Introduction: Understanding Fuel Economy The importance of fuel economy to the successful operation of a trucking company cannot be understated. Fuel is one of the largest variable costs in a trucking venture, and, while no trucking operation can control the cost of fuel, it has at least some control over the amount or rate of consumption. Rock-Solid Rules Every 2% reduction in aerodynamic drag results in approximately 1% improvement in fuel economy. Above 55 mph, each 1 mph increase in vehicle speed decreases fuel economy by 0.1 mpg. Worn tires provide better fuel economy than new tires, up to 7% better fuel economy. Used lug drive tires can get up to 0.4 mpg better than new lug tires. Ribbed tires on the drive axles provide 2–4% better fuel economy than lugged tires. Every 10 psi that a truck’s tires are underinflated reduces fuel economy by 1%. The break-in period for tires is between 35,000 and 50,000 miles. Tires make biggest difference in mpg below around 50 mph; aerodynamics is the most important factor over around 50 mph. The most efficient drivers get about 30% better fuel economy than the least efficient drivers. Idle time is costly. Every hour of idle time in a long-haul operation can decrease fuel efficiency by 1%.
Open this up and take a look, you may be glad you did.
Although, this white paper was primarily intended for the trucking industry, there's a lot in this applicable to anything on the road. I encourage everyone to at least take a look at it. There are most likely things applicable to you. With the current situation you and I are in, the price of everything especially fuel is going to keep going up. Having transported vehicles and cargo all over this country, I can honestly say that avoiding wrecks and saving fuel are the two most important aspects.
Rams
[This message has been edited by blackrams (edited 04-22-2021).]
Have you ever heard of "sticktion" ? That is the turbo getting ?gummed up? due to residue.
I've heard of it but never experienced it. My assumption is that if you run clean fuel, turbos have significantly less issues with gumming up. I learned a hard lesson several years ago about buying the cheaper fuels. The attached pic should explain why I no longer use Mom and Pop fuel stops unless I absolutely have to.
This is something I studied thoroughly in the last 15 years of my career. The last company I worked for, a 48 state refrigerated carrier, ran super singles on drives and trailer, added trailer skirts and we were looking into hub caps and tail cones before I left.
Of course as a flatbed carrier, all of the aerodynamics in the world will not help you if your load is dirty. I'm sure you know about parasitic drag. If you are hauling some odd shaped equipment, you could have a Cd worse than a sheet of plywood. Sometimes a tarp can help. Wind resistance increases at the square of the increase in velocity and is worse in cold weather.
During my career, from the early 1970s to the 2010s, fuel economy for big trucks doubled because of improvements in tire and engine technology, and aerodynamics.
[This message has been edited by williegoat (edited 04-22-2021).]
Of course as a flatbed carrier, all of the aerodynamics in the world will not help you if your load is dirty. I'm sure you know about parasitic drag. If you are hauling some odd shaped equipment, you could have a Cd worse than a sheet of plywood. Sometimes a tarp can help. Wind resistance increases at the square of the increase in velocity and is worse in cold weather.
During my career, from the early 1970s to the 2010s, fuel economy for big trucks doubled because of improvements in tire and engine technology, and aerodynamics.
The only obvious odd thing that I see is the way the trailer is hitched, but I figured that was because at that angle, it could hit the bodywork of the pickup. It's still morning out here in the great southwest.
The only obvious odd thing that I see is the way the trailer is hitched, but I figured that was because at that angle, it could hit the bodywork of the pickup. It's still morning out here in the great southwest.
You got it right.
Due to the bad fuel, we had to load up the Dodge shown on the trailer but, knowing the ass end of the second trailer would be dragging if we coupled to the in bed hitch, I used the factory installed class five hitch with a 2 5/16th ball and pulled the rig home that way. 650 miles from home, 93 feet long, tandem trailers. We sure got a lot of looks. Figured we would get pulled over for doing it but, got passed by 7 different LEOs and passed by several different weigh stations with State DOT folks watching us and nothing was said.
I left the truck on the trailer idling (as best as it could) so we could leave the running lights and 4 way emergency flashers going the entire trip home. We tried to stay away from major traffic areas by re-routing around them which meant some two lane roads and small towns. Making some of those in town turns with a rig that long with the multiple hitches was interesting at some points. I've pulled tandem trailers before but, that was a very long trip home.
As I tell my wife, every trip is an adventure.
[This message has been edited by blackrams (edited 04-22-2021).]
I thought about the lights, but figured he had some kind of "jumper" pigtail.
Didn't have one, was no where near a truck stop at two in the morning. Once I got it set up and working, I decided to run with it. Didn't expect it to last but, once the sun came up, we figured a higher power was on our side and kept rolling.
BTW, that Ram pulling the whole rig didn't get very good fuel mileage on the way home but, it still pulled like a freight train. The Dodge on the trailer did great fuel mileage wise.
Rams
[This message has been edited by blackrams (edited 04-22-2021).]
The most efficient drivers get about 30% better fuel economy than the least efficient drivers.
....
So that looks like the biggest variable in your list. Can you describe what the Efficient Drivers are doing that is so beneficial? My dad always warned against jackrabbit stops/starts and speeding. What else is there?
So that looks like the biggest variable in your list. Can you describe what the Efficient Drivers are doing that is so beneficial? My dad always warned against jackrabbit stops/starts and speeding. What else is there?
Sorry for the delayed response, been on the road. Just returned from a trip from Hattiesburg to the beaches SC, then north to Pittsburg, PA, then home.
Your dad was right, jack rabbit starts waste fuel. Winds and aerodynamics makes a huge difference also. Having clean lines for air to flow over always results in better fuel mileage. Speed kills, not only people but, the faster you go, the more fuel you're going to use. I constantly amaze others with the fuel mileage I can get with my vehicles but mostly with my trucks and trailers. I recently hauled a Porsche and a BMW for my BIL on my lowboy gooseneck trailer. He was driving his Ford pickup pulling another small trailer, my load was much greater than his. My trucks are all 6.7l Cummins diesels. His Ford is a turbo'd V6. This is where how the vehicle is equipped comes in to play. He also likes to get there and not spend any more time on the road than he has to. We moved the cars and cargo leaving at the same time but he quickly left me in his dust. I drove about 5 mph below the posted speed limit. He exceeded it but, I'm not sure by how much but he said he was bumping 75 mph. He got there before me but, not by much.
Regardless, the different power trains and different driving techniques made a huge difference. My truck got right at 17.5 miles per gallon, his was 12 mpg. We'd have been a lot closer had he stayed closer the my speed. Driving technique and the way your vehicle is equipped make a huge difference. Head winds and tail winds will also greatly effect fuel mileage. As the posted article says, there's a lot of things that go into saving fuel used per mile but, unless I'm in a hurry for some reason, I usually follow the practices I've described. Speed equals fuel that equals money so, if I'm going to speed and burn excessive fuel, I had better be making it up in some way financially.
Rams
[This message has been edited by blackrams (edited 04-27-2021).]
Originally posted by Notorio: So that looks like the biggest variable in your list. Can you describe what the Efficient Drivers are doing that is so beneficial? My dad always warned against jackrabbit stops/starts and speeding. What else is there?
Your previous President, Barrack Heusain Obama, said we can reduce global warming and save fuel, by being sure our tires are inflated to the correct air pressure.
Your previous President, Barrack Heusain Obama, said we can reduce global warming and save fuel, by being sure our tires are inflated to the correct air pressure.
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Originally posted by cliffw:
A friend of mine just recently participated in a day long race. He driving a GMC one ton dualy diesel P/U truck. (class equal).
He washed and waxed his truck before the race.
Based on what I've been told (and it makes sense to me) our former President was correct.
One could assume that anything that cleaned up the air flow over or passing a vehicle would reduce parasitic drag. So, not only does washing and waxing make the vehicle look better and protect the waxed parts from corrosion, it may help in reducing parasitic drag.
I'm no expert, I simply hate wasting money. On this trip from MS to SC, PA and home again in MS, my overall average was 20.4 mpg pulling a 25 foot lowboy gooseneck trailer. That ain't bad, I don't care who you are. Of course, being retired, I have all the time I want to take to get it done (theoretically).
Rams
[This message has been edited by blackrams (edited 04-27-2021).]
Based on what I've been told (and it makes sense to me) our former President was correct.
One could assume that anything that cleaned up the air flow over or passing a vehicle would reduce parasitic drag. So, not only does washing and waxing make the vehicle look better and protect the waxed parts from corrosion, it may help in reducing parasitic drag.
I'm no expert, I simply hate wasting money. On this trip from MS to SC, PA and home again in MS, my overall average was 20.4 mpg pulling a 25 foot lowboy gooseneck trailer. That ain't bad, I don't care who you are. Of course, being retired, I have all the time I want to take to get it done (theoretically).
Rams
All very impressive. Yeah, the speeding habit can be hard to brake (pun intended.) In my youth I was known as Lead Foot
Does the same hold true in space? Not 'much' drag other than the pull of gravity, but is it truly zero drag?
An interesting question. Obviously, I'm not qualified to answer that but, other than waves of light, I'd think that only acceleration and changing direction would apply to fuel mileage in space.
So that looks like the biggest variable in your list. Can you describe what the Efficient Drivers are doing that is so beneficial? My dad always warned against jackrabbit stops/starts and speeding. What else is there?
Depending on the types of roads you operate on and the types of vehicles, there are some very useful and proven techniques that I used to teach to both beginning and experienced drivers. Each of these techniques also has other benefits in safety and can reduce wear and tear on vehicle components.
It is important to be aware of your surroundings. Look ahead to where you will be 15-20 seconds in the future. Make note of potential hazards so you can position yourself in such a way that sudden movements will be less likely. Every time you use your brakes, you have to make up for it by using the throttle. That costs fuel.
Be aware of the condition of the traffic light ahead. If it is red and there is stopped traffic, go ahead and let up on the throttle and with some timing and practice, you will be able to go through traffic lights without coming to a complete stop and possibly in a higher gear. I learned to teach this trick in downtown L.A. and would demonstrate it on a weekly basis to a group of experienced truck drivers in downtown Phoenix. Don't tell me it can't be done.
There is a technique known as "progressive shifting" (no, not like the current administration) where you shift out of the lower gears at a lower RPM, progressively increasing that engine speed with each higher gear. In other words, get out of each gear as soon as possible. You don't need all of that torque in the lower gears.
There are also obvious things like trip planning and keeping idle times to a minimum.
[This message has been edited by williegoat (edited 05-02-2021).]
I wanted to state something about Aerodynamics vs Trucks; There has always been the big debate about the tailgate being up or down- either is still (Basically) bad, aero-wise; Two ways to go for improved aero on a pickup truck; A) Install a lid or tonneau cover...This a big improvement.....But by far the best thing to do is to B) Install a camper shell even with the roof of the cab- The flat back-end is (Basically) a Kamm effect situation where the air-flow breaks cleanly from the vehicle....This seems contradictory to people with limited Aerodynamic knowledge.
My father was an aircraft worker/ Foreman/Supervisor at NAS Alameda, so I was completely immersed in all thing aero from a young age.
I also did some diagrams of how different wing/spoiler setups on our Fieros can create down-force vs Drag...
Originally posted by cvxjet: The flat back-end is (Basically) a Kamm effect situation where the air-flow breaks cleanly from the vehicle....This seems contradictory to people with limited Aerodynamic knowledge.
That is simply not true. The Kamm tail effect depends on some taper. This is obvious to anyone who has ever followed a tractor-trailer on a motorcycle. There is quite a bit of turbulence even sixty to eighty feet back from the trailer. A tapered tail cone on a trailer can net a fuel savings of better than six percent.
quote
Originally posted by williegoat:
This is something I studied thoroughly in the last 15 years of my career.
[This message has been edited by williegoat (edited 05-02-2021).]
I wanted to state something about Aerodynamics vs Trucks; There has always been the big debate about the tailgate being up or down- either is still (Basically) bad, aero-wise; Two ways to go for improved aero on a pickup truck; A) Install a lid or tonneau cover...This a big improvement.....But by far the best thing to do is to B) Install a camper shell even with the roof of the cab- The flat back-end is (Basically) a Kamm effect situation where the air-flow breaks cleanly from the vehicle....This seems contradictory to people with limited Aerodynamic knowledge.
My father was an aircraft worker/ Foreman/Supervisor at NAS Alameda, so I was completely immersed in all thing aero from a young age.
I also did some diagrams of how different wing/spoiler setups on our Fieros can create down-force vs Drag...
You do have a point reference the airflow going over/around pickup points but, what you are omitting is the flat ass end on trucks. Even on pickups. To smooth out that airflow, the ass end of the pickup with tail gate or, the back of the cab without a tail gait still provides for that area where the vehicle must over come the aerodynamic affects of that surface. Aerodynamic Engineers always attempt to smooth out the airflow characteristics of all aircraft. One would have to assume that automotive engineers are attempting to do the same thing. That low pressure area you're describing has to be reduced to the lowest value possible to actually increase fuel mileage.
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Originally posted by williegoat:
That is simply not true. The Kamm tail effect depends on some taper. This is obvious to anyone who has ever followed a tractor-trailer on a motorcycle. There is quite a bit of turbulence even sixty to eighty feet back from the trailer. A tapered tail cone on a trailer can net a fuel savings of better than six percent.
This is factual. Anything with a flat ass end has a portion of that area that is actually holding back the vehicle as in a vacuum situation. A tapered wind flow device smooths out the air flow. A few years ago there were a group of hypermilers that were trying to build tapered cones for the back or their Honda, Toyotas or other fuel efficient vehicles. Some got some amazing fuel mileage numbers.
The Kamm tail was a compromise between the reduced drag and the unwanted lift of the tapered tail. A few years later, a guy from Texas did a lot of work on the lift problems.
Look at the ass end of a modern LMP car.
[This message has been edited by williegoat (edited 05-02-2021).]
Obviously, it would be better to have (Very) gentle taper to the rear- But how would that work on a Pickup? Or a semi? If you have a steep taper it will create lift and drag. Remember the rear of the incredibly ugly 3rd-gen (92-95) Taurus? It was all rounded and tapered....and it's aero was bad......It is better to chop the tail off clean rather than have the air slowly trying to disengage while creating more drag.
On my 1973 Mustang I made an airdam that rammed the air in from directly in front of the radiator >>Below the Bumper<< while the air to the sides was deflected outward....And then I completely blocked off the GRILL- even used foam strips to seal around the headlights and between the grill and the hood. I had driven it in a cross-head-wind once and the front was floating- Uncontrollable above 60 mph; ALL of the air that hit below the hood-line was (Originally) rammed under the hood, which had 3000 square inches of surface- so 1/10 PSI would create 300 lbs of lift!
After my mods I had it up to 95 mph passing 3 semis and 2 cars on highway 97 above Mt. Shasta- it was rock-solid.
If you want to put a 100 foot taper on the back of a semi then you can have better aero- but it will be a ***** to back-up.....
Here is some food for thought, something to read, or just look at the pretty moving pictures put together by some that you would probably describe as "people with limited Aerodynamic knowledge".
Maybe you could call these guys and explain aerodynamics to them. I just don't understand what you are saying, being an old retired gearjammer and stuff.
Originally posted by cvxjet: I wanted to state something about Aerodynamics vs Trucks; There has always been the big debate about the tailgate being up or down- either is still (Basically) bad, aero-wise; Two ways to go for improved aero on a pickup truck; A) Install a lid or tonneau cover...This a big improvement.....But by far the best thing to do is to B) Install a camper shell even with the roof of the cab- The flat back-end is (Basically) a Kamm effect situation where the air-flow breaks cleanly from the vehicle....This seems contradictory to people with limited Aerodynamic knowledge.
Mythbusters and others including Truck manufacturers has done gate up vs down for years for light trucks and other types... Gate up and air Roll in the bed and little compress so air moves very well around the rest of the body to get best MPH. Tonneau cover is close to same. Gate Down or Off get Worse MPH cause by Drag.
Most to all Bed Caps does Not get best MPG and have other problems. These act like most Vans and have big flat rear w/ issues of air sucking on the back of truck. Many that drives on Dirt Roads or in Winter often have a hard time seeing thru back windows on vans, truck w/ caps, and "old school" Station Wagons because low pressure air there drops dust snow etc. Rear glass wipers often don't help for same reason. While makers of these vehicles have reduce the air flow problems w/ rolled edges etc. still happens.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
Some thing else that seems to work for me is, never trying to accelerate while going up hill. Just maintain the speed you were at or, keep the rpms within the power band.. In my current one ton, that sweet spot seems to be in the 1500 rpm range. Always try speeding up when using gravity to help. It's a small thing but, if you work at it, it does seem to pay dividends.
Use non ethanol gasoline to get better mpgs. But it may not save costs as its not subsidized.
That might not work out well for blackrams
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Originally posted by blackrams:
Some thing else that seems to work for me is, never trying to accelerate while going up hill. Just maintain the speed you were at or, keep the rpms within the power band.. In my current one ton, that sweet spot seems to be in the 1500 rpm range. Always try speeding up when using gravity to help. It's a small thing but, if you work at it, it does seem to pay dividends.
Ram
Knowing just what to ask from an engine, and how to ask nicely can make all the difference in the world. Kind of like some women.
Back when trucks still had pyrometers and manifold pressure gauges (before computer controlled engines), I drove an E6-350R Puppy Dog that would blow away an NTC-400 on a hill and get 6.8 mpg while the Cummins was lucky to get 5.5.
I could keep the exhaust around 910o and get 23 lbs of boost on a cool day (air-to-air CAC). The NTC was cooking at 1250o and making about 14-15 lbs of boost.
All that extra fuel went out the stacks as heat and smoke. Some guys used to think that smoke equaled power.
[This message has been edited by williegoat (edited 05-05-2021).]
Hell, I even talk nice and say sweet things to my Cummins if it'll get me a half mile per gallon better fuel mileage. Don't tell my wife that though. But, I do realize that not everyone has the time or patience to plan ahead and try to save a few bucks on fuel. I suspect more folks will start doing that as the cost of fuel continues to rise. I want to take a moment to thank Ole Joe for killing that pipe line. I know it's not the only reason costs are rising but, doing that sent a message to everyone. Just about everything moves by truck, if it costs more to get that product or produce to it's destination, it's going to cost the end user/consumer more. Biden supporters, don't say you weren't warned.
2.5: My Cummins burns diesel. But, you may be correct in gas burning engines. I suspect anything with corn alcohol in it is less efficient or so I'm told.
Rams
[This message has been edited by blackrams (edited 05-05-2021).]
hmm I remember a craze of burning french fry oil "biodiesel"
Might not be much cheaper though either.
I had a friend with a "source" for that cooking oil. That's all he ran in his older diesel. He had barrels of it but, it has to be filtered several times to ensure it's clean enough to go through injectors. He spent a lot of money on a filtration system and that system took of a lot of space in his shop. Not suggesting it isn't worth it but, you gotta have a source and I'm not sure it's worth it for all the time he spent messing with the system. But, as the price of fuel goes up, that craze will come back.
If you read the article you will see that Willie had one of his biodiesel plants in Carl's Corner, Texas. I have been to Carl's Corner, every time I passed through (on IH 35 just south of Dallas). He has a large truck stop there which is almost a Willie Nelson museum.
