OK, so how do I create low pressure in the engine 
compartment so that more air flows in? Someone must know 
what the intended engineering airflow was supposed to be in 
our vans.

Thanks,
Chris

---- Original message ----
>Date: Fri, 23 Aug 2002 00:23:56 +0100
>From: Clive Smith <clive.harman-smith@NTLWORLD.COM>  
>Subject: Re: Custom Scoop Update - Should you care! FISH Y  
>To: vanagon@GERRY.VANAGON.COM
>
>Scoops do not pull in air
>Aerodynamics, especially guessaerodynamics is not a black 
and white subject
>(my normal rant).
>F1 aerodynamicists are at the top of the tree for this 
reason - with 3D
>objects moving close to a ground plane it gets even more 
complex.
>So for someone to think they know exactly whats going on 
without a lot of
>empirical back-up (exhaustive real size testing and
instrumentation) is just
>wishful thinking - even today, its not an exact science - 
though its getting
>pretty good with computational fluid dynamics (that were 
one of the driving
>forces behind the development of supercomputers - if that 
gives you an idea
>of whatyou're asking!
>
>Anyway, I'm having to pick and choose exactly what you're 
asking, as that is
>so vague...
>.. you want of know if air gfoes into an input hole (flush 
or scoop) and if
>so, wahat sort of flow rate.
>
>If you really have read all the back mails on this subject 
then you'll know
>something already - as I and others have waxed technical 
more than once,
>although I must say, and admit, that most has been to 
DISPEL incorrect ideas
>ans statements, rather than to state SPECIFICS - for the 
reasons outlined
>above.
>
>.. but if you have read ALL previous you'll know this - 
UNLESS THE EXIT VENT
>IS AT A LOWER PRESSURE THAN THE INLET THEN THE FLOW RATE 
WILL BE COMPROMISED
>OR NEGATED.
>
>Also, I wouldn't go directing fresh air over just cylinder 
#3 - a bad idea
>for simple reasons.
>
>The boundary layer on a Spitfire wings at 400mph is about 
an inch thick
>(meaning that the velocity 1" away from the surface is
still only 99% of
>that of the full stream velocity). It is unlikely to be 
more than about 1/4"
>thick at the back of your van at 60mph so even a splitter 
plate 1" away
>SHOULD allow plenty of full stream air to flow in - 
PROVIDED their isn't a
>big separation bubble sitting just in front of the intake, 
PROVIDED the
>total cross sectional area of the duct entrance is matched 
to the duct
>itself, PROVIDED the sink at the other end of the duct can 
handle the flow
>volume and PROVIDED the sink (exhaust) pressure at that 
flow rate is
>significantly lower than atmospheric (but I'm not prepared 
to say how much!)
>and no doubt provided a few OTHER things as well.
>
>Experimentation with a grasp of fundamental principles, an 
open mind and
>devise instrumentation to prove the case - e.g. smoke flow, 
tufting etc. are
>cheap.
>
>Technicians know what they know
>Engineers know what they don't know
>
>If you have studied your subject to such an extent that you 
know areas of
>knowledge exist, but maybe you don't know their specifics, 
that is quite a
>powerful situation to be in - much better than when you 
don't know whats
>round that big blind knowledge corner - or even that the 
blind corner
>exists!
>Put simpler - a little knowledge can be a dangerous thing.
>
>Hope this helps a bit more (but something makes me think 
I'm going to regret
>responding - again)
>
>Clive
>'88 Syncro Transporter
>
>----- Original Message -----
>From: "Robert Steven Fish" <fish@SALZBURG.CO.AT>
>To: <vanagon@GERRY.VANAGON.COM>
>Sent: Thursday, August 22, 2002 11:50 PM
>Subject: Re: Custom Scoop Update - Should you care!
>
>
>> A List Member asked whether these air vents actually do 
suck in air, or
>vent
>> out air.  I am still not certain that anyone has answered 
this clearly.
>>
>> I have followed this thread with interest, as I live in 
Austria now, and
>was
>> forced to remove my rear side running lights.  As these 
are now gone,
>there
>> is a nice large space, especially on the driver's side, 
where a cutout
>could
>> be made and a scoop could be constructed to pull air in 
while driving...
>it
>> could even be directed pretty much directly onto cylinder 
#3 if the design
>> was good.
>>
>> Before I consider this for the left or right or both 
sides... it would be
>> good to know what really happens to the air as one 
drives.  If you create
>> airflow using scoops (and if it even works at all, is 
another question)
>> where does the resulting flow end up going... and does it 
result in bad
>> things, like creating backflow or vacuum areas anywhere.
>>
>> How far out must one actually go, to obtain a 
successful "scoop" effect?
>> Would an inch end up pulling any air in??
>>
>> Aerodynamics experts on the list... PLEASE set us all 
straight on this
>> mess... and deliver  the final word, so we all can get on 
with our lives.
>>
>> RSF
>>
>> IMPORTANT!!! In order to reply to me, you must have the 
word "FISH"
>> somewhere in the subject line of the email.  Otherwise it 
goes directly in
>> the trash.
>>
>> <�)))>{   <�)))>{   <�)))>{   <�)))>{   <�)))>{   <�)))>{
>>
>> <�)))>{   <�)))>{   <�)))>{   <�)))>{   <�)))>{   <�)))>{
>>
>> Robert S. Fish
>> Salzburg, Austria
>> 1987 Wolfsburg Vanagon 2.1 GL Weekender
>> 1987 Golf Cabriolet
>> 1991 Golf
>>