The ultimate in 18 wheeler aerodynamics, -from Walmart?

[Mandilon]

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

http://truckinginhighgear.com/walmart/

[GMAN]

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.

[allan5oh]

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

[GMAN]

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:

[allan5oh]

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.

[Maniac]

I don't see why we shouldn't have a truck that gets that much mpg today

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

[allan5oh]

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.

[One]

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?

[allan5oh]

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.

[Mandilon]

GMAN
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 expenditur

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

GMAN
Of course, they would probably just raise prices to compensate for the lost income.

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.

allan5oh
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

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

It would take a huge combination of things:

- New "length" rules to account for boat tails.

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

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

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

One
no mention of synthetic lube?

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

[allan5oh]

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

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.

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

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

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

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.

[Flying W]

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."

[allan5oh]

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!

[Double L]

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

[Flying W]

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).

[BanditsCousin]

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....

[Bandit102]

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.

[Mandilon]

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

allan5oh:

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.

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

[GMAN]

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.

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.

[ncnewbie]

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.