by caseydog » Sat Mar 29, 2008 10:09 pm
I can't generally feel my TD behind me at highway speed, but I'm sure I pay a price in fuel economy as I go faster.
With or without the TD, I tend to "go with the flow" of traffic, and on long stretches of Interstate highways, try to find a speed where I can set the cruise-control and not have to mess with it.
I also keep my TD tires at about 25PSI to keep the TD from bouncing as much. The tires stay cool, so I know they are safe at that pressure, but I probably hurt my gas milage just a bit.
Here is a paragraph from a Road & Track article that explains how the amount of power (energy) needed to move a car through air increases as speed increases. This example talks about what it takes for a car to go 200 MPH, but you can still see the pattern at lower speeds.
... it takes gobs of power to reach 200 mph. The air resistance grows with the square of speed. Stick your hand out the side window of your car at 60 mph and feel the resistance. At 180, that force will be nine times stronger, should you be foolish enough to give it a try. Don't. And at 200, it will have more than 11 times the force! What's more, because the power requirement of a car grows with the cube of speed, this means it will need 37 times more power to go 200 mph than to maintain 60. It boggles the mind.
My build journal is
HERE