Ram 1500 EcoDiesel

[KrisZ]

Originally Posted By: dave1251
Originally Posted By: OVERKILL
Originally Posted By: dave1251
But torque is more important when hauling a load vs horsepower. Torque is the capability, horsepower is the ability to get the job done faster. Without sufficient torque you will never get your load moving. That is why even some semi engines that have a 450HP will have 4 or 5 times of this amount in torque output.


Torque is a measure of twisting force, it doesn't imply work being performed. You can have torque without movement. However, horsepower is work being performed. The higher the horsepower, the greater the amount of work being performed.

Now, horsepower is derived from torque and RPM. RPM is the rate at which torque is being applied, resulting in work.

Here's the equation for horsepower:

Originally Posted By: Wikipedia
Torque is in pound-foot units, rotational speed (f) is in rpm and power is required in horsepower


So for example you can have two engines with vastly different amounts of torque, but as long as they make the same horsepower, they are able to perform the same amount of work:

So, say we have a diesel engine with the following specifications:

1,800RPM limit
1,500 lb-ft of torque

Using those two values, the diesel engine produces 514.1HP

Say we have a gasoline engine with the following specifications:

8,000RPM limit
337 lb-ft of torque

Using those two values, the gasoline engine produces 514.1HP


Both engines are able to perform the same amount of work. The difference is that the gasoline engine does it in "smaller chunks" by applying less torque, but at a greater rate. What this is relevant to is gearing. Since the diesel engine has a maximum RPM of 1,800, it must be geared accordingly. Since the gasoline engine has a 8,000RPM maximum, it can be geared steeper to be able to provide the same amount of force to the wheels to move the load.



Thank you for the physics lesson.


Not really. Work= Force*Distance, there is no power in the equation. So if you are not moving you are not doing any work, no matter how fast the engine is able to apply the said force.

That is why gearing, aka torque multiplication, plays a role as well as engine torque value. So using the above example, the engine with 337 lb-ft of torque would need a torque multiplication so high to match the 1500lb-ft engine, that the output gear would probably not fit in the engine bay.

Hence, we don't have big rigs with engines that have ~300 lb-ft of torque because both engines cannot perform the same amount of work all by themselves, they need appropriate gearing to do that and while in theory it can be done, but in practice it is not feasible.

 

[A_Harman]

Originally Posted By: KrisZ
That is why gearing, aka torque multiplication, plays a role as well as engine torque value. So using the above example, the engine with 337 lb-ft of torque would need a torque multiplication so high to match the 1500lb-ft engine, that the output gear would probably not fit in the engine bay.

Hence, we don't have big rigs with engines that have ~300 lb-ft of torque because both engines cannot perform the same amount of work all by themselves, they need appropriate gearing to do that and while in theory it can be done, but in practice it is not feasible.


It wouldn't be such a big deal to design a compound reduction gearbox to boost the 337 ft*lb of torque in the high speed engine to the 1500 ft*lb of torque put out by the low speed engine. But I agree that you wouldn't want to do that. The reason 8000 rpm racing engines are not used in big rigs is economics. They would burn way too much fuel and require too many rebuilds compared to the big diesel. And a truck driver would much prefer doing a 10-hour day driving an engine running 1800 rpm instead of 8000.

 

[Hokiefyd]

Originally Posted By: KrisZ
Work= Force*Distance, there is no power in the equation. So if you are not moving you are not doing any work, no matter how fast the engine is able to apply the said force.


Power IS the equation. Power is the measurement of the rate at which work is performed.

You said that if you're not moving, you aren't doing any work, no matter how fast the engine is able to apply the force. If the engine is turning, work IS being performed. Now, your VEHICLE may not be moving, but that doesn't mean that work isn't being performed. The crankshaft is spinning...work is being done. That work may be absorbed by a slipping clutch or torque converter, which means that it's being converted into heat. But work is being done.

 

[OVERKILL]

Originally Posted By: A_Harman


I added a few little qualifiers in your post to clarify the issue.


Yes, you are 100% correct, power is work being performed for a given amount of time, thank you for your edit

Quote:
Word problem:
An engine is producing 400 Horsepower. How much work does it do in 10 seconds?



2,200,000 lb-ft.

1HP = 550 lb-ft/s

400HP = 220,000 lb-ft/s, so over a 10 second period, we end up with 2.2 million lb-ft.

 

[IndyIan]

I think the big draw of the ecodiesel and the ecoboost is that they have lots of torque available at low rpm, just like any vehicle specifically made to pull, tractor, or tractor trailer. Sure the pentastar will do the same work, but only after 4 downshifts to get it into its power range.
For farm tractors a huge factor is lugability, or how much the torque increases as rpms drop, since many tractors can't downshift without stopping. Lugability allows you to hold the gear and still do the work(say climbing a hill in the field while plowing) but at a slower rate.
In a automatic pickup, lugability isn't as important but everyone likes how an engine can build torque without shifting all over the place.

 

[Hokiefyd]

Originally Posted By: IndyIan
but everyone likes some people like how an engine can build torque without shifting all over the place.


Fixed it for ya. ;-)

After years of owning only low-rev V-8 engines, I have grown to prefer an engine that can spin a little freer. Nothing wrong with V-8s...I'd just prefer one that spins to 6,500-7,000 and pulling to one that runs out of breath by 4,500 rpm because its torque peak is not far from idle speed.

 

[itguy08]

Originally Posted By: Miller88

Is it still that bad? I remember for a few years the bottom 4 were Chrysler, Dodge, Jeep, "RAM". Chrysler made some pretty unreliable vehicles for a while. Seems like they try to do more than GM or Ford for thinking outside of the box ... but just don't have the quality control (or engineering?) to make things work well.


Yup, it's still that bad:

 

[kkreit01]

I bet a lot of those issues are with the new 8.4 entertainment systems, and air suspensions. Both have been problem-some on the forums....just like Ford's growing pains with MFT a few years back.

My Ram has been problem-free, and my Jeep has had 1 some-what major warranty repair. However, I have read of a few stories of Grand Cherokees being in the shop more than on the road. I recently saw a used '14 Summit on the lot with 7k miles. I would be real worried to buy a used vehicle like that. Who would take that big of a loss and dump a $55K suv after a few months?

Interesting that Lincoln is way up the ladder -- when each model has a nearly-identical Ford twin. Of course Ford probably outsells them 100:1.

 

[SteveSRT8]

Originally Posted By: Hokiefyd
Originally Posted By: IndyIan
but everyone likes some people like how an engine can build torque without shifting all over the place.


Fixed it for ya. ;-)

After years of owning only low-rev V-8 engines, I have grown to prefer an engine that can spin a little freer. Nothing wrong with V-8s...I'd just prefer one that spins to 6,500-7,000 and pulling to one that runs out of breath by 4,500 rpm because its torque peak is not far from idle speed.


Nuttin' wrong with a power curve. Flat mesas of torque are very practical but rarely come in stimulating cars. Just be careful, as there are V8's with fun power curves and real revs on tap.

But it's a very personal thing...

 

[SteveSRT8]

Originally Posted By: kkreit01
Interesting that Lincoln is way up the ladder -- when each model has a nearly-identical Ford twin. Of course Ford probably outsells them 100:1.


VERY astute observation. The much adored JDP indices do not give production volumes, which are EXTREMELY relevant to the number of issues reported overall.

 

[rjundi]

Originally Posted By: itguy08
Another Swing and Miss by Chrysler...

Also, look here for the cost savings #s:

http://news.pickuptrucks.com/2014/02/gas-versus-diesel-do-the-math-first.html

In particular the costs broken down:

I'll make mine the superior Ecoboost, thanks. Ram = Pretty boy truck.


Gotta love fanboys who make this forum a validation for their purchase choices.

Glad they came up with the option. Diesels crush gasoline counterparts in torque if you do more than drive around with an empty bed or like effortless acceleration in normal driving. I believe this v6 pumps out 420lb-ft torque at 2000 rpm.

 

[Jarlaxle]

Originally Posted By: dave1251
Originally Posted By: Stewart Fan
Originally Posted By: A_Harman


My 235 HP Dodge Ram 2500 came from the factory with a 17,000 pound tow rating.


My '07 Ram 3500 with the 325/610 5.9 CTD was only rated for 15,500.

An '01 2500 wasn't rated for 17,000


No "only" 14,150lbs of trailer weight with GCWR of 20,00lbs.

But your view on horsepower and towing was refreshing for about the first 24 hours. But torque is more important when hauling a load vs horsepower. Torque is the capability, horsepower is the ability to get the job done faster. Without sufficient torque you will never get your load moving. That is why even some semi engines that have a 450HP will have 4 or 5 times of this amount in torque output.

Also the max towing rating is not totally dependent on engine output rather than the chassis, braking, differentials, and transmission.


NO, WRONG! HORSEPOWER (and proper gearing) is the relevant number. This is basic physics: one horsepower equals one horsepower!

 

[Jarlaxle]

Originally Posted By: A_Harman
Originally Posted By: KrisZ
That is why gearing, aka torque multiplication, plays a role as well as engine torque value. So using the above example, the engine with 337 lb-ft of torque would need a torque multiplication so high to match the 1500lb-ft engine, that the output gear would probably not fit in the engine bay.

Hence, we don't have big rigs with engines that have ~300 lb-ft of torque because both engines cannot perform the same amount of work all by themselves, they need appropriate gearing to do that and while in theory it can be done, but in practice it is not feasible.


It wouldn't be such a big deal to design a compound reduction gearbox to boost the 337 ft*lb of torque in the high speed engine to the 1500 ft*lb of torque put out by the low speed engine. But I agree that you wouldn't want to do that. The reason 8000 rpm racing engines are not used in big rigs is economics. They would burn way too much fuel and require too many rebuilds compared to the big diesel. And a truck driver would much prefer doing a 10-hour day driving an engine running 1800 rpm instead of 8000.


Not only is it not a big deal, it has been done! An M1 tank is powered by a turbine...it makes ~1500HP, and no more than 200lb/ft. (It idles over 10,000RPM and redlines north of 45,000.) It is simply geared way down to move the 60+ ton tank.

 

[itguy08]

Originally Posted By: rjundi

Gotta love fanboys who make this forum a validation for their purchase choices.


Why is that? Pickuptrucks.com did their tow test and found Ram had the lowest payload of ALL the 1/2 tons. As I found out, that directly correlates to tow ratings.

Everyone says they are below average in reliability.

If I wanted validation I'd have bought a GM as they have "the better quality" vs Ford. One thing is for certain, Ram is below average.

Quote:
Glad they came up with the option. Diesels crush gasoline counterparts in torque if you do more than drive around with an empty bed or like effortless acceleration in normal driving. I believe this v6 pumps out 420lb-ft torque at 2000 rpm.


Really? Cause any turbo engine has a flat torque curve.

Let me show you this, straight from the rear wheels of an Ecoboost:

 

[Hokiefyd]

Originally Posted By: SteveSRT8
Originally Posted By: kkreit01
Interesting that Lincoln is way up the ladder -- when each model has a nearly-identical Ford twin. Of course Ford probably outsells them 100:1.


VERY astute observation. The much adored JDP indices do not give production volumes, which are EXTREMELY relevant to the number of issues reported overall.


JD's numbers are normalized to production numbers. They are problems reported per 100 vehicles. So Lincoln's score of 104 is directly comparable to Ford's score of 140.

Lincoln had 104 problems per 100 cars, which means that, on average, every car had at least one problem and four cars had two problems.

Ford had 140 problems per 100 cars, which means that, on average, every car had at least one problem and 40 cars had two problems.

All the way down to Mini; with 185 problems reported for 100 cars, almost every car had two problems. Only 15 cars (out of 100) had one problem.

Again, JD isn't presenting an aggregate total of problems, they are presenting a rate of problems occuring.

 

[Coprolite]

Diesel will become more advantageous as the sulfur limits for gasoline get tighter and the price differential against diesel evaporates.

I am still waiting for a smaller truck with diesel. The ones I have overseas got quite good mileage while carrying heavy loads.

 

[RangerGress]

So much wrong in this thread it's embarrassing.

1. Hp isn't all that useful. Torque is all. Since HP really just boils down to torque X rpms, all hp really brings to the table is the ability for the engine to wind out.

I race cars. Hp has some utility because if your engine has a broad power band, say lots of torque from 3krpm to 7k rpm then you don't have to shift very often. That's good in a race car. In a DD hp isn't all that meaningful because once you get outside of the engine's optimum torque band you just shift gears. Hp doesn't bring anything to the table that a bunch of gears in your transmission can't substitute for just fine. The new Ram has 8 gears.

2. The payload capability posted in this thread is wrong. The payload in the Ram 1500 isn't great, but I'm ordering a Crew cab and it's published payload is ~1600lbs.

3. It's not reasonable to compare mpg figures across different engine types. Engines and engine management systems have efficiency characteristics that vary all over the map. My old 2006 Ford F-150 got 20mpg on the freeway but 7mpg pulling my 7klb enclosed trailer. My 2000 F-250 diesel gets 16 on the freeway and 13 towing. According to various reviews, it looks like the Ecodiesel will get 30mpg on the freeway and 17 towing my trailer. Note how the gas engine in the relatively late model F-150 fell on it's butt when towing, yet the F-250's diesel was barely affected by the load. My point is that one can't blithely make comparisons as to how different loads will impact an engine's efficiency. It has to be tested.

 

[supton]

Takes btu's to do work. Ecoboost and other tricks attempt to reduce waste when not working. Hardly a surprise that motors will start to converge to the same fuel usage when under load; actually it's a surprise when they don't, as it indicates one is better optimized for the work before it.

When people talk torque vs hp all I can think is: torque is low rpm horsepower. Lots of torque off idle vs little torque off idle, guess what: lots of torque off idle means it has more hp off-idle.

I agree, I prefer off-idle torque. I spend most of my life piddling around; high rpm hp is something just not useful in daily life. I'd rather tow, or drive up a hill, in top gear than in 2nd so I had enough hp (and rev's) to get the job done. But for something that is rarely used at its limit, like a truck which is usually being used as a commuter and only occasionally towing at its limit, a wide torque band and lots of rev's ought to get the job done.

I've said it before: if I couldn't hear the motor doing its job, nor feel it shift, I probably wouldn't care what it's really doing under the hood. I doubt the typical consumer would either.

 

[JHZR2]

Originally Posted By: itguy08
Really? Cause any turbo engine has a flat torque curve.

Let me show you this, straight from the rear wheels of an Ecoboost:

Im sorry but those torque curves look sort of lousy. My turbo cars put more or less full torque right off idle.

Why does that thing take to nearly 3000RPM to make max torque, when you need it at like 1200 and then to be sustained?

 

[RangerGress]

Ecoboost sucks as a tow vehicle. Under a decent load the mpg drops below 10.

In the post above I neglected to mention diesel prices. Lots of talk in this thread of a big delta between gas and diesel prices, but the delta is exaggerated. Diesel prices vary far more than gas prices so you have to shop a little harder. I see a 40cents/gallon delta within 10mi of our house all the time. When I was towing with my 2006 F-150 I had to buy midgrade because the tow "tune" that was intended to spare the transmission by reducing downshifting, required midgrade octane. By checking diesel prices on the Internet I was always able to find diesel for 7-8% more then midgrade gas.

So once/month I tow 12-14hrs round trip to an event. With the F-150 I got 7mpg, and with the Ecodiesel it's looking like 2.5x that. 2.5x the gas mileage with 7-8% more expensive fuel. That's not chump change.