06 w900l mxs c15 625 poor fuel economy

So since you own an FLD, just like I did for 7yrs, then you already know the only differences between it and a classic is the length of the hood, headlights and set-back axle. The grille, cab, radiator and basically everything else is the same. I will agree that it is also the best truck I too had owned. Unfortunatley I traded it for an aerodynamic truck and so far it was a bad move. My 387 gets worse mpg and costs more to repair than that FLD did. But hind sight is 20/20

There are many 379/389 and W9's out there getting well over 6mpg and with a proper setup and spec, you can get into the 8's

 

Have Mr.Haney reflash that Acert and you'll change your tune about it instantly. I've had mine done for a few months now and it's a totally different animal.

Not totally true, there's a difference between having the power and using it. A 700hp truck can get better mileage than a 400hp truck unless you drive with your foot in it all the time. I went from 475 to a stage 1 tune which is supposed to be about 700 to the ground and you instantly notice you barely have to step on it to pass, you hardly ever have to downshift which helps keeps the RPM in the ideal range. How you drive can mean more than what you drive.

What most fail to realize is you can have a nice shiny truck AND make money. I would take any FLD over the new junk FL is pumping out. Like I've said before, there are PLENTY of 20yr old KWs, Petes, Mack's and Classic FL's running around.......In 20 years how many T2000's or Volvo 780s are going to still be alive not to mention looking good? The day I have to drive a playschool truck covered in air tabs, trailer skirts and a goofy tail just to make a living is the day I quit.

 

I have no dog in this fight. I have friends that do real good with aero trucks and friends who do real good with hoods. Just a little food for thought here that most don't really think of.

I would like to take exception with this, though. And, please don't think I'm picking on you here, I'm certainly not.

I'm a pilot and my hobby is building airplanes. I've built and flown two kits, and one of my own design. I'm currently building another of my own design. I've learned a whole h3LL of a lot about aerodynamics in the process. Enough to know that truck designers would be pretty #### poor aircraft designers. Also, they are trying to balance the practical requirements of a truck with the aerodynamics.

You assume that the 387 is more aerodynamic, but based on what? I'd argue that you traded a pretty aerodynamic truck for a little less aerodynamic one. People think because the overall shape in more round that it's more aerodynamic, and that's just not so. The FLD and the 387 are not that far apart in the aerodynamics department. In fact, I'd give the FLD with a Condo sleeper the nod over a 387, if you were pulling a box. The FLD's aerodynamics really is much better than a hoods'. Aerodynamics alone, however, does not guarantee better fuel mileage. Too many other variables. Way too many.

Some people will try to tell you that aerodynamics make no difference, but you won't see too many airplanes with hoods and square tails. There's a reason. There's also a HUGE portion of the truck that people COMPLETELY forget about when it comes to aerodynamics....the bottom. The bottom surface is HUGE when it comes to aerodynamics and that's just tough on a truck. Lots of really dirty, swirling, draggy, resistant air under a tractor trailer, even the aerodynamic looking ones.

A lot of it's marketing, too. The 387 looks a lot more aerodynamic than it is. A round front does not always mean the best aerodynamics. You have to think about it in terms of how many times the airflow moving over the truck is disturbed. The 387 may look like a T-2000, but aerodynamically there's a world of difference.

Again, I think it's possible to do just fine with a hood, and there are many aero trucks that are horrible. I'd like to say that all things being equal, an aero truck would always do better. The problem with that statement would be that in trucking, all things are NEVER equal.

I guess my point is, that just because your truck is round and has a smaller grill, doesn't necessarily make it a truly aerodynamic truck. There are just too dang many other places on the body that affect things. However, when you are selling trucks, or anything else, perception plays a HUGe role in profiting from an idea.

Or maybe I'm just wrong and completely crazy.

 

Oh, and anytime I've had anything on an airplane begin to flop, be it a fairing or aluminum skin, or composite covering, there's been a HUGE aerodynamic penalty.

Lots of these aero trucks I see running down the road have fiberglass fairing flopping around all over them. That leads me to believe that a lot of these aerodynamic "improvements" are more of an aerodynamic penalty and are only there for looks and to sell trucks.

 

The only reason I traded the FLD was for more space. It was a flat-top with 38" single sleeper. It was perfect for when I was running local, but once I went OTR, it got cramped. I also owned the truck outright for 7yrs and I was very tired of giving uncle sam $10k at the end of each year. So I got the 387 for 2 reasons I guess, but in hind-sight, I should've kept the FLD and worked less. Oh well, as long as this truck makes it 2yrs then I'm happy. My house will be paid off and I can go do something else if need be.

 

How can that be. According to most people here, there's no money in trucking and you can never pay for a truck and you'll die a slow agonizing death by starvation if you try.

 

The key is to pay cash for the truck When you don't have a payment, this line of work is actually fun and you can make a great living. It's the guys who become O/O and go buy brand new trucks and then are not mechanically inclined that usually don't make it and wonder why they didn't, but the company they worked for prior made it just fine LOL!

I actually was told by my accountant that I needed more deductions or I needed to make less $ due to bumping up unto the next tax bracket. So I bought a truck for depreciation and take a week off each month.

 

Well I think this is another first for this thread. I think you are the first person that just said an aero truck is designed the way it is for looks. I don't believe I have heard anyone say how much they love the look of the aero truck.

The money that goes into testing of aero dynamics is mind stagering. If you listen to manufacuters they will tell you the test they have to perform to get that "green" certification adds about 5% to the price. Hmmm, not sure about that but they do have to spend a lot of money in wind tunnels and provide detail engineering specs so that it can be computer simulated.

All the flopping is a driver not taking care of his equipment. Run it as designed and unless you have a design flaw it will be better than running a brick as it is designed.

One of the reasons I have not addes the trailer fairings is the whole "flopping" thing. They have to be disigned with some flex and I see a lot of them doing a lot of moving around on the road. I am sure when they got certified based on computer simulation they didn't run a simulation of what it would be doing after running 150,000 miles with bent brackets and such. But, CA says they have to have them so every new trailer will have them.

 

http://www.fleetequipmentmag.com/Content/Site310/ContentBlocks/66391PeterbiltF_00000026201.pdf

Take a look at this article. I think it's pretty interesting. They extol the virtues of wind tunnel testing before pointing out that it's still guessing and wind tunnels CANNOT produce real world conditions. All the wind tunnel testing in the world and, still, the underside of a T-2000 or 387 Pete is as aerodynamically inefficient as any 379 Pete or W-900L. That's a HUGE surface area of the truck that's catching lots of drag and wind that's completely ignored.

I guess I really wasn't saying that they were designing a truck that's aerodynamic for folks who like that look, but rather for folks to look at and think, "WOW! That thing MUST be really cheap on fuel. Look how aerodynamic it is. It's got to be. It's round and has a sloped hood."

In the end, though, they'll make a sleeper that has more room and sacrifice some efficiency because room and spaciousness does not need computer modeling to be measured.

I've always kind of viewed wind tunnel testing as a reference point, or a place to see where changes can be made. Computer modeling may take lots of information and combine it to get a more educated guess, but it's still a guess. The concept of global warming and climate change are based mostly on computer modeling. Do you believe Al Gore's movie as the gospel? Is it possible that all the EPA, Smart Way and wind tunnel testing will still give way to profits? Would you buy anything, solely because it's CARB and SMartWay approved?

I'm an airplane guy, so I'll always believe that aerodynamics are important. However, being an airplane guy and researching and dealing with actual aerodynamic principals and rules in the building of a few of my own airplanes have taught me to spot things as snake oil. I'll again use Al Gore, global warming, and the concept of "being green" as an example of how this can be misleading. Ethanol was going to fix global warming. Turns out it takes close to two gallons of fuel to produce a gallon of ethanol. Incandescent light bulbs have been outlawed in favor of those idiotic little coily things, because we are saving our planet with them. Turns out that they have mercury in them, don't put out the same amount of light, and don't last as long as we were told they would. Computer modeling, though, said they were better. Al Gore used computer modeling to make tons of money off of an animated movie to scare people into following his anti-capitalistic political ideology.

What's snake oil and these examples have in common? $$MONEY$$ Somebody is making HUGE profits off of the "science" that claimed those coily lights are eco friendlier than they are. There's lots of money in ethanol, even though research on how much energy it would save may have been skewed. Al Gore's movie has been proven to be politically biased, factually inaccurate, and generally wrong. I doubt, though, he'd have come out and said that, knowing it would have cost him millions. I doubt the folks at SmartWay donate their time. And let's not forget politics. All this EPA, CARB, SmartWay stuff is politically charged and motivated. It's all "feel good" politics. They have to justify their existence, too.


At the end of the day, somebody has used computer modeling to produce a result they wanted so they could profit. Did Peterbilt design and market the 387 because they liked the way it looked? I'd say they did it to compete with other manufacturers. Do you think they produced the most aerodynamically truck they possibly could? I don't. Otherwise the sleeper wouldn't bubble outward behind the door. The cabs would be much narrower. The windshields would be raked back a whole lot further. Styling plays a role in selling trucks, too. I think they probably took a design, made it roughly look like they wanted it, and then used computer modeling (i.e., wind tunnels and computer modeling) to clean it up aerodynamically the best way they could and still have a useable truck that had adequate room, that you could see out of, and that looked to the average person like it should save lots of fuel.

Of course, this is all my theory. My Dad recently upgraded almost all of his trucks with newer used trucks. He bought a T-660, thinking it was going to be a great truck for fuel economy, and his old FLD that the T-660 replaced is still better on fuel mileage. He also bought four used W-900's. They are COMPLETELY IDENTICALLY SPEC'D with three T-600's he had. The W-900's that he replaced the T-600's with are getting less fuel economy, with the same drivers. He replaced a 670 Volvo with the fourth W-900. That truck is doing BETTER than the Volvo. The Volvo was similarly spec'd. All of these trucks are Cummins powered and, I think, have ten speeds. My Dad likes red engines. Go figure. Conventional wisdom says that the T-660 should be doing better, the W-900's are performing as expected, and you'd think the Volvo would've come out better. Guess there are too many real world variables.