Approx. % increase of mpg while adding bed cover
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From: Great Lake State
Ford has been doing wind tunnel tests for 35 years. The "white smoke" is mostly used for visual confirmation of design changes, NOT for measurement of resistance.
In a wind tunnel you can set the velocity, density, and area and measure the Cd (drag coefficient) and the resulting info contains dependencies of object shape and inclination, as well as the effects of air viscosity and compressibility. Videos of the "white smoke" are more interesting than looking at a digital readout and a bunch of calculations. Yes, of course Ford is keeping secrets about the aerodynamic efficiency. Wouldn't want Chevy to change their "square" wheel wells!
As stated earlier, in the early 80s they just used a sheet of plywood and found that the last 1/2 of the bed covered made measureable differences.
In a wind tunnel you can set the velocity, density, and area and measure the Cd (drag coefficient) and the resulting info contains dependencies of object shape and inclination, as well as the effects of air viscosity and compressibility. Videos of the "white smoke" are more interesting than looking at a digital readout and a bunch of calculations. Yes, of course Ford is keeping secrets about the aerodynamic efficiency. Wouldn't want Chevy to change their "square" wheel wells!
As stated earlier, in the early 80s they just used a sheet of plywood and found that the last 1/2 of the bed covered made measureable differences.
Blunt
Joined: Mar 2015
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From: Alberta, Canada
Ford has been doing wind tunnel tests for 35 years. The "white smoke" is mostly used for visual confirmation of design changes, NOT for measurement of resistance.
In a wind tunnel you can set the velocity, density, and area and measure the Cd (drag coefficient) and the resulting info contains dependencies of object shape and inclination, as well as the effects of air viscosity and compressibility. Videos of the "white smoke" are more interesting than looking at a digital readout and a bunch of calculations. Yes, of course Ford is keeping secrets about the aerodynamic efficiency. Wouldn't want Chevy to change their "square" wheel wells!
As stated earlier, in the early 80s they just used a sheet of plywood and found that the last 1/2 of the bed covered made measureable differences.
In a wind tunnel you can set the velocity, density, and area and measure the Cd (drag coefficient) and the resulting info contains dependencies of object shape and inclination, as well as the effects of air viscosity and compressibility. Videos of the "white smoke" are more interesting than looking at a digital readout and a bunch of calculations. Yes, of course Ford is keeping secrets about the aerodynamic efficiency. Wouldn't want Chevy to change their "square" wheel wells!
As stated earlier, in the early 80s they just used a sheet of plywood and found that the last 1/2 of the bed covered made measureable differences.
That might work on an early 80's design, but that's all changed now. Comparing that test done in the 80's on an 80's truck means nothing on a 2015+ F-150. Comparing apples to giraffes much
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Been trying to locate the video of the MB water tank test that shows the flow over the bed. It was pretty telling where the drag comes into play, and how dropping the tailgate affected where the drag moved. Would have liked to see what a cover and cap did.
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From: SE Michigan
Giraffes cannot fit in the bed, nor will they increase MPG.
This is one of those threads
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From: Kansas
Never said my opinion was a fact, but I did say there were some real life condition tests done which showed no improvement or even a decrease in MPG. I'm guessing it's different from brand to brand as aerodynamics are not the same from models to models.
Quote :
Based on our testing here at Ford Motor Company with our trucks, tunnel covers are more efficient.
And their testing was based on what type tonneau cover and in which conditions? The 1000$ one they try to sell you at the dealership, or the 200-300$ Tonneau that most of us end up buying because it's ridiculous to pay that much for a piece of plastic?
Shooting white smoke at a truck that's inert is certainly a good indicator, but it's not a conclusive test.
Quote :
Based on our testing here at Ford Motor Company with our trucks, tunnel covers are more efficient.
And their testing was based on what type tonneau cover and in which conditions? The 1000$ one they try to sell you at the dealership, or the 200-300$ Tonneau that most of us end up buying because it's ridiculous to pay that much for a piece of plastic?
Shooting white smoke at a truck that's inert is certainly a good indicator, but it's not a conclusive test.
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From: In the Heartland
Why would that be an issue, especially for a recurring topic that really isn't sensitive to time? Would you rather have yet yet another thread on it, with the same topic? This comment would make sense if it was titled "2015 rebate info" or something similar.
Last edited by silvius; Jan 21, 2018 at 02:15 PM.
Blunt
Joined: Mar 2015
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From: Alberta, Canada
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Joined: Feb 2020
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From: Pacific Northwest
I came to this thread looking for info on what mpg I can expect now that I have added a tonneau cover to my newly bought 2013 F150 XLT/XTR with the 3.5L Ecoboost motor.
So I now know that there is no reliable information. But the thread with its arguments is very amusing.
What I know: the "air bubble" effect that has been talked about by many here is a turbulence phenomenon. As such, it will vary dependent on a number of factors including the relative velocity of the air. Or in this context the speed of the truck. But there are two other factors that are even more important:
Unless you never carry anything in the truck's bed (so why are you driving a pickup instead of a sedan??), what you are carrying is going to disrupt the "air bubble" to an unknown degree. Probably carrying a full load of plywood would have less effect than carrying a dirt bike; possibly carrying a half load of tossed in firewood would be more disruptive than a full load of neatly stacked firewood. Since we are talking now about the problems with disrupting a laminar flow, it is quite possible that a few sticks of firewood rolling about on the floor of the bed would destroy the "air bubble" at certain speeds.
A properly fitted tonneau cover avoids these problems. It may not contribute to mpg in an empty pickup on a day without wind, but it sure as hell is going to eliminate several losses of efficiency in real world conditions.
So I now know that there is no reliable information. But the thread with its arguments is very amusing.
What I know: the "air bubble" effect that has been talked about by many here is a turbulence phenomenon. As such, it will vary dependent on a number of factors including the relative velocity of the air. Or in this context the speed of the truck. But there are two other factors that are even more important:
- Whether there is any cross wind component that would disrupt the presumed laminar flow over the top of the cab into the bed of the truck
- How smooth the effective bed of truck happens to be.
Unless you never carry anything in the truck's bed (so why are you driving a pickup instead of a sedan??), what you are carrying is going to disrupt the "air bubble" to an unknown degree. Probably carrying a full load of plywood would have less effect than carrying a dirt bike; possibly carrying a half load of tossed in firewood would be more disruptive than a full load of neatly stacked firewood. Since we are talking now about the problems with disrupting a laminar flow, it is quite possible that a few sticks of firewood rolling about on the floor of the bed would destroy the "air bubble" at certain speeds.
A properly fitted tonneau cover avoids these problems. It may not contribute to mpg in an empty pickup on a day without wind, but it sure as hell is going to eliminate several losses of efficiency in real world conditions.