Here's some stuff I've collected elsewhere (as the OP has so well-titled this thread):
(.pdf 3.2 Mb)
KENWORTH WHITE PAPER ON FUEL ECONOMY
http://www.loadtrek.net/loadtrek_net...whitepaper.pdf
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(ARTICLE) HEAVY DUTY TRUCKING
Hands-On Tips For Buying Fuel, Driving & Spec'ing For Better Economy
Tips For Drivers
Tips For Drivers
***** In a major study, The Technology and Maintenance Council of the ATA identified the major factors that most affect fuel economy. The top 10 are:
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1: Driver skills, then,
***** 2: Speed - especially with poor aerodynamics
***** 3: Cooling fan "on" time
***** 4: Electronic versus mechanical engines
***** 5: Using rib tires in every wheel position
***** 6: Cutting idling time
***** 7: Using single semi-trailers instead of doubles
***** 8: Using a roof fairing rather than a flat roof
***** 9: Using a roof fairing rather than a raised-roof sleeper
***** 10: Slowing down 5 mph
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I do have an FEA study done as part of a guys graduate thesis in engineering. It was of a pickup truck and he recommended an air dam and side skirts plus rear wheel well skirts with a sloped bed cover.
http://www.dtic.mil/cgi-bin/GetTRDoc...c=GetTRDoc.pdf
Powerstroke Nation - View Single Post - Who here gets higher MPG's and what is your secret?
I can always tell when I've made a good aero move. The truck gets quieter in terms of road noise and I can hear the engine better.
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As a rule, an increase in noise is a sign of increased drag that is reducing your aerodynamics.
It turns out the biggest gains are to be found on pickups not by dropping the tailgate (a common misconception), but by installing a tonneau cover. "A tonneau cover improves the aerodynamics dramatically on all pickup trucks," according to Ford's Wegryn. "In general, a tonneau cover can provide a drag reduction of 2 to 7 percent, depending on cab style, box length and overall vehicle Cd. Average fuel economy improvement ranges from 0.1 to 0.3 mpg." From an aero standpoint, it doesn't make a difference if you choose a soft or hard cover.
To improve Cd, designers may make the following changes:
Round the edges of the front end
Tune the grille and fascia openings
Tune the wheel openings
Place spats (small spoilers) in front of the tires to reduce turbulence
Tune the size and shape of the outside mirrors and their attachment arms
Reshape the water channel on the A-pillars
Adjust the front fascia and air dam to reduce drag under the vehicle
Add side skirts
Tune the deck height, length and edge radius
Install a rear spoiler
Adjust the angle of the rear window
Tuck up the exhaust system
Use a diffuser to tune air coming off the underside
Install "belly pans," underbody panels that cover components and smooth airflow
Improving Aerodynamics to Boost Fuel Economy
General Motors Co. will begin testing to determine whether closing the openings in the grille will have a significant impact on truck fuel economy. Movable slats would block the grille openings to improve aerodynamics. Temperature, humidity, vehicle speed and other sensors will determine when the electric motor should automatically open or close the slats.
Wind tunnel testing is planned over several weeks.
http://www.autonews.com/apps/pbcs.dl...EM06/302159901
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. . where the torque curve crosses the HP curve is the optimum speed for IC engine efficiency. In mine it is 1750 rpm or 59 mph (it's a diesel). In another experimentation process, I ran at 59 on the freeway for about 300 miles and got the mileage up to 26 . . at 65 mpg falls off to 22 and at 70 it falls to 18. 70 mph is way outside the peak torque curve and the induced drag bucket is getting huge.
DIY Electric Car Forums - View Single Post - Pickup truck Aerodynamics
Delivering 555 lb.-ft. of torque at 1,400 rpm and 305 horsepower at 2,900 rpm, the 2004 5.9-liter High Output Cummins Turbo Diesel . . . .
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Keep your pyrometer under 600°F and keep your boost pressure under 5 PSI when solo. Learn the combo for towing!
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TAG III
"I work for a manufacturer of industrial engines, turbochargers, reciprocating and centrifugal compressors. Our company's engineering standards for installation of our equipment require a minimum of 5 diameters of straight pipe ahead of a turbocharger inlet. Any less and a flow straightener (such as the TAG, turning vanes, etc.) must be used.
A dyno run where the engine\drivetrain is under constant loading, or towing over long distances, stationary engine service, marine service and such is where the difference would be most obvious, as stated above. Anywhere the engine is under constant loading and producing power in a relatively constant band."
Dodge Diesel - Diesel Truck Resource Forums
We have been getting good reports of mileage increases using the Turbo Air Guide III (TAG-III). Last week one of the techs at a Dodge dealer in our area did a dyno and emissions tests using the TAG-III in his personal truck. The dyno results showed little to no change in hp and torque even though the tech says he feels more power driving the truck. This is expected as dyno runs are full throttle excursions and are not indicative of the conditions while driving. The emissions test showed a dramatic reduction in emissions, (i.e. smoke, which is a good thing) and he reported a 2mpg increase in fuel mileage.
Dodge Diesel - Diesel Truck Resource Forums - View Single Post - Want fuel mileage increase, but not power
Most of the time what we see with the TAGs on the Dodge Cummins is 0-1mpg gains empty and generally 1-4mpg on trucks that are towing. It is possible to gain mileage with the TAGs. On my truck, I gained about .5mpg empty, but a solid 3mpg towing on multiple trips. Others have had better results than mine and some have had less results than I have. In Jeff's 2004/Auto we have seen very small mileage increases, but his truck is always driven empty and in town so it is difficult to see small increases, but he still won't take the TAG-III out because of how it makes the truck run.
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AEROCAPS HOME - A Project to improve the Aerodynamics of a Pickup using an Aerodynamic CAP
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(In regards big trucks (Class 8); extrapolate:
The #1 factor in getting better fuel mileage is to REDUCE HORSEPOWER DEMAND. This is a combination of vehicle configuration, condition, load and DRIVER OPERATION.
The #2 factor in getting better fuel mileage is to AVOID RUNNING THE ENGINE WHEN YOU ARE NOT MOVING.
The #3 factor in getting better fuel mileage is the engine.
Everyone wants to look at the engine first , because they think the part that burns the fuel is the most responsible for fuel economy. I'll discuss this first and then get to the other issues.
Most modern on-highway diesel are capable of BSFC's in the low .300's or better (high .200's) at cruise rpm. This is pretty damn lean compared to earlier engines and I haven't seen any after-market accessories offer an improvement.
So, as far as the engine, you just need to make sure the engine is mechanically/electronically correct to start.
Check air and fuel filters.
Inspect air intake and exhaust systems. Look for leaks in the after-cooler piping, after-cooler core etc... Best way is to plug at each end of after cooler piping and pressurize entire assy to test for leaks.
Check exhaust for blown manifold and turbo gaskets. look at manifold and turbo hot housing for signs of overheating. A visual of the cold side is helpful, looking for damaged fins, rubbing etc...
If mechanical engine, check timing. Also check linkage to pump. Check fuel settings if seals or broken, Check air air/fuel ratio controls, (aneroid, puff limiter etc..)
If electronic, check for fault codes and possibly do a timing and sensor calibration.
Check fuel pressure.
Make sure engine is up to operating temp. Usually 190°
Check fuel quality: Fuel should be 35 API at 60°. Thinner winter blend will reduce fuel mileage considerably.
Fuel heaters: should be thermostatically controlled. Off in summer and only on when needed in the winter.
Oil: use 10w30 in all but the hottest weather. If you are running 15w40 in the winter it's hurting fuel mileage. You will see 4-5psi lower oil pressure, but it won't hurt anything.
Clutch fan: must cycle on and off. Fans require 15-18hp to run.
BLACK SMOKE: There should be no black smoke when changing gears or accelerating. Black smoke means the engine / fuel system is out of tune and adjustment for fuel economy. BLACK SMOKE is MONEY going out the exhaust pipe.
VEHICLE: many considerations here. Start with tires. make sure they are properly inflated (wish i had $$$ for every tractor that showed up for a dyno that had low tire pressure)
Tread design: rib is better than on/off road and heavy lug tread is terrible, run rib tires when possible. Low profile has much lower rolling resistance too.
Drive line: check drive-shafts for misalignments and vibrations. Rears must track straight, worn misaligned rear suspensions can cost you. An eyeball along the edge of the rears to the front can give you a quick check here. Use fuel saving synthetics in trans and differentials.
Vehicle aerodynamics / configuration: This varies greatly with different type of power units and trailers. The best possible is a Cab-over-engine (COE) with roof fairing, side fairings and very few protruding accessories, pulling a smooth side van trailer. Everything having ribbed low pro tires
The worst is a big conventional with no fairings, big external air cleaners , big mirrors, horns, fuel tanks, visors, no fairing, pulling a flatbed with a big bulky load, with lugged tall tires.
HORSEPOWER DEMAND: The horsepower that is needed to maintain a certain speed. i.e. how much horse power needed to overcome wind and rolling resistance, determines the fuel you will burn to cruise down the highway. This is called HORSEPOWER DEMAND. It also determines how much RESERVE HORSEPOWER is available for pulling hills and passing other trucks etc...
EXAMPLE: If two trucks have 400hp and truck #1 requires 160hp to maintain 60 mph and truck #2 requires 220 hp to maintain 60 mph, truck #1 will of course have better fuel economy AND have 60 more RESERVE HORSEPOWER to pull hills.
So aerodynamics play a huge role in fuel economy, particularly at speeds above 55-MPH (55 wasn't a arbitrary number when it was the federal speed limit)
Above 55-MPH "AERODYNAMIC HORSEPOWER DEMAND INCREASES BY THE CUBE OF SPEED INCREASE".
How this plays out is a truck that can achieve 7 MPG at 55 MPH, will get 6 MPG at 65 MPH and only 5MPG at 70MPH
Aerodynamic considerations include having a roof fairing that matches the height of the trailer. The trailer should be as close to the tractor as possible. Ideal distance is 15-18 inches, never more than 24 inches. Side fairings help close this gap without the trailer being to close for sharp turns.
At distances over 24" inches between the trailer and the tractor, drag goes up considerable. by 48" you have the drag of TWO FULL FRONTAL AREAS. Might as well have the trailer beside the truck! So much for the stretched out "west coast" look.
It can be tough to improve an existing tractors aerodynamics, but you can add a roof fairing and side fairings. Avoid putting on a lot of bulky accessories like visors, bigger mirrors, dual external air cleaner, huge bumpers, horns, flaps hanging everywhere, etc... Remember, driving an un-aerodynamic rig fast, will hurt fuel mileage even more.
DRIVER OPERATION: This is the big one that no one wants to face up to. However there is a BRAND NEW PICK-UP TRUCKS WORTH OF FUEL SAVING$ PER YEAR AVAILABLE (to those that operate well VS those that don't)
#1 Cruise speed: I just went over aerodynamics and horsepower demand. More time at lower speed will save you big on fuel.
#2 Cruise RPM: most modern trucks will operate efficiently in the 1400-1600 rpm range depending on model of engine. Cruise at this rpm (in the lower range of it if possible) Do not gear down a step to run at 1800rpm or higher
USE CRUISE CONTROL, many electronic engines alter timing maps in cruise control for better steady-state economy
3# PULLING HILLS: Diesel have a fuel curve inverse to the torque curve. (on some electronic engines this flattens out)
A typical 400 hp engine may burn 18 gallons per hour (GPH) at 1800 RPM, But only 14 GPH at 1200 RPM. Meanwhile it has MUCH MORE TORQUE AT 1200 rpm.
What does this mean? You generally pull hills at max fuel. You want to pull hills in the highest gear you can and keep the engine at peak torque/ lower GPH.
A big mistake is to drop a gear and run at the hill at higher rpm where the engine uses more fuel and has less torque. This is a fuel wasting downward spiral were you have to make successive gear changes burning more fuel and going slower and slower.
Stay in the highest gear as long as possible in hills, if you can crest the hill at or above 1000rpm, it's usually o.k. to do so.
Think about the savings in hilly terrain, hill after hill BURNING 14GPH vs 18GPH to get the job done. Add that you are usually pulling at a higher speed with correct method so you spend less time at max fuel consumption.
#4 GEAR CHANGES: Shift progressively, use only enough RPM to get into the next gear. Taching out every gear is a waste of fuel, especially in city driving
#5 COOL DOWN: Use exit ramps and truck stop access roads to cool your engine down before shutting it off. If you can coast in to a stop using very little fuel and keeping the exhaust temp down, there is no need to let the truck idle several minutes before shutting it off. Idling is a big waste if fuel and five minutes has a way of turning into twenty-five.
#6 IDLE TIME : THE BIGGEST WASTE OF FUEL OF ALL. Any time that engine is running and the truck isn't moving hurts tank mileage and your wallet. It is also unnecessary engine wear. Shut the truck off whenever you can. Cool engine down as outlined above. Consider alternate heat/cooling options for over the road trucks. These are best installed when the truck is new for maximum payback.
An electric blanket or good sleeping bag can get you a few more comfortable hours in sleeper without having the truck running.
#7 DRIVE SLOWER (did I say that yet?)
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Comment by dieselralph
2008-03-25 13:40:53
I work for an engine maker. I work with a lot of fleets to get them to spec trucks with our engines. Here is a tip sheet you should consider and aerodynamics play an important part the faster you go. (difference between a square nose and an aero truck can be up to 15% improvement in fuel economy!)
The one thing I see over and over is gearing problems. Many times diferences in one truck vs another is one is geared for power and one for fuel efficiency. Never spec one engine the same as another. Use the engine manufacturers gearing recommendations. A C-15 uses different gears than a Series 60 than an ISX. You gear a Cat like a Cummins and it will get horrible fuel economy. Gear a Cummins like a Cat and the drivers will complain about power. Each has its sweet spot. Also, if you buy a used truck, keep in mind the speed the original owner drove at. You buy a 379 and more than likely the owner let it run over 72 mph. Dont expect to drive it at 55 and feel all the power. They probably geared it tall for the high speed and sacrificed drivability at 55 in top gear. Also, stay in top gear 90% of the time and use cruise 70% or more. Cruise is alway .2-.4 mpg better than pedaling on long trips.
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. (Drive 65 vs 75 and save 1 mpg regardless of the truck you drive. Thats about $10,000 a year if you drive 100,000 miles)
§ Worn tires provide better fuel economy than new tires, up to 7% better fuel economy.(Brand new vs. end of life)
§ Used lug drive tires can get up to 0.4 mpg better than new lug tires. (used means broken in)
§ Ribbed tires on the drive axles provide 24% better fuel economy than lugged tires. (new vs new)
§ Every 10 psi that a tire is 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%.
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TIRES
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(Article) OVERDRIVE Magazine 12/2008
"Matching Tire Pressure to Load" (John Baxter)
The tires contact patch should be as large as possible while keeping a healthy amount of pressure and maintaining even contact between all the areas of the patch and the road. That means adjustment to reach the optimal pressure for the load, rather than inflating the tire to the same cold pressure all the time, says Doug Jones, customer engineering support manager at Michelin North America.
Matching pressure to load | Overdrive - Owner Operators Trucking Magazine
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(Article)
BULK TRANSPORTER NEWS 9/2008
"Five tips to control your tire costs and improve vehicle performance, safety
With tires ranked as the second highest operating cost after fuel, a solid tire maintenance program can help reap solid dividends. Knowing the proper inflation level for your truck tires is crucial. TMC Recommended Practice (RP) 235 states the following determines the correct air pressure for a given load:
Tire size and load rating
Weight carried on each axle
Number of tires on each axle
Maximum speed the vehicle travels during its operation
Five tips to control your tire costs and improve vehicle | With tires ranked as the second highest operating cost after fuel, a solid tire maintenance program can help reap solid dividends | Sept 2008
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(Website)
Barry's Tire Tech
. . I hope you noticed how flat the wear index is for the radial tire. I interpret this to mean that conducting a "chalk test" is not a good way to determine what the best pressure is for wear.
Barry's Tire Tech
(One of the screwups in the Ford Explorer/Firestone fiasco was that the tire pressure spec'd by Ford left no reserve. 20% is recommended.)
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(.pdf)
FIRESTONE MEDIUM & LIGHT TRUCK DATA BOOK
(see pages 52 for truck fuel economy discussion; and page 64 (+/-) for load /pressure tables.) (Go to the man'f'r of your tires, download and copy).
http://www.trucktires.com/firestone/...ckDataBook.pdf
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