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Old 05-26-2008, 08:22 AM   #2 (permalink)
Harpo
EcoMudder
 
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Join Date: Mar 2008
Location: Gainesville, FL
Posts: 79

Harpo's Honda - '05 Honda Civic VP
90 day: 42.64 mpg (US)
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Me too

I'm watching this. I have a 6x12 as well that I tow to MTB Races. I only get about 12mpg behind the Ram1500 HEMI MDS. I can get 18.5+mpg when not towing the box. I'd guess around 1650lbs loaded for racing.

Same rules apply. Run Max Pressures for conditions, and keep speeds down. I can tow at 62mph in overdrive, but once I try to start averaging 65+, I need TowHaul, which defintely uses more Throttle Position changes and higher average Fuel Flow. Staying out of Cruise on hilly sections, and driving with load works great as load goes up.

I'll tow about 3500-4500 miles this year to race venues. So one or two mpg would be a big help at $4/gal. I've looked at pre-fabbed domes for the nose, but they have low return on investment unless you are really stacking up the miles. Without a High Cap, trying to get the air over the box is all but impossible. I've seen that 30degree nose has highest effectiveness when towing without sidewind. Reducing underbody drag with trays and fairings. Reducing drag at the rear seems easiest with some simple extensions in the rear or aerotab like vortex devices. There's an easy 10-15% drag reduction in the front that is hard to build, and another 10-15% in the rear that probably takes less overall effort.

http://www.nosecone.com/table.htm

Do some googling on Tractor Trailer drag reductions and there's a bunch of designs. Most make the asssumption of a high truck-trailer spoilers and gap wings, but there are some with good info on the box alone.

http://www.freightwing.com/about2.htm

http://www.marama.org/diesel/frieght...DCAeroOvw2.pdf


That coroplast will need some good bracing for the nose. I've used 1/2" and 5/8" aluminum tubing used in race car fuel lines. It's moldable, light, and can be flatted to drill holes through for attachment points. I got mine at Summit and comes in variety of rolled sizes.
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Last edited by Harpo; 05-26-2008 at 09:06 AM..
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