Class 8 Truck modifications

[vortex]

It is no secret that tire rolling resistance decreases as tires age. Mostly this is due to tread wear and overall thinning of the crown. About 2/3 of tire rolling resistance comes from compression and bending of the crown. Rubber is an inefficient spring in that it does not restore all of the energy used in straining it. Some strain energy is diffused as heat and the difference between applied and restored energy is hysteresis loss or rolling resistance. A thinner tread compresses less so it suffers less hysteresis loss. You could shave or "buff" new tires, reducing tread thickness to decrease rolling resistance but it is difficult to rationalize any ROI due to the decreased service life of the tire.

Another smaller factor decreasing a tire's rolling resistance as it ages is the natural age-stiffening of the rubber compound. A higher modulus compound reduces total tread compression and therefore strain hysteresis loss (rolling resistance).

You might pre-buy your tires a year or two in advance and age them yourself in some very hot outdoor facility as a steel shed, sheltered from UV and test strategy for yourself. It is difficult to say definitively how much this compounding hack will decrease rolling resistance as compounds vary and some may be more resistant to aging factors than others.

[robertwoodliff]

Just to add to the " confusion " it may be of value to look at " SunFoil Project Update ; Mk-8 Install, Mk-9 Revealed, Flexible PV Assessed. " on Youtube . The addition of a solar panel to keep the battery in as near fully charged condition , to save the alternator cutting in . In a diesel this is less relevant that petrol / gasoline , but should still give aid . One thought Chris had , was to put a HHO driven by solar to avoid the energy being taken from the battery / alternator .

[armygreywolf]

My time is a bit limited but have you covered tire brands yet? There are more than a few companies who have discovered retreads are costing them fuel efficiency. I bet it's already been mentioned but full alignments of both truck and trailer are paramount, a hundreth of a degree of trailer runout puts it into the wind about 2 inches.

Engine modifications: I used to hotshot for the oil and gas industry. I worked for a company that supplied parts for gensets at the various drilling sites. On a cummins they respond very well to exhaust side porting, ultimately I purchased a steed speed manifold but porting the stock manifold as well as the head helped my mileage about 4% and lowered egts a bit too.

Other modifications on a modern common rail truck you might think involve parasitic drag, pump and fan, but the pump has a built in relief that is pretty dang good at allowing it to free spin and the fan on most modern cummins engines can be stopped with a finger, usually they use a hydraulic actuator that turns the fan on and off as needed. An electric fan with enough CFM capacity for the horsepower rating of the truck would both cost thousands of dollars but also potentially be detrimental to hill climbing with a load.

I see water injection is being tested, it works and is commonly used all over the diesel industry, sometimes by OEMs. You actually can increase injection timing a few degrees to pick up some efficiency, however if you run out of water it is going to make the injector tips very very hot.

Do the trucks used give the driver feedback about fuel consumption live on their displays? Some new(er) trucks are using adaptive cruise control with a variety of efficiency functions now too, including pick up trucks.

Oil. I wanted to bring it up because I own a few diesels. Not too long ago CK became the latest oil standard, it's been CJ-4 for years but now with the latest efficiency and wear improvements CK is the new standard. So far I have tried Delo and Rotella CK formulations. Personal observations, the engine is just a bit quieter, it takes longer to warm up by a minute or two and the EGTs are a bit lower. I don't have a solid metric yet for fuel efficiency because this is only my second oil change so far. I suspect a 1-2% improvement over the bulk Delo I was using. In this catergory there is alot to be learned, I suggest heading over to bobistheoilguy.com to learn more. Oil temperature can also be a big player, I like to see my oil temp around 10-15 degrees higher than my water temp. I like coolant to be around 200 on a cummins, it's about what they design most of their engines to run at efficiently.

Does your company own the reefers they are hauling too? If so there is something to be said about making sure the apus in the vans are running well, have the proper refrigerant level and the coils are clean. I bet you've noticed it by now that the fuel use of those reefers can be all over the map. It would be something to take a look at.

I will check back tonight or Monday when I get the chance to sit down and read the whole thread, GOOD LUCK SIR!

[Shepherd777]

Originally Posted by craysus

If an engine manufacturer could deliver the most efficient engine taking into account a lot of external sources, and other pieces, forums such as this would NOT exist..

Modern diesel engines are hyper fuel efficient, with astronomical fuel rail pressures, and a multitude of other internal improvements.

If one is getting poor fuel mileage, it is not the fault of the modern diesel engine, it is the fault of every other component on the vehicle.

Just my 2 cents, but I have been building hyper fuel efficient Class 8 trucks since 1983.

[stoatwblr]

I'll stay away from the engine and drivetrain, except to note that for all the naysaying, Cummins and the other makers all produce heavy engines which are generally as optimally tuned for fuel consumption as they can get and still stay within emissions regulations. Trying to feed them with alternative fuels is usually counterproductive.

That said, if you move from external belts to a more-electric environment you might get a couple of percent.

Aero is one of your big wins, especially if you concentrate on smoothing the blunt front and the vortex-inducing rear as well as the underside but without rigorous A-B-A testing over long periods to remove driver bias in short tests it can be hard to quantify.

I'll add to the comments about wheels and moondiscs with this caveat - spray.

It's not uncommon for heavy vehicle aero "improvements" to make spray throw significantly worse on heavy vehicles. When you do test, please pay attention to where the water's going during wet conditions.

Something to consider if it's not fitted already is an exhaust heat recovery system - with appropriate plumbing and controls this can be used to achieve faster system warmup, then might be used to drive a separate stirling-based electrical generation system to feed your accessories. You might find you can practically deploy an ammonia adsorbtion cooler for the cab or reefers too. No matter how much you improve the aero or drivetrain friction, there's pretty much always 50-100kW of energy going out the exhaust on a longhaul rig, if you can find a practical (cost-effective) way to harness it.

[coachgeo]

move some of your engine load to solar. For example, your Electronic engine cooling and electronic AC power demands can be facilitated by solar. Your aerodynamic wind deflector above cab can be loaded up with cells as can the hood.

IMHO over the road trucks should be designed like Locomotives. The diesel engine is just a generator that keeps capacitors charged. Capacitors power the electric engine that drives the wheels. The actual trailer of goods being hauled sits inside a skin loaded with solar cells. Skin just clamps to each trailer after it is latched to the truck.

I wonder too if aerodynamics can be smoothed by passing turbulent air thru fins of wind generators that redirects air to a stable flow. This in effect capitalizes a bad thing (turbulence already is creating drag) and smooths it out while creating electricity. If one can get the drag of the wind generator to equal the former drag of the turbulent air... then net effect is no "additional" wind drag created by generators. A win win.

[gumby79]

Originally Posted by freebeard

That's pretty amazing. Do you have any theory as to why everyone doesn't do it?

Lasy, uninformed, people would just put free tap water in . Thinking it's water, all water is the same tap is just free , why should I have to buy "special water" the Manufacturer is just trying to make a buck. Thinking I have put tap in my radiator all my life with no problems, not realizing that they have been replacing radiators evry 5-10 years Insted of every 40-60 years. Same thing gos for HHO . You can see this with the DEF people are trying everything they can to bypass the systems. Sighting I allerady have to buy diesel why did they add a gimmick forcing me to buy the blue Juice.
In Las Vegas Nevada my sister is recommended to replace(not flush thats every1-2) the raidator every 5-7 years by many shops, because the tap water is plugging the core with Alkali precipitate. They just call it plugged. .

craysus
Also obviously if you tune for water and the system fails or you run out of water it's not good.... But similarly running out of diesel ain't such a good idea either..

Add a floatto the resavor that signals the computer to switch maps and shut down the injection system.

Shepherd777
Modern diesel engines are hyper fuel efficient, with astronomical fuel rail pressures, and a multitude of other internal improvements.

Agreeda CR Cummins with a 1-3000lbs weight penalty gets the same MPG as as my aero modded 12V 6BT 5.9-160 mechanical injected Cummins, but there is room for more
Keep up the good work . .

[freebeard]

Shepherd777 — It's good to see you in the thread.

Originally Posted by armygreywolf

On a cummins they respond very well to exhaust side porting, ultimately I purchased a steed speed manifold but porting the stock manifold as well as the head helped my mileage about 4% and lowered egts a bit too.

https://www.google.com/search?q=diy+extrude+honing

Originally Posted by coachgeo

I wonder too if airdynamics can be smoothed by passing turbulent air thru fins of wind genertors that redirects air to a stable flow. This in effect capitalizes a bad thing (turbulance already is creating drag) and smooths it out while creating electricity. If one can get the drag of the wind generator to equal the former drag of the turbulent air... then net effect is no "additional" wind drag created by generators. A win win.

Ain't gonna happen.

[coachgeo]

Originally Posted by freebeard

....Ain't gonna happen.

few details would be educational to many.

[Kevin Cooper]

I have a few comments for you regarding truck aerodynamics. I have been involved in the development of virtually all of the aero add-ons used today. The work was done in the wind tunnels of the National Research Council of Canada form 1976 untill today. Current trucks have much lower fuel consumption than several decades ago. The largest contributor to this improvement has been aerodynamic improvements. I would recommend both boat-tails and trailer skirts for your fleet, assuming that you already have the cab-mounted aero packages and cab extenders. For more info download the Society of Automotive Engineers paper SAE 2003-01-3376, entitled "Truck Aerodynamics Reborn – Lessons from the Past" by Kevin R. Cooper, Aerodynamics Laboratory, NRC Ottawa, Canada. For more info contact Kevin@CooperAero.com. Good luck.