Date: Sun, 18 May 2008 20:40:44 -0700
Reply-To: Keith Ovregaard <kovregaard@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Keith Ovregaard <kovregaard@GMAIL.COM>
Subject: MPG and Decoupler (was Belly pans for speed /mpg)
Content-Type: text/plain; charset=ISO-8859-1
You guys got me curious about what MPG gains (if any) can be attributed to
installing a decoupler. OK, OK, so I have a little too much time on my
hands! Anyway, in June of 2006 I emptied my wallet for one and now that 2
years has passed, I have some stats to pass on to all of you.
Prior to the installation, I logged 6009 miles in the new-to-me 1990 Syncro
Westy. Average MPG was 16.09.
After installation, I logged 11594 miles with an average MPG of 16.28.
Bottom line: No significant difference. If you are looking to improve
mileage, forget it. But if you want more functionality in terms of ease of
maneuvering at slow speeds and less wear and tear on the drive train,
running a solid shaft/stiff VC, it does do that. Probably less tire wear,
but I have no data on that other than 20K mi. on the Mich. LTX LT215/75/R15
tires that have seen very little wear.
On Sun, May 18, 2008 at 9:22 AM, aatransaxle <daryl@aatransaxle.com> wrote:
> I just put on a decoupler in a syncro the other day and here is his first
> report..He is on the quest for 30 mph, so we will see...
> I'm not so sure of his long term numbers,(or even the short term ones) but
> he has been keeping consistent track of mileage...we will see...
> I was just figuring the better mileage was that he was heading South from
> here to Portland...thats down hill isn't it??
>
> <<<From customers email message.....>>>
> Hey Daryl,
> Preliminary results:
> Pre De-Coupler mileage (tested 3 times) = 16MPG
> Post D/C install = 20 MPG - 65 MPH/I-5 South/130
> miles/6.5 Gallons
> Pleased with purchase.
> Coasts like til Tuesday.
>
> Cheers,
> PM
>
> Post that on the site if you like.
> 30MPG is possible despite science, math or traditional
> thinking !
>
>
>
>
> Subject: Belly pans for speed /mpg
>
>
>
> While the vanagon might just be the worst-shape possible for efficient
>> aerodynamics, small improvements add up. Maybe the Sprinter vans are
>> worse
>> shapes..The Aztec has to be pretty close, and the Scion is no Ferrari,
>> either.
>>
>> The "details" do make a difference, however. Small changes or
>> improvements add up.
>> Smoothing the underside of a Van would certainly show some measurable
>> improvement in it's aerodynamic efficiency..thereby giving it more top
>> speed
>> and better gas mileage. For the amount of 'work' involved in fabricating
>> something for the underside of a van, it might be worthwhile doing. With
>> a
>> vehicle lift and some basic tools it'd be pretty simple to fab up some
>> kinda
>> belly pans that would work well.
>>
>> It is pretty amazing how small aero details can make a difference. I
>> used
>> to laugh at the lengths my good friend and engine builder went to with his
>> Porsche 928 for the Open Road events..But he's now a member of the "200mph
>> Club". He would spend hours, after arriving at a race in Nv. taping up
>> his
>> car, removing mirrors, wipers, etc. Then when we, too, "moved up" to the
>> Unlimited Class, I found he was right on by attending to those details
>> before each speed run.
>> Mirrors on?...Lose about 15mph. Windows down? at least 25mph. Nose of
>> car set too low? 10mph.. One size wider tires? 10mph..It all matters.
>> As
>> you get into the highest speeds, it matter even more..(speed is also
>> related
>> to 'cubic dollars'.)
>> So if one was to keep a van for another 20 years, after putting on some
>> undertrays, you'd certainly save on the fuel, even if it was just 2/10s of
>> a
>> mile per gallon.. I bet filling that luggage space in a Westy top might
>> help a bunch also. The front of any vehicle is the most important,
>> because
>> any vortex or turbulence created at the front end continues to create drag
>> all the way back over the whole shape..
>>
>> Somewhat interesting is the fact that as racecar aerodynamics have
>> improved, the 'wing' has been eliminated. The Wing, on racecars, was used
>> to increase downforce..the car's ability to generate traction by using the
>> air to 'push' it down onto the track. Now, the engineers have refined the
>> underside shape of the racecars to generate the same downforce.
>> essentially
>> by shaping the car's underside like an upside down airplane wing..and
>> creating 'negative lift' to pull the car down onto the track...
>>
>> Don Hanson
>>
>
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