Ram HD 1000 lb-ft MPG loop

[ib516]

Towing 29k. Nice to see they have a gauge that tells you how "full" the DPF is now. That's handy....

VIDEO

Almost 9mpg pulling 29k, which means about 37,000 GCW. Pretty incredible. Interesting that the driver information center (EVIC) mpg was dead on too.

[ShinerBock]

FishOnOne wrote:
Kind of like outboard motors. The current crop of four stroke V6 motor configurations are typically 200, 225, 250HP and are all essentially the same except for some different tuning. Having said that, my experience is a boat rigged with the highest HP motor usually last longer than one rigged with the lowest HP motor, because the higher HP engine can turn a larger prop and move the boat at a given speed while running lower rpms compared to the lower HP motor running that same speed.

Exactly! Aside from maintenance, the duty cycle of the engine plays a large role in longevity. The harder it has to work, the shorter it's expected lifespan.

Heck, even Howstuffworks.com gets it.

"How the car or truck is driven also affects how long the engine lasts. The harder an engine has to work, the shorter its lifespan tends to be. Applications like towing heavy loads, repeated extreme acceleration and deceleration, revving the engine past its redline or driving at top speed for long periods of time can all decrease how long an engine lasts."

Factors Affecting Automotive Engine Longevity

If you had two of the same exact medium duty truck pulling the exact sames loads at 65 mph with one truck having a 200hp/520lb-ft B6.7 and the other having a 325hp/750lb-ft B6.7L, the 200hp will have to work much harder at higher rpms to pull the load more often increasing wear and reducing longevity. However, the 325hp truck will cost more up front and there is a fine line where that higher cost will pay for itself or the lower power variant will be more cost effective in a fleet of trucks. This is why multiple power levels are provided for these various applications and duty cycles, not because the lower power versions last longer.

Same goes for gas versus diesel. Yes, the gas will not last as long pulling the same loads, but it costs a lot less up front than a diesel. Sure you will get your money back in the long run and a consumer buying a vehicle for personal use can easily wait to get their money back on one vehicle, but some fleets may not have the up front capital for tens or hundreds of diesel trucks even though it may or may not be the more cost effective option in the long run.

[FishOnOne]

Kind of like outboard motors. The current crop of four stroke V6 motor configurations are typically 200, 225, 250HP and are all essentially the same except for some different tuning. Having said that, my experience is a boat rigged with the highest HP motor usually last longer than one rigged with the lowest HP motor, because the higher HP engine can turn a larger prop and move the boat at a given speed while running lower rpms compared to the lower HP motor running that same speed.

[ShinerBock]

wnjj wrote:

ShinerBock wrote:
Actually the article I posted stated exactly have been saying the about how horsepower levels vary depending on the application the engine will be used and and they are not decreased for longevity reasons.

If not for longevity, what possible reason is there to suggest a lower HP for a truck that is working in the mountains?

Cost would be the only reason to spec a lower hp truck. If it will bused one the highway or for heavy loads, then a higher horsepower is recommended but you will have to pay more for the driveline to support that added power and GVWR/GCWR. Similar to how you have to pay more for the Aisin if you want the 400 hp/ 1,000 lb-ft Cummins and the 30k tow rating.

However, it if it used in low speed urban applications in the mountains then a lower hp may be acceptable if you are wanting to cut down on upfront cost, but it may lead to increased wear if you go too low and the engine has to work hard all the time.

Essentially, the only negative for going too high for the application is up front cost, and the negative for going too low for an application is longevity.

"Matching the right hp and torque ratings to your application. How do you choose among hp and torque options? An underspec’d engine presents performance and potential premature maintenance issues. If you over-spec, you pay a much higher cost per unit without a corresponding return on investment. How do you strike the right balance?"

All About Medium-Duty Work Truck Engines

[wnjj]

ShinerBock wrote:
Actually the article I posted stated exactly have been saying the about how horsepower levels vary depending on the application the engine will be used and and they are not decreased for longevity reasons.

If not for longevity, what possible reason is there to suggest a lower HP for a truck that is working in the mountains?

[ShinerBock]

RoyJ wrote:


So, let's see, even when there's clear evidence, from your own article, that supports a theory different than yours, you'll still find every excuse in the world to deny it?

Re-read what McKenna said, drivetrain component wasn't the factor in THIS case, you made that up. He clearly said it was driven by elevated duty cycle of doing heavy haul in mountains.

At this point nothing would convince you. Again, start a new thread, I'm done here.

Actually the article I posted stated exactly have been saying the about how horsepower levels vary depending on the application the engine will be used and and they are not decreased for longevity reasons. The right displacement of the hp level depends on the the duty cycle of the application which I am shocked that you,being the expert on medium/heavy duty engines and all, didn't know that larger diesel engines have more torque and achieve peak power/torque level at lower rpms. Actually... no I am not surpised especially since you thought all of these engine operated under the same constant load.

Uhm, I never said the said anything about drivetrain so I am sure where that is coming from. Being that he is the director of powertrain and the article was talking about engine ONLY, most of what he was talking about and what I quoted from him was about engine and how he stated that technology and materials used in today's engine allow us to have greater power densities without sacrificing engine longevity. However, other link have stated it if you would have taken the time read them which is obvious that you did not since we are still having this conversation.

"However, with diesel engines for Class 6 and 7 trucks, there may be 10 or more horsepower and torque ratings to consider, making engine selection significantly more complex. The approximate cost difference between the lowest and highest horsepower ratings, when factoring in a heavier transmission required for the higher horsepower engines, can run an additional $8,500-$10,000, or more.

Spec'ing Medium-Duty Powertrains for Optimum Performance



"The approximate cost difference between the lowest and highest hp ratings, factoring in a heavier transmission required for the 300 hp engine, is as much as $8,500. This variance in engine hp/torque availability and cost is common across all Class 6 and 7 truck OEMs"

https://www.government-fleet.com/146164/all-about-medium-duty-work-truck-engines

[RoyJ]

Cummins12V98 wrote:

Nope! It was a dog to protect the engine. De tuned.

ShinerBock wrote:
That is not accurate and this old assumption needs to go away with the Dodo.

RoyJ wrote:
So you're saying given the exact same displacement, and the same metallurgy of the components - their operating life remains identical regardless of stress level?

ShinerBock wrote:
Yes, at least from what I have seen in the dyno cells when I worked at Cummins.

He emphasizes that before making such a decision it’s crucial to study the expected duty cycle for the truck. “If the truck is going to be loaded close to maximum or operate out West or through Eastern mountain ranges on a consistent basis, we would recommend the customer spec an MP8 with the lowest horsepower to get the job done,” McKenna explains.

So, let's see, even when there's clear evidence, from your own article, that supports a theory different than yours, you'll still find every excuse in the world to deny it?

Re-read what McKenna said, drivetrain component wasn't the factor in THIS case, you made that up. He clearly said it was driven by elevated duty cycle of doing heavy haul in mountains.

At this point nothing would convince you. Again, start a new thread, I'm done here.

[ShinerBock]

RoyJ wrote:


And THIS is why you have to be careful cherry-picking quotes to only suit your agenda Shiner. Did YOU read the entire article you posted?

Yes,it mirrors exactly what I have been stating, but also talks about multiple displacements being better suited for certain applications and duty cycles.

RoyJ wrote:
Read that very clearly - what word did he use? Duty Cycle

And that is exactly one of the things I said effects the longevity of an engine. You can have the same power output for an application, but two different duty cycles in those applications. You can have two applications that need 400hp to tow the same 50k at 65 mph, but one duty cycle is constant grades while the other is mostly flat land. A larger displacement 350hp engine is needed for the one pulling grades because it will run at a lower rpm, while the smaller displacement is probably better for the flat land because its fuel cost will be lower especially since it will not be at full load all the time.

RoyJ wrote:
Why does he advise you to select the LOWEST hp, only to up-rate it later for resale? It's because it affects engine life at high duty cycle, despite them all being "emissions certified".

To save on upfront costs of having to pay for added drivetrain components to handle the higher power and to keep their drivers from tearing up the driveline. We have fleets that do this all the time where they spec the minimum hp allowable for their application and the turn it up to the highest they can for resale since higher power figures are more desirable to used truck buyers. I have personally reprogrammed many CAT engines to higher power levels for resale.

However, you only have a certain emission certified power levels you can increase the truck to depending on application. Some applications may not allow the engine to be programmed at the highest possible power level, but can be programmed at a higher level that it currently is. You need to register the ESN to get the tune from the engine manufacturer and they will let you know the highest power level you can go.

RoyJ wrote:
Notice above a GCW he made a cut-off based on DISPLACEMENT? We know the upper end of the 13L rating (485hp) overlaps with the lower end of the ISX15 rating (400hp, EPA13). Why didn't he simply say: beyond 130k lbs, use a 450+ hp engine?

Because a 485hp 12.9L has lower longevity that an ISX15 @ 485hp.

Actually if you read, it is based on application and duty cycle. A 485hp 12.9L may be great in a flat land application duty cycle, but it does not produce enough torque in an application with a lot of grades pulling heavy loads. Similar to how a lower power level 6.7L does not produce enough torque and will not last long in an application meant for a higher power level. The less power/less torque engines will be at max load almost more often than higher horsepower/higher torque/higher displacement engine won't in these applications.

Also, higher the displacement engines make peak horsepower and torque at lower rpms. Generally, the higher displacement, the lower the peak power/torque. This alone allows bigger displacement engines to last longer because they don't have to work as hard/turn as many rpms to do the same work as an equally power rated smaller displacement engine. However, in certain applications where you are not loaded heavy all the time like fuel truck, a smaller displacement engine with the same power level is ideal since it is more efficient and lighter.

RoyJ wrote:
He explains that with such duty cycles, “higher displacement is an advantage when it comes to fuel economy. The larger engine size enables broader power and torque curves so the engine can be operated at lower rpms than smaller engines for improved fuel economy. Given that as well as the proven longevity of these engines, we simply do not see the 15L market declining.”

He specifically talks about LONGEVITY of the "15L market".

Again, based on application and is due to the fact that higher displacement engine make power at lower rpms than smaller engines. In most heavy haul applications with a lot of hills, a smaller displacement engine will not last long and will be very inefficient because it will have to be at much higher rpms than a larger displacement engine.

Same goes with a lower power engine of the same displacement in an application meant for a higher power engine.

RoyJ wrote:
Again, there's hp overlap between and ISL/ISM(ISX12)/ISX15. I've shown you before an ISL can be up-rated to 450hp for fire/emergency/RV applications.

The reason for the overlap is due to what I stated above. Yes, they are making the same power, but they are all spinning at different rpms to do it. The larger engine will spin at lower rpms due to their power band. It's like pulling up a grade with a N/A V6 of the same horsepower as a V8 that makes more torque at lower rpm.

RoyJ wrote:
Why don't they spec a 450hp ISL for a 160,000lbs B-train? Because it won't have the desirable service life of a 450hp ISX15. And before you say it, yes, both engines will be operating "flat out WOT", so emissions efficiency is not a concern...

Again, because the make power/torque at different rpms. A 450 ISL or L9 only makes 1,250 lb ft of torque at 1,400 rpms (and is only available in medium duty applications) while a 450 X15 makes 1,850 lb-ft at 1,000 rpm. You will not be at as high of an rpm in the ISX15. The ISX15 also reaching peak hp at a lower rpm as well which inherently makes it last longer in that application since it would not be working as hard. That is if the ISL could move the load with 600 lb-ft less. Oh, and before you say just add shorter gears, if you do that then it will not be able to run at highway speeds.

[RoyJ]

ShinerBock wrote:


Sizing the engine

And THIS is why you have to be careful cherry-picking quotes to only suit your agenda Shiner. Did YOU read the entire article you posted?

He emphasizes that before making such a decision it’s crucial to study the expected duty cycle for the truck. “If the truck is going to be loaded close to maximum or operate out West or through Eastern mountain ranges on a consistent basis, we would recommend the customer spec an MP8 with the lowest horsepower to get the job done,” McKenna explains.

Read that very clearly - what word did he use? Duty Cycle

Why does he advise you to select the LOWEST hp, only to up-rate it later for resale? It's because it affects engine life at high duty cycle, despite them all being "emissions certified".

“Our 13L MX is integrated into all of our models except for refuse trucks,” Sproull relates. “It can handle GCWs up to 130,000 lbs.; get beyond that, and the ISX15 would come into play.”

Notice above a GCW he made a cut-off based on DISPLACEMENT? We know the upper end of the 13L rating (485hp) overlaps with the lower end of the ISX15 rating (400hp, EPA13). Why didn't he simply say: beyond 130k lbs, use a 450+ hp engine?

Because a 485hp 12.9L has lower longevity that an ISX15 @ 485hp.

Starting from the top, Jones says that Cummins regards the 15L market as very stable “and one that we might argue will grow. There’s simply no replacement for (higher) displacement when it comes to fuel economy, reliability and longevity in a 65,000- to 80,000-lb.-GCW operation running mostly on highway pulling loads.”

He explains that with such duty cycles, “higher displacement is an advantage when it comes to fuel economy. The larger engine size enables broader power and torque curves so the engine can be operated at lower rpms than smaller engines for improved fuel economy. Given that as well as the proven longevity of these engines, we simply do not see the 15L market declining.”

He specifically talks about LONGEVITY of the "15L market".

Again, there's hp overlap between and ISL/ISM(ISX12)/ISX15. I've shown you before an ISL can be up-rated to 450hp for fire/emergency/RV applications.

Why don't they spec a 450hp ISL for a 160,000lbs B-train? Because it won't have the desirable service life of a 450hp ISX15. And before you say it, yes, both engines will be operating "flat out WOT", so emissions efficiency is not a concern...

Once again - start a new thread and we can continue the discussion. I have plenty of other sources.

[ShinerBock]

Cummins12V98 wrote:
You guys have fun. Tired of looking for topic related info.

Actually, the 400 hp/1,000 lb-ft 6.7L Cummins has a lot to do with what we are talking about.

Roy is saying the reason for the various power levels is due to longevity. He thinks that the higher the power level the less longevity meaning that the 400hp/1,000lb-ft Cummins will not last as long as the 200 hp medium duty version or even the 370 hp/850 lb-ft version with the 68RFE.

I on the other hand am saying that the reason for the different power levels in the 6.7L is due to emissions of each class/configuration, spec'ing the engine for each application, and cost ( i.e. having to upgrade the drivetrain to for each power level similar to how you have to pay more for the Aisin to get 400hp/1,000lb-ft). From my experience in seeing these engines tested at Cummins, there was no significant difference in the longevity of each stock power level or even higher than stock power levels(to a point) if correctly spec'ed for the application, and longevity is was more effected by duty cycle, maintenance, and how many cold starts per miles driven. The internals were shown handle well over these power levels day in and day out without any significant or noticeable reducing in their longevity.

[Cummins12V98]

You guys have fun. Tired of looking for topic related info.

[ShinerBock]

RoyJ wrote:
All you manged to show was the correlation between hp level and emissions - that's not "backup" to your statement that hp has no correlation to engine life.

What I said was a lower hp will effectively enhance engine life. You failed to prove otherwise.

Start a new thread and I'll show you plenty of industry evidence. There's nothing magical about "MD trucks" - every engine on earth, steam turbine, lawn mower, ship engine, jet engine, bulldozer, behave the same way. Increase power output, and down goes the life expectancy. It's comical you even try to deny that.

It is clear that you didn't read any of the links I posted. They all stated what i have been saying that the reason for multiple power levels in medium duty trucks is due to emissions, application, and cost. Not one of them say anything about how higher power levels not lasting longer unless it is the wrong power for the application where a higher power level in an application where a lower power level will do will have a lower return on investment due to the increased up front costs, and a low hp engine will not last long in an application meant for a high hp engine because it has to work to harder. You are not taking real world applications into account in this fantasy land where all engine run at a constant speed.

I don't see how it is that hard for you to understand given all of the links and information I posted even though you have failed to provide one link proving otherwise. You have absolutely zero experience with modern medium/heavy duty diesel engines and you are trying to tell me and all of the experts in the industry in the links I have provided that we are wrong.

Here are some more links. Please read them because they back up exactly what I am saying.

This one also goes into having the right displacement for right application as well as power level, but it also backs up what I am saying.

"According to David McKenna, director of powertrain sales & marketing for Mack Trucks, truck engines have in the past several years evolved rapidly with new technologies to deliver greater efficiencies to meet customer expectations.

He says there now is a trend to smaller-displacement diesels for certain applications.

“At one time,” he relates, “it was a given that going to a smaller engine that produced higher horsepower would result in the trade-off of shorter longevity. And that was acceptable to some customers running ultra-light operations. But fast forward 20 or 25 years to today, and now we have the technology—including the materials the engines are built from—to make them lighter without sacrificing performance or longevity.”

McKenna adds that by one mark engines have changed markedly in the past 30 or more years. “Back in the ’70s,” he points out, “the average power density for highway diesels was 25 hp. per liter. In the ’80s and ’90s, that measure rose to between 29 and 31 and now it ranges from 36 up to 39 hp. per liter. So the size and weight once needed to get 350 hp. from an engine can now deliver 400 hp.”

Sizing the engine



"If you’re spec’ing a Class 6 or 7 truck, engine selection becomes more complicated. For example, the Isuzu Diesel 6H 7.8L in the Chevrolet Kodiak C-7500 offers five different horsepower and torque options, ranging from 215 hp and 560 ft.-lb. torque to 300 hp and 860 ft.-lb. torque, with 230 hp and 260 hp in between. The approximate cost difference between the lowest and highest hp ratings, factoring in a heavier transmission required for the 300 hp engine, is as much as $8,500. This variance in engine hp/torque availability and cost is common across all Class 6 and 7 truck OEMs.

Matching the right hp and torque ratings to your application. How do you choose among hp and torque options? An underspec’d engine presents performance and potential premature maintenance issues. If you over-spec, you pay a much higher cost per unit without a corresponding return on investment. How do you strike the right balance?"

All About Medium-Duty Work Truck Engines



"Consider where your trucks will do the majority of their hauling – whether it’s in the city, the highway or in suburban areas will determine how they should be geared. Trucks properly spec’d for city applications have higher axle ratios and lower speeds.

Trucks spec’d for highway or suburban runs have a lower rear axle ratio for higher speeds and better fuel economy. Running city spec’ed trucks on the highway will eat away at your profit line through increased fuel consumption and piston crown and bearing failures in the engine."

Medium-duty spec’ing tips

[RoyJ]

All you manged to show was the correlation between hp level and emissions - that's not "backup" to your statement that hp has no correlation to engine life.

What I said was a lower hp will effectively enhance engine life. You failed to prove otherwise.

Start a new thread and I'll show you plenty of industry evidence. There's nothing magical about "MD trucks" - every engine on earth, steam turbine, lawn mower, ship engine, jet engine, bulldozer, behave the same way. Increase power output, and down goes the life expectancy. It's comical you even try to deny that.

[ShinerBock]

And some people believe that the earth is flat as well, but that does not make it so.

Back it up with facts. I have backed mine up with actual words from truck engine makes and other professionals in the industry saying varying power level is due to emissions, application, and cost.

Back up yours with someone from the industry saying the same thing you are that the reason for lower power levels is due to engine longevity in modern medium duty trucks.

[RoyJ]

Nah, power output of an engine determines its life, and its ability to serve continuous duty power loads vs low duty cycle occasional power.

GVWR requires power, but not longevity. If you want both (train, prime movers), then you need larger displacement engines at lower state of tune.