I'm wondering what sort of fuel economy you have been getting on class 8 trucks, and what engine/ tranny/ rear ratio it has. My two trucks both have Cummins Big Cams, NTC 290 and NTC 300. The straight truck (NTC 290 in a Ford LTS 9000) has gotten as much as 6 or 7 mpg. My neighbor that runs 6 or 8 semis told me that they are going more toward 60 series Detroits. He claims that they got 12 mpg running light with a flatbed, and 9 or 10 loaded. Heck, my F-250 7.3L doesn't always get that much! I was just wondering on what your thoughts are on various engines and trucks, fuel economy and longevity? He also said that the Cummins are more likely to need an overhaul at 600,000 miles, more or less. Thanks! Paul
On short trips here in the hills hauling dirt or my equipment around I get somewhere around 6 to 6.5mpg. On longer trips I get about 8mpg. Detroit 60 (500hp) with 10 spd., 4.33 gears, and 11/24 tires.
Making a claim is one thing. Proving "they got 12" is another... Getting 9 or 10 loaded? I don't think so. My first new truck (3rd from top) was a Mack Superliner, E9@500hp, 12sp trans... At 80,000 lbs, 5.5-6.5 was easy to. Progressive shifting and staying in the peak torque range is the key. When your boost drops off and your exhaust temps climb, it's time to down shift. With my V8 Mack, I didn't drop a gear that often. When I would drop one, it wasn't until I hit 1000 rpms Thats right, 1000 rpms... Seems low, but its a Mack and thats what sets them apart from any other truck engine. My 86 Pete (top pic) with an 8V92TA@475hp was thirsty. No matter what I tried or how hard or easy I ran, 4.75-5mpg was as good as I could get. A buddy of mine with an 02 Pete (2nd from top) with an 3406E@550+hp, super 10 gets 5-6.5 consistently. Another friend of mine with a 05 Frieghtliner with a series 60@575hp, 18 speed gets 5-6 mpg every day. Can I prove it? I'll take you for a ride... I run both of their trucks whenever they need a hand or I feel like getting outa town. Sorry bout yer Ferd. My Ram averages 15.5-16 mpg hand calculated. Now thats an 11,000 lbs truck (bottom pic)
We have a 2006 Kenworth T800 dump with a Cat 475hp C15 and 18spd, mileage is about 5 to 5.5 mpg. Our 1989 Peterbilt dump with 475hp Detroit 60 and 13spd gets anywhere from 5.5 to 7.5 mpg depending on load, hills, etc. We also own a old but low milage 1976 International 4300 tandem axle boom truck with National 600 crane. It has a Cummins NTC290 and 10spd and have never checked the milage since it really never drives too far and spends more time running stationary than driving. Now I didn't know they were still putting in 8v92's in 1986. But your milage figures are about right. We had a 1976 Peterbilt dump with a 8v92 and got similar milage. Also once owned a 1981 Peterbilt 359 with Cummins Big Cam 400 that was turned up to 475 with a 13spd. And it got anywhere from 4.5 to 5.5 mpg depending on how hard you drove it, etc. But I still think that this truck would outpull our newer trucks.
hauling grain n14 cummins 18spd 3.73 rears 525 horse 6.0mpg 82k lbs
06 IH 7400 with a 300hp DT466, weighs just over 30k empty (gross is 54k)& gets a tankful avg of 4.4mpg. Mostly city driving though. Glad I dont have to pay for it! Ironically, the one I used to drive is a 94 IH 4900, DT466 with the fuel turned way up, gov springs tightened, and timing advanced gets 5.5mpg. It weighs 27k.
Just finished a 300 mile round trip to do a job. The trip is out through the desert and then up over a mountain range. Lots of steep hills and winding mountain roads. I was towing my equipment trailer with a 17K lb backhoe aboard. I have done this trip before and got 7.8mpg. This time there were fierce winds (40-50 mph). On one long 8 mile steep grade that I used to take at about 2/3 throttle in 9th gear, I had to go to 8th with my foot in it in a couple of places. This time I only got 6.6mpg. I have noticed that pulling an equipment trailer produces a lot of wind resistance as apposed to hauling a heavier load in the truck with no trailer. I have a long uphill grade near where I live that I travel a lot. It is easier to pull with a full load in the truck and no trailer, than with no load in the truck and the trailer with equipment on it; and the load with the truck full is 20K lbs heavier.
We have a 1984 Diamond Reo with a Cummins 400 Big Cam and I agree, that truck will pull.
Resistence and wind drag The reason is becuase of the resistence the trailer adds. You also have wind drag when pulling. Whereas when you have truck full and no trailer you reduce the resistence and drag.
I'm driving the companies 97 Ford LTL 9000 with a 3406E @ 475HP 8LL and 4:33 rears in 46K Rocks! On the hard road I get 5.5 to 6.8; just last Thursday I was driving to a Local Landfill dumping clean dirt! The pit was a muddy mess! The semi's bringing trash to the tipper were getting stuck! The flats were also getting stuck! They had to clean the tracks of the dozers 4 times! I ran for 9.75 hours on that job and burned 66.5 gallons of fuel; equaling 3.84 MPG! There were lots of hills and a rural highway with turns and stops! Never got to run at a cruise; either accelerating or breaking.
Now we're talkin close to $ 1.oo a stupid mile at 4 miles to the gallon...Ouch..:Banghead
My Paystar has a Cat C13 470/485 horse engine, double over Eaton 18 speed and 4.30 rear gears. I legal gross 35,700kg and run a mix of city and highway driving. When I had it checked on the computer at Toromont Cat a couple times it showed 5.1 mpg overall (including idling) and 5.3 driving. Mind you those gears are not ideal for highway driving (1600 RPM at 100 kph) but even on site, nowhere near as good as the old mechanical motor Macks I used to run. The very best I ever got out of it was I made a 4 hour trip on the highway empty. I did the progressive shifting, stayed out of the boost and set the cruise at 90 kph/55mph. I got 8.3mpg (but that's extremely rare.) Hey RollOver Pete. You had a Superliner!:notworthy:notworthy:drinkup I used to drive one, a tri-axle dump pulling a pony grossing 140,000+, hauling salt. We got all big hills up here and it used to get 5.5 all the time and could pass tandem freight haulers all day long in the hills. It had some pump work done to it. Absolutely my favourite truck of all time.
Cat3406 475HP, 120 mile around trip, mixed back roads and highway hauling 28 tons 4.5 miles per gallon.
I just got back from an 1800 mile trip with my Ford L9000 with a Big Cam 300, 9 speed and 4.33 rears, pulling an equipment trailer. I was averaging around 5.5 mpg. Much of the time I had my foot to the floor and could only get 60-65 mph out of it going up the Platte river valley (I-80 in NE). Does that seem normal, or should that 300 have more snot than that? GVW was probably only in the mid to upper 50s. Anyway, someone was telling me the other day that he was getting 8mpg with his Big Cam 400 in his Kenworth pulling a detach trailer. I don't know about that...? Shoot, even my '01 F-250 with the Powerstroke only was getting 9 mpg with a goosneck trailer on a 1000 mile trip. What I find interesting is that fuel mileage doesn't seem to be related to HP ratings. In fact, some of the higher hp rigs that you guys have (475- 525 hp) seem to do as well or better than some of the lower hp stuff. makes me wonder why I don't turn my 300 Cummins up to 450 or so! What would I lose? Traditionally in cars, it was always the wimpy little ones that got better fuel mileage. Interesting.... At least it is to me. Paul
Will the truck go any faster than that empty? These electronically controlled engines are often governed to max out at about that speed, especially if it was a former fleet truck. Electronically controlled engines can often be turned up with just reprogramming.
8 mpg is quite reasonable for a 400 NTC Cummins. I used to run a big cam 400,1987 vintage, and I had it turned up, number 8 button in the pump over 235 pounds of rail pressure, big injectors, etc. and it was quite easy to get 7.5/8 mpg if driven properly (low boost pressure, low rpm). Those old mechanical motors were way more efficient then these new "environmentally friendly" electronic junk. I don't know about light loads, flat roads, but I used to haul heavy (140,000 pound gross) through rolling 8 to 12% grades and I always found bigger was better on fuel. You don't have to push them as hard. Used to get 5 mpg with a Mack E9 500 V8 the same as the 350's were getting. P Backus what rpm were you at when you were going 65? I ran an old binder with your same setup and from what I remember it had no top end either. I think the top gear in those 9 speeds might be on the low side?
The truck is an '85 with the mechanical engine yet- not a fancy thing on the truck! When running down the river valley, or on the level, it would/could cruise at 75mph pretty easily- even 80mph. The RPMs are only at 1500 or 1600 at 65 mph, so it isn't governing out. I realize that with such tall gears it won't pull a hill as easily, but it sure seems to be on the edge of what it can do, and I don't have enough experience with different trucks to know if that's just normal for 300hp. My straight truck has the NTC290 and seems to do a little better, but it is wound out at 2200 @ 68mph, plus the GVW doesn't get as high as the semi will. Not a big deal really- they are both farm trucks, but I do go out of state once in a while. Thanks Steve and Paystar! Paul PS. I wonder what it would take to change a Cummins 855 from a 300 to a 400? It already has the aftercooler. Gaining 3 mpg, plus some nice power sure would pay for itself, I'd think!
Check out www.dieselinjection.net It will take you to Pittsburgh Power, click on Bruce Mallinson's power and torque articles. He's a master of all things Cummins. There is a lot of info there. I'm pretty sure the injectors are different and maybe the turbo, but there is a lot you can do with your pump. Check the articles though, because I've been around Mack and Cat power a couple years now and my memory aint what it used to be. I have all the specs in my closet somewhere? if you ever need me to dig them out.
I was reading this thread and I saw over all most of the drivers were getting 4-6 mpg given truck configurations and loads and that would also mean that everyone’s odometer/hour meters were in a calibrated state to give the most accurate mileage. What I am curious is how does this new diesel change the mileage? Since the older trucks aren’t motors aren’t set up to be complainant to this new fuel? Also how many of you drivers use bio-diesel and is it a worthy fuel substitute? When I’m on the road from time to time I try to listen to the box when my wife isn’t talking and all I keep hearing is drivers complain about the fuel prices. Understandable complaints but I am more interested in how you guys keep the axels turning and also find economy during these uncertain times. I see a lot of drivers that still keep the hammer matted going up and down I-95. :Cowboy