The ultimate in 18 wheeler aerodynamics, -from Walmart?
 

This is is a L-A-R-G-E file but worth the wait :sad:

http://truckinginhighgear.com/walmart/

http://007planb.com/images/405-Giant-Ferrari.jpg

I have read about these type of things before. I am not sure how much the average owner operator would save compared to the cost of the modifications. I think that anything we can do to reduce drag or get better fuel economy is good. Anyone thinking about purchasing anything such as these should consider the cost/benefit of the expenditure.

Wasn't it wal-mart that wanted a 12 mpg truck by 2015 or something like that?

That sounds familiar about the 12 mpg truck. I don't see why we shouldn't have a truck that gets that much mpg today. We could save a ton of money. Of course, they would probably just raise prices to compensate for the lost income. :evil:

It would take a huge combination of things:

- New "length" rules to account for boat tails. The rear of a 53 foot dry van accounts for 1/3 of aero drag. This needs to be reduced in order to get better fuel mileage.

- Increased efficiency of the engine, instead of decreasing that we've seen over the past while. Cummins has a prototype engine that recaptures lost exhaust heat, and converts it to energy. Detroits new DD15 is going to use turbocompounding, it's coming out in March

- Lower rolling resistance. Super single tires, and a perfect alignment.

- Better aero, the cascadia looks to be the current front runner. I'd prefer a ZERO trailer gap as well. Skirts on the side of a 53 foot van. Better under vehicle aerodynamics. Smooth "plates" covering the wheels of drive and trailer wheels. Deck plate so that wind doesn't go under the truck, and slam into the front of the trailer.

- Direct drive transmission. Reduces driveline losses about 1-2%.

- Low churning differentials, or maybe only one drive differential.

- A speed between 55 and at MOST 60 mph.

- ZERO idling

Doing ALL of these things I could possibly see 12 mpg.

I agree, I think truckers news or Roadstar had a 30 year anniversary edition in the truck stops last month and mentioned the same thing.

30 years ago avg MPG was in the mid 5's, not a whole lot has changed since then, pretty bad I think considering all the changes in car MPG

Yes but the big thing is the economy cars have low HP. Our trucks now have more HP then they ever did.

We haven't changed a damn thing for trailer aero, just some truck aero.

We drive faster then we did 30 years ago.

Zero idling???you go ahead and run your engine without warming it up and shut her down nice and hot and see how long it will last you.

no mention of synthetic lube?

I have an espar engine heater, works far better then plugging it in or idling it.

I take it easy the last while before parking, by the time I'm backed in the EGT's are usually around 300.

A properly formulated spreadsheet could easily show the break-even point. Any spreadsheet professionals out there?

Even if THEY did, we'd B paying the American terrorists (domestic oil co.'s) INSTEAD of THOSE islamic (et al foreigners, like the idiotic Shov-ASS [chavez?]) terrorists , since we wouldn't B importing as much oil.

There's a company in San Diego experimenting with exhaust heat to produce current thus replacing the alternator.

What is the current allowable lenth? I thought 57' trailers were now allowed but I haven't seen any on the road.

BUT, the increase in MPG more than justifies the the loss, thus OD's are COST-EFFICIENT.

I believe synthetics are the way 2 go (less profits 4 the terrorist). Amsoil's website probably lists the benefits.

The alternator really doesn't produce much drag. Fully charging it's only around 2 hp. Something like turbocompounding or exhaust heat recapture can produce up to 50 "free" horsepower.

Some states, yes, but I'm talking about across the board

No and no. Take a 10 spd overdrive with 3.58 gears, and a 10 spd direct with 2.64 gears. Both behave exactly the same, same startability and shift points. But in the final gear the torque goes right through the direct drive, and has to go through a gearset for the overdrive. This results in a 2-3% or so gain in fuel mileage. Schneider has known this for years, and they always spec direct drive trucks. It's the way of the future. Unfortunately 2.64's are the lowest numerical gearset currently availabe. If one wants to run efficient 22 LP tires, the top speed is very limited. Much like 3.58's with an overdrive transmission with 22 LP tires.

At 70 mph you'd be screaming at 1600 rpms.

With direct drive and fuel efficient tires(22.5 LP's or super singles) you need to run slow. That's why you don't see direct drive transmissions very much.

Allan5oh........great posts with good information. I also read that the alternator only accounts for about 2 hp.

I know this isn't related to aerodynamics but your gearing example brings me to my question. Where can I find an article explaining gear ratios? Or can someone here explain it to me? I ask this as I can't find an explanation of it anywhere, and most drivers I've talked to don't understand it beyond saying that one is for higher speeds versus another for higher weight. Any info would be greatly appreciated.

Oh, and Mandilon........As Ron White said, "you can't fix stupid." One can't even begin to figure out where to start in correcting such a statement as yours.

"Even if THEY did, we'd B paying the American terrorists (domestic oil co.'s) INSTEAD of THOSE islamic (et al foreigners, like the idiotic Shov-ASS [chavez?]) terrorists , since we wouldn't B importing as much oil."

Flying W... I did an explanation on here somewhere, I'll try to find it and give you the link.

The quick and dirty is that the # is how many times the driveshaft spins vs. tires.

For example, 3.90's the driveshaft would spin 3.9 times every time the wheels spin.

This gives torque multiplication, but reduces the speed that the truck can run.

Consequently, a truck with 3.55's can run much faster, but torque is multiplied less.

If anyone is interested, I got my greasy hands on an EIGHTY page aerodynamics report from TMA. Very good stuff. There's 12 pages on mirrors alone! Trailer gap, deck plates, trailer rear and side fairings, truck belly fairings, very cool stuff!

I'd much rather have an areodynamic truck over a large car.

I appreciate the response, and look forward to seeing the link. My understanding of torque is that torque helps you accelerate. So the 3.90 would get you up to speed (highway) quicker but not be as efficient/smooth/etc once there as the 3.55 gear ratio?

I understand this is an aerodynamics forum but ultimately we are talking about fuel mileage. Well a few of us might just want better aerodynamics so that we can have the window down with less noise from the howling wind when driving. 8) So picking the right gear setting for the application should improve fuel mileage (or could)? There has to be a buyers guide or something addressing this. I'll keep looking.

I can't speak for the others but I'd be interested in that TMA report (mirrors, deck plates, and truck belly fairings particularly).

Maniac,

30 years ago, mpg's may have been in the 5's, like today. However, todays engines are burning cleaner than back then. EGR, for example....

Anyone hear that guy on XM Trucking channel on the weekends? He's pretty sharp until he says something stupid like "We don't need this horsepower we're making today. We used to have 235 to 290 and we made it up the hills just fine" Well, I remember those days, and I DON'T remember getting up the hills just fine.

Why would anyone want to waste evan TWO HP when it can be gotten 4 FREE from the wasted heat from the exhaust :?:

Alternators are in the upper half as problamatic (tires are #1) as far as breakdowns. What's THE COST of an alternator breakdown, lost revenue et al :?:

God Bless all

I remember those engines. The first truck I bought had a 238. The truck just kept on going. It would pull up the steepest mountains, but take much longer to get there than the newer more horsepower engines. On flat ground they would do as well as the big hp engines. Unfortunately, there are a lot of big hills in this country. We could still get along with the smaller engines, but would spend more time climbing the hills. That truck only got about 5 mpg as I recall.

I'd like to see that report allan5oh. I'm looking for info that covers mileage increases on just the tractor to get a feel for how much aerodynamics would play if pulling a flatbed or tanker. Most always describe a tractor-van combo and cumulate the results rather than saying "the slanted windshield resulted in 1.2% gain, the single wide tires on the tractor .8%..." etc.

ncnewbie: The link below is to the Kenworth fuel efficiency pdf. It lists the % gain for individual tractor items. I read somewhere that these are not cumulative. But they should at least provide some insight as to their effect. Page eight of the Kenworth White Paper states that a low roof results in better aerodynamic performance with a flatbed or tanker. Which then makes me wonder as to the benefit of the other aerodynamic improvements for flatbeds/tankers.

http://www.kenworth.com/brochures/FuelEfficiency.pdf

GMAN, et al: Were loads heavier back then (80k+) with those smaller engines? I'd love to see the mpg results of a modern aerodynamic tractor (chassis improvements, etc) with those smaller engines. It would be interesting to see if there is a mpg improvement or not.

When I started we were not allowed to carry as much weight as today. Trailers were not as long, either. Most trailers were 45' long. Many of those 238 engines pulled around 80,000 pounds as there are still some on the road today. Those were dependable engines, but fuel economy wasn't so much of a consideration back then. Trucks get better fuel economy today. Modern trucks are also much more comfortable. I don't think we have come very far on fuel economy from 30 years ago. It seems to me as though we could have done much better in improving fuel mileage.

I think they're more focused on diesel engines burning cleaner at the moment while focusing on mileage 2nd. I think once all the bugs are worked out with EGR and ULSD, the next main focus will be MPG's. Things like aerodynamics should be on the forefront now, as they can be a complete project separate from engine efficiencies.

I think the government grants to drivers (APU units in WI, newer diesel engines in CA) are a good start. Kinda like college grants for disadvantaged students to achieve success, we are no different.

I heard about the old days from my Dad. Things like waking up 2 hrs early to light a BBQ grill under the cabover to get it warmed up enough to start on a cold winter morning make me feel spoiled. My Dads buddy (62 y/o) talked about mixing a little kerosene with diesel because it was a few cents cheaper than diesel helped, having to carry a 55 gal drum of oil (slight exxageration) and the days of spring ride suspension let me know that guys like you (Gman) really paid your dues! :D

In my last 9 months of being O/O with my semi-largecar, I've learned the best way is to keep the left door shut and stay off the throttle. I have been using Howes every now and then, but my Dad swears by "Power Service" (although I haven't found that yet. He had a nose cone put on his HHG van to help fuel economy and belives the centramatics help tire life and provide a very modest mpg increase. Also, while pricey, aluminum wheels on all 18 help.

How efficent are the sideskirts of the Conway trucload trailers? I wish someone could gove me a number. I'm sure they help. I think I benefit from that advantage, as probably 2% if the members on CAD can crawl under my trailer (present company definitely excluded!)

I dont know how efficient the side skirt are, but we are ripping them all off the trailers now when they go into the shop. They sit too low and if you have to back over a curb, they tend to get damaged.

those side skirts are made by freight wing.

Thanks for the link Flying W

Anyone have any experience with the Liberator (or other brand exhaust)? How accurate are their claims of 5-10% improvement?

http://store.getliberator.com/Produc...ctCode=LES-001

I don't have any experience with the Liberator, and am not an engineer, but the two articles I could find on it make me skeptical at best. The words "under certain circumstances" make the rest of the article doubtful at best to me. Or stating one thing, and then following up with something that sounds good but in reality has absolutely nothing to do with the first statement like the quote below. I'd love to see someone try claiming that their unrealized fuel gain is a "manufacturing defect."

"AET is the only company in the heavy truck muffler industry that makes
specific mileage claims," Bergesen said. "And we are so confident in the
quality of our product that we are offering a lifetime guarantee against
manufacturing defects to original owners."

If the product were as good as it seems there should be plenty of information to fill an article with. I see two articles with very little supporting their claim. Just my $0.02 worth.

http://www.theautochannel.com/news/p...ess030996.html

http://www.theconcreteproducer.com/i...ticleID=589107

Great information guys...thanks!

I know its rather complex and will add weight, but perhaps a two speed axle would be the answer like they had in the early days with gasser trucks that were lucky to push much more over 100hp while carrying quadruple their weight. Besides, if BMW can create an excellent car with a direct drive standard transmission, there's no reason KW, Freightliner, Pete or any other truck manufacturer can't do the same with more wind noise.

**Can you overdo TALL gearing?

I recall reading about someone who tried this (of course I can't find the reference now), who was not very happy with the results. The new gearing was so tall that the truck's already slow acceleration became unbearable. He ended up using lower tranny gears longer and more often, and with much more throttle than before, which negated the theoretical fuel economy benefit of the swap.

So is it possible to overdo things exclusively via gearing? Sure. Your OEM final drive was chosen by the engineers to balance fuel economy & performance. Depending on how & where you use your rig, you could easily go too far:

Heavy loads: your OEM gearing / final drive is designed so the engine can handle a full load of cargo. If you regularly carry a lot of weight, changing the final drive could be a problem.

Hills: if you live in a mountainous/hilly area, you may already often be at the "limit" of drive-ability with your stock gearing & final drive.

Clutch wear: changing the final drive may require much more aggressive clutch use to get moving in first gear. If you drive in an area where you regularly have to accelerate briskly to accommodate other drivers, this will reduce clutch life.
Just a thought.

Keep On Trucking