v10 torque vrs diesel

Here's the OP's original question. With all the side spats I'm sure he's moved on by now but just in case.

tres perros wrote:
Hello folks

I have been looking for a used class A leaning towards a diesel as I plan on towing a Jeep and travel west coast, rockies

Evidentially I am told that the newer V10 fords have very similar torque range ( a model change with an extra valve)

So Id love to hear some opinions regarding this, including if maintenance/warranty contracts are any cheaper...

Thanks ahead of time! This is a great forum and has been very helpful

Keith

Yes, maintenance contracts and overall maintenance will be cheaper but given your intended use I'd go diesel.

Reasons.
1. Generally heavier construction, including more towing capacity and CCC

2. Ride, can't beat air bags, and depending on the model even a 36' rig the only way you can tell a truck went by the other direction at 60mph on a 2 lane road is by watching it.

3. Engine noise is in the back, you can hold a conversation at normal levels going up an 8% grade while towing 6500lbs of Jeep and trailer.

4. Turbo diesels put out rated power up to 10,000'. Folks seem to like to toss around formulas, here's another one.
HP Loss = (elevation x 0.03 x horsepower @ sea level)/1000

A ways back after another thread like this I went to THIS website and did some calculations. Based on the latest and greatest 362HP Ford engine, if you go back to the more affordable 310HP engine (pre '05?) it gets correspondingly lower results.

Starting with 362hp ****** 350 hp turbo diesel
0000' 362.0 hp ************ 350 hp
1000' 351.1 hp ************ 350 hp
2000' 340.3 hp ************ 350 hp
3000' 329.4 hp ************ 350 hp
4000' 318.6 hp ************ 350 hp
5000' 307.7 hp ************ 350 hp
6000' 296.8 hp ************ 350 hp
7000' 286.0 hp ************ 350 hp
8000' 275.1 hp ************ 350 hp
9000' 264.3 hp ************ 350 hp
10000' 253.4 hp ************ 350 hp


Now the Diesel coach will weigh more, ours with 100gal fuel and 100gal water with stuff to camp for 4-7 days comes in at 25,300lbs and still has 2700lbs of CCC available.

For us the ride, quiet, CCC and towing capacity made it no contest. Believe me, I'm a cheap SOB, I tried to make a much cheaper (or newer/nicer) gas unit work but it just didn't pencil out as we spend all our time in the OP's target area.

One more article from the RV Tech Library to consider:

Torque:

We'll begin with torque. Torque is basically the measurement of force. It's raw energy or force at it's most basic level and it's measured in reference to a rotating shaft. Therefore it's an ideal measurement for automotive engines, which have a rotating crankshaft. Torque is measured in foot-pounds. If an engine has a shaft with a arm sticking out that is 1 foot long and it can lift 500 lb, then that engine is rated at 500 ft-lbs. If the arm is 2' long and still lifts 500 lbs, then that unit is rated at 1,000 ft-lbs, because 2' times 500 lbs = 1,000 ft-lbs. Conversely if an engine lifts 250 lbs with a 6' arm, then it is rated at 1,500 ft-lbs, because 6 times 250 = 1,500. However, if we shorten that arm to 2', it can lift 750 lbs, rather than 250.

Torque is a given "ability" to move something. It says nothing about the speed that it will lift it at, just the ability to lift it. The engine RPM does not affect torque. But by coupling this engine through a set of gears we can multiply torque. If this engine is turning 2,000 RPM and produces 1,000 ft-lbs of torque and we then reduce the gear ratio to 2:1 the output shaft will only be turning at 1,000 RPM but the 2:1 ratio will increase the torque to 2,000 ft-lbs. Therefore transmission (and rear axle) gearing can multiply torque at the expense of speed or RPM.

An RV is pretty heavy, therefore torque is important to get it moving. It will take more power to get it moving and for climbing grades than it will to keep it moving at speed on a level surface. That's why all vehicles use a transmission to gear down the engine, increasing torque when accelerating or climbing grades. Once at speed the transmission is placed in a higher cruising gear to keep the engine RPM down when the extra torque is not needed.

In order to climb a grade a given amount of torque is required. The torque required will depend upon the percent of grade as well as the loaded weight of the RV. If you do not have adequate torque available to climb that grade your speed will fall and you'll eventually come to a stop if the grade is long enough. But, as we saw earlier, by downshifting into a lower gear we increase our available torque at the rear wheels so that we can make it up the grade.

Note that so far we have not expressed anything about the speed at which we are doing this work, only how much torque is required to get it done.



Horsepower:

While torque defines how much work can be accomplished, horsepower determines how fast we can do it in. Horsepower is really nothing more than a mathematical equation. Horsepower is torque times RPM. The actual formula is:

Horsepower = Torque x RPM / 5252

We saw earlier that torque is multiplied by selecting different gear ratios but horsepower is not affected by RPM. When you select a lower, say 2:1 gear ratio, you increase your torque by 2 but your output shaft RPM is reduced by half so you don't gain or lose any horsepower. Because horsepower better defines the speed at which you can perform work it is more apt to define how fast you can accelerate or climb a grade, rather than the ability to do so.



Effects of Engine RPM:

We need to understand that a 400 HP engine doesn't put out 400 HP all the time. This power only comes in at it's rated peak power RPM. It develops very little power at idle and that power gradually increases throughout it's RPM range until it reaches it's peak power engine speed. We don't all drive around with our foot on the floor and the engine revving away at high RPM all day long so we rarely see the rated horsepower. Most of the time we are driving with far less.

Not all engines produce horsepower the same way. One engine may be rated at a higher horsepower than another but it may be a very steep climb to get to that rated power level, which may be at a very high RPM. The other engine might achieve it's lesser rating at a much lower RPM and the power may build up quite a bit faster than the one with a higher horsepower rating. Yet, the lower engine will actually have more power because those lower RPMs are where you will normally be using that engine. This is particularly common in diesel engines when compared to gasoline engines.

Remember, horsepower is torque times RPM. Engines produce more horsepower at higher RPM but torque drops off after a given point. Generally, the additional RPM is more than enough to overcome the drop in torque. A 340 HP 8.1 liter gas engine commonly used in an RV puts out 340 HP at 4,200 RPM and 455 ft-lbs of torque at 3,200 RPM. These are the maximums and the RPMs at which they occur. When driving down the highway at 2,400 RPM that engine will have somewhere around 300 ft-lbs of torque and 175 HP. Further slowing the revs down to 1,700 RPM by using the top overdrive gear will improve fuel economy by reducing the revs that engine is pulling. Unfortunately, the power figures drop even further. But, on a level highway, that's not a problem. A 5.9 liter Cummins ISB diesel is rated at 300 HP, which is 40 less than the 8.1 liter gas engine. However, this 300 HP comes in at 2,650 RPM and the 600 ft-lbs of torque comes in a 1,500 RPM. Under normal cruising speeds the RPM of the Cummins will be around 1,700 RPM, at which it is putting out 200 HP and 600 ft-lbs of torque. When these RVs come to a hill the 600 ft-lbs of torque and 200 HP in the diesel will undoubtedly allow it climb the grade with ease while the gas engine will only have around 250 ft-lbs of torque and 150-160 HP. If this grade is going to require 400-500 ft-lbs to climb, then the diesel will climb right up but the gas engine will need to downshift two gears to multiply the torque enough to ascend the grade. Plus, the reduced horsepower means that it'll probably lose speed and time compared to the diesel.

Another consideration of engine RPM is fuel economy. Engines are basically big air pumps. The faster they spin, the more air they move through them. But engines run on a pretty consistent ratio of fuel to air, generally between 14:1 and 18:1. So for every 14 - 18 gallons of air that you run through them you also run 1 gallon of fuel through them. Revving the engine higher will consume more fuel. There's times where that's necessary but cruising at speed on a level highway isn't the time for that. You want to keep your RPM nice and low to conserve fuel. If your engine has to kick down a gear every time it comes to a slight rise then you aren't working at a very good efficiency and it's going to cost you at the pumps. By choosing an engine that's better matched for your coach and your driving style, you'll get better efficiency. While not everyone needs a 12 liter 600 HP Blastomatic diesel for their coach, you do need to add more power when you add more weight. Also, higher speeds will impose a larger aerodynamic drag on the front of the coach so you'll want to have enough power to handle that without having to stuff your foot through the floor all the time. With the increased trend towards heavier coaches the latest gas powered chassis have gone to 6 speed transmissions and a lower, more powerful rear axle gear ration. That way they still have enough power to make it up steep grades while allowing the engine to rest back down to a lower RPM when cruising.

Summary:

Torque is what gets the job done and horsepower is how fast you get it done.

Remember that it's not so much the "rated" maximum horsepower that's important as is the actual power at the RPM you'll be driving at. This is why the lower RPM diesels have greater torque and also put it where you need it compared to gasoline powered engines which rev much higher and have a steep power curve to climb before getting there. The smaller engines will need to rev higher to multiply their torque and in the process consume more fuel. Nonetheless, they will all get you up the hill, although not all at the same speed.

If you're going to use an engine to power a car, truck, or motorhome you end up converting the engine's power into a force of propulsion. This force is used for acceleration, for cruising, for climbing grades, etc.
And, you can calculate how much force it'll take to accelerate a given mass to a certain speed within the distance you choose,....level ground or inclination.
Human beings are intelligent enough that they've designed different engines for different applications. We even say things like, "you wouldn't take a knife to a gunfight..."

Why are diesel engines better for certain applications? Here's a respected explanation, by a respected expert, Gale Banks:

Now let's take a look at diesel engines. The most significant differences from spark ignition engines are that diesels have no air throttle, fuel is injected directly into the combustion chamber, diesel fuel is used instead of gasoline, and the heat generated by the compression of the air in the cylinders ignites the fuel when it is injected. Diesels also operate in a narrower RPM band than gasoline engines, and have lower peak RPM. This is because with direct fuel injection it is difficult to have good air/fuel mixture formation and full combustion over a broad RPM range. The higher compression ratio and cylinder pressure of diesel engines also requires heavier rotating and reciprocating components that limit maximum RPM. Few diesels operate at speeds above 4000 RPM, and most run notably slower than 4000 RPM. Diesels are thermally more efficient than gasoline engines because they operate at higher compression ratios than gasoline engines, and they have fewer pumping losses. Additionally, diesel fuel typically has about 11 percent more energy per gallon than gasoline. Typical diesel fuel has 138,700 BTU per gallon whereas typical gasoline has 124,800 BTU per gallon. Diesels can also run on much leaner air/fuel mixtures than gasoline engines, especially at idle. Let's look at these things more closely.

Higher compression ratios result in more efficient burning of fuel in four-cycle engines. Most of today's gasoline engines operate with static compression ratios between 8:1 to 10:1. Special high-octane gasoline permits slightly higher compression ratios (usually for racing), but the added cost and availability of high-octane (high lead) fuels precludes the use of higher compression ratios in most applications. Diesel engines, by comparison, operate at compression ratios between 14:1 and 24:1. Gasoline engines cannot operate at these higher compression ratios because the air and fuel is already mixed together before it enters the cylinder. At compression ratios above those usually used in gasoline engines, the heat of compression would cause the mixture to self-ignite too early, causing "engine knock", parts damage, and a significant reduction in power. In a diesel, the air and fuel are handled separately. Only air goes into the cylinder on the intake stroke, and the pressurized fuel is injected after the air is compressed. During the compression stroke, the temperature of the intake air rises to as much as 1400º F. When injected into this hot environment, the fuel self-ignites. The injection of fuel is timed for minimal emissions, efficiency, and maximum torque generation. As with the spark timing in gasoline engines, the fuel injection timing is advanced slightly in some, but not all, diesel engines as the RPM rises. However, it should be noted that turbocharging quickens the burn time of the air and fuel as boost pressure rises. This means initiation of the fuel injection pulse must be retarded, or delayed, as boost pressure rises in a turbo diesel. In most diesels, the fuel injection timing changes for rising RPM and rising boost cancel each other out, and the timing of the beginning of the main fuel injection pulse remains relatively fixed. Depending on the design of the diesel engine, its intended usage, and emissions requirements, the fuel injection pulse can be set to begin as much as 24º - 26º before TDC, or it may be set to occur as late as TDC. In the Banks Sidewinder, for example, fuel is injected beginning 24º before TDC on the compression stroke.

Gasoline engines operate within a narrow air/fuel ratio range of approximately 12:1 to 15:1, although some modern "lean-burn" technology engines have been able to achieve significantly leaner air/fuel ratios.Diesels can operate with a broader range as rich as 15:1 or as lean as 60:1, however, going richer than about 22:1 to 25:l produces excessive temperature, soot, smoke, and poor fuel economy. Some aftermarket diesel chip manufactures simply dump in excessive fuel for power, causing the engine to operate in the undesirable rich range, as evidenced by plumes of black smoke. Thermal efficiency of diesels can be, and is, further enhanced with turbocharging to increase the available air (oxygen) to support combustion of more fuel. Gasoline engines cannot tolerate significantly higher cylinder pressure from turbocharging without creating preignition and/or detonation unless high-octane or ultra-high-octane gasoline is used.




Sidewinder engine on the dyno

Diesel engines also have significantly lower pumping losses than do gasoline engines. Since diesel engine power output and engine speed are regulated by varying the air/fuel ratio through controlling the amount of fuel injected, there is no need for an air throttle. Consequently, there are only minimal pumping losses on the intake stroke. This also means that unfortunately there is virtually no engine braking when the driver backs off the fuel throttle pedal unless an exhaust brake, such as the Banks Brake is installed, but that's a separate story. If the diesel is turbocharged, boost pressure can actually help generate "positive torque" on the intake stroke. Diesels do have high pumping losses on the compression stroke due to high compression ratios, but that is offset by nearly equal rebound on the power stroke, as explained earlier. Significant pumping losses occur only on the exhaust cycle, especially under boost conditions when a turbocharger is used, and such losses are more than offset by the added torque generated on the power stroke if the turbocharger is properly matched to the engine. The foregoing is assuming the exhaust conduits are sufficiently unrestricted for the size and power output of the diesel. If not, increasing the efficiency of the exhaust system will result in significant power gains. This is why products such as Banks Power Elbow, Monster Exhaust, Monster turbine outlet pipe, and Dynaflow mufflers work so well.

With all of the above taken into consideration, especially the lower pumping losses and greater thermal efficiency, it becomes clear why diesel engines are more efficient and produce notably more torque than similar displacement spark ignition engines. However, there's more to the story. In describing the operation of the gasoline engine, it was noted that once the intake valve had closed, the thermal potential for that intake charge was set. The same is not true for diesel engines. The thermal potential for the power stroke in the diesel can be controlled by the amount of fuel injected and the length of time it is injected. The only limits to that are the amount of air in the cylinder to support combustion and the capacity of the fuel injection system. Because fuel can be injected longer into the power cycle to sustain effective cylinder pressure, torque output can be dramatically increased. This is largely responsible for the massive torque numbers diesels are able to produce.

This is from an article that I read. It makes sense to me... But the reason we purchased a DP was for the ride, floorplan and we got a great deal on it.

To the OP, get the coach that has a floorplan you and your spouse both like and what you can comfortably afford. Then get out and enjoy your purchase.

Here's the article I read:

How are Torque and Horsepower Different?

In the language of physics, torque is known as a moment of force. It is a twisting force, as opposed to linear force that acts to displace any object in a straight line. Suppose you are tightening a nut using a wrench. Torque is the vector product of liner force applied at the end of the wrench, multiplied by length of wrench from point of contact with nut to wrench end. For example, a force of 100 pound exerted at the end of a 1 foot length wrench, will translate into a torque of 100 pound feet (lb-ft).

An engine crankshaft revolves in a circular fashion due to torque generated by displacement of engine cylinders. Thus torque is the twisting force exerted by the engine on the crankshaft. This exerted torque ultimately gets translated into linear motion of the car moving ahead, as it is applied to the wheels via transmission.

Horsepower is a unit of power. It is used to measure total power output delivered by the engine or work done by engine per unit time. There are many types of horsepower units but the one that is used in car specifications is mechanical horsepower. The equivalent unit of horsepower is ft-lb/min and 1 Hp (horsepower) is quantitatively equal to 33,000 ft-lb/min. This should be remembered as the mechanical horsepower formula.

If you know the torque value, then horsepower at a specific engine RPM can be calculated using the following formula:

Horsepower = (Torque X Engine RPM) / 5250

If you put in some RPM values in this formula, you can get an idea about the range of power that your car engine can provide.

Thus horsepower measures the forward thrusting power of a car. It is a numerical estimate of work done by the engine per unit time, as opposed to torque which is a measure of the twisting force exerted by the engine.

When designing an engine that can deliver a specific amount of horsepower, an automobile engineer needs to calculate the amount of power generated from the engine created torque. The horsepower delivered by a car engine is directly proportional to the overall torque generated in the crankshaft. Further, torque generated is dependent on the total displacement capacity of the car engine.

So there is a limitation set by maximum possible displacement (measured in cubic centimeter), that is generated by the engine. There is a maximum constraint on the torque that can be generated by an engine which automatically sets a limit on maximum horsepower that it can generate.

A car with an engine of high torque value will pick up speed faster, while a car with high horsepower will attain a higher maximum speed.

Torque and horsepower are both deeply related to each other and need to be taken into consideration while designing an engine or reviewing its performance.

427435 wrote:

uncleluap wrote:

ed1 wrote:
As an engineer (retired) I'm always amused by the arguments over diesel vs gas torque. The interesting part is that your diesel, generating 800 ft lbs at 1500 RPM, is exactly equivalent to your gasser generating 400 ft lbs at 3000 RPM. Why? Because both engines drive the same size wheels but at different engine speeds, so the gasser has a final gear ratio which is 2X that of the diesel. Guess what the 2:1 gear ratio does?- it multiplies the gasser's engine torque by a factor of 2. So, at the rear wheels, both engines provide the SAME torque.
now to be fair, the diesel is humming in the rear of the coach, while the gas engine is roaring under your feet.

This discussion always reminds me of the specifications for the M1A1 Abrams tank. 135,000 lbs, top speed of 60 mph, able to climb 45% slopes! And all with 270 ft lbs of torque!

How do they do that? They generate the torque at 30,000 RPM, then feed it into a 10:1 reduction gear. So then you've got 2700 ft lbs and 1500 HP at 3000 RPM.

I seriously doubt you are correct on your figures however your never going to see a ford V10 in 40ft 4 slide pusher style Motorhome
The reason being is a V10 ford gas engine does not produce enough torque at any RPM to move 36K+ up hills etc at any where near accepted level,s of speeds and reliability

Again, it's not the torque but the hp (and enough gears) that actually move a MH uphill.

The reason you don't see gassers in bigger MH's is that the people with the money for a 40' MH are also willing to pay the money for an air-ride suspension system and to have the engine/transmission in the back (quieter).

What you said is simply wrong about torque and HP. Anyone reading this should just apply real life logic and fact to understand why ALL bigger rigs have diesel motors with much higher torque. They can handle heavier loads and move them up hills better because of their higher torque.

crappie_fisherman wrote:
...I've driven a 2 valve V10 pulling a 9000# TT (i.e. 17,000#'s combined) all over and I mean ALL over this beautiful country...didn't find any hill that I couldn't climb...did I slow down...sure...did I expect to...sure...

I now drive a 30,000#+++ 4000# toad Class-A with a diesel...in the few trips we've taken since getting it...the 6 speed Allison transmission sure is nice to have...if I had a 6 speed tranny behind my 2V V10...I'm sure that experience would have been easier on me as a driver...driving the 2V V10 loaded to 17,000#'s took driver control and attention to the road and the upcoming road/hills...

Thus far I've found I can simply set the cruise on the coach and the trans has yet to downshift out of 6th...on the SAME roads my V10 would downshift out of 4th...I KNOW that when we head to real hills...I'll use more gears on the coach...but comparing same roads to same roads...the Cat and Ally combo handles them much easier even though were more than twice the overall weight (coach and toad)...HP wise...my 2V V10 had 325HP...my Cat has 350HP...

Hehehe, and just to keep the 'fun' going, Joe:

..Your V10 in the Ex was putting about 220 of its 310 HP actually to the wheels most of the time (cruising down the highway, turning maybe 3000 RPM at 65-70mph). Same as mine was.

However, your Cat is putting about 300 horsepower to the wheels most of the time (cruising down the highway, turning maybe 2000 RPM or so).

Soooo, bottom line is the diesel is able to put more actual horsepower to the ground than the V10 during everyday driving, even though the peak torque rating of the gasser may in some cases be higher (like on the newer 362 HP V10s). Hence the reason it can stay in 6th gear and feels so much more powerful (and it ##$% sure ought to, for how much more $$ it costs compared to a gasser V10!!!)

Had your V10 been geared different so that it too was putting 300 horsepower to the ground like your Cat does, and you didn't mind it (V10) turning 4500 rpm or whatever all day to put out that much horsepower....The V10 too, would have stayed in one gear and rarely downshifted just like your Cat does now. But you wouldn't have liked hearing it turn that fast all the time, haha.

(Disclaimer: All numbers above are rough guesses, and are only used to illustrate the point on how gassers and diesels power/torque curve are different. )

Anyway, I think these discussions go on and on, due to the fact many just don't truly grasp the definition, etc. of torque and horsepower, and don't understand why a diesel thats rated for less peak horsepower than a gasser can feel so much more powerful. Add that to the fact that so many folks on internet forums insist on proving to everyone that they're right and the other guy is wrong...Wellll, you end up with a bunch of 13 page discusssions on this topic, hahaha. :)

It *IS* fun and entertaining to read, though, regardless. :)

If I had been satisfied with a gasoline motorhome, I could've saved me significant monies. Experienced taught me that traveling in your own airplane is NOT as convenient and comfortable as going in your own big diesel pusher(and bringing along your own SUV).
But, "each one to their own poison".

It's funny how these Gas V. Diesel threads NEVER seem to end...LOL...

It truly is akin to Hensley or not, chevy V ford V dodge, fridge on or off while driving, etc, etc, etc...LOL

I've driven a 2 valve V10 pulling a 9000# TT (i.e. 17,000#'s combined) all over and I mean ALL over this beautiful country...didn't find any hill that I couldn't climb...did I slow down...sure...did I expect to...sure...

I now drive a 30,000#+++ 4000# toad Class-A with a diesel...in the few trips we've taken since getting it...the 6 speed Allison transmission sure is nice to have...if I had a 6 speed tranny behind my 2V V10...I'm sure that experience would have been easier on me as a driver...driving the 2V V10 loaded to 17,000#'s took driver control and attention to the road and the upcoming road/hills...

Thus far I've found I can simply set the cruise on the coach and the trans has yet to downshift out of 6th...on the SAME roads my V10 would downshift out of 4th...I KNOW that when we head to real hills...I'll use more gears on the coach...but comparing same roads to same roads...the Cat and Ally combo handles them much easier even though were more than twice the overall weight (coach and toad)...HP wise...my 2V V10 had 325HP...my Cat has 350HP...

Joe.

427435 wrote:

michelb wrote:

427435 wrote:
...
Again, a 300 hp diesel engine won't climb a hill faster than a 300 hp gas engine moving the same load----------at least at altitudes under 3000 ft. Turbocharged engines (gas or diesel) do have advantages at higher altitudes.

The small gas engine is not irrelevant------------it serves to prove the point about the differences between hp and torque.

I would strongly disagree with this. Our 275HP (might even be 325HP) gasser will not keep up with a 300HP ISB, ISC or CAT 3126E.

Our old 98 Pace Arrow 36B gasser weighs about 20k lbs on the road and is MUCH slower climbing hills than in our 03 Phaeton DP (330HP) even with the DP pulling a toad on a dolly (total weight easily over 30k lbs).

I'm not saying that everyone needs to buy a diesel as the gas engine will get you over the hill and it does what it needs to do but there's a huge difference between a gas engine with 300HP/400 ft.lbs torque and a diesel with 300HP/600 ft. lbs or even 900 ft. lbs of torque.

I suspect you weren't willing to run your gasser at 4000 rpm when climbing a hill. I'll routinely hold my V10 at 4000 to 4500 rpm when climbing hills. Works great.

FWIW, I'm sure I had pedal to the floor and let it climb as fast as it could (which on some inclines was probably 15-20 mph by the time we got to the top).

It's possible that the engine needed a tune-up (although it seems to run fine).

I'm just comparing my personal experience with a 98 PaceArrow 36B (Chev 454 Vortec - roughly 20k lbs on the road) and with a 03 Tiffin Phaeton 40RH (CAT 7.2 - roughly 31k lbs with dolly and toad). Both engines have roughly the same HP but there's a huge avantage in climbing in the DP even though the DP is more than 50% heavier on the road. As someone else mentioned, the 6 speed Allison on the DP vs transmission on the gasser could be a significant part of the difference.

Horse power is for speed, torque at the wheel is for power. Diesel over gasoline by a long shot. No comparison!