Diesel truck with best MPG

[Code54]

I have to disagree - RPM's do have an effect on wear - rub 2000 grit sandpaper across a table 10 times in a minute, on a second table do it 100 times in a minute, then on the third table take it to 1000 times in a minute - after 10 minutes which one has more wear? The one where you rubbed it 10000 times of course. Same exact principle in an engine. If you do some additional research you will note the average gas engine is not expected to go 300,000 miles without a rebuild, this is especially true with big bore v8's that go into pickups. If all things were equal for these gas engines as your statement portrays why are the "big rigs" not gas instead of diesel - they could just jump the RPMs up, get better mileage, the same power, lower maintenance costs, lower initial cost, same amount of time to a rebuild and get cheaper fuel - seems like a massive advantage for the transportation industry.

As for making the undercarriage last, I agree that washing the underside throughout the year and especially in the winter is a great way to make things last longer. It is a lot more work and sort of a dirty job but it is amazing how much better it holds up overtime. (or the other option is move south where their is no sea water or salt, that really makes it a lot easier!)

 

[dodge man]

400 ft-lbs = 800 ft lbs??? I don't think so! Maybe the horsepower will be the same at the RPM's you listed, but what will the torque be on the gasser at the lower rpm? Take an extreme case a 900cc motorcycle engine vs a 900cc diesel tractor engine. The motorcycle engine is probably making 5 times the horsepower as the tractor engine. In theory, it would power the tractor, but how long will it last at 10,000 rpms? The diesel engine won't work on a motorcycle anymore than a high strung motorcycle engine will work on a tractor. My point is you just can't compare power curves between diesel and gas engine, they are too much different.

 

[buickanddeere]

400 ft-lbs = 800 ft lbs??? I don't think so! Maybe the horsepower will be the same at the RPM's you listed, but what will the torque be on the gasser at the lower rpm? Take an extreme case a 900cc motorcycle engine vs a 900cc diesel tractor engine. The motorcycle engine is probably making 5 times the horsepower as the tractor engine. In theory, it would power the tractor, but how long will it last at 10,000 rpms? The diesel engine won't work on a motorcycle anymore than a high strung motorcycle engine will work on a tractor. My point is you just can't compare power curves between diesel and gas engine, they are too much different.

The sand paper example is invalid as the ratios are totally out of line.
10,000 hrs at 1800rpm is just over 1,000,000,000 revalutions .
Tell me how 3600rpm up a hill for 30 seconds is going to make any measurable difference.
If you do the math, the extra 900 rotations a few times per trip is a rather small factor vs the 1,000,000,000 turns in a life time.
There are some people here who are confusing light duty truck engine durability which spend the bulk of their operating life. At less than rated rpm and at 40-60 HP rolling down the road . Instead of producing 90+% of rated power when ever running.
An engine where the concern lays about rpms is a totally different application of being a prime mover. Which is not a set of parameters to measure a light truck engine.
As far as gassers go. They are the low rpm torquers of the gasoline engine family.
The only reason diesels are not reved higher . Is the short cam timing required to obtain enough compression pressure/heat to start when cranked. The short cam timing doesn't allow the engine to breath at high revs.
Ever wonder how a diesel makes high rpm power at pulls? It's cammed like a gasser and started with either the high cranking rpms.

 

[buickanddeere]

Just saying the diesel was the first choice until the EPA and CAFE ruined a good thing. The introduction of common rail injection and now the particulate filters . Also the diesel now being over priced vs. gasoline compared to 20-30 years ago is a factor.
Gassers have came a long way from the sputtering short lived, fuel hogging clunks they used to be.

 

[Code54]

I agree about the particulate filters (PF) and the pricing. The PF killing the ability of the engine to breath and hurt the fuel mileage. Diesel are over priced there is no doubt about that. I don't think that are really worth the 8K added price but for me it was a needed option. The only good thing is mostly you do get a higher resale on a diesel over a gas motor so I hope to recoup at least part of the investment when I sell it down the road.

 

[Diamondpilot]

Just saying the diesel was the first choice until the EPA and CAFE ruined a good thing. The introduction of common rail injection and now the particulate filters . Also the diesel now being over priced vs. gasoline compared to 20-30 years ago is a factor.
Gassers have came a long way from the sputtering short lived, fuel hogging clunks they used to be.

I have not agreed with most of this thread but this post is spot on. Diesels have lost the edge other than the low end torque dept but the gasers are so good now days and will only get better. Just look at what Ford has done with that little 3.5L Eco Boost that runs circles around the big blocks of just 10 years ago.

As for the diesels lasting forever, that is kind of true and kinda not. I know two guys with diesels with over 500,000 miles. One is a 04 Ford F-350 and the other is a 05 Dmax. The Ford has had 1 tranny, a transfer case, 2 turbos, 3 complete front ends, a rear axle rebuild, numerous seals, injectors, glow plugs, sensors, ect. The Dmax is on its 3 rear axle, 3 tranny, new front end, a couple of alternators, a radiator, numerous hoses and seals, glow plugs, 2 sets of injectors, ect. There is no way anyone would put this much money into a gasser. For what these guys have spent they could have bought a new truck at around 300,000 miles when the repairs started stacking up. To be honest, both trucks are just plain worn out.

Chris

Chris

 

[Peacock]

I have not agreed with most of this thread but this post is spot on. Diesels have lost the edge other than the low end torque dept but the gasers are so good now days and will only get better. Just look at what Ford has done with that little 3.5L Eco Boost that runs circles around the big blocks of just 10 years ago.

As for the diesels lasting forever, that is kind of true and kinda not. I know two guys with diesels with over 500,000 miles. One is a 04 Ford F-350 and the other is a 05 Dmax. The Ford has had 1 tranny, a transfer case, 2 turbos, 3 complete front ends, a rear axle rebuild, numerous seals, injectors, glow plugs, sensors, ect. The Dmax is on its 3 rear axle, 3 tranny, new front end, a couple of alternators, a radiator, numerous hoses and seals, glow plugs, 2 sets of injectors, ect. There is no way anyone would put this much money into a gasser. For what these guys have spent they could have bought a new truck at around 300,000 miles when the repairs started stacking up. To be honest, both trucks are just plain worn out.

Chris

Chris

How in God's name has a fella gone through 3 Allison trannies and 3 AAM axles?

 

[Diamondpilot]

How in God's name has a fella gone through 3 Allison trannies and 3 AAM axles?

Both trucks are bone stock. Not new trannys, just rebuilds. Same with the rear axles. Mainly seals on the rear axles seem to be the problem area.

The point is on both these trucks of two different brands once they hit about 300,000 miles the repairs really stack up. The trucks are just worn out and not reliable for doing the work they were when newer. I know a few guys with gas trucks with 250,000 or more and they are worn out also or getting near. Yes, the diesel engine trucks are still running strong but the other stuff really adds up. I am not anti diesel, I have one and owned 4 others in my time. Just dont think I would buy another unless something changes. The gassers are just too good now days.


Chris

 

[Peacock]

Well my own truck has well over 300k on it with very minimal repairs.

At the shop I work in we service quite a few Cummins powered trucks with well in excess of 300k with relatively few real repairs. Basically the only trucks that we actually replace parts like transmissions and axles on have had little to no maintenance.

Just had a guy with 830k in his '03 3500 2wd Ram. We did 100% of his service. In that time the only stuff we did were 1 set of injectors, 1 transmission overhaul and then a few seals including a new timing case gasket(this is pretty intrusive on a CTD). The truck was used for travel trailer deliveries all across the country. It literally had a trailer hooked to it constantly.

 

[Diamondpilot]

Well my own truck has well over 300k on it with very minimal repairs.

At the shop I work in we service quite a few Cummins powered trucks with well in excess of 300k with relatively few real repairs. Basically the only trucks that we actually replace parts like transmissions and axles on have had little to no maintenance.

Just had a guy with 830k in his '03 3500 2wd Ram. We did 100% of his service. In that time the only stuff we did were 1 set of injectors, 1 transmission overhaul and then a few seals including a new timing case gasket(this is pretty intrusive on a CTD). The truck was used for travel trailer deliveries all across the country. It literally had a trailer hooked to it constantly.

The Ford I mentioned also hauled campers, the GM hauls tractors. Don't get me wrong, they both still run and will probably hit double that millage but the rest of the truck still needs stuff over time. All brands and all trucks will. Seals, hoses, brake lines, bushing, springs, shocks, switches, knobs, ball joints, U-joints, bearings, ect. It gets to the point where its not worth the battle and its time to retire it to farm duty where it never goes far from home.

I have personally seen two trucks with over 1,000,000 miles. One was a GM gasser about 12 years old that delivered paper all over Chicago. The guy told me it was on its 4th engine and I dont remember all the other stuff he had replaced. The other was a 04 F-250 that delivers sea food in Florida. It was a diesel and was on the original engine and again had multiple other things replaced. Its just a fact of life that they will wear out or last forever if you want to just keep throwing parts on them.

Chris

 

[forgeblast]

Doesn't help. The stuff bubbles and holds salt and moisture against the metal. Oiling twice a year and pressure washing salt and mud out of crevices will get a chassis to 15-20 years instead of 10-15 years. This still leaves items like rotten brake and fuel lines. Rusted through rear diff coves, fuel tanks or oil pans. Any work starts to require a torch or penetrating oil to reduce the number of twisted off fasteners.

Thanks for the info, It will keep me from wasting money!

 

[dieselcrazy]

I think as far as best mpg would be the first gen. Dodge cummins '92 - '97, and some in '98, 12 valve 5.9 liter. I've owned a 93 4x4 regular cab 5 speed with wide oversized tires, ran a tank through and checked it running 65 - 70 mph and got 24 mpg. Engine was stock.. I owned a '98 4x4 automatic 24 valve quad cab that best averaged 18 mpg. Owned a '99 4x4 5 speed quad cab, 18 mpg,, put a chip, intake, exhaust on, & on hi setting, still 18 mpg (normal driving). Owned a '06 4x4 automatic mega-cab stock, and normal to easy driving saw 16 to 18 mpg.. All Dodge w/ the cummins. My grandpa had a 2 wheel drive '93 or last year of the first gen. dodge WITH the overdrive, and saw 26 mpg driving from AL. down to FL. to buy a light airplane (empty) , and towing a light trailer that came with the airplane back to AL. checked a tank of fuel at 24 mpg! - this truck had less than 20,000 miles on it. My '93 4x4 had 250,000 miles. -sold only because manual trans. needed rebuild & stiff ride, -wish now I would have kept ... '06 vw auto Jetta diesel 40 to 45 mpg... '01 vw manual 5 spd.Jetta diesel 38 to 45 mpg., -tuned up...

 

[3v0]

Obviously there are parts of the country with little rain and no salt on the roads in the winter. Older trucks from these areas do not have issues with rust esp frame rust.

I have an 78 F150 Colorado truck and the only rust is above the rear wheel arches.

 

[alaskakubota]

When people say they pull 20,000 lbs and get 15 mpg on here i discredit the whole statement. Not going to happen unless coasting. I think most people that own these beasts see 17 +/-1 most of the time. Sure you might hit 20mpg for a 5 mile staight away. I know I cant make it a whole tank without towing anything, but looking at my lie o meter on my 07 5.9 cummins, I see 18ish and I know that is off by a few. ANd it aint reading low! I have 6 speed manual and a gear vendors overdrive. My 02 got around the same, my 98 12 valve got around the same, and my 97 7.3 was real close to that as well. Pulling 24,000 lbs I see 9. I need the secret recipe of getting 15 pulling 20,000 as I will change my style. Pulling enclosed trailer I get 10 which is 27' but high. I used a buddy's 07 duramax (lost cylinder #6 on stock truck at 87,000 miles and out of warranty) and I got the same mileage as my dodge. THey all are close. I just ordered a 13 5500 and I plan on getting 13 average. Cant compare against 2500 but dont read all the hype. Some one said 74mph, and 24 or 25 mpg. WHatever!!!!!!

 

[sd455dan]

OK for sake of argument I will you the 400 =800 argument (especially since I saw the same argument stolen from another site). But while you are running twice the rpm to do the same work, I am putting less wear on my engine because it isn't turning nearly as many times.


Regardless, I like my diesel. I didn't say you had to.

There is something missing here, about how torque moves vehicles not horsepower, You can have torque without horsepower but you can't have horsepower without torque because horsepower is just a mathematical derivative of the torque and rpm


( resultant moment of Force applied at a distance ) twisting force , the ability to move heavy objects from a dead stop. Take that equalizing equation, if the object takes all of the torque to get it moving, I can hear that gas engine revving twice as high, to get the horsepower and totally smoking the clutch trying to get the weight to start moving due to lack of low rpm torque.... or an automatic equipped gas engine barely moving the load because the gas engine isn't to it's torque peak so it stalls the converter and and doesn't have the torque to pull the RPMs up to get the load moving if it is not geared low enough.
.
Now I know this is an extreme example but there are cases where this has occurred, Diesels have an advantage in this respect... I guess one of the easiest ways to understand the way the vehicles act (feel) when moving heavy loads, is to actually pull a heavy trailer with two mathematically matched by horsepower, gas and diesel trucks.

Once most people have pulled the same heavy trailer with the gas verses diesel- differences become obvious... now if you only tow once in a while and only over short /medium distances, gas is the way to go....:2cents:

 

[sd455dan]

I think as far as best mpg would be the first gen. Dodge cummins '92 - '97, and some in '98, 12 valve 5.9 liter. I've owned a 93 4x4 regular cab 5 speed with wide oversized tires, ran a tank through and checked it running 65 - 70 mph and got 24 mpg. Engine was stock.. I owned a '98 4x4 automatic 24 valve quad cab that best averaged 18 mpg. Owned a '99 4x4 5 speed quad cab, 18 mpg,, put a chip, intake, exhaust on, & on hi setting, still 18 mpg (normal driving). Owned a '06 4x4 automatic mega-cab stock, and normal to easy driving saw 16 to 18 mpg.. All Dodge w/ the cummins. My grandpa had a 2 wheel drive '93 or last year of the first gen. dodge WITH the overdrive, and saw 26 mpg driving from AL. down to FL. to buy a light airplane (empty) , and towing a light trailer that came with the airplane back to AL. checked a tank of fuel at 24 mpg! - this truck had less than 20,000 miles on it. My '93 4x4 had 250,000 miles. -sold only because manual trans. needed rebuild & stiff ride, -wish now I would have kept ... '06 vw auto Jetta diesel 40 to 45 mpg... '01 vw manual 5 spd.Jetta diesel 38 to 45 mpg., -tuned up...

My 03 3500 H.O. Cummins Quad Cab short box SRW 4x4 NV5600 3.73 axles
Used to be driven 3000 miles one way, empty it could consistantly get 22 MPG hand figured on these trips...but I believe the #s are special as far as common rails are concerned because of these features of the HPCR 2003
1) Non EGR, (no in cylinder egr cam either)
2) No catalytic converter
3) No dpf-or regen
4) No extra injection events compared to later versions
5) H.O. 305 hp 555lbs. torque not sure if the high output helps mileage or not - but that is how the truck is equipped

I believe they also changed the pistons, head, turbo and made other (improvements?) the following years, would love the extra HP and torque - but not if I have to give up any mileage to get it-Have read multiple sources stating that installing hubs on the front axle that can be free wheeled is worth 1.5 mpg, and tuner maybe another 1.5mpg should be able to get 25 empty hiway at say 62 mph ... plausibly When funds permit the MPG improvers. Maybe other years are better but 22 empty at 62 mph hiway and ONLY hiway is excellent imo The lie O meter reads +- 28+ cruising on level ground at just over 60 when the hand figured mileage comes out at 22

My vote for the common rails would be the above combo, but with 2 wheel drive and 3.42 or 3.23 axle if available...?? The first gens may still be the ultimate ticket ...mileage wise

I do wonder what can be wrung out of the new Dodge 1500 that is rated at 25mpg with a few mods- as far as unloaded hiway mileage???

 

[CliffordK]

Don't forget the 80/81/82 Diesel VW Caddy Pickups.

A bit smaller than some of the others, but it is hard to beat 45 MPG or so in a pickup.

 

[newbury]

Don't forget the 80/81/82 Diesel VW Caddy Pickups.

A bit smaller than some of the others, but it is hard to beat 45 MPG or so in a pickup.

It's not hard to beat if you don't have to carry anything.

One of the problems with them, besides the incredibly small cab, was their load capability about 1,000 lbs MAX, that includes 250lbs for me.

I owned a '79 VW Rabbit diesel, on one 400 mile trip, lightly loaded, it got 65 mpg. It usually got about 50 around town. But it had half or less the carrying capacity of my '09 VW JSW TDI which has gotten 47mpg.

I like the carrying capacity of my dually (about 2 tons plus) and the MPG of my TDI, they both have their place.

 

[Raspy]

My 03 3500 H.O. Cummins Quad Cab short box SRW 4x4 NV5600 3.73 axles
Used to be driven 3000 miles one way, empty it could consistantly get 22 MPG hand figured on these trips...but I believe the #s are special as far as common rails are concerned because of these features of the HPCR 2003
1) Non EGR, (no in cylinder egr cam either)
2) No catalytic converter
3) No dpf-or regen
4) No extra injection events compared to later versions
5) H.O. 305 hp 555lbs. torque not sure if the high output helps mileage or not - but that is how the truck is equipped

I believe they also changed the pistons, head, turbo and made other (improvements?) the following years, would love the extra HP and torque - but not if I have to give up any mileage to get it-Have read multiple sources stating that installing hubs on the front axle that can be free wheeled is worth 1.5 mpg, and tuner maybe another 1.5mpg should be able to get 25 empty hiway at say 62 mph ... plausibly When funds permit the MPG improvers. Maybe other years are better but 22 empty at 62 mph hiway and ONLY hiway is excellent imo The lie O meter reads +- 28+ cruising on level ground at just over 60 when the hand figured mileage comes out at 22

My vote for the common rails would be the above combo, but with 2 wheel drive and 3.42 or 3.23 axle if available...?? The first gens may still be the ultimate ticket ...mileage wise

I do wonder what can be wrung out of the new Dodge 1500 that is rated at 25mpg with a few mods- as far as unloaded hiway mileage???

I have an '04 305/555. These seem to be the best of the common rail for mileage and better than the 04.5 and later models.
I have a Smarty on mine that allowed me to advance the timing and it did help the mileage.
I also have Dynatrac free spin hubs and have seen no mileage increase with them. The 1.5 MPG increase just isn't there.

 

[dodge man]

My truck is also a 305/555 04. They are often called an early 04 as they were made before Jan. 1, 2004. They actually do have an extra injection event, they have two. I was able to haul down 15 mpg towing a 6000 lb trailer with a car on it a couple of weeks ago. I was surprised it was that good.