Date: Sat, 28 Jul 2007 16:41:53 -0700
Reply-To: Jake de Villiers <crescentbeachguitar@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Jake de Villiers <crescentbeachguitar@GMAIL.COM>
Subject: Re: Power output of actual vans? (long)
In-Reply-To: <ac1f198b0707281516p1ff5d358x8beb040e49ed6d91@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Jim, I was trying to find the dyno results on your site and failed. Is it
just me or are they cunningly hidden?
On 7/28/07, Jim Akiba <syncrolist@bostig.com> wrote:
>
> it's interesting because the undercladding for syncro that we're also
> looking at would apparently also help in this regard. Lot's of the
> off-road
> guys are actually using large sheets of teflon attached to support
> structures as skid plating these days. Corrosion proof, very tough, light,
> and take impact well if properly supported. Also very easy to CNC route.
>
> The water tank and scale model would be interesting to play with, I'm
> quite
> excited to try the solid model in CFD software though, as with the right
> setup it should be pretty accurate.
>
> Jim Akiba
>
>
> On 7/28/07, Alistair Bell <albell@uvic.ca> wrote:
> >
> > Finally a worthwhile discussion :)
> >
> > Frank, hats off on your undercarriage work. Definitely a do-able
> > solution. The rear low press problem is harder. Instead of trying to
> > fair that area how about an attempt to "curve the flow" in there?
> > While not nearly as effective it may be more practicable. I'm
> > thinking of wings/winglets on top and sides. We've seen some full
> > width top wings and the smaller deflectors (linked posted on list a
> > few years ago, NZ? firm making small deflectors).
> >
> > A splitter also may be effective. Flat panel perpendicular to rear
> > hatch, length to be determined.
> >
> > I have a spare small water tunnel that my revell Vanagon model would
> > fit in. Would be useful for flow visualisation and perhaps some
> > scaled drag values.
> >
> >
> > Alistair
> >
> >
> > On 28-Jul-07, at 1:01 PM, Frank Grunthaner wrote:
> >
> > In a message dated 7/28/07 11:05:21 AM, syncrolist@bostig.com writes:
> >
> >
> > > Ha I liked your reply Frank. Excellent. We have multiple dyno
> > > charts all
> > > taken from the same chassis dyno for a vanaru 2.2, tiico HO, 2
> > > wbxers, 4
> > > different zetecs, 1 supercharged zetec, and coming soon e85
> > > naturally aspirated
> > > zetec, and e85 supercharged zetec.. as well as the upcoming turbo
> > > kit(the entire
> > > exhaust tract is now complete) Having all this info from the same
> > > dyno is
> > > quite nice, and really the only way to do it. As Mark points out,
> > > it is the
> > > "complete" inforamtion that is really required. BTW Frank, Clint(a
> > > listmemeber
> > > and solidworks guru) is helping us model the vanagon so we can put
> > > it into a
> > > CFD virtual wind tunnel... my intention is to build a collaspable
> > > colluder
> > > cone (see through on top) to see how much fuel efficiency we can
> > > gain at cruise
> > > with a simple strap on cone of reasonable size that is easy to
> > > produce and
> > > inexpensive. I think given the low pressure area we always drag
> > > around behind
> > > us, it may be a substantial improvement.
> > >
> > > Jim Akiba
> > >
> > >
> > > Jim,
> >
> > Egad a reply to one of my rants! Exciting! I fully agree that results
> > from
> > the same dyno with the same operator seriously increase the quality
> > of the data
> > but more importantly the reality factor inherent in its comparative
> > interpretation. For some time my son and I were developing a
> > Solidworks based model of
> > the Westfalia to tighten up the drag issues. Our power numbers come
> > to second
> > difference velocity curves taken at the Pomona International Dragway
> > (when
> > unoccupied by paying nutsos). We were also looking at FemLab for a
> > far more
> > detailed treatment.
> >
> > In the course of these experiments, two areas showed enough promise to
> > warrant some measurements. We looked at the rear drag profile and
> > undercarriage
> > sealing. For the rear drag issue, we modeled pressure zone profiles
> > and put
> > together three plastic hemi-balloons and taped then to the rear. I
> > have to go back
> > to my notes at the time but we reduced drag by 12 to 18%. In one
> > test, the
> > number was 33% but it couldn't be duplicated. (In the spirit of some
> > tuners, I
> > should have used this for an SAE paper). The upshot of this was that
> > I got pulled
> > over (we were testing at night on the Palmdale highway) by the CHP
> > and got
> > ticketed for occluded rear vision. Went to the court to fight the
> > ticket. Had a
> > full sheaf of papers. The judge listened attentively (!). He remarked
> > that
> > when younger he had had a bay window bus that just blew all over the
> > road and
> > asked if such mods would have any effect on stability. I offered that
> > it was in
> > the relm of possibility. I them looked around the courtroom to see
> > blank stares
> > for a mass of humanity that that must have thought I came from area 51.
> > Finally the judge stopped the discussion, announced that this was the
> > singularly
> > most unusual anti-ticket response he ever heard, congratulated me for
> > originality and dismissed the ticket with a warning about frightening
> > other drivers at
> > night.
> >
> > The point here relates to the fundamental flaw. The rear balloon
> > worked, we
> > had an idea for speed related inflation, etc, etc, but no answer for
> > rear
> > vision. Practicality --- zip, but fun.
> >
> > The second idea worked well and is a real solution. The open
> > underside of the
> > vanagon is a real drag component. We got a set of thin 0.0625 inch Al
> > sheet
> > stock and enclosed (frame rail to frame rail) and basically covered the
> > underside from the front to the transmission. We added louvered slots
> > for the
> > radiator air flow, left the spare tire cover operable and stayed away
> > from suspension
> > components. Big decrease in drag - minimum 8% max 15%. 15% came when
> > we added
> > the Diesel sound box cover. Serviceability was a problem. The system
> > has been
> > removed as I complete the front to back dual muffler system for the
> > TDi and
> > the diesel fired heater. No temperature measurements, but we provide
> > for air
> > inlets at front by gas tank and at egress at the rear. Work in progress.
> >
> > Frank Grunthaner
> >
> >
> >
> >
> > **************************************
> > Get a sneak peek of the all-new AOL at
> > http://discover.aol.com/memed/aolcom30tour
> >
>
--
Jake
1984 Vanagon GL
1986 Westy Weekender "Dixie"
www.crescentbeachguitar.com
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