Diesel truck with best MPG

   / Diesel truck with best MPG #141  
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!)
 
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   / Diesel truck with best MPG #142  
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.
 
   / Diesel truck with best MPG #143  
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.
 
   / Diesel truck with best MPG #144  
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.
 
   / Diesel truck with best MPG #145  
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.
 
   / Diesel truck with best MPG #146  
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
 
   / Diesel truck with best MPG #147  
Diamondpilot said:
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?
 
   / Diesel truck with best MPG #148  
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
 
   / Diesel truck with best MPG #149  
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.
 
   / Diesel truck with best MPG #150  
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
 

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