Mileage Question

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Hey all you CDT (and other Diesel) owners, what kind of fuel mileage do you average, inner city and highway?

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2000, QC, 4x4 AT, LWB, I post 13-14mpg avg around town, my over the road avg is 19.5, indicating about 22mpg while at cruise speeds of 65-70mph
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I get about 125% of a Chebbie 1/2-ton, while making about 2.5x the power, and weighing about 50% more :)
About 19MPG in mixed (50/50) driving... 21 on straight highway runs. 23 if I keep it in the right lane at 55. 15-16 if I'm playing "make the rice rockets look even sillier".
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Tom Lawrence wrote:

Yeah right on the 2.5 x power. If the gas truck is geared properly, it will pull just about as much as a oil burner will. It is all in the gearing. Deisel are usually geared correct to match their narrow power/RPM range to the load while gas truck are rarely geared properly. I have hualed a 13k loaded equipment trailer a few time with my K3500 with not problems or big fuss. Heck 30 years ago I was hualing 23k grain trailers 20 miles to a mill at harvest time before there was even the dream of a CTD dodge with a 72 GMC 3/4 ton 4wd with a 350, a 4 speed and 4.10 axle ratios and NEVER had a problem getting the load moving or keeping it moving. It was traction limited in 2wd first/granny gear even when loaded and would frequently leave marks into the surface of the county roads when starting out because on the high torque loads placed are contact point of tire to road. I could even pull the loads out of the field in 4 lo most of the time if the ground was not too soft and again it was traction limited not power limited. A freind pulled too with a F250 and a 351 with 3.54 axles and a automatic but he would stall out with a load in soft ground and not even be able to spin the tires even in low range. It was no match for my old GMC in pulling power. That truck was one of the last of the beasts before emmissions set in big time. I used to pull a load 4 horse trailer with it a lot too and never had any problem hold speed in 4th on any interstate hill and got 10 to 11 MPG doing it too. One time when I was redoing a dam I hauled 2ea 5k cement drain pipes at once on a equipment float with a total weight of close to 15k 60 miles on the interstate atspeed limit without any real problems. You just need the gears and the proper drive line, not a oil burner to move a lot of weight.
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Give us a break with the 30 year old stuff. Get current will ya.
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You just don't get it do you? First, I doubt you know anythign about Tom's truck. Second, gearing will elt you do about anything, at a sacrifice of something else. To get a gasser to pull what a diesel will, you can lower the gearing, at the sacrifice of top end speed and fuel mileage.

More bullshit. Factory gearing almost always allows an engine to run at 1500-2500RPM while crusing at highway speeds in top gear. Try doing the math.

Think how much easier it would have been with a diesel. Oh... sorry... thats right, you don't know that since you've never owned one.

Actually, I'll bet there was a dream of a CTD Dodge, since the late 70's was when Dodge put a small diesel in the pickups to begin with.

Never said you had a problem, but wouldn't it be nice to double or triple your fuel mileage while doing all that work?

Which is fancied up lack of knowledge speak for: Couldn't get enough traction to move the load at high RPM, and don't have enough power at low RPM to turn the tires.

Yup, it was all because of emissions that power went away.....

Wow, all of 10-11 MPG? I get 25MPG at 60MPH pulling a 6000lb trailer. When I pull in the 4wd, I don't worry about using more fuel, because it doesn't.

You aren't getting this. At all. Its FUEL EFFICIENCY that we like. Plus, some of what you describe shows exactly how limited you are with a gasoline engine in a hauling truck.
Increasing sales of diesel powered trucks of all brands don't lie.
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Yeah.... right. I figure about 250HP at the crank for a typical 1/2-ton V8. I'm easily at 625HP at the flywheel, so by my math, that's two and a half times more.

So will a golf cart.... but it's gonna be REEEAAAALLLLLYYYYYY SSSSSLLLLLOOOOOWWWWW

Nope... it's all in the horsepower. You want to move a load of <X> lbs. at <Y> speed, you need <Z> HP. Period.> I have hualed a 13k loaded equipment trailer a few time with my K3500
Good for you.... what was your mileage while doing that?

30 years ago, I was crapping in a diaper... things change.

Go find me an over-the-road commercial truck that pulls 60-80K and runs on gasoline. I'll wait here...
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sheesh and what's the torque?

a
at
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Flywheel? I dunno... a little over 1100 at the wheels on the dyno, but that was an inertial dyno. A load dyno would probably show more.
Those poor stock U-joints.... :(
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they havent broke yet? *grin*

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It's actually all about the torque. Horsepower doesn't really do anything; just a mathmatical expression of Torque:RPM relationship. Torque is the force that gets you moving, spins your tires, wins races, tugs the 80k trailer, etc. That's why a 250hp tractor trailer will do so much more than a 250hp rice burner.
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God Damn, ask a simple question about mileage and this is what I get! Glad to see the group is still as dysphunctional as ever! <VBFG>

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Well... I _DID_ at least answer your question before making a left onto tangent boulevard... :)
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hell...
Okay.... put a lug wrench on your wheel's lug nut. Stand on the wrench (so you're tightening it). Lotta torque you're applying to the lug nut, right? Did it move? Hmmm.... thought it was all about the torque?

Exactly... it's a FORCE. Just like you pushing on the side of your house. You're applying a force. The house isn't moving, so you're accomplishing no work.

Really? I bet the 250HP ricer will whip up on that 250HP semi on a drag strip. Why? Better power (there's that HP thing again) to weight ratio.
To further illustrate that it's not "all about the torque"... a Formula 1 racecar's engine makes about 900HP, yet have a torque peak of somewhere around 270ft.lbs. A 4.7L V8 in a Ram makes more torque than that. So, let's put the 4.7L in the F1 car, and it'll go even faster, right?
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Yeah.... pretty much :)
But you make a perfect point: torque without motion is useless. Motion, without any force behind it (if such a state could exist), is equally as useless. They're both components of power. So back to my original statement - you want to sustain a given weight at a given speed - you need a certain amount of power to do so. How you arrive at that power output doesn't matter.
Let's arbitrarily say you want to move 10,000lbs at 30MPH. After factoring in drag, inertia, etc. etc., you conclude you need 175HP to do that. You may produce that power with an engine putting out 600ft.lbs. of torque, turning at ~1500RPM, or an engine putting out 200ft.lbs. of torque, turning at ~4600RPM.
Ever caclulate, or seen mention of, a drag car's horsepower based on trap speed and weight? Same principle. You can't calculate torque that way, because you don't know the RPM.
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Actually, these are very different statements, because force (torque in this case) can exist without producing movement, as in our lug wrench scenario, when it is insufficient to produce work. But work can never exist without force, because there has to be something creating the motion over time/distance to be measured.

That's because torque isn't calculated, it's measured. Point being that HP is a function of torque... it isn't a force, it isn't doing anything, it is just an expression of how much is being done by the forces in play... almost like a comentator to a ball game, they're not involved in the playing of the game, but they are necessary in helping know what is going on...sort of...
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Tom Lawrence wrote:

I agree with Matthew. It is all about torque. Torque is NOT limited to static measurements. Torque can be applied in motion. Being a mechanic I sure hope you know what a running torque is. Horsepower cannot be measured without motion but torque can. Horsepower cannot be measured at all without torque.
How do you figure out horsepower numbers? It's torque x rpm / 5252. Horsepower is nothing more than an expression of torque mathematically diluted by rpm. No matter what engine you measure, the torque rating is the basis of the hp measurement. Horsepower will *always* be lower than torque below 5252 rpm and *always* be higher than torque above 5252 rpm. Horsepower is just a marketing gimmick dreamed up in the 1800s by James Watt to sell steam engines. And you are still buying it.
Torque is the key to acceleration. Acceleration is expressed as g force. The g force potential can be figured for any vehicle by knowing the thrust and weight of the vehicle. You can figure out what the thrust is by knowing the torque output of the engine, the transmission and rear gearing, and tire diameter. I can explain this in more detail if you'd like me to.

Torque can measured as both static and dynamic forces.

That power to weight ratio you speak of is actually a thrust to weight ratio. Weight and driveline efficiency is the key to this race.

Peak ratings aren't much of a factor here. F1 engines must be strong throughout the entire rpm range, up to 18,000 rpm. If the 4.7L V8 can produce more than 270 lbs/ft of torque through 18,000 rpm, then yes, it would be faster.
Comments from the last F1 race winner's engine team on torque and acceleration:
http://www.renaultf1.com/en/season/australia/index.php?news=tcm:3-33758 Fernando Alonso's engine engineer Remi Taffin explains how to get the best out of the RS25 V10 in Australia. "Melbourne is a tough circuit for engines: its succession of straights broken up by slow corners mean good torque is more important than peak power in order to accelerate out of the slow and medium-speed corners."
http://www.renaultf1.com/en/season/canada/index.php?news=tcm:3-36828 Remi Taffin, Engine Race Engineer. "A torquey engine is always a plus-point in Canada, as it allows the car to launch out of the slow corners when accompanied by good traction. Gear ratios must also be studied carefully in order to be able to optimise the torque curve of the V10 around the lap."
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The original statement was that to move a load of x lbs. at y MPH, requires z HP. However that HP is created, be it lotsa torque with low RPMs, or little torque and lotsa RPM, matters not.
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Somehow, people are missing the fact that HP is the force with motion, which indicates work done, or capable of being done.. I'll readily agree that its an arbitrary unit, but that unit comes from a finite formula that can have the same result despite different numbers being plugged in.
I think the quotes from the F1 guys are comical. Both refer to specific tracks... wonder what they say about other tracks where wide open running dictates that HP is the key?
Also comical is the statement that no matter what engine you are looking at, torque is the basis of the hp rating. No quite true. Many dynos measure kW, which can be converted directly to HP. Most industrial engines have a kW rating, and most overseas diesel manufacturers, especially the Europeans, use kW ratings without hp being mentioned until it hits the US market.
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