Could you post picture s of the modified top?
I have a photo that shows the airflow over various Vanagon tops and the Westy Pop-top is by far the worst - even the high-top has better airflow.

How about installing a sheet metal cover over the bottom of the Vanagon so that the underside is smooth?
You could also use it as a plenum to direct the radiator air out the back of the van to try to improve the airflow.

BTW- If you look under most new cars, the trend is to have smoother undersides

http://www.autozine.org/technical_school/aero/tech_aero.htm

Todd
'88 Westy

Does anyone remember during the gas crisis of the '70s,  Car & Driver (I think) had a series of articles where they modified a car to improve gas mileage - I think it was a Vega. As I recall they blocked off part of the grill and added and air damn and side skirts. (and tiny tires)

 -------------- Original message ----------------------
From: Phil Stanhope <surfmobile007@YAHOO.COM>
> Interesting point, The Porsche 928 looks to me like
> its bumper directs alot of the windflow underneath the
> car, much like our high riding westys/syncros do.
> Underneath most cars, its not smooth and wind
> resistance will be greater the higher up your car
> rides. So, i think Installing lower coils along with a
> quick release spoiler under the bumper......(a big
> one.....for long trips only) would be the way to go.
> But if i lower my westy i wont get that nice floaty
> ride that i love so much.
>
> -Phil 84' Westy Tiico'ed
>
>
> --- John Reddick <svyolo@YAHOO.COM> wrote:
>
> > I saw some pics from a wind tunnel test on Vanagons.
> >  The stock passenger
> > van is .44, the US spec Westy is .50.  I am
> > currently driving a Westy with a
> > modified "aero" front end for the Westy top.  It is
> > getting better mileage,
> > but due to adverse traffic/winds, I could nail down
> > good numbers.  It is
> > definitely getting somewhere between 5-10% better
> > mpg.
> >    The Porsche 928 is a horrible example of
> > aerodynamics, despite its sleek
> > look.  Its Cd was similar to a Vanagons when it
> > first came out, but I
> > believe they tweeked it in the mid 80's so it was
> > mid/low .30s.
> >     Westy's sold in Europe had a bunch of variants
> > on the top design.  One
> > common one was the same rear as the US model, but a
> > sleeker front.  That is
> > basically what I built for the front of my Westy,
> > although the first one is
> > far from beautiful.
> >
> >     John
> >
>
>
>
>
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