Quote:
Originally Posted by aardvarcus
I don’t have extreme confidence in these numbers yet, but I have collected a few similar mostly highway tanks with and without the shell, same route, same pump sort of thing. Three of these tanks without the shell averaged 25.4 two tanks with the shell averaged 26.6, implying a 4.7% increase.
The reason I don’t have extreme confidence in the numbers is that I have noticed that both stop and go traffic and use of AC seem to drive fuel economy down, more so than I have experienced in other vehicles. I am not sure what to think of that fact yet. I am going to be doing plugs/wires/sensors on the engine soon. Also I plan to put heat rejecting tint on the windows and add some cab insulation to reduce the AC use.
I still feel the transition from the body to the shell is hurting me, I am planning on adding some thin aluminum strips formed to the contours to cover this gap, which would stop right at the front of the factory hatch. These would be attached to the shell mechanically. I tried to do something with fiberglass in this area when I initially created the shell but had issues…
I am still trying to form a good plan for the underbody coverage, one area of particular drama is between the front and rear tires. I am thinking running a flat bottom from the frame all the way out to the tires outside edge, turning up and forming a box shape, turning back in where the rockers pinch seam is, basically boxing in the area where the side steps usually go. This would give me a good surface to mount my tire spat flaps on.
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The old-school,SAE testing protocol was to drive at a constant highway speed,with and without,on the same route,same day,as soon as possible.This reduces variables down to one,about as much as we could hope for.In mixed driving,you'll get a composite number,but it will impossible to arrive at a delta-Cd.
At a steady highway speed,a 10% drag reduction is going to net you close to a 5% improvement in MPG.A two-to-one,shoot from the hip metric.
You ought to see around 10% better mpg.