Date: Thu, 16 Dec 1999 09:14:24 -0500
Reply-To: Bob Donalds <bostneng@FCL-US.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Bob Donalds <bostneng@FCL-US.NET>
Organization: Boston Engine Exchange
Subject: Re: Air intake "scoops"
Content-Type: text/plain; charset=us-ascii
Per Lindgren wrote:
>
> Bulley wrote:
>
> > Perhaps you haven't seen/felt the unbelievable amount of suction the type 2
> > motor's cooling fan produces at 3,500 rpm. I don't think there is any
> > danger of air 'stagnating' on top of the motor, and getting hot, no matter
> > how efficient your scoops.
>
> Maybe not, but there is certainly no need for scopes, is there? And I know how
> much air it sucks, I have felt it, and my 73 Squareback isn't far behind in
> suction either.
>
> PerL
> 87 Syncro 112i
Perl & Bulley and the list
air scoops nasa ducts and engine compartment temps are something I
have spent a few moments on. see the my web site
http://www.bostonengine.com for 3 pictures in the gallery of scoops
photos winning racer, winning the race and #11.
as the engine warmed up and the air temps increased in the formula vee
engine compartment the car would slow by a couple of seconds per lap
until I cut 2 scoops (see winning racer picture) that let in fresh air
directly at the intake manifold and carb. also years ago while dyno
testing another FV engine while changing a main jet I left a rag on the
intake manifold. we then made the next power run and a increase of 4 hp
in power much more than a main jet change would should give. the the
owner of the dyno after scratching his head looked at the engine and
said lets make that run again without the rag we did and lost what we
had gained. cooler engine comparments and intake manifold temps as well
as the air temps at the intake make a big diff as to the engines output.
look at the air intake horn on the vanagons theres a card board divider
to keep the incoming air on the right side scoop from mixing with the
engine air.
the home made scoops on my 73 van much like the one on my van in
picture # 11 in the photo gallery made a 20 degree F. differance around
town on a 80F day the engine compartment temp went from 100 F down to 80
F
the engine comparment in the air cooled car has a slight vacuum when you
add scoops the
comparment goes from vacuum to positive pressure on the highway the fan
moves more air threw the engine.
Gen Berg wrote about the the air flow on his bus and the differance the
vent widows and mirrors made in air pressure and vacuum when they where
open and closed they interrupted the air flow and made the cooling fan
less effeciant
air scoops help but mostly in the warm weather not a good idea for the
cold winter as they will prevent air cooled engines from warming up as
much as needed to allow complete
combustion and prevent the unburnt gas deluting the oil. the main reason
to change the oil as often as VW said was oil delution. you air cooled
types go smell your oil!
I have a couple of pictures of scoops on vanagons taken at the VW museum
in Germany
they are going to be posted on my web site in the next day or so I will
post when they are up.
Bob Donalds
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