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Old 07-28-2017, 10:42 PM   #31 (permalink)
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I have a fully modern suv with direct injection, a modern 6 speed with double oveedrive, and quite extensive aero treatments, and if I go 70, I lose 10% fuel economy over going 62. Imho, 70mph speed limit should not be allowed, for safety and environmental reasons.

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Old 07-28-2017, 11:29 PM   #32 (permalink)
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Quote:
Originally Posted by Isoldmysaturn:( View Post
Imho, 70mph speed limit should not be allowed, for safety and environmental reasons.
I'm not totally unfavorable to a 70 MPH speed limit, even though it does adversely affect fuel-efficiency. Anyway, though I'm not an eco-nazi, I understand that a relatively lower speed is advantageous on that matter too, not just because of the lower emissions out of the tailpipe but also due to the fewer energy spent on oil drilling, refining and the supply to the fuel stations.
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Old 07-29-2017, 01:08 PM   #33 (permalink)
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under 70 mph

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Originally Posted by Merlyn2220 View Post
So I started hacking off some of the rear of the shell, in an attempt to figure out what was going on with the cavity and taper. I removed the center upper section (with taper) at about 100 miles into a tank, and ended up with 14.27mpg. With the 12 degree side taper and upper section and A/C use I was around 13.9-13.9mpg. So the center was a definite negative, even with a reasonable taper.

At 240 miles into the next tank, I hacked off the sides to be ~4" long, following the general shape of the body from a side view. 15.24mpg is a dramatic improvement over the previous tanks. HOWEVER....part of that is because I was having overheating problems and not running the A/C much, and driving slow to keep the highway temps down. This followed up with 15.67mpg for the next tank, with no other aero changes. I'd attribute the extra 0.5mpg to mostly driving well under 70mph on the highway while I swapped parts (thermostat, pump, hoses and radiator) and it seems to be back to normal. So this tank should tell me what real impact there is from hacking off my abomination of a tail!
*Driving 70 mph vs 55 mph would effectively increase your drag by 1.619 X
*It 's like increasing the Cd by the same factor.
The 'naked van,@ Cd 0.38 would go to Cd 0.619.
*Aero power and fuel would increase by 2.061 X.
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Old 07-29-2017, 09:30 PM   #34 (permalink)
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Quote:
Originally Posted by cRiPpLe_rOoStEr View Post
I'm not totally unfavorable to a 70 MPH speed limit, even though it does adversely affect fuel-efficiency. Anyway, though I'm not an eco-nazi, I understand that a relatively lower speed is advantageous on that matter too, not just because of the lower emissions out of the tailpipe but also due to the fewer energy spent on oil drilling, refining and the supply to the fuel stations.
I understand the desire to get places faster, there were times in Germany I only had one day to go see some sight, and going 144MPH was hugely advantageous to that goal, but a: that car didn't get the same extreme a difference in economy like this one, and b: that was the only way I could see the country. at the same time, people who only wanted to go 60 were allowed to without getting harassed by the police, unlike the united states.
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Old 08-07-2017, 05:00 PM   #35 (permalink)
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Amazing work! No skirts yet? will you do front skirts also? Would love to see those.

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