Class 8 Trucks
 

Anyone out there that's made and tested fuel savings on class 8 trucks by way of aerodynamic and/or powertrain changes?

I'll try to throw up some pictures of our different tractors and list some changes I'd like to do to improve them. Most of them would be pretty simple and obvious changes. Currently I might as well be taping plastic bags to the sides because that's how obviously stupid things were designed all in the efforts of style.

The stacks on most of our trucks are currently just behind the doors and I think the benefit would be quite huge if I was to move them behind the sleeper. I have no idea what kind of mileage improvement I could expect on the first obvious fixes but I'm looking forward to finding out now if I can only get the boss to agree!

Looking forward to hearing any ideas or knowledge people have on the subject :cool:

I would love to tackle this project head on. I know there is room for improvement on these large trucks. However, the first change has to be with your drivers attitude towards saving you guys diesel.

Have to started keeping fuel logs? I would start there. Establish a before baseline with each individual truck and get the cooperation of the drivers. Explain what you are going to do and why. Heck if possible try implementing an incentive program for participation and improvement.

After that there are many tweaks that can be done before you get into altering the trucks. Driving techniques and driver attitude may get you the svings the company needs.

I would be more than happy to help you pro bono of course, so drop me a pm if you like and we can get a more technical plan going. Because if we can make this work then we have a blueprint any of us can market to fleets in need.

Hey trikk thanks for showing your support.

Yes I forgot to mention we did put a fuel saving incentive program together and implemented it 2 months ago as well as a dwms (don't wreck my *&#) bonus.

So when you get a chance, post up a picture of these bad boys, having a solid background with tractor trailers it would definately be cool to try and apply some ideas to these beasts.

Here's some stuff I'm currently running by the boss. I'm thinking of running one truck as more of a prototype for possible fleet wide changes.

2 of our older trucks are Columbia model freightliners with Mercedes engines that are perhaps a bit underpowered for the job but are lightweight and aren't as bad aerodynamically as our more classic styled trucks. There also the trucks most likely that the boss would let me make any changes too however unlikely he is to period.

1) move the 2 exhaust stacks from the side of the trucks to a single stack behind the sleeper

2) the air breather is currently under the hood which is better then the outside but I think we are pulling in warm air from beside the engine. With what could be a small bit of fibreglass work I think we can pull that air from the outside instead which should give us a power boost.

From there I'm not sure except some other smaller projects like possibly moving antennas/horns/covering up some holes in the bumpers that serve no existing purpose and perhaps shedding some unneeded weight.

We currently have regular tire service that is supposed to be on top of keeping tire pressure up but I sometimes suspect this isn't happening as well all our newer trailers have a psi system that in theory should be keeping are tires at the proper inflation.

Also I have to be roughly sure that there is going to be a positive return on investment it is a business after all it's not like the truck has an unlimited life span to endlessly recoup money.

any ideas are welcome though throw them out there please.

I'm sure you have weight restriction to deal with too ...

What techniques do your drivers use now? Do any of them coast to stops @ idle? Do you have to downshift to brake or are the air brake setups enough to stop the truck? How much unnecessary idling do they do? I don't mean shut them off at lights or anything, but do they unload with the truck running? leave them on during lunch breaks, etc?

The tires could be your first focal point, now keeping them @ max psi to sidewall may be the safest way to go, around here truckers use re-treaded tires and I would never trust those at any psi.

I agree removing the stacks will help. Simply pipe or dump the exhaust under the truck or out the side and away from the main air stream will save weight and start giving small benefits.

How about wheel discs? Switching your lighting to LED's. The less the alternator has to work the better ...

oh and pics pics pics ... stop teasing us and making us guess in the dark ... LOL

Unfortunately we don't have tracking units at this point to watch there driving habits. Once inawhile we get them hooked up at the shop and get a readout telling us there breaking habits, idle time etc.

With the new performance system a few of them are really trying to make the goals so I don't imagine they're idling like they used to do.

I should send out a common sense driving habit newsletter with some fuel saving ideas as well. I've already told them what slowing down by 10mph would do for them.

Also we haven't ran recaps on our company trucks for a few years we don't trust them either.

I'm working on the photos I know we have some on one of our computers

Oh and yes we are rocking LED's

Are any of them over night sleepers?

Very good ideas so far. I can't stress enough the incentive plan. I can tell you from firsthand experience that people drive much differently when they're not footing the fuel bill (or in your case, getting a bonus for NOT using a lot of fuel.)

I think a hybrid system would be ideal for these trucks, as they waste fuel spinning up the turbocharger heading uphill, and then waste the momentum with the Jake brake downhill. Running the engine to keep up the electrical, air and A/C while parked is another problem easily solved by such a system.

The problem, of course, is the weight of the batteries. With a mandated 80,000 pound limit, every pound up front is a pound that can't be carried (for profit) on the back. Maybe the NTSB can come up with rules that allow the extra weight of hybrid systems to exceed the 80,000 threshold (say, 80,000 max allowed, plus up to 2,500 pounds of batteries.)

As to your problem, is there any way to enclose what's loaded on the flatbed? Maybe a curtain-side trailer with a boattail on the back, like these?


Tim

If your class 8 is the typical semi here in the states then here are more suggestions ...

Fenders for the rear wheels of the truck and perhaps trailer. Design fiberglass fenders that cover as much of the wheels as possible, even side skirt style, thus reducing air turbulence from that part of the truck.

Also are you running dual wheels on the tractor or a single per axle? The single wheel may appear to be more wasteful but is actually a more fuel efficient alternative to running the dual wheels on the tractor. It also reduces weight by eliminating an extra rim & bead lock ring.

If you do not run these trucks at their full 80K pound capasity all the time I always thought a bounce house like inflatable bag that could fill the gap between the cab and trailer would help improve air flow over and around the trailer, using hot air from the exhaust to keep it inflated with a small exhaust vent for when the bag is compressed on tight truck turns.

More to come ...

The trucks are long haul so yes they are all outfitted with sleeper births.

We run the northwest states and have a licensed GVW of 98,000lbs stateside. But you are correct weight is almost always an issue. You are also correct about the wasted energy. There's a lot of excess heat from the engines and especially the exhaust. As well running the engine fan to keep things cool while pulling those hills is a drain on our horsepower. If we could collect energy from other sources otherwise wasted to power things like a guys fridge or that engine fan I'd think that would help but those are overhauls well beyond my means unless they are selling systems like that as kits.

We've thought about Tautliner trailers before but the cost outlay is much higher and they don't work with a lot of unload and reload situations that load with an overhead crane etc.

Also are trailers are flatdecks. If they were Vans I'd have some ideas far beyond what I've seen anywhere so far hehe. It would deal with the gap between the tractor and trailer

Check out this site .. Home

They have an a/c heater system for your trucks that is independant of the engine and electric loads, thereby letting you sit overnight without idling the trucks. That alone could save you big bucks at the pumps.

I guess aerodynamics is still a big issue with trucks, but how about the single wide tire vs, dual skinny tires? I don't know if the single tire has lower rolling resistance or not but it might be something to look into.

Also something simple would be coasting downhills in neutral, and pulse and glide should have good benefits for such heavy vehicles.

Can trucks maintain air pressure at idle in a long panic stop?

Wheelskirts

The super singles you are referring to have been tested and are a fuel & weight savings but unfortunately they don't have the same weight acceptances where we travel so we can't use them on our units at this point.

The sad thing is there's improvements that can be made but many are cut off from us due to the rate at which government moves on things

Just a few links I found for you two to chew on.... :thumbup:

Freight Wing Incorporated - 6% fuel savings with our Aerodynamic Trailer Skirt, The Belly Fairing and Gap Fairing.
Aerodynamic improvements & flow control boost fuel efficiency in heavy trucks
Aerodynamic Truck Trailer Cuts Fuel And Emissions By Up To 15 Percent
Increase diesel truck fuel economy and mileage efficiency with AirWedge

Also think about gap reducers between cab and trailer and Boat tail the trailer.

HTH

here's another link --> SmartWay Tractors and Trailers - Partners - SmartWay Transport Program - EPA

What kind of trucks? Kenworth W900 or something more aero like the Kenworth T2000?

There has been a ton of work done on this. The sheer diversity of howtrailrs are used defeats any "one size fits all" mods.

I do know this: leave your underhood air filters alone. They are the optimum setup.

We have some W900's in the fleet nothing aero like the T2000. Most of our trucks sport a classic truck look like those of the longnose kenworth W900's. The freightliner columbia models are probably are most aerodynamic trucks in the fleet which isn't saying a whole lot.

Our Columbia models are like this one but the sleepers are smaller and the exhausts are not behind the sleeper but just behind the doors.

Yeah it's virtually impossible to really make our flatbed trailers aero friendly. I think all I can do with the trailers is look to eliminate uneeded weight and find a good cheap tire with the least amount of flexing.


About the underhood air filters though it just doesn't seem optimum. When the trucks are in the yard I'll try to get a photo or two of what I'm talking about. They seem to be in a location that would most likely pull in hot air which can't help our power situation out any (this is on the columbia models)

I don't know if this carries over to diesels at all, but in my Insight I get better fuel economy with warm intake air - 100-130F, as opposed to whatever comes in from the outside. I think it allows the ECU to run a leaner mixture.

Of course economy is not the same as power - on long flat stretches the Insight doesn't need much power to maintain speed, and I suppose with the trucks it'd depend on how it's geared. So maybe a flapper valve to pull in cold outside air when power is needed (like on hills), or warm air when cruising on the flat.

You're going to have a hard time "fooling" a diesel computer into running a leaner mix - at least based on intake air temp.

The whole reason why your gas engine pulls fuel is in order to cool things off in the combustion chamber and prevent precombustion that a "hot mix" could be succeptible to. Um, precombustion isn't an issue in diesels. Forget about it.

Plus, why would you ever want to intake warmer air on a TURBOCHARGED AND INTERCOOLED engine? By the time you go through all that processing, you're not going to affect precharge air temperature anyway.

By the way, most gas engines NOT ONLY pull fuel when they see high intake temps, but they will also pull out timing. Um, power and efficiency (power per fuel) go down when this happens. It will vary in magnitude from computer to computer, but you're trying to convince your computer to use less gas. In the end, the computer will correct based on O2 sensor readings. I'm pretty convinced warm air is a placebo effect. Didn't work on my vehicle.

If you better understand what goes on inside your computer, you can better understand what to do outside. Warm air does not make a combustion process more efficient. It makes it worse. Maybe your computer does something funny, but the basics of Carnot/Rankine cycle dictate that a cooler charge/sink temp is more efficient at harvesting the heat energy from the source. Always.

Yes diesels are different then gasoline engines when you're talking about intake air cool should be a good thing on diesels.

also I forgot to link a photo of a freightliner columbia. This one isn't ours but it's similar it has a larger sleeper though and the exhaust is behind the sleeper like ours should be.

http://ppgmedia.buysell.com/ppgphoto...04-display.jpg

also...........now I know there is those things out there that are too good to be true and maybe this is and if I was one truck I'd likely stay away from an item like this................. but what do you all think of fuel preporators?

I'm waiting for one to come in to test and well could be an absolute waste of cash or worse cost me more but if it works I could save a lot with it when you multiply it by a fleet worth of trucks. There seems to be some legitimate testing behind it. Has anyone ever toyed with one of these?

http://www.pureflowtechnologies.com/FP200C.htm

Weird my pics didn't attach on my original post... so here they are.

few more...

That crazy cab design is by this guy named Colani, he does all kinds of smooth designs like that, just google him. He's got a killer mustache too!! lol

Huh? Seems to me the reason the gas engine pulls in fuel is to burn it. Sure, there are some old designs - aircraft engines & two-cycles - that used fuel for cooling, but that's ancient.

Because it might give better fuel economy? As in maybe there's a good reason why those trucks have their air intakes located where they are?

That's the same thinking that says an engine has to have an A/F ratio around 14:1, and can't possibly run at 21:1 or leaner?

I don't claim to be an automotive engineer. I just know what happens to the mpg display on a cool day, when the ScanGauge shows IAT around 60 degrees, and I hook up the duct that brings warm air off the cat to the intake. The mpg goes up significantly. If I said I knew for sure how or why this works, I'd be lying. I just know it does work.

Can't tell from the picture, but it looks like that visor over the windshield might mess up airflow.

Also, if you always haul flatbeds, could you somehow do a taper back from the sleeper to the top of the load?

Is this on a gas or diesel engine? Warmer intake air should help out reducing pumping losses on a gasser at part load, but on a diesel w/ no throttle to incur said pumping losses there's no point.

"Lean" and "rich" have no meaning to a diesel. Unlike in a spark-ignition engine, where the combustion is of a fuel vapor/air mixture, the diesel combustion event occurs of the surface of the droplets squirted out of the injector. Diesels usually operate in an "excess air" condition. If they don't, they belch black smoke.

Yeah, you might get a little more power from sucking in cold air but that would only matter at max road load.

The increased aero drag from an external air filter more than overwhelms any imagined efficiency gain.

What truckers need is a trailer without wheels aligned in different directions (according to a Cummins study on optimum fuel economy).

I don't know how many intermodal trailer bases I've seen with wheels that looked like a cartoon clown car. Getting wheels that don't wobble and are properly aligned is a good start, but hard/impossible to implement.

Tractor owners often pick up what ever is next on the list. No say in the matter. Paycheck or not. Efficient or not. Alignment is key.

yes a proper alignment is huge. If you're unaligned it's going to cost mpg and improperly wear our expensive tires.

Bigdave we are almost always loaded to max weight. Also, I'm of course not thinking of putting the air filter outside just possibly pulling the air into our internal air filter from the top side of the hood. Any new drag caused from that would be pretty minimal.

Class 7 and 8 tractor-trailer are aero-dogmeat because of the chief virtue of the tractor-trailer setup: flexibility. Class 5 and 6 straight trucks may offer some scope for aero-improvements although most of these are local delivery trucks. However there are the hotshotters.

Check out this site for trucking aerodynamic improvements.

SOLUS - Products and Inventions for Fuel Economy

It has a few NASA engineers and PHDs that have applied their knowledge and skills to come up with a few simple cost effective solutions. They have employed computational fluid dynamics and wind tunnel testing as well as on the road testing to verify there methods.

This is relevant to the topic, unfortunately not a possibility for the application being discussed.

I saw a tractor trailer pass me this morning and its trailer was rather odd. First it had a large dome in front of the trailer to break up the air.:thumbup:
Then after the kingpin and clearing the tractor, the trailer floor dropped to within 1-1/2 feet of the ground and the entire side of the trailer had a side skirt that cleared about 8" off the ground. That lead to the the very small rear wheels on this trailer. By small I mean they were the size of your average suv wheel, no where near the 22.5" I see on standard trailers. It had eight on the back like all other trailers. After the wheels the side skirts sloped up to meet the back of the rig at what looked like an angle between 10 - 15 degrees. And to end it all it has a rounded rear that spanned from top to bottom, I guess the best boattail attempt I have ever seen on a rig that large.

All in all this beast was 48' feet long and I think the tail made it 53, it looked hinged so it could swing out of the way for loading. It was the first time I saw anything that resembled an attempt to help aero on a production scale. Of course the tractor was all smoothed out with the stacks tucked behind the cab, gas tanks were covered and even the rear wheels had full fiberglass covers and skirts. I wish I had my camera handy, it really was a neat thing to see.

Oh and he was hauling ass, I had to do 80 to get near it to notice all of this ..:eek: ANd when I did, I experienced a suction effect instead of the normal air pushing me into the next lane, which I thought was kinda cool.

The members of this forum have discussed several solutions to get fuel economy for Class 8 trucks. Here is another, there are currently on the market a fender for class 8 trucks that is certified for the reduction of fuel. This fender is designed and manufactured by Meka Form. These fenders not only reduce your fuel bills, but save you money on your operating cost, and they have a very good return on investment.

Here the link an some photos:

Meka Form Fenders

http://www.mekaform.com/media/presse/meka_econo01.jpg

http://www.mekaform.com/media/presse/meka_econo02.jpg

http://www.mekaform.com/media/presse/meka_econo03.jpg