mississippi and Louisiana just post Katrina.
There are a few things you can do to get better mileage.

 

[BAMAboy18]

Best friend has an F250, I think 2003 (last year of the 7.3) he previously had 2 different later models with the 6.0s. This one came set up with the full Banks upgrades, superchip tuner and airbags. I was with him when he picked it up and we drove 250 miles running 85mph and were getting 35mpg! When we got home and he was driving normal Hwy speeds he got as high 50mpg (this was not loaded) he could tune it for tow mode and pull a 23,000# 5th wheel with the air bags inflated you couldn't even feel it running 70-80mph. He got robbed and they stole his tuner, after he replaced it he could not replicate the performance. He pondered selling it a few times, I adamantly talked him out of it. So last year after installing a new glow-plug solenoid it caught fire. He was so disgusted (just did full suspension and new paint) he went shopping for a new truck, $80K O_O
He took the $8K insurance money and added another $5K and had the engine & tranny performance built, rewired and a new mondern tuner (IDK which, but he says top performance setting is labeled "ludicrous") He can roll coal and smoke 4 tires as long as he wants, no new truck around here can touch him. So long story short; new ain't always better. I'm no longer self employed, therefore can't justify a truck like that. Mine is a 2016 2.5 Frontier that my ole lady daily drives. When I was a contractor, my mindset was the business paid for my trucks/maintenance, so my prices included that in the overhead.

 

[turbobrick]

DOT reg is 26,001 -> CDL on a commercial vehicle everywhere.

Had a buddy lose a rear tire on an SRW towing on the freeway.....

......just saying, that's the concept of redundancy, dually is a thing for a reason, especially if you load a 14k trailer.

Single is only the way to go if you have to do it off-road rough terrain jobsite, so I assume that's your main reason?

https://www.truckpaper.com/listings/trucks/for-sale/209519477/2012-freightliner-business-class-m2-106

2012 FREIGHTLINER BUSINESS CLASS M2 106​

$45,000
Cummins ISB 245HP
39k Miles
Allison Auto
26k GVW Under CDL

Yeah, we're not anywhere near CDL territory, just service trucks that have to get places in the snow. We don't tow anything for work, so we really don't need the capacity. Most of our trucks sit at around 10k ready to work. I'd hate to try and drive a dually service truck into the hills or up to the ski resorts just for the extra tires. Duallies have their place, but I think a lot of people end up with them and their mileage and maneuverability suffer for no reason.

 

[krw]

Will get pulled in circles by any new 6.7

I had ‘07 HO 5.9 w 6 spd manual trans. Sold it and bought new ‘15 6.7 Ram. Never had lack of power issue with either. Both are good trucks

 

[Jim Out]

I bought a Dodge Cummins Diesel 2500 automatic transmission new in 2001. At the time, diesel fuel was a few cents cheaper than regular gasoline and I had a 1974 3/4 ton Chevy with a 5 speed. I hauled tools and building materials everywhere I went, pretty much, so It was loaded all the time. It averaged around 10 mpg and I shifted it maybe a million times a day. I got the automatic because I just got tired of shifting that thing all the time.
The 5.9 24 valve didn't really improve the mileage because 1) it's an auto and 2) I bought it with 4.11 gears. I definitely didn't want a dually and Dodge only made dually 1-tons then. I wanted that Cummins, though and got as heavy duty 3/4 ton as I could assemble. It averaged about the same and I think the best mileage was maybe 14 if I could keep it at about 45 mph. I still have this truck and it's a nearly daily driver. About 10 years ago, I installed an ATS transmission with some other upgrades. SOLID shifts, improved the mileage maybe 1 mpg but maybe not even that. About 2 years ago, I got worried about the factory original turbo and decided to replace it.
Wellllllll, I ended up doing a complete engine rebuild, twin turbos, head studs, cam, injectors, hot rod injector pump, intake, 5" exhaust from the turbos back, low and high fuel controllers. I have not put this on a dyno but that combination of stuff is supposed to give me about 750 hp. The difference is VERY noticeable. I've always been a motorhead. Mostly, I still drive it like I always have but now I can pass someone like I'm on my motorcycle.
Now I say all that to say this...the factory hp was something like 220 and mileage around 10 mpg. I spent about $15,000 on this engine and now have 750 hp...so a little more than 3x. The mileage went from 10 to a solid 18 mpg...so not quite double. Had I realized that improvement, the $15k would have been washed away many years ago, especially when I was buying $6.00/gal fuel around Mississippi and Louisiana just post Katrina.
There are a few things you can do to get better mileage.

I have to question 750hp out of that motor, what torque numbers do they claim?

The addition of the Allison trans is more likely the major source on the mileage front. With my manual it was impossible for me to do as good a job as a computer shifting, now that I have the 18 speed autoshift (you only use the clutch for start and stop) and double the displacement (14L vs 7.2) I still get the same fuel mileage and unlimited speed and cargo control.

https://www.barringtondieselclub.co.za/caterpillar/3114-3116-3126/cat-3126b-spec-sheet.pdf

https://www.barringtondieselclub.co.za/detroit/s60/series-60-spec-sheet-collection.pdf

Not to mention with a real diesel engine I get a Jacobs brake not an exhaust brake, just like "4wheel drive is not 4wheel stop", going up a 10% is not the same as going down one.


I mean, this isn't perpetual motion or alchemy, there is only so much energy density in any fuel and there is no such thing as 100% loss free transmission of power.

 

[jinxx4ever]

there's a reason 90% of hot shotters, drive Dodge's powered by Cummins. If your going to pull any loads at all, diesel is the only way to go. Just having a work truck for around town, buy a gas eater, you'll b fine. I'm on my 2nd 1ton dually. 06 i bought in 07. Just turned 217,000 today. I've put some money in it over the years, but i use the hell out of it. It's a truck not a pickup to drive to the supermarket which most use their pickups for. As far as mileage, i never even bother to check,, if i was worried about mileage, i wouldn't buy a pickup.

 

[GreenGO Juan]

I have to question 750hp out of that motor, what torque numbers do they claim?

The addition of the Allison trans is more likely the major source on the mileage front. With my manual it was impossible for me to do as good a job as a computer shifting, now that I have the 18 speed autoshift (you only use the clutch for start and stop) and double the displacement (14L vs 7.2) I still get the same fuel mileage and unlimited speed and cargo control.

https://www.barringtondieselclub.co.za/caterpillar/3114-3116-3126/cat-3126b-spec-sheet.pdf

https://www.barringtondieselclub.co.za/detroit/s60/series-60-spec-sheet-collection.pdf

Not to mention with a real diesel engine I get a Jacobs brake not an exhaust brake, just like "4wheel drive is not 4wheel stop", going up a 10% is not the same as going down one.


I mean, this isn't perpetual motion or alchemy, there is only so much energy density in any fuel and there is no such thing as 100% loss free transmission of power.

You can get a fully built 12v up to those numbers reliably. Stock no. But the build he described yes. And at that power it was likely around 1500 ftlbs of Torque, really depends on the cams profile. The issue with the 5.9 that restricts its over all power potential is the head flow, There’s only so much port and valve. I remember talking to Stucky about it when they were trying to sort out his transmission, at the time he had the fastest street legal diesel truck in the world.

1994 Dodge Ram 2500 - Stuckey Racing Truck - Diesel Power Magazine

Check out this 1994 Dodge Ram 2500, the 1200hp racing truck packing a Cummins turbodiesel, only in DieselPowerMag.com, the official website of Diesel Power Magazine.

www.google.com

And the heavily modified trucks, properly tuned do get better gas mileage.

 

[sirhrmechanic]

My current 2018 Ram 3500 Cummins is 950 Ft Pounds. Stock. If I had wanted to pay extra for HO version, I was 1050 or something even more insane.

I can put a car trailer with 3 tons of antique car behind it in an enclosed trailer... and not even notice.

The 6-cyl Cummins is an amazing motor. Not that I approve of all the computer shit. It's too complex now. But EMC does some incredible things to big, long-stroke diesels.

Sirhr

 

[jinxx4ever]

My current 2018 Ram 3500 Cummins is 950 Ft Pounds. Stock. If I had wanted to pay extra for HO version, I was 1050 or something even more insane.

I can put a car trailer with 3 tons of antique car behind it in an enclosed trailer... and not even notice.

The 6-cyl Cummins is an amazing motor. Not that I approve of all the computer shit. It's too complex now. But EMC does some incredible things to big, long-stroke diesels.

Sirhr

my brother just bought an 18 with an auto trans. Damn smooth

 

[sirhrmechanic]

my brother just bought an 18 with an auto trans. Damn smooth

I wish I could get one in a Manual... so much better for plowing. Which is main job of truck when not towing.

Push in clutch as you hit the bank.

But noone makes a good manual diesel any more. Or I'd buy one in a heartbeat.

Sirhr

 

[Jim Out]

You can get a fully built 12v up to those numbers reliably. Stock no. But the build he described yes. And at that power it was likely around 1500 ftlbs of Torque, really depends on the cams profile. The issue with the 5.9 that restricts its over all power potential is the head flow, There’s only so much port and valve. I remember talking to Stucky about it when they were trying to sort out his transmission, at the time he had the fastest street legal diesel truck in the world.

1994 Dodge Ram 2500 - Stuckey Racing Truck - Diesel Power Magazine

Check out this 1994 Dodge Ram 2500, the 1200hp racing truck packing a Cummins turbodiesel, only in DieselPowerMag.com, the official website of Diesel Power Magazine.

www.google.com

And the heavily modified trucks, properly tuned do get better gas mileage.

I've been debating this since before Ford (I still have my '97 non-intercooled F250 w/80,000 miles) dumped the International 7.3 and started selling the "6 uh 0".

O-ring heads and unobtainum bolts and what-not....

I absolutely want to build a rat rod with a 5.9 Cummins, but toys are one thing and building something to reliably "do work" is a different process IMHO.