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Old 06-20-2008, 04:58 PM   #8 (permalink)
Big Dave
Master EcoModder
 
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Join Date: Jan 2008
Location: Steppes of Central Indiana
Posts: 1,314

The Red Baron - '00 Ford F-350 XLT
90 day: 27.99 mpg (US)

Impala Phase Zero - '96 Chevrolet Impala SS
90 day: 21.03 mpg (US)
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Yes, my mirrors fold back but I never run that way because I am blind as a bat to the rear without them. My bed fairing is completely opaque.

I have considered going to “paddle” mirrors if I can supplement them with a rear view CCTV. This may be what I do after I redesign the bed fairing.

The bed fairing was indeed huge. I got there in two steps. First, I documented the open bed MPG, then installed a hard flat tonneau. Testing indicated a 1.5 MPG improvement. Then I whipped up my “fastback” fairing for a pickup show. It improved another 1.5 MPG. I then removed the fairing and ran open bed (tailgate up) for a couple weeks and – sho’ ‘nuff! – my MPG dropped off 3 MPG and when I restored the fair the MPG jumped back up 3 MPG. So I am real solid on the efficacy of a fastback bed cover.

The big drawback of the crude bed cover is that it limits my utility. My summer plan is a new and improved version (10-11 degree slope) with simple wooden bows holding up a custom made snap-on cover, kinda like a boat cover. This cover could be either easily “peeled back” or removed to accommodate bulky bed loads. I don’t know if the improved bed fairing will improve MPG or not but if not I’ll know I have pumped that particular well dry.


When we ran the thread with the graduate thesis from the naval officer his FEA work indicated that side skirts would make the air dam even more effective. I have a pair of running boards that I removed from the truck a few years back (when I slammed it). If I modify these running boards into faired-in side skirts I’d look for another 0.3 or 0.4 MPG over just the air dam. I have some more rip-stop conveyor belt so I can hog them close to the ground with no worries about dragging. If I can realize an improvement of 0.3 MPG that will mean a 1 MPG (4%) improvement from managing the air flow beneath the truck. The bottom of the truck is very rough and has a lot of hot surfaces.

Wait til I put another gear on this truck!
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2000 Ford F-350 SC 4x2 6 Speed Manual
4" Slam
3.08:1 gears and Gear Vendor Overdrive
Rubber Conveyor Belt Air Dam
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