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Old 12-15-2008, 02:51 PM   #3 (permalink)
aerohead
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bubble

Quote:
Originally Posted by Buddy View Post
I'm a new member and am BLOWN AWAY that such a forum exists. I drive a 2002 Toyota Highlander 4WD V6. The 2 modifications that I have made is adding a ScanGuageII, which helps me drive economically, and using AMSOIL. The rear end of my SUV is similar to that of 18-wheeler, i.e., a square block. You may have noticed that some 'big-rigs' have added a plastic 'bubble' to the rear of their trucks, so that the air can flow smoothly rather than create turbulance. Their bubble is on a hinge so that it swings out of the way and the 2 doors can be easily opened. If this didn't help mileage, I don't think the trucking companies would be spending money on it. Question #1 - does anyone have data on their savings? My plan is to go to a plastic fabricator and have a similar bubble made out of clear plastic, and have it fasten to the hatchback on 4 slots/bolts that can be tightened down. I hope the weight isn't too much, but I can always beef-up the hydraulics lifts for the hatchback. Your feedback would be greatly appreciated.
Buddy,I think your on the right track.Over the Turkey-Day holiday,I brought back a rear hatch off my friend's Highlander(it was damaged in a collision and replaced) to help fashion exactly what you're talking about.He has the 4-cyl version,2WD,and is getting 28-mpg on HWY.We calculated that a 30-inch extension (measured from hatch surface,not rear of bumper) will push MPG to 32.0.------------------------- These "boat-tails" have improved mpg for my VW bus,CRX,and T-100.------------------------ I would caution you about Plexiglas ( I've never worked with Lexan).If it fractures it will come apart on you.There is no fiber matrix to it and it has zero strength in tension once it begins to fail.You might consider a more robust super-structure which can stand up to pot-holes,jarring,vibration,etc.,and add a Plex or Lexan window to that.------------------------ Also,if you are going to swing it from above,be careful to examine any interference do to the hinge geometry,which might occur at the roof/hatch intersection when your proposed extension is attached and fully open.
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