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Old 01-14-2010, 05:06 PM   #9 (permalink)
aerohead
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wake

Quote:
Originally Posted by fourfa View Post
fair enough. Just hoping to optimize this truck for highway speeds as much as possible, lots of long miles getting to wherever I'm offroading/camping/backpacking/climbing etc. Unfortunately the 32" knobby tires, full-size spares, chassis lift, and lots of gear and tools in the back are not negotiable. I'm pretty clear on how to proceed with a belly cover and grill smoothing, but don't want to leave other low-hanging fruit unplucked.

An experiment with a car-top box yielded a 6mpg loss (FAIL). I have it set up now so I can store it in the bed until I get to the trailhead, then move it on top to make sleeping room. The bigger tires yielded about a 1mpg loss (corrected for true distance). If aerodynamics could get that back, I'd be happy. 21mpg at 65 is the best hwy I ever got fully stock (4.0L V6), which already seems much better than the usual off-roading crowd gets.
The taller cap has aggravated your frontal area,increasing the wake area canceling out some of the gains a cap can give.
If you could exploit something like JEEP's swing-away spare tire holder,you might be able to fashion a short boat tail which doubled as storage area,which allowed easy access to the rear hatch.
You might see 3-4 mpg with this single mod.
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