[TomB985]

Originally Posted by Musicman

Before everybody starts jumping on me for being a long-hood hater, let me say that I am not.

I am!!!:lol:

[rank]

Originally Posted by Musicman

If that is true, check your fuel economy driving into a 30mph headwind, and then turn around and see what it is running with a 30 mph tail wind. Driving into that 30mph headwind, I might get 5.5 mpg. Running with the tail wind I could get as much as 8 mpg. Take it from a physics phan, above 45mph, wind resistance is by far the largest factor in fuel consumption. If you don't want to take it from me, Google "wind resistance fuel economy" and see what others who are probably smarter than me have to say. Find one trustworthy source that agrees with you (other than longhood owner operators who are trying to make themselves feel better about driving a concrete block) and get back to me. Also, those breathers in the grand scheme of things are nothing when compared to the effect of drag on the entire truck at 70 mph. Also, 2% increase in fuel cost at $4 per gallon, 6 mpg, and 140k miles a year is almost $1900 a year, or nearly $10,000 over five years. I hope they're pretty, because those cans are going to be awfully expensive.

In my post I wasn't really arguing the fact that head winds affect fuel mileage. Of course they do. To my way of thinking, driving 60 mph in a 30 mph head wind is the same as driving 90 mph on a day with no wind.

No my point was more about drag coefficents.

1. what is the drag coefficient of a Columbia vs say a FLD120 flat top, with ground effects & without stacks?
2. how does that lesser drag theoretically equate to fuel mileage, with all other variables equal?
3. when pulling a flat or a tanker, does an aero truck with a high rise bunk even have a lesser drag coefficient than a long hood with a flat bunk? If it does, I suggest that it may be minimal.

I guess I'm suggesting that a long hood with a flat top will get similar or possibly even better mileage pulling a flat or a tanker than a aero high rise pulling the same type of trailer.

Now, let's take this one step further and compare long hood hi-rise to aero-hi rise. In this case, it safe to say that the only real difference in the drag coefficient is coming from the sloped "anteater" hood? How much can that hood really effect fuel mileage?

[solo379]

Originally Posted by rank

How much can that hood really effect fuel mileage?

It depends on a speed you're traveling. Even windshield wipers affect drag some how, or CB antennas....
And the faster you go, then more is the difference. But in general, I'd guess the difference is around 0.5 mpg average, assuming all other things, are equal...

[Musicman]

Originally Posted by rank

To my way of thinking, driving 60 mph in a 30 mph head wind is the same as driving 90 mph on a day with no wind.

Yes and no. I do know what you mean, but there are other less dramatic factors as well: increased rolling resistance from tires heating up at the higher speed, increased friction in all drive line parts would be the two primary additional factors in actually driving 90 mph.

Originally Posted by rank

No my point was more about drag coefficents.

1. what is the drag coefficient of a Columbia vs say a FLD120 flat top, with ground effects & without stacks?
2. how does that lesser drag theoretically equate to fuel mileage, with all other variables equal?
3. when pulling a flat or a tanker, does an aero truck with a high rise bunk even have a lesser drag coefficient than a long hood with a flat bunk? If it does, I suggest that it may be minimal.

I guess I'm suggesting that a long hood with a flat top will get similar or possibly even better mileage pulling a flat or a tanker than a aero high rise pulling the same type of trailer.

Now, let's take this one step further and compare long hood hi-rise to aero-hi rise. In this case, it safe to say that the only real difference in the drag coefficient is coming from the sloped "anteater" hood? How much can that hood really effect fuel mileage?

Rank, if you understand how wind resistance really works, you'll know that the sloped hood means a lot. The overall height of the tractor doesn't mean nearly as much as the "profile" of it. Think of a truck driving down the road as a diver hitting the water from a ten meter board. In diving, one of the main goals is to minimize splash upon entry into the water... the smaller the splash the less the resistance between the diver and the water. What would be the result if a very petite diver hit the water with palms facing the water instead of pointed fingers? Big splash, right? Maybe even a bigger splash than say, a very large diver hitting the water with perfect form and fingers pointed directly toward the water? That hood, as Solo has already said, accounts for quite a bit of mpg improvement.

[Maniac]

Tankers and aerodynamics are non existent, don't know why everybody thinks they are.

Take a real close look at this fine specimen, notice how the front fender scoops up air, also notice how the trailer axles stick out, and the ladder, look at the ribs and the box on top for the dome, and all the other thing that interupt air flow.

While this is an uninsulated tank, the only difference is the smooth polished appearance of the outer insulation.

NO aerodynamic advantages NONE, I get the same fuel mileage as a van, only thing is the cross winds SOMETIMES don't effect me, thats it

[mike3fan]

just use the img and quote tags

[Maniac]

I don't have any, they don't show up

[mike3fan]

Originally Posted by Maniac

I don't have any, they don't show up

I don't either I just enter them myself [img]pic[/img] [ quote]text[/quote]

[Maniac]

OK, Mike, fixt it !

[YerDaddy]

Originally Posted by Musicman

How much do you really think that air heats up in the fraction of a second that it spends inside that under-hood air cleaner before it is moved into the intake? I’m sure you really don’t know and neither do I, but a tiny amount of common sense and a teensy amount of science knowledge would allow us to deduce that it couldn’t be more than a degree, if that much.

It's the compression of the air by the turbo compressor wheel that greatly heats up the air. If the air heats up before being compressed, the compression will multiply that extra few degrees into something more substantial. Just 30 degrees makes a big difference in engine performance. Compare daytime driving in Phoenix in July with driving in the evening in Kentucky in April.